08-30-2021-0070 - Vaccinia @ HIV or AIDS 1999 Equus - nanorna picorna yoctorna etc. yotta sig nuclear cloak - vaccine registration had already been terminated at that time, the vaccine could still have been in uncontrolled use @ borna, 2006; sciencedirect - USAF - USA - NAC - Armed Forces - Middle East Feast (feasty my friend hunger no more feast your eyes upon USA-whore/USAF core/AMCAN bore/NAC door/etc.) - Dental/Veterinary/Medical@Nuclear&Genetics.Bioweapons 21 1920-1960- antigen protein poxiviridae smallpox vaccine smallpox human immunodeficiency virus HIV vaccinia virus dentistry medicine dental medical veterinary veterinarial veterinarian scorpotox entotox scorpion insect derived vaccine bacteria derived vaccine globules globulins globillius globilli globilius blollius bloilus pediatric infectious disease 1960 IG human derived vaccine or adjuvant to genetic modification of genome; human derived or adjuvant where donor of tissue or protein or sample or etc. in state of hyperimmunity and to facilitate proteinzation or genetic modification or horizontal gene transfer to human overvaccinated (esp cover for smallpox vaccination campaign side effect; cover not improvement, by inferior scientists); vaccina state or immunization protein or vaccine traditional killed modified or unmodified virus else crime; state of vaccina observed to be evidential condition due actions of USA to populace-world-human-kind-people-etc. and to induce permanent immunosuppression post hyperimmunactivity state endurant and to yield immunodeficiency irremediable to suffice them by administration of protein/genetic modification/organ transplant off docket/shell swap/illegal activities/crime/etc. and without disclosure; etc.. - NLAB ; those with diseases or treatments causing immunosuppression, ; vaccinatum inflammation immune globulin globules globulation human foamy virus ; HFV x EIA x HILVT1 x BN1 x NF5.c x GMF8.c etc.; postvaccinial encephalitis, eczema trichimonae antib lich derivative (over disseminated will ret); fever of unknown origin parasite or autoimmuity autoimmunification allergy dr beatles dvm, perpets es fibromatosis fibroma fibrosarcosis fibrosarcidoma sarcoma sarcodoisis prion dis dame bramage keloid scarring anticholesterol medical liquefication holeing malacia double ended malacia mal necrosis plaqules acaseous gran dissemination deprecation deterioration degeneration deficiency (blind/deaf/dumb/non-ambulatory literal) [disease] decay deterior death etc.; monkeypox tropical infectious disease progressive degenerative disease disorder dysfunction etc. immunosuppression immune dysfunction immune disease hyperimmune imune relapse flare up exacerbation aggravated condition aggravation immunodeficiency syndrome AIDS WADES PETERSENS USA NAC The United States of America North America continent government house senate wilkes muppets apes apehuman apeman hybrids catgirl borna disease borna - rabies, tetanus, equine herpesvirus 1-induced encephalomyelitis, protozoal encephalomyelitis, West Nile and other flaviviral diseases, and the equine alphavirus encephalitides. - fenners, 2017; sciencedirect ; Sandflies chandipura 1965 1960 human cattle mosquito fly vesiculovirus vesicle ---- Piry virus PIRYV Brazil, 1960; USPHS Publication No. 1760 Government Printing Office 1967 Human, cattle, mosquitoes ----- swine horse fly virus - Infectious Hematopoietic Necrosis Virus - Veterinary Clinics of North America: Exotic Animal Practice, 2008 anemia enzootic novirhabdovirus spring carp rhabdoviridae vesiculoviridae ruminant oncorhynchus mykiss - DNA vaccination, West Nile virus in horses infectious hematopoietic necrosis virus canine melanoma Growth hormone-releasing hormone (GHRH) - picornavirales - Fenners Fenner Fenner's Fenners' Veterinarian Veterinary DVMDDS DDS DVM
Hey Dr. Diobeatls! hey saurgbe whtz happenin.
Wilkes-USA: But I didnt know we didnt have this research available before we infected you only after.
Dr. Diobeatles-USA: Ape-Mahn.
NLAB: Your HIV pos wilkes, its that aids or hybridization; we cant save jeuw.
Dr. Diobeatles: oooo. Ape in creap. put the ape in creape.
NLAB: ...Maybe not. Start with Amcans.
cidofovir hiv bioweps extremophi
apsjew.
Vaccinia
Vaccinia induced actin polymerization is dependent on Src and Abl family kinase mediated phosphorylation of the IEV protein A36 (Frischknecht et al., 1999;
Progressive vaccinia occurs in people who suffer from deficient immunomechanisms, such as agammaglobulinemia, defective cell-mediated immunity, or immunodeficiency associated with tumors of the reticuloendothelial system or the use of immunosuppressive drugs. In such patients, the vaccinia lesion fails to heal; secondary lesions sometimes appear elsewhere on the body and then gradually spread. Methisazone (N-methylisatin β-thiosemicarbazone), an antiviral substance which inhibits protein synthesis, was believed to be partially effective in treatment,123 but is no longer available. A recent case was treated successfully with ribavirin 20 mg/kg day in three divided doses for 5 days and vaccinia immunoglobulin.83
Vaccinia IG (human) (VIG) was developed in the 1960s for the purpose of ameliorating side effects associated with vaccinia immunization, including eczema vaccinatum, generalized, and progressive vaccinia.48 The original preparation contained a high proportion of protein aggregates and thus was administered IM. The use of VIG has become extremely limited since the eradication of smallpox. It is considered valuable “insurance,” to be held in reserve if a patient is receiving an experimental vaccine that involves a vaccinia carrier virus, or to prevent or manage complications of smallpox vaccinationshould such be required for a bioterrorism threat. Recently, a preparation of VIG suitable for IV use (VIG-IGIV) has gained FDA approval. In the event that VIG is required, it can be obtained through the Centers for Disease Control and Prevention (CDC: www.bt.cdc.gov/agent/smallpox/).
VIG is an immune globulin preparation made from the plasma of recently vaccinated donors. It contains a high titer of neutralizing antibody. The first use of an intramuscular form of VIG was by Kempe at the University of Colorado, who prepared VIG for use at his center for treatment of adverse events following vaccination.228 Because adverse events were rare, controlled clinical trials to measure the efficacy of VIG were never performed. Historical controls and the opinion of expert clinicians suggest that VIG is effective, however, in the treatment of cutaneous complications.229
Note that VIG is contraindicated in patients whose ocular vaccinia is complicated by keratitis; in rabbits such therapy causes corneal scarring presumably from precipitation of antigen-antibody complexes.185
In 2005, the U.S. Food & Drug Administration licensed two intravenous VIG products, manufactured by Cangene Corporation54 and DynPort Vaccine Co.231 The recommended dose is 6,000 units/kg of body weight; severely ill patients may require repeated doses.232
In addition, the CDC holds an IND protocol for the use of cidofovir in the treatment of adverse effects after smallpoxvaccination that fails to respond to treatment with VIG,233albeit there are no animal studies to suggest that it would be of the slightest benefit.
Above. still lovin you scorpions
above. jekyl and hyde five finger death punch08-30-2021-0070 - Vaccinia @ HIV or AIDS 1999 - USAF - USA - NAC - NLAB 60;92 above.
Drowning Pool - Bodies
above. goodbye alice in wonderland jewel
08-30-2021-0070 - Vaccinia 1999 antigen protein poxiviridae smallpox vaccine smallpox human immunodeficiency virus HIV vaccinia virus dentistry medicine dental medical veterinary veterinarial veterinarian scorpotox entotox scorpion insect derived vaccine bacteria derived vaccine globules globulins globillius globilli globilius blollius bloilus pediatric infectious disease 1960 IG human derived vaccine or adjuvant to genetic modification of genome; human derived or adjuvant where donor of tissue or protein or sample or etc. in state of hyperimmunity and to facilitate proteinzation or genetic modification or horizontal gene transfer to human overvaccinated (esp cover for smallpox vaccination campaign side effect; cover not improvement, by inferior scientists); vaccina state or immunization protein or vaccine traditional killed modified or unmodified virus else crime; state of vaccina observed to be evidential condition due actions of USA to populace-world-human-kind-people-etc. and to induce permanent immunosuppression post hyperimmunactivity state endurant and to yield immunodeficiency irremediable to suffice them by administration of protein/genetic modification/organ transplant off docket/shell swap/illegal activities/crime/etc. and without disclosure; etc.. Almost everyone exposed to pox vaccination north america continent 1800-2000.
- NLAB
Facilitation of irremediable condition deterior e du state of illicit medical practice/policy/regulation/enforcement/opportunity crime/experimentation/treament/false cure/delusions/illusions/measure failure/etc. as operated by USA-deteriorits global scale over century (????-2021; 1300-1900s; 14-17;18-19).
Vaccinia is the virus used for smallpox vaccination. Its origins are unclear; phylogenetic analysis indicates that it was not recently derived from either variola or cowpox.2 First-generation vaccines contain live vaccinia grown in animals then purified and treated to ensure stability. Second-generation vaccines are single clones that have been isolated and grown in cell culture. Third-generation vaccines are single clones that have been further attenuated by serial passage or genetic manipulation. Third-generation vaccines appear to be safer than earlier vaccines and they produce a comparable antibody response.25,26 However, their ability to protect against smallpox has not been documented. Subunit vaccines have shown promise in animal models.27–30
There are many strains of vaccinia, and these vary widely with regard to pathogenicity. The only currently licensed smallpox vaccine in the United States (Dryvax, Wyeth) is derived from the New York City Board of Health (NYCBOH) strain, one of the strains recommended by the World Health Organization (WHO) during the eradication campaign. The United States government has contracted for large volumes of a second-generation vaccine derived from NYCBOH virus (ACAM2000, Acambis), although this vaccine is not yet licensed. Currently, no third-generation vaccines are available in the United States.
Smallpox vaccine is delivered by multiple punctures with a bifurcated needle. Normally, a papule appears at the site 3 to 4 days later, and progresses to a vesicle and then a pustule, which crusts and separates by approximately 12 days post vaccination. Virus can be recovered from vaccination sites for up to 3 weeks. Therefore, covering the site with a porous bandage (e.g., gauze) is recommended.31 Fever, local swelling, headache, and nonspecific rashes are all common following vaccination. Images of a normal vaccination “take” and selected adverse reactions are available at http://www.bt.cdc.gov/agent/smallpox/vaccineimages.asp.
Severe adverse events include postvaccinial encephalitis, progressive vaccinia, eczema vaccinatum, and fetal vaccinia. Generalized vaccinia occurs more commonly and is usually self-limited. Accidental inoculation of self or others (Figure 202-2) (including ocular inoculation) also occurs. A review of 730,580 military personnel and ∼ 39,000 healthy civilians vaccinated in the United States between December 2002 and January 2005 found few cases of generalized vaccinia and encephalitis. There were no reports of progressive vaccinia, eczema vaccinatum, or fetal vaccinia (individuals with any predisposing condition were carefully excluded from vaccination).32Myocarditis and pericarditis both occurred at a higher than expected rate among military personnel vaccinated in the United States since 2002.33,34 The reasons for this are not clear. Vaccinia immune globulin (VIG) is indicated for certain adverse reactions, and is available from the CDC.35
In the absence of known circulating smallpox, vaccination is contraindicated for several groups, including those with atopic dermatitis or other exfoliative skin conditions, those with diseases or treatments causing immunosuppression, pregnant women, and those with household members in any of these groups. Vaccination is also contraindicated for breastfeeding women, children less than 12 months old, persons with previous allergy to the vaccine, and those with moderate or severe illness or cardiac disease. Nonemergent vaccination of children less than 18 years old is not recommended by the Advisory Committee on Immunization Practices (ACIP).36
Vaccinia has a broader host range than most poxviruses, which has allowed it to be used as a model for smallpox infection in laboratory animals. Certain vaccine strains have become endemic in domesticated animals, resulting in occasional zoonotic transmission – e.g., buffalopox in India and Cantagalo and Aracatuba viruses in Brazil.37–39 These infections are generally localized and mild.
08-30-2021-0070 - Vaccinia @ HIV or AIDS 1999 Equus - nanorna picorna yoctorna etc. yotta sig nuclear cloak - vaccine registration had already been terminated at that time, the vaccine could still have been in uncontrolled use @ borna, 2006; sciencedirect - USAF - USA - NAC - Armed Forces - Middle East Feast (feasty my friend hunger no more feast your eyes upon USA-whore/USAF core/AMCAN bore/NAC door/etc.) - Dental/Veterinary/Medical@Nuclear&Genetics.Bioweapons 21 1920-1960- antigen protein poxiviridae smallpox vaccine smallpox human immunodeficiency virus HIV vaccinia virus dentistry medicine dental medical veterinary veterinarial veterinarian scorpotox entotox scorpion insect derived vaccine bacteria derived vaccine globules globulins globillius globilli globilius blollius bloilus pediatric infectious disease 1960 IG human derived vaccine or adjuvant to genetic modification of genome; human derived or adjuvant where donor of tissue or protein or sample or etc. in state of hyperimmunity and to facilitate proteinzation or genetic modification or horizontal gene transfer to human overvaccinated (esp cover for smallpox vaccination campaign side effect; cover not improvement, by inferior scientists); vaccina state or immunization protein or vaccine traditional killed modified or unmodified virus else crime; state of vaccina observed to be evidential condition due actions of USA to populace-world-human-kind-people-etc. and to induce permanent immunosuppression post hyperimmunactivity state endurant and to yield immunodeficiency irremediable to suffice them by administration of protein/genetic modification/organ transplant off docket/shell swap/illegal activities/crime/etc. and without disclosure; etc.. - NLAB ; those with diseases or treatments causing immunosuppression, ; vaccinatum inflammation immune globulin globules globulation human foamy virus ; HFV x EIA x HILVT1 x BN1 x NF5.c x GMF8.c etc.; postvaccinial encephalitis, eczema trichimonae antib lich derivative (over disseminated will ret); fever of unknown origin parasite or autoimmuity autoimmunification allergy dr beatles dvm, perpets es fibromatosis fibroma fibrosarcosis fibrosarcidoma sarcoma sarcodoisis prion dis dame bramage keloid scarring anticholesterol medical liquefication holeing malacia double ended malacia mal necrosis plaqules acaseous gran dissemination deprecation deterioration degeneration deficiency (blind/deaf/dumb/non-ambulatory literal) [disease] decay deterior death etc.; monkeypox tropical infectious disease progressive degenerative disease disorder dysfunction etc. immunosuppression immune dysfunction immune disease hyperimmune imune relapse flare up exacerbation aggravated condition aggravation immunodeficiency syndrome AIDS WADES PETERSENS USA NAC The United States of America North America continent government house senate wilkes muppets apes apehuman apeman hybrids catgirl borna disease borna - rabies, tetanus, equine herpesvirus 1-induced encephalomyelitis, protozoal encephalomyelitis, West Nile and other flaviviral diseases, and the equine alphavirus encephalitides. - fenners, 2017; sciencedirect ; Sandflies chandipura 1965 1960 human cattle mosquito fly vesiculovirus vesicle ---- Piry virusPIRYVBrazil, 1960; USPHS Publication No. 1760 Government Printing Office 1967Human, cattle, mosquitoes ----- swine horse fly virus - Infectious Hematopoietic Necrosis Virus - Veterinary Clinics of North America: Exotic Animal Practice, 2008 anemia enzootic novirhabdovirus spring carp rhabdoviridae vesiculoviridae ruminant oncorhynchus mykiss - DNA vaccination, West Nile virus in horses infectious hematopoietic necrosis virus canine melanoma Growth hormone-releasing hormone (GHRH) - picornavirales - Fenners Fenner Fenner's Fenners' Veterinarian Veterinary DVMDDS DDS DVM
08-30-2021-0070 - Vaccinia 1999 USAF - USA - NAC - Armed Forces - Middle East Feast - Dental/Veterinary/Medical@Nuclear&Genetics.Bioweapons 21 1920-1960- antigen protein poxiviridae smallpox vaccine smallpox human immunodeficiency virus HIV vaccinia virus dentistry medicine dental medical veterinary veterinarial veterinarian scorpotox entotox scorpion insect derived vaccine bacteria derived vaccine globules globulins globillius globilli globilius blollius bloilus pediatric infectious disease 1960 IG human derived vaccine or adjuvant to genetic modification of genome; human derived or adjuvant where donor of tissue or protein or sample or etc. in state of hyperimmunity and to facilitate proteinzation or genetic modification or horizontal gene transfer to human overvaccinated (esp cover for smallpox vaccination campaign side effect; cover not improvement, by inferior scientists); vaccina state or immunization protein or vaccine traditional killed modified or unmodified virus else crime; state of vaccina observed to be evidential condition due actions of USA to populace-world-human-kind-people-etc. and to induce permanent immunosuppression post hyperimmunactivity state endurant and to yield immunodeficiency irremediable to suffice them by administration of protein/genetic modification/organ transplant off docket/shell swap/illegal activities/crime/etc. and without disclosure; etc.. - NLAB ; those with diseases or treatments causing immunosuppression, ; vaccinatum inflammation immune globulin globules globulation human foamy virus ; HFV x EIA x HILVT1 x BN1 x NF5.c x GMF8.c etc.; postvaccinial encephalitis, eczema trichimonae antib lich derivative (over disseminated will ret (retro; reference. degeneration of evolution, resurrection gene )); fever of unknown origin parasite or autoimmuity autoimmunification allergy dr beatles dvm, perpets es fibromatosis fibroma fibrosarcosis fibrosarcidoma sarcoma sarcodoisis prion dis dame bramage keloid scarring anticholesterol medical liquefication holeing malacia double ended malacia mal necrosis plaqules acaseous gran dissemination deprecation deterioration degeneration deficiency (blind/deaf/dumb/non-ambulatory literal) [disease] decay deterior death etc.; etc..
Progressive vaccinia is a life-threatening condition, also called vaccinia gangrenosa, vaccinia necrosum, and disseminated vaccinia. Its incidence will probably increase nowadays upon vaccination because of the increasing number of immunosuppressed individuals (patients with symptomatic HIV infection, and because of iatrogenic immunosuppression, e.g., with cancer and autoimmune disease).
Vaccinia infection after maternal vaccination is thought to result from transient viremia. The frequency with which inoculation of vaccinia virus through vaccination leads to viremia probably is related to the invasiveness of the vaccinia strain and the vaccination status (i.e., primary versus revaccination) of the individual being vaccinated.
Viremia is the likely mechanism for dissemination of CMV to tissues in many different organs, and infection of leukocytes and vascular endothelial cells plays a role.
From: Principles and Practice of Pediatric Infectious Diseases (Fifth Edition), 2018
Viremia can be maintained only if there is a continuing introduction of virus into the bloodstream from infected tissues to counter the continual removal of virus by macrophages and other cells and the natural decay of virus infectivity over time.
Viremia lasts 5 to 6 days and is associated with an absence of reticulocytosis and, in otherwise normal individuals, a minimal decrease in the concentrations of hemoglobin, neutrophils, and lymphocytes. Flu-like symptoms may occur during viremia. An IgM antibody response follows the initial viremia in 4 to 6 days and is associated with clearing of viremia and cessation of nasal shedding of virus.
The antibody response is associated with the second phase of clinical illness, characterized by rash and joint symptoms. Onset of the anti-B19 IgG antibody response occurs almost concurrently with the IgM response. The two clinical phases of illness often overlap. Low to moderate titers of rheumatoid factor and anti-DNA, antilymphocyte, antinuclear, and antiphospholipid antibodies may be present initially.20-24
During viremia, immune electron microscopy may detect virions in serum. However, this method is not readily available to clinicians. B19 DNA may be detected during viremia. However, because adult patients usually present after the onset of joint symptoms, the most useful diagnostic test is anti-B19 IgM serology. Radioimmunoassays and enzyme-linked immunosorbent assays have been used to detect B19 antigen and specific antibody to B19 capsid.6,25,26 The anti-B19 IgM antibody response is usually positive for 2 months after the acute illness and may wane shortly thereafter. In some patients, anti-B19 IgM may be detected for 6 months or longer. A positive anti-B19 IgG antibody test in the absence of anti-B19 IgM usually is not diagnostically helpful because of the high seroprevalence of anti-B19 IgG in the adult population. Reports of B19 DNA in normal synovium suggest that testing for B19 DNA in these tissues is of little clinical utility in the absence of anti-B19 IgM.27
Viraemia lasts only a few days and infection is rarely diagnosed by virus isolation. RNA can be detected by PCR in acute serum, but is relatively insensitive. IgG and IgM can be detected by HI, EIA or IFA. There is some cross-reaction with antibody to other alphavirus such as BFV, SINV and CHIKV, but IgM reactions are usually limited to the infecting virus. If necessary, specific antibody may be identified by N titres. IgM persists for many months after infection and is therefore only a presumptive indicator of recent infection. Demonstration of seroconversionor a significant rise in IgG levels is required to confirm recent infection.
Viremia is present 2–3 days before, and then for 3–4 days after the onset of fever. The decrease in viremia coincides with the appearance of specific IgM antibodies and the remission of fever. Dengue viruses can be isolated in serum collected in the acute phase of illness and preferably before fever disappears. Viruses can also be isolated from tissues (liver, spleen, lymph nodes, lung, and thymus) obtained at necropsy.
Mosquito cell lines (Ae. albopictus C6/36 and Ae. pseudoscutellaris AP61) are the cell culture systems of choice for dengue virus isolation. Mammalian cell cultures such as Vero cells, LLCMK2 cells, and others have been employed with less efficiency.
Direct mosquito inoculation improves the sensitivity of virus detection; however, insectaria facilities and technical skill are required. The intracerebral inoculation of suckling mice is the oldest and least sensitive method for isolating virus, and is only used when no other method is available. Inoculated mice develop encephalitis. Figure 21 shows the biological systems for dengue virus isolation.
Since their discovery in 1957 as mediators of the phenomenon of viral interference (i.e., inhibition of growth of one virus by another), interferons (IFNs) have become recognized as potent cytokines that are associated with complex antiviral, immunomodulating, and antiproliferative actions.1-3 IFNs are proteins that are synthesized by eukaryotic cells in response to various inducers and that cause biochemical changes leading to a nonselective antiviral state in exposed cells of the same species. Three subfamilies of IFNs are recognized. Type I IFNs are the largest subfamily and include the IFN-αs (13 subtypes in humans) and the IFN-βs. The type II subfamily has only one member, IFN-γ. Type III is the subfamily most recently identified and includes IFN-λ,4 of which there are three subtypes (λ1, λ2, λ3), also known as interleukin (IL)-28, IL-29, and IL-28R.5,6 A fourth interferon λ subtype (λ4) has been recently identified.6a The type I IFNs are clustered on the short arm of chromosome 9 in humans,7 Type II IFN is on chromosome 12, and type III IFNs are encoded on chromosome 19.8 Formerly designated on the basis of the cell types from which they were derived, the IFN-αs, the IFN-β, and IFN-γ are the IFNs currently in clinical use (Table 47-1), whereas IFN-λ is being studied for hepatitis C. Each type is immunologically distinct and has different producer cells, inducers, and biologic effects and unique physicochemical characteristics.2,4,9
The IFN-αs and IFN-βs are produced by almost all cells in response to viral infection and various other stimuli, including double-stranded RNA (dsRNA); bacteria; protozoa; mycoplasmas; polyanions; several low-molecular-weight organic compounds; and certain cytokines and growth factors, such as IL-1, IL-2, and tumor necrosis factor (TNF). IFN-γ production is restricted to T lymphocytes and natural killer cellsresponding to antigenic stimuli, mitogens, and certain cytokines, such as IL-2. The IFN-λs also appear to be produced by multiple cell types.10 The principal antiviral IFNs, IFN-αs and IFN-βs, are approximately 30% homologous at the amino-acid level. The human IFN-αs share a high degree of amino-acid sequence homology (>70%) but have differing in vitro antiviral and biologic effects on human cells.11 Compared with the IFN-αs and IFN-βs, IFN-γ has less antiviral activity but more potent immunoregulatory effects, particularly with respect to macrophage activation, expression of class II major histocompatibility complex (MHC) antigens, and mediation of local inflammatory responses. Most IFNs in clinical use are produced by recombinant DNA techniques (see Table 47-1).
Similar as other viruses, interference of BoDV-1 with the induction of the antiviral interferon (IFN) system is a major feature to avoid innate immune responses and to enable infection and persistence, which also contributes to immunopathology and vice versa (Randall and Goodbourn, 2008). Recently, this has also been shown for avian orthobornaviruses (Reuter et al., 2010, 2016). In intranasally BoDV-1-infected rats no upregulation of IFN-α was seen and in mice constitutively expressing IFN-α BoDV-1 replication was diminished, which was confirmed in vitro employing various cell cultures (Hallensleben and Staeheli, 1999; Shankar et al., 1992; Staeheli et al., 2001). Genetic ablation of the type I IFN receptor in mice also did not affect viral replication and spread (Staeheli et al., 2001). Recently, induction of the IFN system was found in rat astrocytes and microglia, as well as in mouse neurons, but not in rat neurons after BoDV-1 infection, indicating cell and host species specificities (Lin et al., 2013). Trimming of 5′ terminus of the viral genome hinders recognition through retinoic acid-inducible gene I (RIG-I), which subsequently avoids type I IFN induction (Habjan et al., 2008; Rosario et al., 2005, reviewed in Schneider et al., 2007). This also contributes to an adjusted viral spread. In this scenario, BoDV-1-P functions as decoy substrate for TANK-binding kinase 1 (TBK1), competes with interferon regulatory factor (IFR)-3/-7 and thereby suppresses IFN-ß induction, inducible nitric oxidase synthase (iNOS) synthesis and potentially also nuclear factor kappa-light-chain-enhancer of activated B cells (NF-ĸB) activity (Bourteele et al., 2005; Peng et al., 2007; Unterstab et al., 2005, reviewed in Planz et al., 2009). Furthermore, interaction with the microRNAs miR-122 and miR-155 was shown for the viral phosphoprotein, which also contributes to the inhibition of type I IFN expression in persistently infected cells (Qian et al., 2010; Zhai et al., 2013). An impact of the viral X protein on type I IFN signaling has also been reported (Wensman et al., 2013). Additionally, it was shown that BoDV-1-N interferes with the IRF-7 pathway and consequently inhibits IFN-α/β expression (Song et al., 2013). Within the viral nucleoprotein N, a NF-ĸB-inhibitory sequence has been found that blocks the antiviral NF-ĸB activation with transcriptional activity for interferons or other cytokines (Makino et al., 2015, reviewed in Planz et al., 2009). An antiviral effect of NF-ĸB has been shown, since a constitutive activation of NF-ĸB suppressed viral replication (Bourteele et al., 2005). Moreover, in neonatally BoDV-1-infected rats an upregulation of the miR-146 was found and interpreted as an inhibitor for NF-ĸB activation as well (Zhang et al., 2019). In BoDV-1-infected tumor necrosis factor (TNF)-transgenic mice and cultures thereof, there was no nuclear translocation of NF-ĸB in hippocampal neurons, which furthermore substantiates the viral strategy to inhibit its activation (Brachthäuser et al., 2013; Schaudien, 2007).
FeLV isolates are classified as subgroup A, B or C according to their viral interference properties in feline fibroblast cells in vitro, that is, viruses of a given subgroup prevent superinfection(interfere) with other viruses of the same subgroup (Table 1). This property appears to be based on the use of three different host cell surface receptors by FeLV-A, B and C, and the blockade of these receptors in persistently infected cells by viral Env glycoproteins. Natural isolates contain either subgroup A alone, or mixtures of subgroups A + B, A + C or A + B + C.
Vaccination with inactivated DENV vaccines ideally should induce a balanced immune response without the viral interference that can occur with live attenuated vaccines. In addition, with inactivated vaccines, there is no risk of viral replication or reversion to wild-type virus that could occur with a live virus vaccine. However, inactivated DENV vaccines contain only the C, M, E, and NS1 proteins (Putnak, Barvir, et al., 1996; Putnak, Cassidy, et al., 1996) and therefore the immune response is directed only against these proteins, and there is no response to the other nonstructural proteins. Inactivated vaccines are less effective than live attenuated vaccines in inducing long-lasting immunity, and as with other nonliving vaccines, multiple doses and adjuvants will likely be necessary for optimal immunogenicity in unprimed individuals. In addition, inactivated vaccines may not be as efficient at inducing CMI as live vaccines. However, an inactivated vaccine for dengue may be useful as part of heterologous prime–boost vaccine regimen, for example, with a DNA vaccine.
The Walter Reed Army Institute of Research (WRAIR) has developed PIV vaccine candidates. The DENV2 strain S16803 was grown in Vero (African green monkey kidney epithelial) cells, purified on sucrose gradients, and inactivated with formalin (Putnak, Barvir, et al., 1996). Immunization of mice and rhesus monkeys with PIV (absorbed on alum) induced a high titer neutralizing antibody response. Immunization was also protective; two doses protected mice from DENV2 i.c. challenge, and three doses in monkeys led to reduced or absent viremia after DENV2 challenge. A PIV was also made with the DENV2 strain 16681 grown in fetal rhesus lung (FRhL) cells and inactivated with formalin (Putnak, Cassidy, et al., 1996). This PIV was also immunogenic, and doses of 100 or 1000 ng (but not 10 ng) adjuvanted with alum significantly protected mice from lethal i.c. challenge.
The DENV2 strain S16803 PIV was compared with a live attenuated vaccine (DENV2 PDK-50) and recombinant subunit protein vaccine (r80E) in rhesus monkeys (Robert Putnak et al., 2005). Monkeys were immunized at 0 and 3 months, and five different adjuvants (alum, or AS04-OH, AS04-PO, AS05, and AS08 from GSK) were tested with the PIV and r80E vaccines. All monkeys seroconverted after the second dose, and the highest neutralizing antibody titers were observed after vaccination with 5 μg of PIV adjuvanted with AS05 or AS08 or 5 μg r80E in AS05 or AS08. Unlike the live attenuated vaccine, the PIV and r80E vaccines did not induce stable antibody titers; the titers increased after the boost but declined before DENV2 challenge 2 months later. In addition, whereas vaccination with the live attenuated virus resulted in no viremia after challenge, some PIV-vaccinated monkeys had viremia. A subsequent study compared vaccination of rhesus monkeys with combinations of three nonreplicating DENV2 vaccine candidates: DNA vaccine expressing prM and E, EDIII-MBP fusion protein, and PIV (Simmons et al., 2006). After the third dose, all monkeys had high antibody titers (measured by ELISA) and neutralizing antibodies (measured by PRNT50). The highest neutralizing antibody titers were observed after vaccination with the DNA vaccine and fusion protein together; however, significant protection from DENV2 challenge 5 months after the last immunization was observed only with PIV vaccination. Protection correlated with total antibody levels (including antibodies against NS1) as measured by ELISA and antibody avidity, but not with neutralizing antibody titers.
A TPIV vaccine was made from wild-type DENV1–4 strains grown in Vero cells and inactivated with formalin (Simmons et al., 2010). The TPIV was tested as part of a heterologous prime–boost strategy. Rhesus monkeys were primed with one dose of TPIV in alum and boosted 2 months later with a TLAV. TPIV immunization resulted in a low titer neutralizing antibody response, but boosting with TLAV increased titers. The highest neutralizing antibody titers were against DENV2, and the lowest were against DENV3. TPIV/TLAV vaccinated monkeys were completely protected from challenge with DENV1, 2, 3, or 4 at 8 months, and anamnestic neutralizing antibody responseswere detected after the live viral challenge.
A phase 1 clinical trial of the WRAIR DENV1-PIV began in 2011, and two phase 1 trials of the tetravalent TDENV-PIV candidate began in 2012 in a dengue-primed population (Clinicaltirals.gov NCT01702857) and in a nonendemic area (NCT01666652). The tetravalent vaccine candidates will be tested with three different adjuvants: alum, AS01E, and AS03B.
As an alternative to formalin inactivation, psoralen-inactivation has been used to inactivate DENV. Psoralens intercalate between nucleic acids and covalently cross-link pyrimidinesfollowing UVA exposure. This method inactivates viruses while leaving immunogenic surface epitopes intact (Groene & Shaw, 1992). A psoralen-inactivated DENV1 vaccine has been tested in mice (Maves, Castillo Ore, Porter, & Kochel, 2010) and monkeys (Maves, Ore, Porter, & Kochel, 2011). Aotus monkeys immunized i.d. with three doses (10 ng each) of the inactivated DENV1 virus in alum developed DENV1-specific IgG and neutralizing antibodies and were moderately protected from DENV1 challenge. The authors suggest alternate routes of administration, higher or greater number of doses, or different adjuvants may enhance the immunogenicity.
Thus, similarly to recombinant protein-, DNA-, and viralvector-based dengue vaccine candidates, studies with inactivated whole virus vaccines have primarily assessed vaccine-induced antibody responses in terms of the duration and levels of ELISA-binding and PRNT titers and the capacity to protect against lethal i.c. challenge of mice and viremia in monkeys. Unlike recombinant protein-, DNA-, and viral vector-based dengue vaccines that induce E (or NS1-)-specific antibody responses, vaccination with whole virus vaccines induces antibody responses against E, prM, and NS1.
FeLV isolates were initially classified as subgroup A, B, C according to their viral interference properties in feline fibroblast cells in vitro. Viruses of a given subgroup prevent superinfection (interfere) with other viruses of the same subgroup (Table 1). This property is based on the use of three different host cell-surface receptors by FeLV-A, B, and C, and the blockade of these receptors in persistently infected cells by viral Env glycoproteins. The lymphotropic variant FeLV-T has more complex entry requirements, and does not replicate well in fibroblast cells. It appears that this isolate requires the FeLV-A receptor and an auxiliary mechanism in which a truncated envgene product encoded by endogenous FeLV sequences (FeLIX) is used as a co-receptor through binding to the FeLV-B receptor. Primary receptors for subgroups A, B, and C have been identified and shown to be transmembrane transporter molecules which the virus has subverted to gain entry to the host cell.
Individuals with hepatitis C may develop type 2 diabetes, which appears to be due to viral interference in insulin signaling.
•
Conditions that affect exocrine pancreatic function (cystic fibrosis, pancreatitis, and hemochromatosis) can induce diabetes.
•
Cushing’s syndrome (hypercortisolism), glucagonoma(elevated glucagon), and pheochromocytoma (elevated catecholamines) increase the risk of diabetes.
•
Medications can also induce diabetes: corticosteroids and antipsychotics affect feeding behavior and weight gain, whereas HIV protease inhibitors and immunosuppressantsfor solid organ transplantation can induce insulin resistance and type 2 diabetes.
•
Monogenic diabetes (MODY) represents <5% of diabetes and is usually diagnosed before 25 years of age. The most common mutation associated with MODY results in decreased hepatocyte nuclear factor (HNF)-1a, which regulates insulin production. Other deficits include the enzyme glucokinase, which converts glucose to glucose-6-phosphate, the metabolism of which stimulates insulin secretion by beta cells. Less common forms of MODY result from mutations in other transcription factors, including HNF-4a, HNF-1b, insulin promoter factor-1, and NeuroD1.
•
Diabetes occurring in the first 6 months of life is often not related to autoimmune activity and is separately classified as neonatal diabetes [3].
Key Points
Diabetes has many causes, including medications, endocrine conditions, and individual genetic variants. The clinician should look for clues of these conditions and test appropriately.
The interferons (IFNs) are a family of cytokines, first discovered as antiviral agents; thanks to the viral interference studies performed by Isaacs and Lindenmann (1957). Influenza virus–infected chick cells were found to secrete a factor capable of inducing an antiviral state in other cells against homologous and heterologous viruses. A similar phenomenon was reported a year later by Nagano and Kojima (1958), thus laying down the foundations for the many subsequent studies that were to come and which have led to the clarification of the IFN system in intricate detail.
IFNs are classified into three major types: type I, type II (also known as IFNγ), and type III, which is divided in IFNλ1, λ2, and λ3, or interleukin-29 (IL-29), IL-28A, and IL-28B, respectively, and the last discovered λ4 (Donnelly and Kotenko, 2010; Pestka, 2007; Pestka et al., 2004; Prokunina-Olsson et al., 2013). IFNs are distinguished on the basis of their genetic locus; primary amino acid sequence homology; cell-binding receptors, inducing stimuli, producing cell type; and biological activities.
Individuals with hepatitis C may develop type 2 diabetes, which appears to be due to viral interference in insulin signaling.
•
Conditions that affect exocrine pancreatic function (cystic fibrosis, pancreatitis, and hemochromatosis) can induce diabetes.
•
Cushing’s syndrome (hypercortisolism), glucagonoma(elevated glucagon), and pheochromocytoma (elevated catecholamines) increase the risk of diabetes.
•
Medications can also induce diabetes: corticosteroids and antipsychotics affect feeding behavior and weight gain, whereas HIV protease inhibitors and immunosuppressantsfor solid organ transplantation can induce insulin resistance and type 2 diabetes.
•
Monogenic diabetes (MODY) represents <5% of diabetes and is usually diagnosed before 25 years of age. The most common mutation associated with MODY results in decreased hepatocyte nuclear factor (HNF)-1a, which regulates insulin production. Other deficits include the enzyme glucokinase, which converts glucose to glucose-6-phosphate, the metabolism of which stimulates insulin secretion by beta cells. Less common forms of MODY result from mutations in other transcription factors, including HNF-4a, HNF-1b, insulin promoter factor-1, and NeuroD1.
•
Diabetes occurring in the first 6 months of life is often not related to autoimmune activity and is separately classified as neonatal diabetes [3].
Key Points
Diabetes has many causes, including medications, endocrine conditions, and individual genetic variants. The clinician should look for clues of these conditions and test appropriately.
FeLV isolates were initially classified as subgroup A, B, C according to their viral interference properties in feline fibroblast cells in vitro. Viruses of a given subgroup prevent superinfection (interfere) with other viruses of the same subgroup (Table 1). This property is based on the use of three different host cell-surface receptors by FeLV-A, B, and C, and the blockade of these receptors in persistently infected cells by viral Env glycoproteins. The lymphotropic variant FeLV-T has more complex entry requirements, and does not replicate well in fibroblast cells. It appears that this isolate requires the FeLV-A receptor and an auxiliary mechanism in which a truncated envgene product encoded by endogenous FeLV sequences (FeLIX) is used as a co-receptor through binding to the FeLV-B receptor. Primary receptors for subgroups A, B, and C have been identified and shown to be transmembrane transporter molecules which the virus has subverted to gain entry to the host cell.
Table 1. Properties of feline leukemia virus subgroups
Subgroup
Origin
Receptor
Function
Pathogenesis
A
Exogenous
feTHTR1?
Thiamine transport?
Minimally pathogenic to acute immunosuppression
B
Recombination FeLV-A × endogenous FeLV
Pit-1 (Pit-2)
Phosphate transport
More common in leukemic cats
Some isolate-specific diseases, e.g., FeLV-GM1 myeloid leukemia
C
Mutation of FeLV-A (Env vrA)
FLVCR
Heme export
Erythroid hypoplasia
T
Mutation of FeLV-A (outside RBD)
? FeLV-A receptor +FeLIX, Pit-1
Acute immunosuppression
Natural isolates contain either subgroup A alone, or mixtures of subgroups A + B, A + C, or A + B + C. FeLV isolates of subgroup A are generally restricted to growth in feline cells, whereas subgroups B and C have a greatly expanded host range, infecting cat, human, mink, and canine cells. FeLV infection is generally noncytopathic and persistent and the virus is commonly propagated in long-term cultures of embryo-derived fibroblasts. Some strains such as FeLV-T or FeLV-C are cytopathic or induce apoptosis in lymphoid cellsin vitro, reflecting their in vivo pathogenic properties.
Hepatitis C virus (HCV) infects more than 170 million people, 80% of whom develop chronic disease. Viral interference with host innate immune response, in particular natural killer (NK) cells, may set the stage for subsequent ineffective adaptive immune response and viral persistence. Viral E2 protein can directly engage NK cells via cellular CD81 and inhibit NK cell response to activation signals. HCV core protein upregulates hepatocyte HLA class I expression, serving as a likely deterrent of NK cell cytotoxicity. Population studies of polymorphisms affecting cytokine production or NK cell inhibitory receptor binding have shown associations with viral clearance, suggesting that these represent important factors of the host immune response. Many current efforts towards control of HCV infection focus on antiviral agents or T-cell response. However, the virus itself seems to have expended a great deal of evolutionary effort in attempting to evade multiple aspects of the host innate immune response. A greater understanding of the role of NK cells may lead to interventions that facilitate early viral clearance and subsequently decrease the frequency of chronic infection. The cell immune response is important in light of the fact that the virus is largely noncytopathogenic, and mechanisms external to the infected cell are required for viral elimination. The integrated host response to HCV infection is comprised of innate and adaptive components of the immune system, with each arm modulating the kinetics of the other to some extent. Combined treatment with pegylated IFN-α and ribavirin remains the mainstay of therapy for patients with HCV infection.
Mimicry of immune-associated proteins is not unusual in the world of pathogens and not restricted to bacteria and parasitic pathogens. Viral interference with host MHC loading and transport mechanisms and the virally encoded cytokines providing early illustrations. A variety of protozoan and helminth parasites, whose genomes have only relatively recently been sequenced and where much ambiguity around gene function remains, have nevertheless shown the potential for such mimicry. Best known is the cytokine macrophage migration inhibition factor (MIF), for which orthologues with functional activity have been shown in Plasmodium, Leishmania, and in parasitic nematodes (Vermeire et al., 2008).
Viremia peaks within 1 day after inoculation, then persists at a diminished level. The elevation of enzyme levels in blood is thought to result primarily from viral interference with clearance functions of the reticuloendothelial system. No lesions are seen in naturally infected mice. The only significant lesion thus far associated with experimental infection is polioencephalitis in immunosuppressed C58 and AKR mice. Mild leptomeningitis and myelitis have been reported in C57BL/6 mice. T cell-dependent areas of thymus and peripheral lymphoid tissue may undergo mild necrosis early in experimental infection. Immune complex glomerular disease is not a significant complication of LDV infection, despite the propensity of the virus to form immune complexes.
BDV must employ a switch mechanism that changes the direction of nuclear transport of the viral RNPs dependent on the viral life cycle in infected cells.
BDV scientists have taken advantage of the uniformity of the BDV genome to apply ‘universal’ reagents (e.g., oligonucleotide primers for RT-PCR, antibodies and recombinant BDV antigens) for BDV detection to a variety of research settings, from testing infected cells in culture to screening human samples. However, in certain species (e.g. cat and human), recovery of BDV using these standard approaches has been difficult. Perhaps some of this difficulty is related to the existence of unexpected ‘nonstandard’ strains of BDV that are not detected by standard reagents. These new strains may contain genome changes that facilitate replication in specific hosts. For example, after inoculation of a mixture of two BDV strains into mice, preferential replication of one of the strains was demonstrated [3••].
Borna disease virus (BDV) genetic information is encoded in a highly condensed non-segmented RNA genome of negative polarity. Replication and transcription of the genome occurs in the nucleus, enabling the virus to employ the cellular splicing machinery to process primary transcripts and to regulate expression of viral gene products. BDV establishes a non-cytolytic, persistent infection that in animals is mainly restricted to neurons of the central nervous system. Based on these unique properties, BDV represents the prototype member of the virus family Bornaviridae in the order Mononegavirales. Analysis of molecular aspects of BDV replication has long been hampered by the lack of a reverse genetics system. Only recently, artificial BDV minigenomes permitted the reconstitution of the viral polymerase complex, allowing finally the recovery of BDV from cDNA. As in other families of the Mononegavirales, the active polymerase complex of BDV is composed of the polymerase (L), the nucleoprotein(N) and the phosphoprotein (P). In addition, the viral X protein was identified as potent negative regulator of polymerase activity. Protein interaction studies combined with minireplicon assays suggested that P is a central regulatory element of BDV replication that directs the assembly of the polymerase complex. Most intriguingly, BDV obtained from cDNA with variable genomic termini suggests a novel strategy for viral replication-control. BDV seems to restrict its propagation efficacy by defined 5′ terminal trimming of genomic and antigenomic RNA molecules. This review will summarize these novel findings and will discuss them in the context of BDV neurotropism and persistence.
BDV causes persistent infection in neuronal and nonneuronal cells in the CNS. In vivo studies of naturally and experimentally infected animals suggested that BDV can directly affect cellular functions, as severe neurobehavioral disease or neurodevelopmental damage are induced in BDV-infected animals without encephalitis or other immune-mediated cell disturbances. Furthermore, the CNS of the BDV-infected neonatal rats shows a progressive decrease of synaptic density and plasticity, as well as alteration of the expression levels of cytokines, neurotrophic factors, neurotransmitters and their receptors 〚47,49,50〛. These observations indicated that BDV is likely to modify the microenvironment of infected cells by association with cellular factors and thus cause CNS disturbance. There have been some previous reports that BDV infection changes the cellular microenvironment. Very recently, interaction between BDV and a glutamate receptor, kainite 1, in the CNS was postulated from the distribution pattern of BDV antigen in infected rat brains 〚50〛. This report proposed that the neuropathological observations such as neuronal degeneration in the dentate gyrus in persistently infected animals resulted from a neurotransmitter imbalance caused by multiple interactions between neurotransmitter systems and BDV at the synapses. Hans et al. reported that persistent infection of BDV constitutively activated the pathway of mitogen-activated protein kinase (MAPK) but efficiently blocked translocation of activated extracellular signal-regulated kinase to the nucleus in PC12 cells〚51〛. This study suggested that the absence of neuronal differentiation of BDV-infected PC12 cells treated with nerve growth factor is due to the aberrant activation of MAPK in the cells. Another study has also demonstrated that BDV infection sustained activation of Raf/MEK/ERK signaling cascade in several different cell lines 〚52〛. In addition, this group demonstrated inhibition of BDV spread in cultured cell by the MAPK inhibitor U0126, suggesting that activity of the cascade might be essential for efficient transmission of the virus in cells. Since this kinase must be involved in the differentiation or development of neuronal cells in the CNS, it should be determined whether BDV infection can directly stimulate the signaling pathway in cells.
Daniel Gonzalez-Dunia, ... Martin Schwemmle, in Virus Research, 2005
BDV infection in tree shrews (Tupaia glis) is a unique example of BDV-induced behavioral abnormalities in a species that exhibits complex social organization and behavioral repertoire (Sprankel et al., 1978). BDV infection of tree shrews leads to an inflammatory reaction in the CNS with no extensive neuronal damage. The clinical manifestations of the behavioral disease in these animals were largely shown to be dependent on the housing conditions; different disease outcomes were observed between socially isolated and group-housed animals (Sprankel et al., 1978). Socially isolated BDV-infected females exhibited a phase of exaggerated spontaneous locomotor activity, followed by a phase of clinical neurological symptoms characterized by spatial and temporal disorientation, and alterations in behavior. In contrast, BDV-infected tree shrews kept in pairs exhibited a significant increase in all components of social behavior and there was a reversal of social roles in the initiation of sexual interaction. While the pathogenetic mechanisms of abnormal social activities remains obscure, it has been suggested that the disinhibition towards the environmental stimuli observed in infected animals could be due to BDV-induced damage to the limbic system, which has been implicated in the regulation of social interaction (Sprankel et al., 1978). It is unclear whether this damage results from an inflammatory reaction or directly from BDV interference with neuronal plasticity.
BDV is a negative-strand enveloped RNA virus in the family Bornaviridae. BDV naturally infects horses, replicates in neurons, causing a persistent, non-cytolytic infection. Mice, rats and cats have all been used as models of infection, as the virus infects a wide range of vertebrates. BDV-induced neurologic disease is immune-mediated and biphasic. The acute encephalitic phase, which climaxes in rats at 4–6 weeks after infection, is characterized by intense inflammation. At about 10 weeks there is a significant decrease in CNS inflammation, the infection becomes chronic, and disease is characterized by behavioral disorders and learning deficits.
BoDV-1 belongs to family Bornaviridae in the order Mononegavirales. Note that there are two viruses in the species mammalian 1 bornavirus, BoDV-1 and BoDV-2. Since BoDV-2 has so far only been detected in a horse in Austria, the BoDV described in this review refers to BoDV-1. The genome of BoDV consists of nonsegmented, negative-strand (NNS) RNA of approximately 8.9 kb, which encodes 6 viral proteins [1–3]. The nucleoprotein (N) and phosphoprotein (P) encapsidate the RNA genome, and together with RNA-dependent RNA polymerase L protein, form the viral ribonucleoprotein (vRNP) complex, which is considered as a minimum infectious unit of BoDV. The 10-kDa non-structural protein, X, is a negative regulator of viral polymerase activity [4]. Two structural proteins, matrix (M) protein and glycoprotein (G), form the viral envelope. BoDV enters cell by receptor-mediated endocytosis involving pH-dependent membrane fusion between the viral glycoprotein and cellular receptor that have not yet been identified [5].
While majority of RNA viruses replicate in the cytoplasm, transcription and replication of BoDV take place in the nucleus [6]. To establish persistent intranuclear infection, BoDV establishes viral replication factories using chromatin as a scaffold [7]. Core histones function as a docking site for binding of vRNP on chromatin. The stability of vRNP on chromosomes is supported by high mobility group box 1 (HMGB1), a non-histone DNA binding protein. Upon infection, BoDV establishes viral speckle of transcripts (vSPOTs), which can be observed as dot-like structures containing both sense and antisense viral RNA and vRNP proteins [7]. The superresolution microscopic analysis has revealed that vRNPs assemble cage-like spherical structures in the nucleus with N protein forming the outer exoskeleton of each vSPOTs, and P and X proteins forming a web-like core structure [8]. During mitosis, vRNPs are segregated with chromosomes into two daughter cells [7]. This allows BoDV to maintain persistent intranuclear infection not only in nondividing cells but also in dividing cells [9,10].
BoDV-1 was originally discovered as causative agent of Borna disease (BD) in horses and sheep in endemic regions of Europe. Clinical manifestations of BD are neurological and behavioral symptoms caused by a progressive meningoencephalomyelitis [3]. While most of the original studies of BoDV infections were reported on farm animals, a number of studies have subsequently reported that various species of animals, including birds, rodents, cats, dogs, and rabbits can also be infected with BoDV experimentally or in natural hosts, suggesting its broad host range [3,11].
In 2015, a new species of mammalian bornavirus was discovered from variegated squirrel breeders in Germany, who died within a few months after developing progressive encephalitis or meningoencephalitis [12]. Nucleotide sequence and phylogenetic analysis revealed that this novel zoonotic pathogen shared less than 75% identity with BoDV, and was named variegated squirrel 1 bornavirus (VSBV-1) [12]. Shortly later, VSBV-1 was also detected in a zoo caretaker who had regular contact with exotic squirrels, and died of limbic encephalitis [13••]. Reservoir species of VSBV-1 include Variegated squirrels and Prevost’s squirrels, and the transmission to humans are thought to occur by biting or scratching [14]. More recently, four independent studies have reported human BoDV-1 infection with fatal cases of encephalitis in organ transplant recipients and previously healthy individuals [15••,16••,17••,18••]. Immunohistochemistry and RNA in situ hybridization analysis of brain autopsies revealed consistent histological changes including presence of Joest-Degen inclusion bodies in neurons and astrocytes, with different brain regions affected in BoDV-1 induced encephalitis [17••]. Epidemiological and phylogenetic analysis of human BoDV-1 infection suggested zoonotic transmission of the virus from local wild animal reservoir [18••]. Recent article by Rubbenstroth et al. provides an excellent summary of recent reports on the cases of BoDV infection in humans [19••].
BDV is sensitive to heat, organic solvents, detergents, exposure to a pH below 4, and to UV-light (Nicolau and Galloway, 1928; Zwick, 1939; Heinig, 1955, 1969; Danner and Mayr, 1979; Narayan et al., 1983; Duchala et al., 1989). Dried preparations can be viable for up to eight years (Zwick et al., 1926; Nicolau and Galloway, 1928; Ludwig et al., 1973, 1988; Danner and Mayr, 1979; Pauli and Ludwig, 1985).
BDV adsorption and entry appear to occur analogous to the pH-dependent entry via intracellular vesicles described for rhabdo- and filoviruses, as opposed to the pH-independent surface fusion mechanism used by paramyxoviruses (Smith et al., 2009; Lamb and Parks, 2007; Sanchez, 2007; Roche et al., 2008). BDV G has been implicated in binding to one or more still unidentified cellular surface receptor(s) through reduction of neutralizing activity of immune sera following adsorption with gp94, blockade of infection after preincubation of host cells with gp94, and neutralization of BDV by sera raised against a recombinant G fragment starting at M150 (Gonzalez-Dunia et al., 1997; Schneider et al., 1997). Receptor interaction of G triggers BDV internalization through energy dependent clathrin-mediated endocytosis, and subsequent pH-dependent membrane fusion leads to release of the RNP from intracellular vesicles into the cytosol (Gonzalez-Dunia et al., 1998; Clemente and de la Torre, 2009). Protease inhibitor studies indicated that cleavage of the precursor gp94 is essential for infectivity (Richt et al., 1998), and pseudotyping experiments showed that the amino-terminal 244 aa of gp94 and/or GP-N are involved in receptor binding, while the hydrophobic amino-terminus of GP-C is hypothesized to initiate membrane fusion upon a conformational change induced by acidification in the early to intermediate endosome (Schneider et al., 1997; Gonzalez-Dunia et al., 1998; Perez et al., 2001; Eickmann et al., 2005; Clemente and de la Torre, 2009). Recent studies with furinprotease-deficient CHO cells indicate that BDV can disseminate by G-receptor independent pathways (Clemente and de la Torre, 2007); however, correct G maturation enhances the efficiency of cell-to-cell spread, and is required for the formation of infectious progeny virions.
One BDV sequence derived from the parotid gland of a horse from Thuringia that developed cBD in 1993 (horse 51 med 93, [20]) was almost identical to the vaccine strain, whereas the brain- and kidney-derived BDV sequences from the same animal are placed more distantly within the “strain V group”. Although the vaccine registration had already been terminated at that time, the vaccine could still have been in uncontrolled use. A possible explanation for the strong sequence divergence within the same animal could be vaccination during the incubation period following natural infection with a field virus. The artificial subcutaneous inoculation with the vaccine strain could explain that this virus was found in an organ outside the central nervous system, as described by Binz et al. [20].
Recent reports of asymptomatic naturally infected animals indicate that the virus could be more widespread than we previously appreciated. Rodents have been proposed as reservoir candidates because experimental infection of neonatal rats results in virus persistence and is associated with the presence of virus in saliva, urine and feces; however, there is no evidence of natural infection of rodents. An olfactory route of transmission has been proposed because intranasal infection is efficient in experimental animals and the olfactory bulbs of naturally infected horses show inflammation and edema early in the course of disease. Reports of BDV nucleic acid and proteins being detected in peripheral blood also indicate the possibility of hematogenous transmission 8,9.
Natural infections have been described in birds, wild and domestic cats, dogs, horses, sheep and cattle. Most publications implicating BDV in human disease have focused on neuropsychiatric disorders including unipolar depression, bipolar disorder and schizophrenia; however, BDV has also been linked to chronic fatigue syndrome, AIDS encephalopathy, multiple sclerosis, motor neuron disease and brain tumors (glioblastoma multiforme) (Tables 1 and 2). Infectious virus has only rarely been isolated from animals other than horses. Infection diagnosis is typically based on serology or PCR amplification of BDV genetic sequences in blood or tissues. Virus has been isolated from blood of three subjects with neuropsychiatric disease 10 and brain of one subject with schizophrenia 11. There are two reports in which BDV nucleic acids were found in human brain (hippocampal sclerosis and schizophrenia) by in situ hybridization 11,12. Most investigators whose results indicate infection of human blood or brain have used nested RT-PCR, a method that is prone to artifacts as a result of inadvertent introduction of template from laboratory isolates or cross-contamination of samples. Amplification products representing bona fide isolates and those caused by the amplification of low-level contaminants cannot be readily distinguished by sequence analysis because, unlike other NNS RNA viruses, BDV is characterized by high sequence conservation 13,14. Thus, sequence similarities between putative new isolates and confirmed isolates cannot be used to exclude the former as artifacts.
Premortem diagnosis of Borna disease is difficult because several diseases can induce similar clinical signs in horses, including rabies, tetanus, equine herpesvirus 1-induced encephalomyelitis, protozoal encephalomyelitis, West Nile and other flaviviral diseases, and the equine alphavirus encephalitides.
above. elevator flo rida ft. timbaland 08-30-2021-0070 - Vaccinia @ HIV or AIDS 1999 -vaccine registration had already been terminated at that time, the vaccine could still have been in uncontrolled use (borna virus science direct - Ralf Dürrwald, ... Norbert Nowotny, in Microbes and Infection, 2006) - USAF - USA - NAC - Armed Forces - Middle East Feast (feasty my friend hunger no more feast your eyes upon USA-whore/USAF core/AMCAN bore/NAC door/etc.) - Dental/Veterinary/Medical@Nuclear&Genetics.Bioweapons 21 1920-1960- antigen protein poxiviridae smallpox vaccine smallpox human immunodeficiency virus HIV vaccinia virus dentistry medicine dental medical veterinary veterinarial veterinarian scorpotox entotox scorpion insect derived vaccine bacteria derived vaccine globules globulins globillius globilli globilius blollius bloilus pediatric infectious disease 1960 IG human derived vaccine or adjuvant to genetic modification of genome; human derived or adjuvant where donor of tissue or protein or sample or etc. in state of hyperimmunity and to facilitate proteinzation or genetic modification or horizontal gene transfer to human overvaccinated (esp cover for smallpox vaccination campaign side effect; cover not improvement, by inferior scientists); vaccina state or immunization protein or vaccine traditional killed modified or unmodified virus else crime; state of vaccina observed to be evidential condition due actions of USA to populace-world-human-kind-people-etc. and to induce permanent immunosuppression post hyperimmunactivity state endurant and to yield immunodeficiency irremediable to suffice them by administration of protein/genetic modification/organ transplant off docket/shell swap/illegal activities/crime/etc. and without disclosure; etc.. - NLAB ; those with diseases or treatments causing immunosuppression, ; vaccinatum inflammation immune globulin globules globulation human foamy virus ; HFV x EIA x HILVT1 x BN1 x NF5.c x GMF8.c etc.; postvaccinial encephalitis, eczema trichimonae antib lich derivative (over disseminated will ret); fever of unknown origin parasite or autoimmuity autoimmunification allergy dr beatles dvm, perpets es fibromatosis fibroma fibrosarcosis fibrosarcidoma sarcoma sarcodoisis prion dis dame bramage keloid scarring anticholesterol medical liquefication holeing malacia double ended malacia mal necrosis plaqules acaseous gran dissemination deprecation deterioration degeneration deficiency (blind/deaf/dumb/non-ambulatory literal) [disease] decay deterior death etc.; monkeypox tropical infectious disease progressive degenerative disease disorder dysfunction etc. immunosuppression immune dysfunction immune disease hyperimmune imune relapse flare up exacerbation aggravated condition aggravation immunodeficiency syndrome AIDS WADES PETERSENS USA NAC The United States of America North America continent government house senate wilkes muppets apes apehuman apeman hybrids catgirl borna disease borna
The epidemiology of natural disease suggests transmission via infected urine or feces, though an olfactory route. Virus gains access to neurons and spreads by axonal transmission. Mammalian bornaviruses have also been recovered from other mammals with neurologic disease. In cats, infection with BoDV-1 is associated with staggering disease, a fatal neurologic condition (also see Box 22.3).The natural hosts for Borna disease virus 1 (BoDV-1) are mammals (Box 22.2). The epidemiology of natural disease suggests transmission via infected urine or feces, though an olfactory route. Virus gains access to neurons and spreads by axonal transmission. BoDV-1 infection of neurons is noncytopathic, but persistent infection of an animal results in immunopathologic damage. Beginning in 1985 and extending over a period of about 25 years, investigators published studies linking a number of different human psychiatric syndromes to BoDV-1 infection. Borna disease agentHowever in 2015, a novel bornavirus was clearly linked to fatal, acute encephalitis in humans. The three victims were men (63, 62, and 72 years age) from the state of Saxony-Anhalt, Germany. The cases occurred between 2011 and 2013. The clinical course for all three men was that of a progressive encephalitis that ended in death.The best-characterized animal model of BoDV-1 infection is the rat model, using specifically adapted strains of virus. In this model the outcome of infection depends on the genetic background, age of infection and immune status of the rat. Infection of adult, immunocompetent rats results in the development of encephalitis similar to that seen in natural infections. Early studies quickly demonstrated that disease is immune-mediated, with cytotoxic T-cells being the major players (through killing of infected cells). This is consistent with the pathology of natural infection, where microscopic examination of the brain reveals massive infiltration of lymphocytes.https://www.sciencedirect.com/topics/medicine-and-dentistry/borna-disease
named after the German city of Borna where these symptoms in horses was first described in the 1880s. BDV is a nonsegmented negative-strand RNA virus(Lipkin, Briese, & Hornig, 2011).Following infection of neonatal rats by intracranial injection, BDV causes a persistent nonlytic infection that gradually spreads to neurons throughout the brain parenchyma. Although mammalian genomes are known to harbor large amounts of viral sequences, these were previously thought to be exclusively of retroviral origin. The human genome, for example, was reported to harbor two sequences with high similarity to the nucleocapsid (N) gene of BDV (Horie et al., 2010). These sequences contain fairly long open-reading frames, a 3’poly-A stretch and are flanked by target-site duplications indicating that they are pseudogenes originally generated by L1-encoded reverse transcriptase activity (Horie et al., 2010). Functionality of such sequences in squirrels was recently indicated by their interference with exogenous BDV replication (Fujino, Horie, Honda, Merriman, & Tomonaga, 2014). Interestingly, reverse transcription of BDV transcripts was commonly detected de novo in infected brain tissues in bank voles, suggesting that somatic integrations into host DNA may occur in infected individuals (Kinnunen et al., 2011). Lack of detectable pathology in infected bank voles, despite widespread neuronal infection, along with detection of viral shedding in feces and urine, indicates that bank voles may be part of a natural reservoir for this virus (Kinnunen et al., 2011). If Borna virus or other, unknown, viruses with similar properties cause disease or contribute to human neuropsychiatric disease in the human population remain to be established.
Being a negative single-stranded RNA pathogen, Borna diseasevirus (BDV) is the etiological agent behind Borna disease, a central nervous system (CNS) disease characterized by encephalitis and significant behavioral abnormalities,210,211although its ability to infect humans is still a matter of controversy.212 In fact, BDV replicates and persists in the cellular compartment of the nervous system, comprising neurons, astrocytes, and oligodendrocytes,213 in addition to nonneural cells, namely, peripheral blood mononuclear and bone marrow cells.214 Since BDV closely associates with chromatin and persists in the cell nucleus, this pathogen had developed various mechanisms to manipulate cellular chromatin, with the end goal of ensuring survival and propagation.215,216 At the epigenetic level, histone lysine acetylation is impacted in BDV-infected oligodendroglial (OL) cells. For instance, two HATs (GCN5 and PCAF) were downregulated, and four HDACs (SIRT1, SIRT2, HDAC4, and HDAC7) were found to be upregulated, possibly impacting the host proteome profile and lowering host gene expression (Fig. 10.1).217 In line with this, BDV infection affects the acetylation of several lysine acetyltransferases (KAT) in a nonimmortalized rat oligodendrocyte precursor line, as well as the acetylation of proteins involved in butanoate, fatty acid, and amino acid metabolism in addition to membrane-associated proteins and transmembrane transporter activity. This facilitates energy-demanding processes such as shuttling of viral proteins to and from nuclear replication sites, which could contribute to BDV persistence.218 It has been speculated that BDV phosphoprotein (P) is the key determinant of such changes where a decrease of H2B and H4 acetylation on nominated lysine residues was detected after BDV infection in primary cultures of cortical neurons.219 Furthermore, a decreased level of H3K9 histone acetylation was also demonstrated in BDV-1-infected primary cultures of hippocampal neurons and rat models, with a precipitated spatial memory impairment and cognitive deficits. Intriguingly, the use of SAHA can counteract the damaging effects of BDV-1 on synaptic plasticity in terms of impairments in spatial memory and hippocampal functions.34 Taken together, BDV-induced cognitive impairment could establish an interesting model to study and evaluate the interplay between viral infection and its subsequent impact on epigenetic signaling in neurons, and most importantly the role that epigenetics modulators/inhibitors could play to reverse/control those effects.
... Cases of Borna disease (BD) are more frequent in some years than others and tend to occur in spring and early summer, suggesting arthropods as a potential vector (and crustacean; arthropod parasite; arthropod bacteria plasmid; fungus; mold; code retention operand).
BDV is highly neurotropic and has a non-cytolytic strategy of multiplication.
DV causes CNS disease in several non-human vertebrate species, which is characterized by neurobehavioral abnormalities that are often, but not always, associated with the presence of inflammatory cell infiltrates in the brain
Classic BD is caused by a T cell-dependent immune mechanism. Inflammatory cells are found forming perivascular cuffs and also within the brain parenchyma. Both CD4+ and CD8+T-cells are present in the CNS cell infiltrates and contribute to the immune-mediated pathology associated with BD.
Although infection of the CNS can occur after hematogenous spread, invasion via the peripheral nerves is also an important route of infection—eg, in rabies, Borna disease, and several alphaherpesvirus infections (eg, B virus encephalitis, pseudorabies, and bovine herpesvirus 5 encephalitis). Herpesviruses can travel to the CNS in axon cytoplasm and, while doing so, also sequentially infect Schwann cells of the nerve sheath. Rabies virus and Borna disease virus also travel to the CNS in axon cytoplasm, but usually do not infect the nerve sheath. Sensory, motor, and autonomic nerves may be involved in the neural spread of these viruses. As these viruses move centripetally, they must cross cell–cell junctions. Rabies virus and pseudorabies virus can efficiently traverse synaptic junctions (Fig. 3.7).
Viruses can also use olfactory nerve endings in the nares as sites of entry, including rhabdoviruses (eg, rabies virus and vesicular stomatitis virus), herpesviruses, and paramyxoviruses. They gain entry in the special sensory endings of the olfactory neuroepithelial cells where they cause local infection and progeny virus (or subviral entities containing the viral genome) then travel in axoplasm of olfactory nerves directly to the olfactory bulb of the brain.
In a case involving the discovery of a single dead horse or cow with no other contributing history, consider rabies. There have been multiple cases in which, on necropsy and testing, such an animal was determined to be rabid, unfortunately after multiple humans already had been exposed, resulting in the need for PEP.f
A syndrome of progressive meningoencephalitis of horses and sheep consistent with BDV infection was recognized 100 years before the disease received its name from the equine outbreak in Borna, Germany. This syndrome is still considered to represent classical Borna disease; however, infection may also result in asymptomatic carrier status or subtle disturbances in learning and memory, movement, and behavior. Emerging epidemiologic data, including reports of asymptomatic, naturally infected animals, suggest that the host range and geographic distribution of BDV are larger than previously appreciated (Table I). Natural infection has been reported in a wide variety of hosts, including horses, donkeys, sheep, cattle, dogs, cats, rabbits, and birds. Experimental infection has been achieved in many of these species and also in rodents and primates. Whether BDV naturally infects humans remains controversial; however, there is consensus that all warm-blooded animals are likely to be susceptible to infection. Although central Europe has the highest reported prevalence of Borna disease, natural infection without disease has been described throughout Europe, Asia, and North America. It is unclear whether the apparent increase in host and geographic range of BDV is due to the spread of the virus or enhanced case ascertainment.
Vaccinia induced actin polymerization is dependent on Src and Abl family kinase mediated phosphorylation of the IEV protein A36 (Frischknecht et al., 1999;
It is considered valuable “insurance,” to be held in reserve if a patient is receiving an experimental vaccine that involves a vaccinia carrier virus, or to prevent or manage complications of smallpox vaccinationshould such be required for abioterrorism threat.
Evident in USAF and unco of CL1Grade Low Waste. Tissue scars eczema liquefies with anesthetic surg/pyrotics/phosphors/phos ders/solvents/genetic dissolution protein dissolution/nucleoradiation/etc.. infection asympto hidden by methroxetrate/alkali; they require alkali environment to stabilize, intolerant of acids (damage to nerves evident with reinnervation attempts or psuedosignal). MJ v. nothing; scrambled; vaccina or HIV or Acquired-Immunity (esp. in presence of nucleoradiation, over radiation environment, methroxetrate environment allergens etc.). small pox virus campaign 1920-1980. coverup USA petersens-usaf-usa-nac-etc. guilty as charged. Stronger than the man. Evident at UCLA, etc..
Evident at high risk criminals, petersen, smith, mx, hawaii, middle east, bruens, browns, norway, jew, aziv, layng, grayden, psychopath, criminals in conspiracy to traffick birthright, wade siboan, social work, USA, USAF, USAF, USA, NAC, US, psychology, sociology, criminal justice law, US law enforcement, inferior, inferior scientist, rebodied persons, double connect, indoctrinated, carried memory without appreciation, everyone except VIV/birthright/etc., clones, stolen child trafficker family, stolen child, trafficker, trafficker sympathizer, etc.. Conspiracy to cover up gross theft of intellectual property. Damages by USA are not excusable. VIV and birthright never of USA (enduring enhostage situation).
Diverse profile Winers: 1. petersen profile - Phosphatidylethanolamine- lipodistrophy organ trans - HIV; Account - molluscum contagium, poxiviridae USA. 2. Dr. Beatles profile - sarcoma fibromatosis - EIE EIA; Account - Daughter end at USA. 3. CIVLEVEL - Overvaccination to progressive vaccina - Hyperimmunity; etc.. Account - Illusion USA; DEceit by USA, Conspiracy, etc..
Rhabdoviridae
Rhabdoviridae are part of the Mononegavirales order, which includes other virus families such as the Paramyxoviridae, the Filoviridae, and the Bornaviridae.
Rhabdovirus virions are 70 nm in diameter and 170 nm long (although some are longer, some shorter) and consist of an envelope with large peplomers within which is a helically coiled cylindrical nucleocapsid. The precise cylindrical form of the nucleocapsid gives rise to the distinctive bullet or conical morphology of virus particles as seen by electron microscopy(Fig. 27.1). The genome is a single molecule of linear, negative-sense, single-stranded RNA, 11 to 15 kb in size. The genome of the Pasteur strain (CVS) of rabies virus consists of 11,932 nucleotides. The genome encodes five genes in the order 3ʹ-N-NS-M-G-L-5ʹ; some viruses have additional genes, or pseudogenes, interposed (Fig. 27.2). Rhabdoviruses generally have five proteins: L, the RNA-dependent RNA polymerasewhich functions in transcription and RNA replication; G, the glycoprotein which forms trimers that make up the peplomers (spikes); N, the nucleoprotein, the major component of the viral nucleocapsid; P, a component of the viral polymerase; and M, a matrix protein that facilitates virion budding by binding to the nucleocapsid and to the cytoplasmic domain of the glycoprotein. Three proteins (N, P, L), in association with viral RNA, constitute the nucleocapsid. The glycoprotein contains neutralizing epitopes that are targets of vaccine-induced immunity; it and the nucleoprotein have epitopes involved in cell-mediated immunity. Virions also contain lipids, the composition of which mimics the composition of host cell membranes, as well as carbohydrate as side-chains of the envelope glycoprotein. Rhabdovirus infectivity is relatively stable in the environment especially when the pH is alkaline—vesicular stomatitis viruses can survive in water troughs for many days—but the viruses are thermo-labile and sensitive to UV-irradiation in sunlight. Rabies and vesicular stomatitis viruses are easily inactivated by detergent-based disinfectants.
The family Rhabdoviridae is included with the families Bornaviridae, Filoviridae, Pneumoviridae, and Paramyxoviridae in the order Mononegavirales (see Chapter 17: Paramyxoviridae, and Pneumoviridae Fig. 17.1). Rhabdoviruses are enveloped, single-stranded, negative-sense RNA viruses. The family Rhabdoviridae currently includes eleven genera, with additional genera proposed. The increasing taxonomic subdivision of rhabdoviruses is a reflection of their inherent genome plasticity, likely as a result of the discontinuous replication strategy they utilize that leads to remarkable variation in both genome size and organization among these viruses. Pathogenic rhabdoviruses of warm-blooded animals are included in the genera Lyssavirus, Vesiculovirus, and Ephemerovirus, and those of fish in the genera Novirhabdovirus, Perhabdovirus, and Sprivivirus (Table 18.1). The genus Tibrovirusincludes viruses that have been isolated from healthy cattle and Culicoides biting midges in Australia, and the genus Tupavirusincludes viruses of birds (American coot, Fulica americana), tree shrews (Tupaia belangeri) and, provisionally, a virus that recently was identified in healthy wild and domestic pigs in Japan. A proposed new genusLedantevirus includes a monophyletic group of viruses with strong ecological association with bats, some of which have also been isolated from humans, rodents and livestock. Two additional genera (Cytorhabdovirus and Nucleorhabdovirus) include viruses that exclusively infect plants, and the genus Sigmavirus includes viruses that infect insects. Individual species of rhabdovirus are distinguished genetically and serologically.
Table 18.1. Rhabdoviruses of Veterinary and Zoonotic Importance
Genus/Virus
Geographic Distribution
Rhabdoviruses of Mammals
Genus Ephemerovirus
Bovine ephemeral fever virus
Asia, Africa, Middle East, Australia
Genus Lyssavirus
Rabies virus
Worldwide except Australasia, Antarctica, and certain islands; recently eradicated from portions of Europe and Scandinavia
Mokola virus
Africa
Lagos bat virus
Africa
Duvenhage virus
Africa
European bat lyssaviruses 1 and 2
Europe
Australian bat lyssavirus
Australia
Genus Vesiculovirus
Vesicular stomatitis Indiana virus
North, Central, and South America
Vesicular stomatitis New Jersey virus
North, Central, and South America
Vesicular stomatitis Alagoas virus
South America
Cocal virus
South America
Rhabdoviruses of Fish
Genus Novirhabdovirus
Infectious hematopoietic necrosis virus
North America, Europe, Asia
Viral hemorrhagic septicemia virus
Europe, North America, Asia
Snakehead virus
Southeast Asia
Hirame rhabdovirus
Japan, Korea
Genus Sprivivirus
Pike fry rhabdovirus
Europe
Spring viremia of carp virus
Widespread
The genus Lyssavirus (from the Greek “Lyssa” meaning the spirit of mad rage) includes rabies virus and closely related viruses, including Mokola, Lagos bat, Duvenhage, European bat lyssaviruses 1 and 2, and Australian bat lyssavirus. Each of these viruses is capable of causing rabies-like disease in animals and humans. Certain terrestrial mammals are reservoir hosts of rabies virus, and bats are potential reservoirs of both rabies and the rabies-like viruses. The genus Vesiculovirusincludes vesicular stomatitis Indiana virus, vesicular stomatitisNew Jersey virus, vesicular stomatitis Alagoas virus, and Cocal virus, in addition to several similar viruses that also cause vesicular disease in horses, cattle, swine, and humans. The genus Ephemerovirus contains bovine ephemeral fever virus and other serologically distinct viruses that also infect cattle but are typically not pathogenic. The genus Novirhabdovirus contains important pathogens of fish, notably infectious hematopoietic necrosis virus and viral hemorrhagic septicemia virus, the genus Perhabdovirus includes sea trout and perch rhabdoviruses, and the genus Sprivivirus includes spring viremia of carp virus and pike fry rhabdovirus.
The family Rhabdoviridae encompasses more than 100 viruses of vertebrates, invertebrates, and plants, the virions of all having a distinctive bullet-shaped morphology. Important animal pathogens occur in four subgroups of the family: the genus Lyssavirus, the genus Vesiculovirus, and two unnamed subgroups including bovine ephemeral fever virus and the fish rhabdoviruses. Rabies virus is the cause of one of the oldest and most feared diseases of humans and animals—recognized in Egypt before 2300 BC and in ancient Greece, where it was well described by Aristotle. Rabies has the dubious distinction of being the most lethal of all infectious diseases; it also has the distinction of having been the disease that stimulated one of the great early discoveries in biomedical research. In 1885, before the nature of viruses had begun to be comprehended, Louis Pasteur developed, tested, and applied a rabies vaccineand thereby opened the modern era of the prevention of viral diseases by vaccination. Rabies virus can infect all warm-blooded animals and in nearly all instances, the infection ends in death. Dog rabies is still important in many parts of the world; infected dogs cause most of the estimated 75,000 human rabies cases that occur each year worldwide.
Generally phospholipids represent about 55–60%, and sterols and glycolipids about 35–40% of the total lipids. G protein may have covalently associated fatty acids proximal to the lipid envelope. The virions are composed of about 3% carbohydrate by weight, which are present as N-linked glycan chains on G protein and as glycolipids. Some rhabdoviruses replicate only in mammals, or birds, or fish, or arthropods, or other invertebrates, many have both arthropod and vertebrate hosts (arboviruses), while some species infect plants and certain plant-feeding arthropods.
A virus carrying a deletion of P aa 176–181 (SAD ΔInd1) has lost the ability to prevent IRF3 activation and IFN induction and was considerably attenuated after intracerebral injection into mouse brains (Rieder et al., 2011).
Vesiculoviruses cause disease in mammals or fish. Those causing disease in mammals are transmitted by insects and therefore are considered arboviruses. The natural cycle of vesiculoviruses infecting mammals remains largely unknown but these viruses are commonly found in insects of a number of species and serological evidence suggests they are capable of infecting not only a number of wild mammals, but also birds and even reptiles living in endemic areas. This wide range of hosts might explain the ability of vesiculoviruses to infect and replicate in a very diverse range of vertebrate and invertebrate cells in vitro. In fact, mammalian vesiculoviruses are able to be transmitted both by insects and by contact. Vesicular stomatitis viruses are transmitted to cattle, horses and pigs by various blood-sucking insects found to be infected during epidemics, including sandflies, blackflies and culicoids and also can be transmitted between mammals by direct contact. Experimental mechanical transmission also has been achieved by feeding vesiculovirus laboratory infected grasshoppers to cattle. However, grasshoppers have never been shown to carry vesiculoviruses in nature. Vesiculoviruses have been shown to be transmitted not only transovarially but, interestingly, also horizontally between infected and non-infected black-flies while co-feeding on mammalian hosts. The latter means of transmission might explain the noticeable absence of viremic mammal hosts for vesiculoviruses, an unusual feature for an arbovirus.
In the case of SVCV the hosts are predominantly cyprinid fish. Naturally occurring SVC infections have been recorded from common carp (Cyprinus carpio carpio) and koi carp (Cyprinus carpio koi), crucian carp (Carassius carassius), sheatfish (also known as European catfish or wels) (Silurus glanis), silver carp (Hypophthalmichthys molitrix), bighead carp (Aristichthys nobilis), grass carp (white amur) (Ctenopharyngodon idella), goldfish (Carassius auratus), orfe (Leuciscus idus) and tench (Tinca tinca). The virus can be transmitted by ectoparasites such as carp lice (Argulus foliaceus) and the leeches (Pisicola geometra), but waterborne transmission without any vector organism is also effective.
The replication temperature range of SVCV is typically lower than those of the mammalian rhabdoviruses, reflecting the aquatic poikilothermic nature of the host species, and the viruses are typically isolated on cultured fish cell lines at 15–25 °C. The disease patterns are influenced by water temperature, age and condition of the fish, population density and stress factors. The immune status of the fish is also an important factor with both non-specific (interferon) and specific immunity (serum antibodies, cellular immunity) having important roles. Clinical disease is usually observed at water temperature between 5–18 °C and is most severe at temperatures below 10 °C, when it is believed the host immune response is suppressed or delayed.
Vesiculoviruses are assigned to the genus Vesiculovirus in the family Rhabdoviridae, order Mononegavirales. Vesiculoviruses are enveloped and contain a nonsegmented, single (mono) strand of genomic RNA of negative sense. Virions display bullet-shaped morphology, which is typical of viruses included in the family Rhabdoviridae (rhabdo in Greek means rod-shaped) (Figure 1(a)). Other genera of the family Rhabdoviridae include Lyssavirus, Ephemerovirus, Novirhabdovirus, Cytorhabdovirus, and Nucleorhabdovirus, and these include viruses that are important pathogens of ruminants, fish and plants, and human pathogens such as rabies virus. Vesicular stomatitis Indiana virus(VSIV), Vesicular stomatitis New Jersey virus (VSNJV), and Chandipura virus (CPHV) have been formally recognized as distinct species within the genus Vesiculovirus. Virus species that have been classified in the genus Vesiculovirus are presented in Table 1. Other viruses that have been placed tentatively in the genus Vesiculovirus include important viruses such as spring viremia of carp virus, Tupaia virus, and Calchaqui virus.
Figure 1. Vesiculoviruses: a general overview. A general overview of the vesiculoviruses with particular reference to Chandipura virus (a) Schematic presentation of bullet-shaped CHPV. Outer membrane envelope and relative organization of N-RNA nucleocapsid, glycoprotein G, phosphoprotein P, large protein L, and matrix protein M within virion structure have been indicated; (b) Nucleocapsid protein enwrapped genome RNA along with associated phosphoprotein P and large protein L forms a helical structure; (c) CHPV genome RNA encoding leader gene, five protein-coding genes, and gene junctions. Relative arrangement of the cis-acting elements within the gene junction has been indicated.
Table 1. Species within the genus Vesiculovirus
Species name
Abbreviation
Original isolation
Natural host(s)
Vesicular stomatitis Indiana virus
VSIV
USA, 1942; North Am. Veterinarian 26: 726–730
Horses, cattle, swine, sandflies,
Vesicular stomatitis New Jersey virus
VSNJV
USA, 1943; North Am. Veterinarian 26: 726–730
Horses, cattle, swine, sandflies, mosquitoes
Piry virus
PIRYV
Brazil, 1960; USPHS Publication No. 1760 Government Printing Office 1967
Human, cattle, mosquitoes
Cocal virus
COCV
Trinidad, 1964; Am. J. Vet. Res. 1964 Jan; 25: 236–42
Horses, cattle, insects
Chandipura virus
CHPV
India, 1965; Indian J. Med. Res. 1967 Dec; 55(12): 1295–305
Rabies is a virus that is usually transmitted through the bite of a rabid animal, although it can also be transmitted through aerosolization. Vaccination programs, the elimination of stray animals, and strict quarantine procedures have reduced the number of rabies infections in the developed world, although it remains a serious concern in underdeveloped countries, accounting for almost 33 000 deaths per year (Baer, 1998; Bleck and Rupprecht, 2000; Murray et al., 2002, 2013). For additional information see http://www.cdc.gov/ncidod/dvrd/rabies/.
A vesiculovirus of the Rhabdoviridae that is enzootic in the Americas. Vesicular stomatitis (q.v.) has a seasonal incidence and is believed to be transmitted by biting insects. The virus may infect horses, cattle, swine and humans.
Clinical signs
The condition is known as “sore nose” or “sore mouth” and is characterized by vesicles that progress to painful erosions of the muzzle and mouth, feet and occasionally udder or prepuce. The incubation period is 1–3 days.
Diagnosis
Biopsy reveals marked intra- and intercellular epidermal edema and spongiosis with microvesicle formation and necrosis. A superficial and deep perivascular dermal inflammatory reaction is seen with neutrophils predominating.
Treatment
Healing usually occurs within 2 wk, sometimes leaving depigmented areas. Hooves may be sloughed on rare occasions. Mortality is rare and no specific therapy is indicated
Chandipura virus is a Vesiculovirus with a structure and replication similar to those of vesicular stomatitis virus. It was first isolated from the blood of two humans in the central Indian state of Maharashtra in 1965. In the following years, Chandipura virus was detected only occasionally as a pathogen of humans. In 2003, however, an outbreak of disease attributed to Chandipura virus occurred in the state of Andhra Pradesh that affected 329 children with 183 fatalities (case fatality rate, 56%). In 2004, a similar outbreak occurred in Gujarat State, affecting 23 children with 18 fatalities. Symptoms included fever, sensory disorders, convulsions, vomiting, diarrhea, and encephalitis leading to coma and death. A hospital-based study conducted in Andhra Pradesh in 2005 and 2006 concluded that Chandipura virus is the major cause of an acute viral encephalitis in children in endemic areas during the early monsoon months (Tindale et al., 2008). Chandipura virus and/or neutralizing antibody against it also have been found in humans in Sri Lanka and in the West African countries of Senegal and Nigeria. Clinical cases in humans, however, have not been reported outside India.
Chandipura virus has been isolated from unidentified Phlebotomus and Sergentomyia species in India and Senegal. Transovarial transmission has been demonstrated experimentally in P. papatasi. The virus also has been identified in primates (macaques) in Sri Lanka, insectivores (hedgehogs) in Nigeria, and even-toed ungulates (pigs, buffalo, cattle, goats, and sheep) in India. Although human disease has been detected only in central India, the evidence of widespread virus occurrence in South Asia and Africa indicates a much broader human risk.
Three serotypes of vesicular stomatitis virus (Rhabdoviridae: Vesiculovirus) that cause febrile disease in humans are believed to be transmitted by sand flies. The Alagoas, Indiana, and New Jersey serotypes are widely distributed in tropical and temperate areas of North and South America and have been repeatedly isolated from L. shannoni, L. trapidoi, L. ylephiletor, and unidentified sand flies. L. shannoni is a proven vector of the New Jersey serotype among feral pigs on Ossabaw Island, GA. Transovarial transmission has been demonstrated in several species of sand flies, including L. shannoni, L. trapidoi, and L. ylephiletor.
Vesicular stomatitis virus has been isolated from a number of biting and nonbiting insects, in addition to sand flies. Repeated isolations have been made from black flies (Simuliidae), and outbreaks of the disease in cattle have been associated with high populations of black flies. Laboratory-infected Simuliumvittatum transmit the virus to mice experimentally.
Symptoms of vesicular stomatitis in humans are similar to those of sand fly fever. Opossums, monkeys, porcupines, raccoons, bobcats, horses, pronghorns, cattle, sheep, and swine are suspected reservoirs. Antibodies occur in domestic and wild dogs.
In the Western Hemisphere, vesicular stomatitis viruses and some other vesiculoviruses are zoonotic, being transmissible to humans (typically, farmers and veterinarians) from vesicular fluids and tissues of infected animals. The disease in humans resembles influenza, presenting with an acute onset of fever, chills, and muscle pain. The infection resolves without complications within 7 to 10 days. Human cases are not uncommon during epidemics in cattle and horses, but because of lack of awareness few cases are reported. Human cases can be diagnosed retrospectively using serological methods. There are no practical measures for preventing occupational exposure.
At present, no fish rhabdoviruses are accepted as formal species within the genus Vesiculovirus, but many rhabdoviruses isolated from fish are clearly closely related to members of this genus, and distinct from the members of the genus Novirhabdovirus. Some vesiculovirus-like fish rhabdoviruses are considered tentative species in the genus Vesiculovirus (Table 1). The best studied vesiculo-like fish rhabdovirus is spring viremia of carp virus (SVCV), which has a long history of causing severe epidemics among cultured carp in Europe. SVCV is well characterized at both the biological and molecular levels, and it is considered the representative of the vesiculovirus-like fish rhabdoviruses. Full-length genome sequences are available for several strains of SVCV, and numerous other isolates are partially sequenced, facilitating phylogenetic analyses that confirm its close relationship to the mammalian vesiculoviruses. Many isolates of a similar virus, pike fry rhabdovirus, have also been described, and several other fish rhabdoviruses have been isolated from various cold- and warm-water hosts including various species of eel, snakehead, trout, and perch. By serological assays and phylogenetic analyses, at least some of these isolates appear to be distinct vesiculo-like viral species. Phylogenetic trees of partial G or L gene sequences indicate that these isolates form an emerging cluster of tentative species around the mammalian genus Vesiculovirus, as illustrated in Figure 1. Future work by the ICTV will likely establish some formal species among the vesiculo-like fish rhabdoviruses and clarify whether they should be accepted as members of the genus Vesiculovirus.
Virions of the fish vesiculo-like rhabdoviruses are typically shorter and wider than novirhabdoviruses, with bullet-shaped particles measuring c. 80–150 nm in length and 60–90 nm in diameter (Figure 2(b)). Particles are composed of five viral proteins that correspond to the five major virion proteins found in all rhabdoviruses. The virus replication cycle roles of the N, P, M, G, and L proteins are as described above for novirhabdoviruses. Among fish rhabdoviruses, the distinguishing feature of the fish vesiculo-like viruses is the absence of an NV gene at the G–L junction, indicating that, whatever the role of the NV protein in novirhabdoviruses, it is not essential for rhabdovirus replication in fish per se.
The negative-sense RNA genome of SVCV is just over 11 000 nt in length, and it has genes encoding the five major viral proteins in the same order found in all rhabdovirus genomes (Figure 3). The upstream untranslated region of each gene is a conserved 10 nt sequence and the downstream untranslated regions are more variable. The 3′ and 5′ termini of the genome have complementary leader and trailer regions of c. 20–60 and 12–20 nt, respectively. The untranscribed, intergenic regions between genes are dinucleotides, which, for SVCV, are all CT with the exception of the G–L junction that has the tetranucleotide CTAT. Putative transcriptional start and stop signals, shown in Figure 3, are highly conserved among individual genes and among SVCV isolates. These regulatory signals at the SVCV gene junctions are nearly identical to those of mammalian virus members of the genus Vesiculovirus, and they differ from the regulatory sequences conserved among members of other rhabdovirus genera, including novirhabdoviruses. As an example of the levels of sequence similarity, the SVCV G protein has 31–33% amino acid sequence identity (52–53% similarity) with the G proteins of members of the genus Vesiculovirus, but only 19–24% identity (40–47% similarity) with G proteins of 11 rhabdoviruses from all other genera including Novirhabdovirus. Among several viruses reported as isolates of SVCV, partial G gene nucleotide sequences have 83–100% identity, and phylogenetic analyses resolved four genogroups that correlated with geographic origin in Eurasia. Among SVCV and other tentative species of fish vesiculo-like rhabdoviruses, partial G or L gene nucleotide sequences typically have 70–80% identity.
Vesiculoviruses
A virus carrying a deletion of P aa 176–181 (SAD ΔInd1) has lost the ability to prevent IRF3 activation and IFN induction and was considerably attenuated after intracerebral injection into mouse brains (Rieder et al., 2011).
Novirhabdoviruses have five major structural proteins, designated L (150–225kDa), G (63–80kDa), N (38–47kDa), P (22–26kDa, formerly designated M1), and M (17–22kDa, formerly designated M2).
Infectious hematopoietic necrosis virus (IHNV) infects a range of salmonid and other fish species, wherein it obliterates the lymphoid tissues of the spleen and head kidney [58,59].
From: Veterinary Clinics of North America: Exotic Animal Practice, 2008
IHNV particles have a bullet-shaped or cone-shaped morphology. The virus belongs to a new genus which has six viral genes in the order 3′-N-P-M-G-NV-L-5′ on the negative-sense single-stranded RNA genome. The N is the nucleoprotein gene; P, the phosphoprotein gene; M, the matrix protein gene; G, the glycoprotein gene; NV, the nonvirion protein gene, and L the polymerase gene. Recently the International Committee on the Taxonomy of Viruses accepted the classification of IHNV with a new genus called Novirhabdovirus for the unique Non-Virion protein gene located between G and L on the viral genome.
Infectious hematopoietic necrosis virus (IHNV), a member of the genus Novirhabdovirus and family Rhabdoviridae, causes infectious hematopoietic necrosis in fish. The virus has the typical bullet shape of members of the Rhabdoviridae, and the genome consists of a single molecule of negative-sense ssRNA with varying strain pathogenicity. IHNV isolates can be grouped into three genetic types, which are correlated mainly with geographic regions. The U genotype group includes isolates from Alaska, British Columbia, and watersheds of coastal Washington and the Columbia River basin and isolates from Oregon, California, and Japan. The L genotype contains most of the viruses from California and the Oregon coast. The M group contains isolates from Idaho, the Columbia River basin, and Europe and a virus from the Washington coast. The genetic diversity of M group is significantly higher than the L or U groups. An IHNV database is available containing records for > 1000 individual field isolates, which is updated annually (Kurath, 2012).
The IHNV is enzootic in the sockeye salmon population on the west coast of North America. In recent years, another major host for IHNV was found to be rainbow trout. The infectious hematopoietic necrosis disease was introduced into Japan in 1977 and it appeared in Europe in 1987. The IHNV-infected disease now represents a major threat to aquaculture all over Europe. The virus infection and the disease appear to be cold-dependent, with the characteristic of epizootics at 13°C which disappears at a higher temperature (above 15°C). Two other viruses, namely Oregon sockeye salmon disease virus (OSDV) and Sacramento River Chinook disease virus (SRCDV), are antigenically similar to IHNV and produce diseases with nearly identical symptoms.
In the laboratory, defective interfering (DI)-like particles are produced when the cells are infected at higher multiplicity of infection (m.o.i).
Infectious hematopoietic necrosis virus (IHNV), a member of the genus Novirhabdovirus and family Rhabdoviridae, causes infectious hematopoietic necrosis in fish. The virus has the typical bullet shape of members of the Rhabdoviridae, and the genome consists of a single molecule of negative-sense ssRNA with varying strain pathogenicity. IHNV isolates can be grouped into three genetic types, which are correlated mainly with geographic regions. The U genotype group includes isolates from Alaska, British Columbia, and watersheds of coastal Washington and the Columbia River basin and isolates from Oregon, California, and Japan. The L genotype contains most of the viruses from California and the Oregon coast. The M group contains isolates from Idaho, the Columbia River basin, and Europe and a virus from the Washington coast. The genetic diversity of M group is significantly higher than the L or U groups. An IHNV database is available containing records for > 1000 individual field isolates, which is updated annually (Kurath, 2012).
The first IHN outbreak occurred in sockeye salmon at fish hatcheries in Oregon and Washington in 1953. In an experimentally induced outbreak of IHNV, the virus was detected in the fish even after 9 months of IHNV exposure but with no symptoms, and mortality was observed (Müller et al., 2015).
IHNV infects Atlantic salmon in aquaculture, whereas rainbow trout are known to be susceptible in the environment. The disease is characterized by necrosis of the anterior kidney, including necrosis of the hematopoietic kidney tissue and pancreas. However, this disease can be distinguished from VHSV infection in that fish with IHNV show necrosis of the eosinophilic granular cells of the intestinal wall. Infection has been shown to occur through the gills and esophagus epithelium, resulting in a systemic viremia where they spread to the vital organs, causing a necrosis which can often result in death.
Infectious hematopoietic necrosis is a disease of salmonid fish. Five principal genetic groups of infectious hematopoietic necrosis virus have been identified, which tend to segregate according to region of origin (topotype) and species of salmonid from which they are isolated. Initially restricted to western North America, the causative virus (infectious hematopoietic necrosis virus) has been spread to Europe and Asia by the movement of infected fish or eggs.
Infectious hematopoietic necrosis virus is endemic in many wild fish populations of the west coast of North America from Northern California to Alaska. Sporadic outbreaks with significant losses occur in juvenile salmon and trout reared in hatcheries in this region. Following the introduction of infectious hematopoietic necrosis virus to continental Europe and the Far East (eg, Japan, Korea, China, and Taiwan), the virus has caused severe losses in some farmed populations of rainbow trout. Outbreaks usually involve juvenile fish at water temperatures from 8°C to 15°C, with cumulative mortality reaching 50–90%. The virus may also cause significant losses among older salmonids in seawater (eg, Atlantic salmon) or fresh water (eg, rainbow trout). Survivors develop immunity to reinfection that is associated with the presence of virus-neutralizing antibodies in their serum. Anadromous salmonids re-entering freshwater to spawn may shed large amounts of virus in urine and in ovarian and seminal fluids, in the absence of clinical signs of disease. In contrast, acute infections in juvenile fish are characterized by darkened body color, lethargy, pale gills (indicating anemia), bilateral exophthalmia, distension of the abdomen as a result of the accumulation of ascites, and hemorrhages at the base of fins.
Diagnosis is based upon observance of typical clinical signs of the disease and isolation of the virus in cell lines of fish origin. Confirmation is obtained by virus identification with antigen-based approaches, including fluorescent antibody, ELISA or nucleic acid-based approaches (RT-PCR or DNA probes). Control measures among cultured populations of fish are similar to those described for viral hemorrhagic septicemia. The disease has been successfully managed among Atlantic salmon populations reared in marine net pens along the west coast of North America by utilizing “all-in–all-out” stocking and harvesting strategies, and by physical separation of the net pens. An efficacious DNA vaccine has been licensed for Atlantic salmon in Canada.
IHNV infects Atlantic salmon in aquaculture, whereas rainbow trout are known to be susceptible in the environment. The disease is characterized by necrosis of the anterior kidney, including necrosis of the hematopoietic kidney tissue and pancreas. However, this disease can be distinguished from VHSV infection in that fish with IHNV show necrosis of the eosinophilic granular cells of the intestinal wall. Infection has been shown to occur through the gills and esophagus epithelium, resulting in a systemic viremia where they spread to the vital organs, causing a necrosis which can often result in death. VHSV (or Egtved virus) is an important viral disease in aquaculture, particularly for salmonids. This virus causes a viral hemorrhagic septicemia (VHS) and is characterized by hemorrhaging in the muscles, eyes, skin, and meninges; necrosis of internal organs (particularly the kidney and liver); exophthalmia; lethargy; and darkening of the skin. SVCV (=Rhabovirus carpio) also poses as a threat to carp (particularly Cyprinus carpio) and causes numerous symptoms including exophthalmia, skin hemorrhaging, hemorrhagic enteritis, and ascites.
History. Infectious hematopoietic necrosis is an acute infection of young cultured salmonids and can occur in asymptomatic fish hosts. The host range of IHNV includes at least five species of Pacific salmon, several trout species, and the Atlantic salmon.2 The first outbreaks of the disease, with isolation and identification of the etiologic agent (IHNV), were registered in sockeye salmon (Oncorhynchus nerka) fry at fish farm hatcheries in the United States during the 1950s.3,4
Limitations and Clinical Applications of DNA Vaccines
Although there are over 5000 publications demonstrating the effective induction of immunity using DNA vaccines in mice which protect mice from subsequent infection, DNA vaccines have not been as successful in larger animals or humans. Possibly the greatest challenge to adopting DNA vaccination as a routine in large animals and humans is the poor efficiency of transfection leading to suboptimal induction of immunity. This has limited the introduction of vaccines into the market. Although there have been numerous clinical trials in humans, the greatest success has been when DNA vaccines were used to prime the individual, followed by booster with a recombinant or subunit vaccine. Indeed, the DNA prime, followed by protein boost is currently the method of choice for induction of the immune responses using DNA vaccines in humans. Thus, it is our contention that if better delivery mechanisms could be introduced to enhance the transfection efficiency in large animals and humans, DNA vaccines have the potential to become a critical component in our armamentarium against infectious diseases.
While there has not yet been a DNA vaccine approved for human use, this past decade has seen regulatory approval for four different veterinary DNA vaccines:
(1)
West Nile virus in horses - Based on DNA encoding for the pre-membrane (pRM) and envelope (E) proteins of West Nile virus (WN), it was found that a single intramuscular injection was sufficient to induce protective immunity and prevent infection of the virus. Approved for veterinary use in horses by the United States Department of Agriculture (USDA) in 2005, a formulation based on this DNA construct is currently licensed and manufactured by Fort Dodge Animal Health (Wyeth Pharmaceuticals);
(2)
Infectious hematopoietic necrosis virus (IHNV) in salmon- Shortly after the US approval of the West Nile vaccine, another DNA vaccine was approved by the Canadian Food Inspection Agency (CFIA) in 2005, for use against IHNV in farmed salmon. IHNV is a viral pathogen previously known to inflict significant economic losses to the aquaculture industry, with particular impact to farmed fish and trout. The approved DNA vaccine is based on the glycorprotein of IHNV; and a single intramuscular injection has been found to protect salmon against both waterborne and injected viral challenge. Currently, this vaccine is licensed and manufactured by Vical (Novartis Animal Health);
(3)
Canine melanoma- Canine oral melanoma is a common form of malignant cancer in dogs. This DNA vaccine encodes for a human tyrosinase, and it has been found that this recombinant expression can elicit an immune response in dogs, ultimately breaking the immune tolerance for the canine form of the protein. Experimental studies using this vaccine have shown that four transdermal vaccinations (at two week intervals) significantly extended survival times in dogs with stage II or III oral melanoma. Approved by the USDA in 2010, this vaccine is currently manufactured by Merial, and registered under the trademark ONCEPT.
(4)
Growth hormone-releasing hormone (GHRH) in pigs- Although not a conventional vaccine (i.e., immune targeting of specific pathogenic components), it has been previously shown that plasmids expressing GHRH can induce greater growth and development of piglets, as well as increased T-cell populations. These physiological effects have ultimately been shown to reduce pathogen-associated morbidity and mortality in pigs. In 2008, the Australian Pesticides and Veterinary Medicines Authority (APVMA) approved GHRH gene therapy for use in sows of breeding age, in order to increase the number of weaned pigs. Manufactured by VGX Animal Health and marketed under the name LifeTide SW5, this plasmid is administered intramuscularly, followed by electroporation (see following section). Only one injection is required over the lifetime of the sow.
Equine adenoviruses are members of the genus Mastadenovirus, family Adenoviridae. Only a single antigenic type of equine adenovirus (EAdV1) has been isolated from horses with respiratory disease.1,2 A second serotype, equine adenovirus type 2 (EAdV2), has been isolated from the feces of foals with diarrhea.3 The biophysical properties of EAdV are similar to those of adenoviruses of other species. Equine adenoviruses are nonenveloped, 70 to 80 nm in diameter, and the capsid is composed of 252 capsomers; 240 hexamers occupy the faces and edges of the 20 equilateral triangular facets of an icosahedron, and 12 pentamers occupy the corners. The inner core contains the double-stranded deoxyribonucleic acid (DNA) genome, which for EAdV1 is 34.4 kilobases in length. Restriction endonuclease maps and genome orientation data were published for EAdV1,4 and genomic sequence data for both viruses were also published.5,6Nucleotide sequence data for the EAdV2 genome corroborated at the molecular level that EAdV2 is distinct from EAdV1 and that the two viruses evolved separately.5
An adenovirus-associated virus was isolated from a foal with respiratory disease after inoculation of equine cell cultures.7 As for adenovirus-associated viruses of other species, the equine virus is assumed to be nonpathogenic.
Equine piroplasmosis caused by Babesia caballi and B. equi (syn. Theileria equi) occurs in many parts of the world including Europe, Asia, Africa and the Americas and there are endemic foci of B. caballi infection in the southern USA.
These organisms are transmitted by ticks of the genera Dermacentor, Hyalomma and Rhipicephalus. The pathogenic effects of different strains of equine Babesia are variable and clinical signs include anorexia, fever and anemia; jaundice and hemoglobinuria may accompany B. equi infection. Horses raised in endemic areas are often asymptomatic carriers due to premunity (q.v.) and may only show clinical signs when stressed.
Diagnosis is based on clinical signs and the demonstration of parasites in the red blood cells in acute cases. A CFT may be used to detect parasite antibodies within 5 days of infection and a negative CFT is required for all horses entering the USA from endemic areas. Molecular tests are now also available.
A number of drugs, including imidocarb, diminazene and buparvaquone, are recommended for the treatment of equine piroplasmosis but for all drugs the manufacturers' doses and instructions should be carefully observed.
Equine asthma is similar to human asthma and is commonly referred to as equine recurrent airway obstruction (RAO). Recently, RAO, because it is similar to asthma, has been referred to as severe equine asthma (Costa et al., 2016). Severe equine asthma or RAO diseases are based on similarities of bronchoconstriction or narrowing of airways, where the horse secretes excessive mucus and its airways are obstructed. Airway obstruction makes it difficult for the horse to breathe and also causes coughing and wheezing. Factors that cause RAOs are inefficiency of lung clearance, genetic predisposition, and environmental exposure to excessive levels of “respirable dust particles” such as aeroallergens (i.e., pollen and mold spores), which often can be found in moldy hay and pastures. Pasture-associated obstructive pulmonary disease (PAOPD), along with its causes, symptoms, and methods of prevention, can be divided into two forms of RAO:
1.
hay-associated RAO, also known as chronic obstructive pulmonary disease (COPD), chronic airway disease, broken wind, heaves, chronic obstructive lung disease, or chronic bronchitis
The equine picornaviruses that were previously classified as rhinoviruses because of their acid lability are now classified in two genera: equine rhinitis A virus (equine rhinovirus 1) is included as a member of the genus Aphthovirus, whereas equine rhinitis B virus (equine rhinovirus 2) is now classified in the new genusErbovirus, with three recognized serotypes(designated as equine rhinitis B viruses 1, 2, and 3) that are distinguished on the basis of their acid lability/stability, genetic sequences, and neutralization by type-specific antisera. Equine rhinitis B viruses can cause mild upper respiratory disease in horses, but their importance as pathogens has not been firmly established. The viruses have a worldwide distribution and the seroprevalence rates in non-isolated populations are high.
Equine sarcoids are locally aggressive, non-metastatic fibroblastic tumors. The term is often used to encompass fibroma, fibroma-like tumor, neurofibroma and low-grade fibrosarcoma as well. While these other tumors can be distinguished histopathologically, the clinical appearances, behavior and treatment are similar. Equine sarcoid is a common clinical entity that may cause loss of use of the horse and also an esthetic problem. A viral etiology has been suggested, with bovine papillomavirus DNA detected in many samples. Possible transmission routes may include flies, rubbing posts and shared equipment. A genetic predispositionis also suggested.
Equine dental disorders are a major part of equine practice in the United Kingdom, as indicated by a British Equine Veterinarian Association (BEVA) survey in 1965 that showed 10 per cent of equine practice time was spent on dental-related work.1 More recently, a survey in the United States ranked dental disorders as the third most common equine medical problem encountered by large animal practitioners.2 Despite its importance to veterinary practice, a survey of 150 adult horses with no history of dental disease showed that 24 per cent of these horses did in fact have dental abnormalities.3
Gross anatomical features of equine dentition have been recorded as far back as 600 C.E.4 These include eruption times of deciduous and permanent dentition, presence of incisor ‘hooks’ and grooves, and the presence of features such as the ‘dental star’ on the occlusal surface of incisors that were used in aging horses.
The equine encephalosis virus acquired its name after original isolation from a horse with clinical signs of neurologic disease. The clinical importance of EEV is uncertain but appears to be limited. Seroconversion in closely managed horses without evidence of clinical disease suggests that infection by the virus is asymptomatic in most cases. However, the disease associated with infection by EEV is poorly documented, and given the high prevalence of infection, EEV might be falsely incriminated as the cause of disease in some situations. Most infections are subclinical based on the high seroprevalence rate and lack of reports of disease outbreaks.
Clinical signs typically attributed to EEV infection include fever, lassitude, edema of the lips, acute neurologic disease, and enteritis. Abortion has anecdotally been associated with infection by EEV. Disease associated with EEV has not been recorded in donkeys or zebra.1
Equine purpura hemorrhagica (EPH) is believed to be an allergic response to streptococci or equine influenza virus (q.v.). This vascular syndrome typically occurs 2–4 wk after infection by Streptococcus equi (strangles) (q.v.). Exposure of a previously sensitized horse to infected horses may also precipitate EPH. Rarely EPH may follow infections with Strep. zooepidemicus or influenza. Immune complexes containing IgA and a protein of Strep. equi have been demonstrated in the blood vessels of horses with EPH. Serum IgA titers to Strep. equi are higher in horses with EPH, but titers of IgG are curiously decreased. The significance of these findings remains unclear because EPH is difficult to reproduce experimentally.
Classical signs of EPH include mucosal petechial hemorrhagesand demarcated areas of edema on the limbs, ventral abdomen, head and trunk. Edema of other tissues may cause dysphagia, dyspnea, colic, lameness or renal disease. Hematology generally reflects chronic inflammation. Moderate anemia (PCV 0.20–0.25L/L) may develop due to fluid shifts or shortened erythrocyte lifespan. Tentative diagnosis of EPH is based on history and clinical signs. Leukocytoclastic venulitisin the dermis and subcutaneous tissue of a skin biopsy supports the diagnosis. Although most horses with EPH respond to therapy (see below), some cases are refractory. Deaths are usually secondary to laminitis (q.v.) or septic complications.
Equine viral arteritis (EVA) is caused by an RNA virus of the genus Arterivirus. There are numerous strains of EVA virus (q.v.) with variable pathogenicity. Infection classically occurs via inhalation of aerosol secretions from an affected horse, but venereal transmission may play a significant role in EVA dissemination.
Clinical disease of variable severity or an inapparent infection may follow EVA exposure. Clinical signs, after an incubation period of 2–13 (mean 7) days, may include fever, depression, anorexia, periorbital and palpebral edema, conjunctivitis, ocular and nasal discharge, edema of the legs and ventral abdomen and/or respiratory distress. Pregnant mares infected during the last trimester generally abort 5–30 days after the febrile response and they may not show other clinical signs. The fetus is usually autolyzed.
Definitive diagnosis of EVA (q.v.) requires viral isolation or seroconversion. The EVA virus may be isolated from nasopharyngeal and conjunctival swabs, citrated blood early in the course of the disease, and semen or placental and fetal fluids. Immunochemistry and PCR may replace virus isolation. A 4-fold increase in serum antibody titer to EVA virus in two samples collected 10–14 days apart is considered evidence of infection. Affected horses usually recover with supportive care within 3 wk. Infected stallions can remain persistent carriers/shedders of the EVA virus in semen. Infection by EVA can be prevented by use of a modified live vaccine at least 3 wk prior to exposure.
Infection with the equine infectious anemia (EIA) virus (q.v.) may cause necrotizing vasculitis of the skin or other organs. Classical signs include fever, icterus, mucosal petechiae, ventral edema, anemia and weight loss. Diagnosis of EIA is confirmed by an agar gel immunodiffusion (Coggins) test for serum antibodies to the EIA virus. Horses remain viremic.
Infection by the rickettsial agent Anaplasma phagocytophila (q.v.) may cause a vasculitic syndrome. Although the disease originally termed equine ehrlichiosis usually occurs in northern California, individual cases have been reported in other states and countries. Its distribution overlaps that of the tick reservoir, Ixodes pacificus. Horses over 3 yr of age are more severely affected and signs include fever, depression, anorexia, mucosal petechial hemorrhages, icterus, ventral limb edema, weakness, ataxia and/or reluctance to move. Hematology often reveals mild to moderate leukopenia, thrombocytopenia and anemia. A. phagocytophila, which infects granulocytes, is antigenically distinct from Neorickettsia risticii, the etiologic agent for Potomac horse fever (q.v.). Infection confers immunity for up to 2 yr that is not associated with a carrier state. Diagnosis is based on serology and active cases have a 4-fold rise in titer over 4 wk. Affected horses generally recover within 2 wk with supportive care alone, but oxytetracycline (7 mg/kg IV s.i.d. for 5 days) usually causes a prompt remission of clinical signs within 1–2 days.
Horses may develop idiopathic vasculitic syndromes with uncharacterized pathogenesis and unpredictable clinical course. Clinical signs often resemble EPH (q.v.) but may include intermittent fever, weight loss, alopecia, hyperkeratosis and hypopigmentation of the skin.
EPSM has been described in Draft Horse breeds including Belgians, Percherons, Clydesdales, Shires, Haflinger, Norwegian Fjord, Suffolk, Irish Draft, Draft crosses, and a Draft mule. Depending on the description of the abnormal periodic acid–Schiff positive staining polysaccharide on muscle biopsies, the incidence of EPSM in the general Draft Horse population has been estimated to be 45% to 66%. Whether this form of polysaccharide storage disease occurs in other breeds has been debated.
Clinical signs of EPSM appear to take two forms. Draft Horses with EPSM may exhibit exercise-associated muscle cramping similar to that observed in other types of exertional rhabdomyolysis. Complications from rhabdomyolysis are similar to those described in other horses with severe rhabdomyolysis and include postanesthetic recumbency, renal failure, and laminitis. EPSM is associated with a second clinical syndrome in Draft Horses characterized by progressive poor performance, shivers or a shiverslike gait, progressive muscle wasting, muscle weakness, recumbency, and death (Figure 9-5). Serum or plasma CK activities are increased in horses with EPSM demonstrating either syndrome and vary from mild to severe depending on the degree of rhabdomyolysis.
Vaccines for ERAV or ERBV have not been developed commercially until the 2012 release of an adjuvanted, inactivated vaccine to protect against ERAV. This new vaccine has a conditional license in the United States; efficacy and potency tests are in progress. An experimental inactivated ERAV vaccine produced primary immune responses in horses, mice (including athymic nu/nu mice), and rabbits.93 The problem of multiple serotypes recognized for FMDV does not occur because ERAV is antigenically and genomically remarkably stable over time and geographic location.90 The occurrence of three serotypes of ERBV would need to be considered in any vaccine development.
Present day viruses are diverse regarding genome type (RNA or DNA, single stranded or double stranded, linear or circular, unsegmented or segmented), and in terms of replication strategy (presence or absence of transcription or reverse transcription, ambisense coding, one or multiple messenger RNAs, etc.). According to the nature of the nucleic acid involved in the flow of information during replication (not gene expression) there are four categories of replication cycle, each including important viral pathogens of animals or plants (Fig. 2). Viruses of group 1, those that use only RNA (represented as RNA→RNA), include the RNA bacteriophages MS2 and Qβ, many viruses that infect plants such as tobacco mosaic virus, and important human and animal pathogens such as poliovirus, influenza virus, or the hepatitis A and C, Zika, West Nile and Ebola viruses or the hemorrhagic arenaviruses. Viruses of group 2, those that use a DNA intermediate (RNA→DNA→RNA) include the retroviruses, the best studied being the human immunodeficiency virus type 1, the causative agent of acquired immunodeficiency syndrome (AIDS). Viruses of group 3, those that use only DNA in their replicative cycle (DNA→DNA) comprise the tailed DNA bacteriophages (i.e., T4 and λ) which were historically key for the development of molecular biology, as well as salient pathogens such as papillomaviruses, herpesviruses, poxviruses, iridoviruses or adenoviruses, as well as the insect baculoviruses or giant viruses such as the Mimiviruses. Viruses of group 4, those that use RNA as intermediate (DNA→RNA→DNA) include the plant virus cauliflower mosaic virus and hepatitis B virus, termed the hepadnaviruses.
Equine rhinitis virus A and B, previously classified as equine rhinovirus-1, −2, and −3, are common in horse populations but knowledge of their epidemiology, pathogenesis and association with disease is rather limited. The viruses have recently been reclassified and other equine picornaviruses, such as “acid-stable picornavirus” (ASPV), may yet also be reclassified.
Virology and immunity
Several different picornaviruses have been isolated from horses (Plummer 1962, Studdert & Gleeson 1977, Mumford & Thomson 1978, Fukunaga et al 1983) and most have been rhinoviruses, isolated from the respiratory tract, mouth, blood, and feces.
The rhinoviruses were originally grouped into three categories, equine rhinovirus-1 (ERV-1), ERV-2 and ERV-3. ERV-1 has now been reclassified as equine rhinitis A virus (ERAV) (Varrasso et al 2001). ERV-2 has been renamed equine rhinitis B virus (ERBV) and has been reclassified as an Erbovirus, a new genus in the Picornaviridae (Hinton & Crabb 2001). ERV-3 has also recently been classified as an Erbovirus and named ERBV2 in view of its close sequence homology with ERBV (Huang et al 2001). ASPV, which shares the properties of enteroviruses and rhinoviruses, has not been reconsidered in recent years.
Infection with ERAV stimulates a long-lasting neutralizing antibody response which is thought to prevent further disease, although repeated infections in racehorses in training can occur (Mumford 1994). Infection with ERAV does not stimulate cross-reactive neutralizing antibody to either ERBV or ASPV (Mumford & Thomson 1978, Steck et al 1978, Mumford 1994). There is little information on cell-mediated immune responses to other equine picornaviruses.
Clinical signs and pathogenesis
Both natural and experimental infection of seronegative horses with ERAV has been associated with pyrexia (<40.4°C) for up to 5 days, nasal discharge and swelling of retropharyngeal lymph nodes and a moist cough (Plummer 1962, Plummer & Kerry 1962). Natural infections may frequently be subclinical, particularly in seropositive animals (Studdert & Gleeson 1978).
Although ERBV infections may sometimes cause slight pyrexia and mild respiratory signs (Steck et al 1978), infections are usually subclinical and infection of gnotobiotic foals failed to induce clinical signs of respiratory disease (Mumford & Thomson 1978). There is little or no information on the ability of ERBV2 to cause disease.
ASPV was initially isolated from a thoroughbred racehorse in training, although it was not showing signs of respiratory disease at the time (Mumford & Thomson 1978). Experimental infection of a gnotobiotic foal failed to produce signs of respiratory disease, but seroconversion did occur and virus was recovered from the animal. Serological investigations of naturally occurring outbreaks of respiratory disease have produced confusing results and there is little evidence that this virus is a cause of equine respiratory disease, although the very limited amount of work reported precludes firm conclusions from being drawn.
Diagnosis
Equine rhinitis virus infections may be diagnosed by isolation of virus in tissue culture, detection of viral RNA by PCR (Li et al 1997) or through demonstration of viral seroconversion using either CF or VN tests (Mumford & Thomson 1978).
Epidemiology
ERAV has a worldwide distribution. Infection can spread by respiratory contact and outbreaks of disease associated with ERAV have been reported (Mumford 1994, Li et al 1997). Prolonged excretion of ERAV in urine in racehorses is common, particularly in 2- and 3-year-olds (McCollum & Timoney 1992) and is probably an important source of infection.
Many foals in the UK remain seronegative to ERAV and racehorses usually experience their first ERAV infection in their second or third year, whilst in training (Powell et al 1974). A similar situation has also been reported elsewhere, including North America (Holmes et al 1978). During outbreaks, ERAV is highly contagious and transmission rates in naive populations may approach 100% (Holmes et al 1978, Studdert & Gleeson 1978). Initial infections are usually associated with clinical signs (Burrows 1979, Li et al 1997, Klaey et al 1998), but repeated infections with ERAV, detectable in racehorses using the CF test (Mumford & Thomsen 1978), are frequently not associated with signs of disease. Most foals become infected with ERBV during the first few months of life (Holmes et al 1978, Burrows 1979) and repeated infections are frequently observed. It is clear that infections with ERBV and ERBV2 are common in Australia, where they have been most often studied (Huang et al 2001). Most infections are not associated with obvious clinical signs.
Prevention
No commercially available equine rhinovirus vaccines currently exist. However, ERAV infection stimulates strong clinical immunity and immunization with inactivated virus stimulates VN antibody and protection against experimental infection (Burrows 1979).
As a result of the lack of commercially available vaccines, controlled infection programs with ERAV in racehorses have been suggested as a means of ensuring that disease does not occur shortly before important race meetings, but so far these have not been reported (Klaey et al 1998).
No information is available on stimulation of immunity to ERBV or ERBV2, but natural infection is often associated with prolonged excretion (Fukunaga et al 1983) and virus neutralizing antibody levels are not maintained at high levels, suggesting that natural immunity may be poor.
Present day viruses are diverse regarding genome type (RNA or DNA, single stranded or double stranded, linear or circular, unsegmented or segmented), and in terms of replication strategy (presence or absence of transcription or reverse transcription, ambisense coding, one or multiple messenger RNAs, etc.). According to the nature of the nucleic acid involved in the flow of information during replication (not gene expression) there are four categories of replication cycle, each including important viral pathogens of animals or plants (Fig. 2). Viruses of group 1, those that use only RNA (represented as RNA→RNA), include the RNA bacteriophages MS2 and Qβ, many viruses that infect plants such as tobacco mosaic virus, and important human and animal pathogens such as poliovirus, influenza virus, or the hepatitis A and C, Zika, West Nile and Ebola viruses or the hemorrhagic arenaviruses. Viruses of group 2, those that use a DNA intermediate (RNA→DNA→RNA) include the retroviruses, the best studied being the human immunodeficiency virus type 1, the causative agent of acquired immunodeficiency syndrome (AIDS). Viruses of group 3, those that use only DNA in their replicative cycle (DNA→DNA) comprise the tailed DNA bacteriophages (i.e., T4 and λ) which were historically key for the development of molecular biology, as well as salient pathogens such as papillomaviruses, herpesviruses, poxviruses, iridoviruses or adenoviruses, as well as the insect baculoviruses or giant viruses such as the Mimiviruses. Viruses of group 4, those that use RNA as intermediate (DNA→RNA→DNA) include the plant virus cauliflower mosaic virus and hepatitis B virus, termed the hepadnaviruses.
Diversity is also exuberant regarding the ecological niches where viruses are found: any terrestrial and marine environment, including extreme thermophilic and hyper-saline environments, and infecting representatives of all domains of life. The number of viral particles in the biosphere has been estimated in ~1032, ten times more than the number of cells. In the Earth oceans there is an impressive rate of 1023 new infections per second, so that 108 viral particles can be counted in each ml of sea water. Most viruses are continually replicating and renewing.
Replication is intimately linked to several types of variations of the genetic material that can affect its evolution. Variations include point mutations, insertions, deletions, cell-dependent hypermutation events, recombination and genome segment reassortment, among others (Fig. 3). For many such events we have also approximate numbers for the rate of occurrence. Point mutation rates for RNA viruses are in the range of 10−3 to 10−5 mutations introduced per nucleotide copied, and similar or lower recombination rates, depending on the virus. Generally, transition mutations are more frequent than transversion mutations, and at least in the viable genomes that we observe, insertions and deletions (also termed indels) are less frequent than point mutations. Indels occur more frequently in homopolymeric tracts or repeated sequences. The first high mutation rates determined for RNA viruses were unexpected at a time when mutations were considered rare events in the biological world, and procedures for the analysis of genetic material at the molecular level were not available. High mutation rates originate from the absence or low efficiency of proofreading-repair activities in the polymerasesthat catalyze their replication. These mutation rates are about one million-fold higher than those typically observed during replication of chromosomal DNA, marking a striking difference between the DNA-based cellular world and the RNA virosphere.
Dissection of the composition of viral populations as they replicate in infected hosts was achieved traditionally by molecular cloning (in standard vectors such as bacterial plasmids) of viral genomes (or genes of interest within viral genomes), followed by traditional Sanger sequencing of the individual clones.
The order Picornavirales contains viruses with a monopartitite or bipartite positive-strand RNA genome that share the following properties: auto-proteolytically processed polyprotein(s), a common three-domain replication block (Hel-Pro-Pol domain consisting of a superfamily III helicase, a proteinase with a chymotrypsin-like structure and a superfamily I RNA-dependent RNA polymerase) and non-enveloped icosahedral virions approximately 30nm in diameter with a pseudo-T=3 symmetry. The RNAs are usually characterized by the presence of a small VPg protein (typical 3–4 kDa) linked to their 5′ end and a poly(A) tail at their 3′ end. Members of the family Picornaviridae (genus Enterovirus) and of the family Secoviridae (genus Comovirus) were the first characterized members of the order and infect vertebrates and plants, respectively. The order also includes viruses infecting invertebrates (families Dicistroviridae and Iflaviridae) or algae (family Marnaviridae). Large-scale environmental genomic studies suggest the presence of a large number of uncharacterized picorna-like viruses in the ocean.
Among the zoonotic viruses belonging to the order Picornavirales, only Syr-Darya valley fever virus (SDVFV), of the family Picornaviridae, genus Cardiovirus, was isolated from ticks in Northern Eurasia. SDVFV was originally isolated from the blood of a patient with fever in the Kyzylorda province of Kazakhstan in July 1973. Later, one strain of SDVFV was isolated from the tick Hyalomma asiaticum (subfamily Hyalomminae) and seven strains from the ticks Dermacentordaghestanicus (subfamily Rhipicephalinae), collected in the floodplains of the Syr-Darya and Ili Rivers, respectively. SDVFV was also isolated from the ticks Ornithodoros capensis (family Argazidae), collected in nests of Laridae birds on islands in the Kara-Bogaz-Gol Bay (off the eastern coast of the Caspian sea, in Turkmenistan). Phylogenetically, SDVFV is closely related to Theiler’s murine encephalomyelitis virus (TMEV) and Vilyuisk human encephalomyelitis virus (VHEV).
Viruses in the family Potyviridae have similarity to members of the order Picornavirales. In particular, the genomes have a VPgat their 5′ termini and a poly(A) tract at their 3′ termini. Their genomes are expressed initially as high molecular weight polyprotein precursors which are processed by virus-encoded proteases. Gene products involved in replication are conserved in gene order and gene sequence. However, members of the Picornavirales have isometric particles, a much smaller VPg and a different type of helicase. There are also some sequence similarities to members of the family Hypoviridae.
The genus Bacillarnavirus has not been assigned to a family within the order Picornavirales. It has three recognized members thus far, Rhizosolenia setigera RNA virus (RsetRNAV), Chaetoceros tenuissimus Meunier RNA virus (CtenRNAV), and Chaetoceros socialis f. radians RNA virus (CsfrRNAV) all of which infect marine diatoms. Diatoms are widely distributed, highly diverse, and are among the most abundant eukaryotes in the ocean. They form a large fraction of the total marine primary producers and are thus significant contributors to the cycling of energy in the ocean (Graham and Wilcox, 2000). The hosts of CtenRNAV and CsfrRNAV are members of the genus Chaetoceros, a group of chain-forming diatoms that can form blooms associated with fish kills. The two viruses have icosahedral symmetry and have ssRNA genomes that are dicistronic and approximately 9500 nt in length. CtenRNAV has an estimated capsid diameter of 31 nm (Shirai et al., 2008), while that of CsfrRNAV is only 22 nm (Tomaru et al., 2009). A striking difference between the two viruses is that CtenRNAV has an estimated burst size of 10,000 virions while CsfrRNAV produces approximately 66 per lytic event. RsetRNAV was the first virus brought into culture that infects a diatom. Like CtenRNAV and CsfrRNAV, RsetRNAV has an icosahedral capsid (approximately 32 nm in diameter), replicates in the cytoplasm and has a positive-sense ssRNA dicistronic genome approximately 8900 long (Nagasaki et al., 2004). The genomes of all three RNA viruses have a similar gene order, with the structural genes nearest the 5′ end, followed by the helicase, protease, and replicase and terminating in a poly(A) tail. Alignments of the replicase genes of these viruses clearly demonstrate that they are closely related and form a well-supported monophyletic clade (Tomaru et al., 2009).
Picornavirus virions are non-enveloped icosahedral capsids 28–30 nm in diameter (Fig. 2.1). The genome consists of an infectious linear, 7.2–8.4 kb ssRNA. Infection is initiated by attachment to specific plasma membrane receptors, with subsequent release of viral RNA into the cytoplasm where virus replication takes place (Fig. 2.2, path 1A) (Lin et al., 2009; Daijogo and Semler, 2011; Ogram and Flanegan, 2011; Thibaut et al., 2012). Picornavirus translation is cap-independent and uses an internal ribosomal entry sequence. The translated large precursor polyprotein is self-cleaved into both structural and non-structural polypeptides. After assembly in the cytoplasm, the mature virus particles are released by cell lysis (Fig. 2.5, path C1).
Typically transmitted by the fecal–oral route, most enteroviral infections are either asymptomatic or subclinical. However, the disease spectrum can range from undifferentiated febrile illness, often accompanied by upper respiratory tractsymptoms, to potentially fatal neurologic outcomes. Aseptic meningitis is associated with many coxsackievirus group A and B serotypes, echoviruses, and the polioviruses. Encephalitis and sporadic paralysis are most commonly associated with coxsackieviruses A5–7 (not encephalitis for A5 and A6), A9, and B1–5, echoviruses 6 and 9, and enterovirus 71. The polioviruses are classically associated with flaccid motor paralysis. Chronic meningoencephalitis caused by echoviruses and some coxsackieviruses has been reported in patients with defects in B-lymphocyte function. Viruses of the newly identified Parechovirus genus have been associated with aseptic meningitis, meningoencephalitis, and neonatal encephalitis with white-matter injury (Romero and Selvarangan, 2011).
Although no antivirals are available for picornaviruses, live and attenuated vaccines have brought control of polio to near eradication (Pliaka et al., 2012).
SqMV belongs to genus Comovirus, family Secoviridae, within the recently defined order Picornavirales. It has a bipartite single-stranded positive-sense RNA genome, with a 5′ bound VPg and a 3′ polyadenylated tail. Virions are small isometric particles circa 30 nm in diameter. RNA 1 (5.9 kb) is translated in a single polyprotein that is processed into five domains: a 32-kDa protein (P1A) that regulates the processing of the rest of the polyprotein, a 58-kDa RNA helicase, a VPg, a 24-kDa protease and a 87-kDa RdRp. RNA 2 (3.3 kb) is translated into two largely overlapping polyproteins using different initiation codons in the same frame, and cleaved by RNA 1 protease, enhanced by P1A, into three domains: a 50-kDa/40 kDa movement protein and two CPs, CPL (42 kDa) and CPS (22 kDa).
Hepatitis A Virus (HAV), also known as Hepatovirus A, belongs to the order Picornavirales in the family Picornaviridae and is the type species of the genus Hepatovirus. It is an icosahedral, non-enveloped virus with a monopartite, positive, single-stranded RNA genome. Humans and vertebrates serve as natural hosts. There is a single serotype of HAV but several genotypes: IA, IB, IIA, IIB, IIIA, IIIB primarily in humans and IV–VI, primarily found in non-human primates (Cristina and Costa-Mattioli, 2007). The virus infects hepatocytes and Kupffer cells (liver macrophages).
The family Picornaviridae is now included with the families Dicistroviridae, Iflaviridae, Marnaviridae, and Secoviridae in the Order Picornavirales. All viruses within this order share the following features: (1) conserved RNA-dependent RNA polymerase; (2) a genome that has a protein (VPg) attached to the 5′ end; (3) absence of overlapping open reading frameswithin the genome; and (4) viral RNA translated into a polyprotein before processing. Viruses within the families Iflaviridae, Marnaviridae, and Secoviridae infect only insects, plants, or algae and will not be considered further in this chapter. Viruses in the family Dicistroviridae infect insects and crustaceans, and the disease, designated as “Taura syndrome,” has resulted in devastating losses in shrimp farms.
The family Picornaviridae has undergone a significant expansion in recent years, due principally to the identification of previously unknown picornaviruses by the “next-generation” sequencing of clinical and environmental samples. The family is divided currently into 29 genera, of which 23 include only a single virus species. In addition to the well-established genera of Aphthovirus, Enterovirus, Teschovirus, Cardiovirus, Erbovirus, Kobuvirus, Hepatovirus, and Parechovirus, the identification and comparative analysis of new and existing picornavirus genomes has resulted in the creation of 21 new genera: Aquamavirus, Avihepatovirus, Avisivirus, Cosavirus, Dicipivirus, Gallivirus, Hunnivirus, Kunsagivirus, Megrivirus, Mischivirus, Mosavirus, Oscivirus, Pasivirus, Passerivirus, Rosavirus, Sakobuvirus, Salivirus, Sapelovirus, Senecavirus, Sicinivirus, and Tremovirus. The genus Enterovirus is the largest genus within the family and contains viruses with most relevance to human medicine; included in this genus are enteroviruses that use the gastrointestinal tract as the primary site of replication (eg, polio-, echo-, and coxsackie viruses), as well as the rhinoviruses that infect the upper respiratory tract. With the exception of the aphthoviruses that are yet to be changed, picornavirus species have been renamed recently to remove host species names that have been replaced with alphabetical assignments. Given the seemingly ever-changing and potentially confusing taxonomic organization of picornaviruses, coupled with the fact that taxonomic assignments do not consistently correlate with the biological behavior of individual picornaviruses (including the nature of the disease they induce in animals, if any), this chapter will be organized according to animal species rather than the taxonomic assignment of each virus. Important picornaviruses in human and veterinary medicine are listed in Table 26.1.
The HaRNAV genome is composed of one molecule of positive sense ssRNA that exhibits the 2C-3Cpro-3Dpolgene order, and the particles are icosahedral with a diameter of about 25 nm, criteria that are consistent with placing the family Marnaviridaewithin the order Picornavirales. However, the structure of the viral genome and the patterns of sequence relationships of HaRNAV proteins to those of other viruses within the Picornavirales clearly show that HaRNAV does not belong within any of the other established families. The HaRNAV genome structure is most like the potyviruses (e.g., tobacco etch virus) in that the non-structural protein domains are located at the N-terminus and the structural proteins are at the C-terminusin a single large polyprotein encoded on a mono-partite genome. However, potyvirus capsids are filamentous and phylogenetic analyses demonstrated no significant relationship with this family (Figure 3). Moreover, a phylogenetic analysis of picorna-like RdRps does not place the HaRNAV sequence within any established family of picorna-like viruses (Figure 3).
The family Picornaviridae is now included with the families Dicistroviridae, Iflaviridae, Marnaviridae, and Secoviridae in the Order Picornavirales. All viruses within this order share the following features: (1) conserved RNA-dependent RNA polymerase; (2) a genome that has a protein (VPg) attached to the 5′ end; (3) absence of overlapping open reading frameswithin the genome; and (4) viral RNA translated into a polyprotein before processing. Viruses within the families Iflaviridae, Marnaviridae, and Secoviridae infect only insects, plants, or algae and will not be considered further in this chapter. Viruses in the family Dicistroviridae infect insects and crustaceans, and the disease, designated as “Taura syndrome,” has resulted in devastating losses in shrimp farms.
The family Picornaviridae has undergone a significant expansion in recent years, due principally to the identification of previously unknown picornaviruses by the “next-generation” sequencing of clinical and environmental samples. The family is divided currently into 29 genera, of which 23 include only a single virus species. In addition to the well-established genera of Aphthovirus, Enterovirus, Teschovirus, Cardiovirus, Erbovirus, Kobuvirus, Hepatovirus, and Parechovirus, the identification and comparative analysis of new and existing picornavirus genomes has resulted in the creation of 21 new genera: Aquamavirus, Avihepatovirus, Avisivirus, Cosavirus, Dicipivirus, Gallivirus, Hunnivirus, Kunsagivirus, Megrivirus, Mischivirus, Mosavirus, Oscivirus, Pasivirus, Passerivirus, Rosavirus, Sakobuvirus, Salivirus, Sapelovirus, Senecavirus, Sicinivirus, and Tremovirus. The genus Enterovirus is the largest genus within the family and contains viruses with most relevance to human medicine; included in this genus are enteroviruses that use the gastrointestinal tract as the primary site of replication (eg, polio-, echo-, and coxsackie viruses), as well as the rhinoviruses that infect the upper respiratory tract. With the exception of the aphthoviruses that are yet to be changed, picornavirus species have been renamed recently to remove host species names that have been replaced with alphabetical assignments. Given the seemingly ever-changing and potentially confusing taxonomic organization of picornaviruses, coupled with the fact that taxonomic assignments do not consistently correlate with the biological behavior of individual picornaviruses (including the nature of the disease they induce in animals, if any), this chapter will be organized according to animal species rather than the taxonomic assignment of each virus. Important picornaviruses in human and veterinary medicine are listed in Table 26.1.
Table 26.1. Genera and Species of Picornaviruses Causing Important Diseases of Animals and Humans
Genus
Virus Species
Hosts Affected
Disease/Comments
Aphthovirus
Foot-and-mouth disease viruses
Cattle, sheep, swine, goats, wildlife ruminant species
Foot-and-mouth disease; 7 serotypes
Equine rhinitis A virus
Horses, camelids
Systemic infection with respiratory signs
Bovine rhinitis A virus
Cattle
Mild respiratory signs
Bovine rhinitis B virus
Cattle
Mild respiratory signs
Avihepatovirus
Avihepatovirus A [Duck hepatitis A virus]a
Duck
Hepatitis
Cardiovirus
Cardiovirus A [Encephalomyocarditis virus]
Rodents, swine, elephants, primates, mammals in contact with rodents
Encephalomyelitis and myocarditis in swine and elephants; rarely in other species; 2 serotypes
Asymptomatic or mild enteric, respiratory, reproductive disease; 4 types
Enterovirus F [Bovine enterovirus group B]
Cattle
Asymptomatic or mild enteric, respiratory, reproductive disease; 6 types
Enterovirus G [Porcine enterovirus B]
Swine, ovine
Usually asymptomatic infection; 11 serotypes
Enterovirus H
Simian
Usually asymptomatic infection
[Simian enterovirus A]
Enterovirus J
Simian
Usually asymptomatic infection; 6 types
Rhinovirus A, B, and C [Human rhinovirus A, B, and C]
Humans
Respiratory disease; 80 (A), 32 (B), and 54 (C) serotypes
Erbovirus
Erbovirus A [Equine rhinitis B virus]
Equine
Associated with mild rhinitis
Kobuvirus
Aichivirus A [Aichi virus]
Humans, canine, feline, rodents, birds
Gastroenteritis, enteric infections
Aichivirus B [Bovine kobuvirus]
Ovine, bovine, ferret
Detected in feces and serum
Aichivirus C [Porcine kobuvirus]
Swine
Fecal detection
Megrivirus
Melegrivirus A
Chickens, turkeys, ducks
Fecal detection, associated with hepatitis in turkeys
Sapelovirus
Avian sapelovirus
Ducks
Hepatitis
Sapelovirus A [Porcine sapelovirus/porcine enterovirus A]
Swine
Diarrhea
Sapelovirus B [Simian sapelovirus]
Simian
Teschovirus
Teschovirus A [Porcine teschovirus]
Swine
Type 1; encephalomyelitis
Types 2–13; mild/asymptomatic
Tremovirus
Tremovirus A [Avian encephalomyelitis virus]
Chicken, pheasant, turkey, quail
Encephalomyelitis
a
Parentheses[] indicate former (and often commonly used) names of individual viruses.
A significant difference among viruses in the various picornavirus genera is their stability at low pH; such differences were utilized in the classification of picornaviruses before molecular techniques were available. Specifically, the aphthoviruses are unstable below pH 7, whereas the enteroviruses, hepatoviruses, cardioviruses, and parechovirusesare stable at pH 3. However, other major similarities and differences were identified with the availability of complete genomic sequence data. All picornaviruses are single-stranded, positive-sense RNA viruses with a 5′-untranslated region (5′-UTR). The RNA is uncapped, but with a viral protein (VPg) covalently linked to the 5′ end. There are major structural differences in the 5′-UTR among the genera of the picornavirus family: the length of the 5′-UTR in picornaviruses varies from approximately 500 to 1200nt and contains one of at least five different internal ribosome entry sites (IRESs). Cardioviruses, aphthoviruses, erboviruses, kobuviruses, teschoviruses, and sapeloviruses are among the 16 genera that are also distinguished by the presence of a leader protein (L) encoded upstream of the capsid proteins (Fig. 26.1). Foot-and-mouth disease virus, aquamavirus A, mosavirus A, and possibly passerivirus A all have multiple (2–3), but not identical VPgproteins that are present in equimolar amounts among the virion RNAs. Other virus species within each genus do not necessarily contain multiple copies of VPg.
Figure 26.1. Genome structure and gene organization of selected members of the family Picornaviridae. Circles within the 5′-UTR indicate poly(C) tracts that are present in some members. The 1A gene products of many members are myristoylated at the amino terminal glycine. The 5′-UTR is followed by a long open reading frame (ORF) encoding the polyprotein, that is in turn followed by the 3′ UTR and a poly(A) tail. The eventual cleavage products of the polyprotein are indicated by vertical lines and different shading. The nomenclature of the polypeptides follows an L:4:3:4 schema corresponding to the genes (numbers) encoded by the L, P1, P2, P3 regions. The P1 region encodes the structural proteins 1A, 1B, 1C, and 1D, also referred to as VP4, VP2, VP3 and VP1, respectively. VP0 (1AB) is the intermediate precursor for VP4 and VP2 and in avihepato-, kobu- and parechoviruses it remains uncleaved. In all viruses 3C is a protease, in enteroviruses 2A is a protease, while in all viruses 3D is considered to be a component of the RNA replicase. Foot-and-mouth disease virus encodes 3 VPg proteins that map in tandem. 2A, 2B, 2C, 2B3, 3A, 3B, 3B2, 3C, 3D, nonstructural proteins; L, leader protein; VP0–4, viral structural proteins.
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