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Topic:Equine Infectious Anemia
Equine Infectious Anemia (EIA) is a viral disease affecting horses, caused by the Equine Infectious Anemia Virus (EIAV), a member of the Lentivirus genus. The disease is characterized by intermittent fever, anemia, edema, and weight loss, though some horses may remain asymptomatic carriers. Transmission occurs primarily through blood-feeding insects such as horseflies and deerflies, or through contaminated instruments. EIA is diagnosed using serological tests, with the Coggins test being a commonly used method for detection. There is no vaccine or cure for EIA, and management primarily focuses on prevention and control measures to limit transmission. This page assembles peer-reviewed studies and scholarly articles that explore the pathogenesis, epidemiology, diagnostic methods, and management strategies related to Equine Infectious Anemia.
Free-virus and cell-to-cell transmission in models of equine infectious anemia virus infection. Equine infectious anemia virus (EIAV) is a lentivirus in the retrovirus family that infects horses and ponies. Two strains, referred to as the sensitive strain and the resistant strain, have been isolated from an experimentally-infected pony. The sensitive strain is vulnerable to neutralization by antibodies whereas the resistant strain is neutralization-insensitive. The sensitive strain mutates to the resistant strain. EIAV may infect healthy target cells via free virus or alternatively, directly from an infected target cell through cell-to-cell transfer. The proportion of transmission from f...
Proteomic alteration of equine monocyte-derived macrophages infected with equine infectious anemia virus. Similar to the well-studied viruses human immunodeficiency virus (HIV)-1 and simian immunodeficiency virus (SIV), equine infectious anemia virus (EIAV) is another member of the Lentivirus genus in the family Retroviridae. Previous studies revealed that interactions between EIAV and the host resulted in viral evolution in pathogenicity and immunogenicity, as well as adaptation to the host. Proteomic analysis has been performed to examine changes in protein expression and/or modification in host cells infected with viruses and has revealed useful information for virus-host interactions. In this ...
The efficacy of ELISA commercial kits for the screening of equine infectious anemia virus infection. The most used and reliable indicator of Equine infectious anemia virus (EIAV) infection is the detection of its specific antibodies in horse serum. In the present study, the performance of two commercial ELISA tests for the detection of EIAV antibodies as well as the potential advantages of their use as an EIAV infection screening tool were evaluated in 302 horse serum samples. Both ELISA assays showed 100% diagnostic sensitivity, and 92.3-94.3% diagnostic specificity. Discordant results were analyzed by immunoblot. The results showed that both ELISA tests are very efficient at detecting EIAV ...
High genetic diversity of equine infectious anaemia virus strains from Slovenia revealed upon phylogenetic analysis of the p15 gag gene region. The equine infectious anaemia virus (EIAV), which belongs to the Retroviridae family, infects equids almost worldwide. Every year, sporadic EIAV cases are detected in Slovenia. Objective: To characterise the Slovenian EIAV strains in the p15 gag gene region phylogenetically in order to compare the Slovenian EIAV strains with EIAV strains from abroad, especially with the recently published European strains. Methods: Cross-sectional study using material derived from post mortem examination. Methods: In total, 29 EIAV serologically positive horses from 18 different farms were examined in this stu...
Freedom from equine infectious anaemia virus infection in Spanish Purebred horses. No cases of equine infectious anaemia (EIA) have been reported in Spain since 1983. Factors that could increase the risk of reintroducing equine infectious anaemia virus (EIAV) into Spain include the recent occurrence of the disease in Europe and the absence of compulsory serological testing before importation into Spain. Objective: Given the importance of the Spanish Purebred (SP) horse breeding industry in Spain, the aim of this cross-sectional study was to provide evidence of freedom from EIAV in SP stud farms in Central Spain. Methods: Serum samples from 555 SP horses, collected between Se...
Serosurveillance of infectious agents in equines of the Central Valley of Costa Rica. Blood samples from 181 equines from the Central Valley of Costa Rica were collected in the year 2012 to determine the presence of antibodies against selected infectious agents in horses and to determine the risk factors associated with these agents. The presence of antibodies against Equine Infectious Anemia Virus (EIAV), Equine Herpes Virus 1 and 4 (EHV-1 and EHV-4), West Nile Virus (WNV), Influenza A Virus (IAV), Equine Viral Arteritis Virus (EVAV), Babesia caballi, Theileria equi, Neospora caninum and Chlamydia abortus was determined using commercial assays, and risk factors associated with...
A unique evolution of the s2 gene of equine infectious anemia virus in hosts correlated with particular infection statuses. Equine infectious anemia virus (EIAV) is a member of the Lentivirus genus in the Retroviridae family that exhibits a genomic structure similar to that of HIV-1. The S2 accessory proteins play important roles in viral replication in vivo and in viral pathogenicity; however, studies on S2 evolution in vivo are limited. This study analyzed the evolutionary characteristics of the S2 gene of a pathogenic EIAV strain, EIAVLN40, in four experimentally infected horses. The results demonstrated that 14.7% (10 of 68 residues) of the stable amino acid mutations occurred longitudinally in S2 during a 150-...
Equine infectious anemia in 2014: live with it or eradicate it? In the absence of an effective vaccine, the success of the test and removal approach for the control of equine infectious anemia (EIA) cannot be overstated, at least in those areas where testing has been traditionally routine. This article addresses 4 main aspects: what has been learned about EIA virus, host control of its replication, and inapparent carriers; international status regarding the control of EIA; diagnostic and laboratory investigation; and reducing the spread of blood-borne infections by veterinarians. An attempt is made to put these issues into practical contemporary perspectiv...
Prevalence of antibodies against influenza virus in non-vaccinated equines from the Brazilian Pantanal. The prevalence of antibodies against Equine Influenza Virus (EIV) was determined in 529 equines living on ranches in the municipality of Poconé, Pantanal area of Brazil, by means of the hemagglutination inhibition test, using subtype H3N8 as antigen. The distribution and possible association among positive animal and ranches were evaluated by the chi-square test, spatial autoregressive and multiple linear regression models. The prevalence of antibodies against EIV was estimated at 45.2% (95% CI 30.2 - 61.1%) with titers ranging from 20 to 1,280 HAU. Seropositive equines were found on 92.0% of...
Antiviral potency and functional analysis of tetherin orthologues encoded by horse and donkey. Tetherin is an interferon-inducible host cell factor that blocks the viral particle release of the enveloped viruses. Most knowledge regarding the interaction between tetherin and viruses has been obtained using the primate lentiviral system. However, much less is known about the functional roles of tetherin on other lentiviruses. Equine infectious anemia virus (EIAV) is an important macrophage-tropic lentivirus that has been widely used as a practical model for investigating the evolution of the host-virus relationship. The host range of EIAV is reported to include all members of the Equidae ...
Comparative analysis of LTR and structural genes in an equine infectious anemia virus strain isolated from a feral horse in Japan. Although equine infectious anemia virus (EIAV) poses a major threat to the equine industry worldwide, the molecular epidemiology of this virus is poorly understood. Recently, an EIAV strain (EIAVMiyazaki2011-A) representing a new monophyletic group was discovered in feral horses in southern Japan. In the present study, the EIAVMiyazaki2011-A proviral genome is compared with evolutionarily divergent EIAV isolates to investigate conservation of functional elements or motifs within the long terminal repeats (LTRs) and structural genes. This analysis represents a significant step forward in increa...
Equine viperin restricts equine infectious anemia virus replication by inhibiting the production and/or release of viral Gag, Env, and receptor via distortion of the endoplasmic reticulum. Viperin is an endoplasmic reticulum (ER)-associated multifunctional protein that regulates virus replication and possesses broad antiviral activity. In many cases, viperin interferes with the trafficking and budding of viral structural proteins by distorting the membrane transportation system. The lentivirus equine infectious anemia virus (EIAV) has been studied extensively. In this study, we examined the restrictive effect of equine viperin (eViperin) on EIAV replication and investigated the possible molecular basis of this restriction to obtain insights into the effect of this cellular facto...
Epitope shifting of gp90-specific cellular immune responses in EIAV-infected ponies. Unlike other lentiviruses, EIAV replication can be controlled in most infected horses leading to an inapparent carrier state free of overt clinical signs which lasts for many years. While the resolution of the initial infection is correlated with the appearance of virus specific cellular immune responses, the precise immune mechanisms responsible for control of the infection are not yet identified. Since the virus undergoes rapid mutation following infection, the immune response must also adapt to meet this challenge. We hypothesize that this adaptation involves peptide-specific recognition sh...
Infection of equine monocyte-derived macrophages with an attenuated equine infectious anemia virus (EIAV) strain induces a strong resistance to the infection by a virulent EIAV strain. The Chinese attenuated equine infectious anemia virus (EIAV) vaccine has successfully protected millions of equine animals from EIA disease in China. Given that the induction of immune protection results from the interactions between viruses and hosts, a better understanding of the characteristics of vaccine strain infection and host responses would be useful for elucidating the mechanism of the induction of immune protection by the Chinese attenuated EIAV strain. In this study, we demonstrate in equine monocyte-derived macrophages (eMDM) that EIAVFDDV13, a Chinese attenuated EIAV strain, indu...
[Equine infectious anemia–a review]. This article combines essential facts of equine infectious anemia. Beside etiology and epidemiology, emphasis is put on the clinical course and laboratory diagnosis. Finally, control measures and prophylactic issues are discussed.
Identifying the Conditions Under Which Antibodies Protect Against Infection by Equine Infectious Anemia Virus. The ability to predict the conditions under which antibodies protect against viral infection would transform our approach to vaccine development. A more complete understanding is needed of antibody protection against lentivirus infection, as well as the role of mutation in resistance to an antibody vaccine. Recently, an example of antibody-mediated vaccine protection has been shown via passive transfer of neutralizing antibodies before equine infectious anemia virus (EIAV) infection of horses with severe combined immunodeficiency (SCID). Viral dynamic modeling of antibody protection from EIAV ...
Epizootiological investigation of the most important infectious equine diseases in Greece. During the period 2001 to 2008, a total of 7,872 equine sera were tested at the Centre of Veterinary Institutes of Athens. Antibodies against seven infectious diseases of equids were determined: equine infectious anaemia (EIA), African horse sickness (AHS), equine viral arteritis (EVA), West Nile encephalitis (WNE), glanders, piroplasmosis and dourine. Tests for the four viral diseases found 4.5% seropositivity for EIA, 0% for AHS, 3.3% for EVA and 4% for WNE. All sera tested for glanders antibodies were negative. Tests for piroplasmosis detected antibodies against T. equi and B. caballi in 12...
Structural and biochemical insights into the V/I505T mutation found in the EIAV gp45 vaccine strain. The equine infectious anemia virus (EIAV) is a lentivirus of the Retrovirus family, which causes persistent infection in horses often characterized by recurrent episodes of high fever. It has a similar morphology and life cycle to the human immunodeficiency virus (HIV). Its transmembrane glycoprotein, gp45 (analogous to gp41 in HIV), mediates membrane fusion during the infection. However, the post-fusion conformation of EIAV gp45 has not yet been determined. EIAV is the first member of the lentiviruses for which an effective vaccine has been successfully developed. The attenuated vaccine strai...
Use of heavy water (D2O) in developing thermostable recombinant p26 protein based enzyme-linked immunosorbent assay for serodiagnosis of equine infectious anemia virus infection. Thermostabilizing effect of heavy water (D2O) or deuterium oxide has been demonstrated previously on several enzymes and vaccines like oral poliovirus vaccine and influenza virus vaccine. In view of the above observations, effect of heavy water on in situ thermostabilization of recombinant p26 protein on enzyme-linked immunosorbent assay (ELISA) for serodiagnosis of equine infectious anemia virus (EIAV) infection was investigated in the present study. The carbonate-bicarbonate coating buffer was prepared in 60% and 80% D2O for coating the p26 protein in 96-well ELISA plate and thermal stabilit...
Comprehensive analysis of the overall codon usage patterns in equine infectious anemia virus. Equine infectious anemia virus (EIAV) is an important animal model for understanding the relationship between viral persistence and the host immune response during lentiviral infections. Comparison and analysis of the codon usage model between EIAV and its hosts is important for the comprehension of viral evolution. In our study, the codon usage pattern of EIAV was analyzed from the available 29 full-length EIAV genomes through multivariate statistical methods. Results: Effective number of codons (ENC) suggests that the codon usage among EIAV strains is slightly biased. The ENC-plot analysis d...
Lessons in AIDS vaccine development learned from studies of equine infectious, anemia virus infection and immunity. Equine infectious anemia (EIA), identified in 1843 [1] as an infectious disease of horses and as a viral infection in 1904, remains a concern in veterinary medicine today. Equine infectious anemia virus (EIAV) has served as an animal model of HIV-1/AIDS research since the original identification of HIV. Similar to other lentiviruses, EIAV has a high propensity for genomic sequence and antigenic variation, principally in its envelope (Env) proteins. However, EIAV possesses a unique and dynamic disease presentation that has facilitated comprehensive analyses of the interactions between the evolv...
Interstitial lung disease associated with Equine Infectious Anemia Virus infection in horses. EIA (Equine Infectious Anemia) is a blood-borne disease primarily transmitted by haematophagous insects or needle punctures. Other routes of transmission have been poorly explored. We evaluated the potential of EIAV (Equine Infectious Anemia Virus) to induce pulmonary lesions in naturally infected equids. Lungs from 77 EIAV seropositive horses have been collected in Romania and France. Three types of lesions have been scored on paraffin-embedded lungs: lymphocyte infiltration, bronchiolar inflammation, and thickness of the alveolar septa. Expression of the p26 EIAV capsid (CA) protein has been...
The soluble form of the EIAV receptor encoded by an alternative splicing variant inhibits EIAV infection of target cells. Equine lentivirus receptor 1 (ELR1) has been identified as the sole receptor for equine infectious anemia virus (EIAV) and is a member of the tumor necrosis factor receptor (TNFR) superfamily. In addition to the previously described membrane-associated form of ELR1, two other major alternative splicing variant mRNAs were identified in equine monocyte-derived macrophages (eMDMs). One major spliced species (ELR1-IN) contained an insertion of 153 nt, which resulted in a premature stop codon situated 561 nt upstream of the predicted membrane spanning domain. The other major species (ELR1-DE) has a...
Understanding virus-host dynamics following EIAV infection in SCID horses. We develop a mathematical model for the interaction between two competing equine infectious anemia virus strains and neutralizing antibodies. We predict that elimination of one or both virus strains depends on the initial antibody levels, the strength of antibody mediated neutralization, and the persistence of antibody over time. We further show that the ability of a subdominant, neutralization resistant virus to dominate the infection transiently or permanently is dependent on the antibody-mediated neutralization effect. Finally, we determine conditions for persistence of both virus strains. ...
Equine tetherin blocks retrovirus release and its activity is antagonized by equine infectious anemia virus envelope protein. Human tetherin is a host restriction factor that inhibits replication of enveloped viruses by blocking viral release. Tetherin has an unusual topology that includes an N-terminal cytoplasmic tail, a single transmembrane domain, an extracellular domain, and a C-terminal glycosylphosphatidylinositol anchor. Tetherin is not well conserved across species, so it inhibits viral replication in a species-specific manner. Thus, studies of tetherin activities from different species provide an important tool for understanding its antiviral mechanism. Here, we report cloning of equine tetherin and charact...
Inhibition of virus replication and induction of human tetherin gene expression by equine IFN-α1. Type I interferons (IFNs) play important roles in the defense of host cells against viral infection by inducing the expression of a diverse range of antiviral factors. IFNs from different animals likely share similar features with human IFNs, and some of them have cross-species activities. Equine IFN-α was proved effective in both equine and human cells. However, the previous studies mostly focused on the inhibition of virus induced cytopathic effects. In this study, we used virus-specific assays to demonstrate the antiviral activities of equine IFN-α1 in both equine and human cells. Equine ...
Detection and molecular characterisation of equine infectious anaemia virus from field outbreaks in Slovenia. In 2009, a surprisingly high number of animals seropositive for equine infectious anaemia virus (EIAV; 26 horses from 13 farms) were detected in Slovenia. Objective: To develop a polymerase chain reaction (PCR) assay for the detection of the proviral nucleic acid, to phylogenetically characterise the Slovenian EIAV strains and to investigate whether transmission in utero occurred. Methods: Cross-sectional clinical study. Methods: In total, 26 horses (including 2 foals and 4 pregnant mares) and 4 fetuses were examined in this study. A PCR assay using the EIAV F1 and EIAV R1 primers was designed...
From glanders to Hendra virus: 125 years of equine infectious diseases. Josh Slater looks back at the past 125 years of developments in equine infectious disease, including landmark discoveries in microbiology and genomics, and considers what the future may hold.
