Equine Infectious Anemia Research Articles

Comparative assessment of the surveillance systems for equine infectious anaemia, equine viral arteritis and contagious equine metritis in France

Equine infectious anemia (EIA) is caused by a persistent lentivirus infection. Infected horses are lifelong reservoirs for vector mediated or iatrogenic transmission of EIA virus (EIAV). No vaccine is currently available or likely to become so. Therefore control of new cases depends upon the time honored strategy of serological identification of carriers and their disposition by quarantine and or slaughter. In the United States EIA prevalence has declined from 4% in 1972 when the control program began to its current prevalence of approximately 0.001%. The agar gel immunodiffusion (AGID) test has been the regulatory test since EIAV control program began 43 years ago. This 4,000 fold reduction in prevalence underscores the effectiveness of the AGID test but it has a couple of drawbacks: it requires 48 hours to read and is not as sensitive as newer serological tests. Alert clinicians, regulators and horse owners seek to implement and facilitate better management of outbreaks, pre purchase evaluations and import/ export requirements. To address the need for a faster and more sensitive assay we carried out this study to compare a USDAlicensed AGID test kit with a USDA-licensed modified indirect ELISA (MI-ELISA) kit. The serum sample from an EIAV carrier horse was serially diluted and used to determine the analytical sensitivity of each assay: the MI-ELISA was 4-fold more sensitive. A Center for Veterinary Biologics proficiency panel (validated by AGID test) of 20 samples was tested: there was 100% concordance between the two assays. Analytical time point samples from 6 experimentally infected horses were collect over a period 4 months (n¼100): analytical sensitivity of experimentally infected horses was comparable for the two assays. The two assays were used to test known weak positive samples collected from nine carrier horses: the AGID test detected only two but the MI-ELISA detected all nine (Table). Due to the speed (45 minutes) and significantly greater sensitivity of the MI-ELISA reflected in the results of this study, screening of routine samples with it and confirmation of positives by the regulatory assay, AGID test, would serve the needs of the equine industry for better and more rapid risk management. Comparison between the modified indirect enzyme-linked immunosorbent assay (MI-ELISA) and agar gel immunodiffusion (AGID) test in the sensitivity against the sera from weak EIA positive carriers

Evidence of Equine Infectious Anemia Virus (EIAV) in horses from Serbia

Evidence of Equine Infectious Anemia Virus (EIAV) in horses from Serbia

Serologically silent, occult equine infectious anemia virus (EIAV) infections in horses

Serologically silent, occult equine infectious anemia virus (EIAV) infections in horses

Equine Infectious Anemia: seroprevalence in the Northeastern region of Argentina

Equine Infectious Anemia: seroprevalence in the Northeastern region of Argentina

Diagnosis and control of Equine Infectious Anemia in a horse farm located in Buenos Aires province, Argentina

M.A. Vissani*, J Reynal O’Connor , C Olguin Perglione , S. Traverso , G. Gutierrez , I. Alvarez , M. Barrandeguy 1,4 1 Instituto de Virologia, CICVyA, INTA-Castelar, 1712 Castelar, Buenos Aires, Argentina; 2 Laboratorio Equino S.R.L, Buenos Aires, Argentina; Consejo Nacional de Investigaciones Cientificas y T ecnicas -CONICET, Buenos Aires, Argentina; C atedra de Enfermedades Infecciosas, Escuela de Veterinaria, Universidad del Salvador, Pilar, Buenos Aires, Argentina

Overview of surveillance of equine infectious anaemia (EIA) in France in 2012

protein epitopes, the sequence alignment of p26 protein was performed for four major monophyletic groups isolated in North American, China, southern Japan and Ireland respectively. The alignment analysis revealed that the defined linear epitopes were not highly conserved. The corresponding mutants were constructed and expressed in HEK293T cells. The cross-reactivity between MAbs and their respective variant epitopes was analyzed with western blotting and AC-ELISA. The results showed that 9H8 could only recognize EIAV strains isolated from China and Japan, while 1G11 could react with all the four EIAV strains. This result indicated that 1G11 have a broadly recognized capacity to p26 epitope from different EIAV strains and could serve as a useful tool for the development of new methods on the anti-EIAV antibody determination.

Development and evaluation of risk-based surveillance (RBS) for equine infectious anemia (EIA)

Development and evaluation of risk-based surveillance (RBS) for equine infectious anemia (EIA)

Evaluation of the diagnostic performance of equine infectious anaemia (EIA) serological ELISAs as screening tools in control programmes

Evaluation of the diagnostic performance of equine infectious anaemia (EIA) serological ELISAs as screening tools in control programmes

Evolution of clinical, virological and histological findings of equine infectious anaemia (EIA) in naturally infected mules following immune suppression

Evolution of clinical, virological and histological findings of equine infectious anaemia (EIA) in naturally infected mules following immune suppression

Detection of Equine Infectious Anemia virus by insulated isothermal RT-PCR (iiRT-PCR) assay using the POCKIT TM Nucleic acid analyzer

Detection of Equine Infectious Anemia virus by insulated isothermal RT-PCR (iiRT-PCR) assay using the POCKIT TM Nucleic acid analyzer

Equine Infectious Anemia diagnosis in a 3 months old foal

within the insect, the infectious virus can remain in its mouthparts for several hours after a bite. Several studies have shown that EIAV infection has occurred among horses in North and South America, France, Germany, Italy and Romania. So far no evidence of the presence of EIAV in horses was reported in Serbia. In order to determine EIA prevalence among the 5000 horses of the Vojvodina region of Serbia, 316 horse sera have been collected during 2013 and 2014. Serological analysis was performed using Agar Gel Immuno Diffusion test (AGID) as described by the World Organization of Animal Health (OIE) chapter 2.5.6 and by Enzyme Linked Immuno Sorbent Assay (ELISA). Those sera have been tested with 3 different commercial AGID test (Idexx, ID-Vet and VMRD) and two different commercial ELISA tests (Synbiotics and VMRD). With the three AGID kit 311 (98,4%) among the 316 tested sera were found negative and only five (1,6%) sera were found positive for EIA. With ELISA kits results were slightly different and were dependent of the kit producer. Indeed, Synbiotics ELISA gave the same results as AGID tests but VMRD ELISA found 295 negative samples, 5 positive samples and 16 samples were doubtfull. Our study shows for the first time that EIA is present in Serbia and more specifically in the Vojvodina region. Euthanasia and viral characterization of field isolate collected in Serbian horses will be investigated.

Seropositivity of Equine infectious anemia by 2005 to 2014 in provinces of north-west of Argentina

Seropositivity of Equine infectious anemia by 2005 to 2014 in provinces of north-west of Argentina

Efficient control of equine infectious anemia carriers by a concerted use of a modified indirect enzyme-linked immunosorbent assay and an agar gel immunodiffusion test

Efficient control of equine infectious anemia carriers by a concerted use of a modified indirect enzyme-linked immunosorbent assay and an agar gel immunodiffusion test

Argentinean agid test for diagnosis of equine infectious anemia: six years of history

Fil: Bok, Marina. Instituto Nacional de Tecnologia Agropecuaria. Centro de Investigacion en Ciencias Veterinarias y Agronomicas. Instituto de Virologia; Argentina. Consejo Nacional de Investigaciones Cientificas y Tecnicas; Argentina

Validation according to OIE criteria of a monoclonal, recombinant p26–based, serologic competitive enzyme-linked immunosorbent assay as screening method in surveillance programs for the detection of Equine infectious anemia virus antibodies

The Italian National Reference Center for equine infectious anemia (CRAIE; Rome, Italy) developed and validated a monoclonal, recombinant p26-based competitive enzyme-linked immunosorbent assay (cELISA) for the detection of EIA virus antibodies employing the 2010 criteria of the World Organization for Animal Health (OIE). The following parameters were evaluated: cutoff values, repeatability, reproducibility, concordance, analytical sensitivity (Se), absolute analytical specificity (Sp), and diagnostic Se and Sp. Positive and negative predictive values were also defined in relation to the estimated prevalence. When the cELISA was used as a screening test for 96,468 samples in the Italian EIA surveillance program, 17% more EIA cases were detected than by the agar gel immunodiffusion test, and the apparent diagnostic Sp estimated from these samples was 99.8%, which was more than the diagnostic Sp (80.2%) estimated from validation. The high Se and Sp of the cELISA confirm its fit for purpose as a screening test.

Structural Illumination of Equine MHC Class I Molecules Highlights Unconventional Epitope Presentation Manner That Is Evolved in Equine Leukocyte Antigen Alleles.

MHC class I (MHC I)-restricted virus-specific CTLs are implicated as critical components in the control of this naturally occurring lentivirus and in the protective immune response to the successfully applied attenuated equine infectious anemia virus vaccine in the horse. Nevertheless, the structural basis for how the equine MHC I presents epitope peptides remains unknown. In this study, we investigated the binding of several equine infectious anemia virus-derived epitope peptides by the ability to refold recombinant molecules and by thermal stability, and then by determining the x-ray structure of five peptide-MHC I complexes: equine MHC class I allele (Eqca)-N*00602/Env-RW12, Eqca-N*00602/Gag-GW12, Eqca-N*00602/Rev-QW11, Eqca-N*00602/Gag-CF9, and Eqca-N*00601/Gag-GW12. Although Eqca-N*00601 and Eqca-N*00602 differ by a single amino acid, Eqca-N*00601 exhibited a drastically different peptide presentation when binding a similar CTL epitope, Gag-GW12; the result makes the previously reported function clear to be non-cross-recognition between these two alleles. The structures plus Eqca-N*00602 complexed with a 9-mer peptide are particularly noteworthy in that we illuminated differences in apparent flexibility in the center of the epitope peptides for the complexes with Gag-GW12 as compared with Env-RW12, and a strict selection of epitope peptides with normal length. The featured preferences and unconventional presentations of long peptides by equine MHC I molecules provide structural bases to explain the exceptional anti-lentivirus immunity in the horse. We think that the beneficial reference points could serve as an initial platform for other human or animal lentiviruses.

Structural and functional characterization of EIAV gp45 fusion peptide proximal region and asparagine-rich layer

Equine infectious anaemia virus (EIAV) and human immunodeficiency virus (HIV) are members of the lentiviral genus. Similar to HIV gp41, EIAV gp45 is a fusogenic protein that mediates fusion between the viral particle and the host cell membrane. The crystal structure of gp45 reported reveals a different conformation in the here that includes the fusion peptide proximal region (FPPR) and neighboring asparagine-rich layer compared with previous HIV-1 gp41 structures. A complicated hydrogen-bond network containing a cluster of solvent molecules appears to be critical for the stability of the gp45 helical bundle. Interestingly, viral replication was relatively unaffected by site-directed mutagenesis of EIAV, in striking contrast to that of HIV-1. Based on these observations, we speculate that EIAV is more adaptable to emergent mutations, which might be important for the evolution of EIAV as a quasi-species, and could potentially contribute to the success of the EIAV vaccine.

Genetic Evolution during the development of an attenuated EIAV vaccine.

BackgroundThe equine infectious anemia virus (EIAV) vaccine is the only attenuated lentiviral vaccine applied on a large scale that has been shown to be effective in controlling the prevalence of EIA in China. This vaccine was developed by successive passaging of a field-isolated virulent strain in different hosts and cultivated cells. To explore the molecular basis for the phenotype alteration of this vaccine strain, we systematically analyzed its genomic evolution during vaccine development.ResultsSequence analysis revealed that the genetic distance between the wild-type strain and six representative strains isolated from key development stages gradually increased with the number of passages. Env gene, but not gag and pol, showed a clear evolutionary flow similar to that of the whole genomes of different generations during the attenuation. Stable mutations were identified in multiple regions of multiple genes along with virus passaging. The adaption of the virus to the growth environment of cultured cells with accumulated genomic and genetic variations was positively correlated with the reduction in pathogenicity and rise of immunogenicity. Statistical analyses revealed significant differences in the frequency of the most stable mutations between in vivo and ex vivo-adapted strains and between virulent and attenuated strains.ConclusionsThese data indicate that EIAV evolution during vaccine development generated an accumulation of mutations under the selective drive force, which helps to better understand the molecular basis of lentivirus pathogenicity and immunogenicity.Electronic supplementary materialThe online version of this article (doi:10.1186/s12977-016-0240-6) contains supplementary material, which is available to authorized users.

Infection with equine infectious anemia virus vaccine strain EIAVDLV121 causes no visible histopathological lesions in target organs in association with restricted viral replication and unique cytokine response

The live equine infectious anemia virus (EIAV) vaccine strain EIAVDLV121 was developed by in vitro attenuation of a virulent strain, EIAVLN40, in the 1970s, and it has been demonstrated to induce protective immunity under laboratory and natural EIAV infection conditions. The detailed biological features of this attenuated virus remain to be further investigated. Experimental inoculation with EIAVDLV121 did not result in clinical symptoms even with immunosuppressive treatment in our previous studies. Here, we further investigated whether the replication of the vaccine strain EIAVDLV121 in experimentally infected horses causes histopathological lesions to develop in the targeted organs. Both the lungs and the spleen have been demonstrated to support EIAV replication. By evaluating the gross macroscopic and histological changes, we found that EIAVDLV121 did not cause detectable histopathological lesions and that it replicated several hundred times more slowly than its parental virulent strain, EIAVLN40, in tissues. Immunochemical assays of these tissues indicated that the primary target cells of EIAVDLV121 were monocytes/macrophages, but that EIAVLN40 also infected alveolar epithelial cells and vascular endothelial cells. In addition, both of these viral strains promoted the up- and down-regulation of the expression of various cytokines and chemokines, implicating the potential involvement of these cellular factors in the pathological outcomes of EIAV infection and host immune responses. Taken together, these results demonstrate that the EIAV vaccine strain does not cause obvious histopathological lesions or clinical symptoms and that it induces a unique cytokine response profile. These features are considered essential for EIAVDLV121 to function as an effective live vaccine.

Horses naturally infected with EIAV harbor 2 distinct SU populations but are monophyletic with respect to IN.

Equine infectious anemia virus (EIAV) causes lifelong infections ranging from acutely fatal, to chronic, to asymptomatic. Within infected animals, EIAV is found as a quasispecies. Many experimental studies on EIAV, carried out in the U.S. over the past 70 years, have used either the highly virulent Wyoming (EIAVWYO) field strain or various derivatives of that strain. These infections have provided insights into the variety of genetic changes that accumulate in the env gene and LTR in experimentally infected horses. In the current study, we obtained EIAV sequences from blood samples collected from naturally infected Texas horses between 2000 and 2002. We found surface (SU) and long terminal repeat (LTR) sequences clearly related to EIAVWYO and its cell culture-adapted derivatives. Some blood samples yielded SU or LTR sequences belonging to 2 discrete clusters. In these cases, SU and LTR variation between animals was no greater than sequence variation within animals. In contrast, a portion of integrase (IN) was more homogeneous within animals than between animals. These results suggest that specific selective pressures are applied to SU and LTR sequences, potentially driving generation of two distinct sequence clusters within a horse. We speculate that viruses in one cluster may be more highly expressed and easily transmitted while those in the second cluster support long-term inapparent infection. The presence of homogeneous IN sequences within a horse supports the hypothesis that SU and LTR sequences diverged after the initial infection.