Equine Arteritis Virus Resistance (EAVR)
Gene or Region: CXCL16 on ECA11: 50.08 Mb – 50.09 Mb (EquCab3.0)
Reference Variant: AGTG or “Resistant”
Mutant Variant: TCAA or TCGA or “Susceptible”
Affected Breeds: Thoroughbred, Saddlebred, Standardbred, Quarter Horse, Warmblood and others
Research Confidence: Preliminary - Strong correlation in early studies, association was present in multiple breeds with strong candidate genes in the region
Explanation of Results: EAVR/EAVR = homozgygous for Equine Arteritis Virus Resistance EAVR/n = heterozygous for Equine Arteritis Virus Resistance n/n = no variant detected
General Description
Equine Viral Arteritis is an infectious disease with a broad range of symptoms, though most horses will not display any overt signs. However, infection with EAV can result in abortions in pregnant mares, and some stallions persistently shed the virus through their semen. Infection prevalence has been reported to vary among breeds, indicating a genetic component to resistance/susceptibility.
The measured SNPs in CXCL16 were reported to be associated with susceptibility of CD3+ lymphocytes to EAV infection. When all four studied breeds were grouped together, the “AGTG” group of alleles was present in 0% of susceptible horses and 100% of resistant horses. Out of these resistant genotypes, 86% were non-shedder, whereas of the susceptible genotype, 74% were shedder. Thus, a horse that genotypes homozygous “AGTG” for all 4 of these SNPs are classified as at a lower risk for susceptibility to infection.
References
Sarkar S et al., “Allelic Variation in CXCL16 Determines CD3+ T Lymphocyte Susceptibility to Equine Arteritis Virus Infection and Establishment of Long- Term Carrier State in the Stallion.” (2016) PLOS Genetics | DOI:10.1371/journal.pgen.1006467.
Go YY et al., “Genome-wide association study among four horse breeds identifies a common haplotype associated with in vitro CD3+ T cell susceptibility/resistance to equine arteritis virus infection.” (2011) J Virol. 85: 13174-84. PMID: 21994447
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