Dr. Udeni Balasuriya, in collaboration with Dr. Peter Timoney and Dr. Ernie Bailey at the Gluck Equine Research Center, have discovered a genetic basis for the likelihood of a stallion becoming a long term shedder/carrier of the Equine Arteritis Virus (EAV) following infection with the virus.Stallions possessing the Susceptible haplotype, consisting of four specific nucleotide changes in the CXCL16 gene, are significantly more likely to remain permanent carriers of the virus in their reproductive tract than are horses that possess the Resistant haplotype. Stallions homozygous for the Resistant CXCL16 haplotype, while initially shedding the virus in their semen following infection, were found in most cases to clear the virus from the reproductive tract within months following infection. Stallions possessing even one copy of the Susceptible haplotype (heterozygotes) are at greater risk for becoming permanent shedders of EAV.

Since the common course of action following the diagnosis of a stallion as an EAV shedder is castration, this test can identify which horses may indeed become clear of the virus, thus preventing the loss of a valuable breeding animal. In addition, the test indicates which horses have the Susceptible haplotype and therefore are at higher risk for becoming shedders if infected with EAV. In these cases management practices can be implemented such as vaccination and limiting opportunities to become infected.

This work was funded by a grant from USDA-NIFA