OAS1 polymorphisms are associated with susceptibility to West Nile encephalitis in horses.
Authors: Rios Jonathan J, Fleming Joann G W, Bryant Uneeda K, Carter Craig N, Huber John C, Long Maureen T, Spencer Thomas E, Adelson David L
Journal: PloS one
Summary
West Nile virus has presented a significant threat to equine populations since entering the United States in 1999, yet the genetic factors underlying individual horse susceptibility remained unexplored until this research. Using a case-control approach, researchers investigated whether polymorphisms in the equine OAS1 gene—part of the innate immune system's interferon-responsive defences—could explain the variation in clinical outcomes observed across naturally exposed horse populations, drawing parallels with established associations in human and murine studies. The team identified single nucleotide polymorphisms in equine OAS1 and the related RNASEL gene, with statistical analysis revealing that OAS1 mutations significantly correlate with susceptibility to severe West Nile encephalitis; critically, these polymorphisms clustered within the interferon-inducible promoter region rather than the coding sequence. This localisation suggests that disease resistance may hinge on differential gene expression rather than protein structure, indicating that horses carrying certain OAS1 variants produce inadequate OAS1 protein levels during viral challenge. For equine practitioners, these findings offer potential markers for identifying high-risk individuals and could eventually inform selective breeding strategies or inform targeted immunological support protocols for susceptible animals during WNV exposure.
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Practical Takeaways
- •Horses with specific OAS1 genetic variants may have increased susceptibility to severe West Nile encephalitis; genetic screening could identify at-risk individuals for preventive management
- •Understanding genetic predisposition to WNV allows for targeted vaccination strategies and monitoring protocols for genetically susceptible horses
- •OAS1 polymorphisms represent a heritable risk factor that breeding programs could potentially select against to improve population-level resistance
Key Findings
- •Single nucleotide polymorphisms in equine OAS1 gene are associated with susceptibility to severe West Nile virus infection
- •OAS1 polymorphisms are predominantly located within the interferon-inducible promoter region
- •Differences in OAS1 gene expression may determine resistance to clinical manifestations of WNV infection
- •Equine OAS gene cluster structure closely resembles the human cluster, supporting translational relevance of findings