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 IFN-α1 inhibited the expression of viral structural proteins and the production of virions of equine infectious anemia virus (EIAV) and equine arteritis virus (EAV) in equine cells. In addition, equine IFN-α1 inhibited the production of EIAV virus-like particles (VLP) from human 293T cells. An IFN-inducible human gene, tetherin, was induced in 293T cells by equine IFN-α1. Its induction correlated with the inhibition of VLP release from the cell membrane. This result indicates that equine IFN-α1 shares a similar mechanism of action with human IFN-α in regulating antiviral genes expression in human cells.