Canine ASCT1 and ASCT2 are functional receptors for RD-114 virus in dogs

All domestic cats carry an infectious endogenous retrovirus termed RD-114 virus. Recently, we and others found that several live-attenuated vaccines for dogs were contaminated with infectious RD-114 virus. In this study, we confirmed that the RD-114 virus efficiently infected and proliferated well in canine primary kidney cells, as well as three tested canine cell lines. Further, we identified canine ASCT1 and ASCT2, sodium-dependent neutral amino acid transporters, as RD-114 virus receptors. Canine ASCT2 also acts as a functional receptor for simian retrovirus 2, a pathogenic retrovirus that induces immunodeficiency in rhesus macaques. Identification of the canine receptor for RD-114 virus will help in evaluating the risk from vaccines contaminated by the virus.