Identification of Feline Leukemia Virus Variant That Uses THTR1, FLVCR1 and FLVCR2 as Receptors for Infection

The pathogenic subgroup C feline leukemia virus (C virus) arises in infected cats by mutations in the envelope gene (env) of subgroup A FeLV (A virus) that switches the host receptor used for infection. To better understand C virus emergence and potential FeLV variants that may arise, I characterized FeLV Env sequence isolated from the primary FY981 FeLV isolate derived from an anemic cat. I show that the FY981 pseudotype virus is capable of using both the A virus receptor THTR1, and the C virus receptor FLVCR1 for infection, consistent with the FY981 Env being a hybrid A virus/C virus Env. Furthermore, I propose that pathogenic C virus arise in infected cats through FeLV variants or intermediates that are multi-tropic in their receptor use.MAS