ABROGATION OF RESISTANCE TO FELINE ONCORNAVIRUS DISEASE BY IMMUNIZATION WITH KILLED FELINE LEUKEMIA-VIRUS

Abstract

Four week old specific pathogen free cats were immunized with a combined vaccine composed of killed feline leukemia virus and killed feline oncornavirus associated cell membrane antigen containing tumor cells. Immunization induced feline oncornavirus associated cell membrane antigen antibody titers ranging from 1:32-1:256 but did not elicit detectable virus neutralizing antibody titers. Kittens immunized with tumor cells alone developed higher feline oncornavirus associated cell membrane antigen antibody titers (ranging from 1:512-1:2048) than those given the combined vaccine. All kittens were challenged with virulent Snyder-Theilen feline sarcoma virus at 12 wk of age. Seventy-five percent of the kittens vaccinated with combined vaccine and 67% of unvaccinated control kittens developed progressive fibrosarcomas after challenge. None of the kittens vaccinated with tumor cells alone developed progressive fibrosarcomas after challenge. The combined vaccine did not inhibit the induction of feline leukemia virus viremia.