Feline leukemia virus: occurrence of viral antigen in the tissues of cats with lymphosarcoma and other diseases.

Felinie leutkemia viruts antigen is demonstrable by immunodiffusion with rabbit precipitating antiserum to purified felinie leukemia virus. The felinie leukemia virus antigen was found in the tissues of 25 of 33 cats with lymphosarcoma and of 5 of 13 cats with infectious peritonitis. Its presence was correlated with the occurrence of felinie leukemia virus demonstrable by electron microscopy. The one clinically normal cat giving a positive test for feline leukemia virus antigen belonged to a household in which two cats had developed lymphosarcoma. With the exception of a dog with lymphosarcoma induced by feline leukemia virus, the antigent was absent from lymphosarcoma and nonlymphomatous tumors of other species (man, dog, cow, goat, or pig).