Protection of Cats Against Feline Leukemia Virus-Positive and Virus-Negative Tumors by Complement-Dependent Antibody

Antibodies to feline oncornavirus-associated cell membrane antigen (FOCMA) were measured as complement-dependent antibody (CDA) by 51Cr release and by immunofluorescence in sera from 1,482 cats. CDA to FOCMA (CDA-FOCMA) was not detected in any of 335 cats isolated from feline leukemia virus (FeLV) exposure. but it was present in 55 and 57% of healthy viremic and virus-free cats. respectively. living continuously in multicat households where FeLV infection was endemic. Of singly housed pet cats tested, the antibody was detected in 30–45%. By comparison, the prevalence of CDA-FOCMA was 12% in FeLV-infected cats with leukemia and 13% in leukemic cats with no detectable evidence of FeLV infection; these prevalences both differed significantly from appropriate control groups (P