Relationship between humoral antibodies and the failure to develop progressive tumors in cats injected with feline sarcoma virus (FSV)

Using the indirect immunofluorescence technique, antibodies were found in the sera of cats injected with the feline sarcoma virus (FSV). These antibodies reacted with the membrane antigen complex of cells infected with feline oncornaviruses. There was an inverse correlation between the development of progressive tumors and antibody titers. A correlation was also found between the ability of newborn kittens to resist the development of progressive tumors following FSV injection and the presence of antibodies at the time of virus injection. In this case, the antibodies were probably obtained passively from their mothers, who were exposed to feline leukemia virus (FeLV). Antibodies were also found in dogs with regressing FSV induced tumors.