Neutralization of feline leukemia virus with feline antisera to leukocyte alloantigens.

The possibility that normal cellular antigens might serve as targets for antibody neutralization of the feline leukemia virus was investigated. Xenospecific antiserum directed to normal feline cells was shown to inactivate feline leukemia virus grown in fibroblasts. Cat antisera to normal feline leukocyte alloantigens were then prepared, after which persistent viremia was induced in the donor cats. Such alloantisera neutralized virus taken from plasma of the appropriate cat but did not neutralize virus from a different cat. The virus neutralization was dependent on the presence of complement. These results indicate that alloantigens are present at the virus surface and raise the possibility that such antigens may play a role in the natural immune response directed to retrovirus infections.