Suppression of the humoral antibody response in natural retrovirus infections

The feline leukemia virus (FeLV) frequently causes death by predisposing the host to acute infections by other pathogens rather than by inducing leukemia. In a previous study, cats infected with FeLV were found to have prolonged homograft rejection responses but there was no evidence that the humoral immune response was impaired. In the present study, the humoral response to the synthetic multichain polypeptide (L-tyrosine-L-glutamic acid)-poly-DL-alanine-poly-L-lysine, denoted (T.G)AL, was found to be significantly depressed in healthy cats that were naturally infected with FeLV compared to uninfected controls. In cats with persistent FeLV viremia the major antibody response to (T.G)AL, normally seen at days 9 to 14 after immunization, was both delayed and greatly reduced.