Cytotoxic T Lymphocytes in SV40 Infections

Simian virus 40 (SV40) infects monkeys and persists in the latent form in the kidneys of this natural host. However, in nonpermissive hosts, such as rodents, the virus induces neoplasia and the outcome is controlled by the immune response of the host (1 ,2 ). Virus-neutralizing antibodies are responsible for limiting the amount of circulating virus in the natural host, leading to the establishment of latency. In contrast, the nonpermissive host undergoing tumorigenesis develops antibodies specific for the large tumor antigen, or T antigen (T-ag) encoded by SV40. In addition, the T-ag in transformed or tumor cells also serves as the target for cytotoxic T lymphocytes (CTL) that are capable of controlling tumor development (2 ). CTL responses directed against SV40 virion proteins have not been described.