Immunoaffinity purification of a 72K early antigen of human cytomegalovirus: analysis of humoral and cell-mediated immunity to the purified polypeptide.

An early antigen of human cytomegalovirus (HCMV) was purified from infected cells as a 72K polypeptide by immunoaffinity chromatography using a monoclonal antibody. It was located in both nucleus and cytoplasm, and was non-glycosylated and undetectable on the surface of infected cells. Known seropositive subjects had antibody against the purified protein and it elicited proliferative T cell responses in 10 of 16 subjects. Five of 14 T cell lines established in response to the purified protein were predominantly CD8+ and of these two showed major histocompatibility complex-restricted cytotoxicity against HCMV-infected cells. This provides further evidence that antigens expressed at early times may be targets for the immune response during persistent HCMV infection.