Nucleic acid sequences of primate type C viruses in normal and neoplastic human tissues.

Recent reports on the isolation of type C viruses from human cells have generated considerable controversy because of the close relationship of the viruses to the type C viruses of subhuman primates. These findings have been interpreted as evidence for contamination despite the repeated isolation of some type C viruses from separate clinical specimens or from separate frozen primary cell stocks of the same donor. Our laboratory has described a type C virus which is released from the HEL-12 strain of normal human embryonic lung fibroblasts. The HEL-12 virus is related immunologically to simian sarcoma (woolly monkey fibrosarcoma) virus (SiSV) and the endogenous type C viruses of baboons and domestic cats. To demonstrate that the HEL-12 virus is not an adventitious contaminant, fresh human tissues were examined for antigenic cross-reactivity with HEL-12 virus antigens. Some patients with myelogenous leukemia contain circulating immunoglobulins which specifically inhibit the reverse transcriptases of HEL-12 virus and primate type C viruses. In addition, the glomerular immune complexes in patients with systemic lupus erythematosus contain antigens related to HEL-12 virus proteins. Using the techniques of molecular hybridisation, we demonstrate here that HEL-12 cells contain proviral DNA sequences before antigen expression or spontaneous virus release can be detected. We also present evidence for the existence of nucleic acid sequences homologous to HEL-12 viral RNA in the DNAs from certain cancer patients.