Retrovirus expression in normal and pathogenic processes of man.

C-type viruses have been isolated from primates only on rare occasions. To date, an endogenous C-type virus of man has not been isolated. Nevertheless, the evidence for C-type viral expression in human tissue increases. Evidence for viral antigen expression during human gestation and the pathogenesis of systemic lupus erythematosus (SLE) is summarized. The data are discussed in connection with the current hypotheses that retroviruses may participate in both normal and abnormal biologic processes.