The presence of complement fixing antibodies to Rous sarcoma virus (Schmidt-Ruppin strain) in patients with various forms of neoplasia.

The presence in men of antibodies to Rous sarcoma virus, an oncogenic virus of avian origin, was demonstrated. The highest antibody incidence was found in patients with various forms of cancer (34.4%, as against the value of 12% recorded in blood donors); these patients also showed an increased antibody level - 1/64 titers were detected in 43 out of 7 patients. The possibility of a human infection with animal oncogenic viruses is discussed, without excluding the hypothesis of a paraimmune reaction.