An enzyme-linked immunosorbent assay for an antigen related to non-A, non-B hepatitis and its antibody: partial characterization of the antigen and chimpanzee transmission.

An enzyme-linked immunosorbent assay (ELISA) was developed based on sera from patients convalescent from non-A, non-B hepatitis and haemophilia A patients who had been frequently treated with commercial blood products. Using this ELISA, an antigen was detected which appears to be related to non-A, non-B hepatitis. The antigen is provisionally designated as DS-antigen (DS-Ag). The serum of another patient with haemophilia A, which was strongly positive for the DS-Ag, caused a typical case of non-A, non-B hepatitis in a chimpanzee. DS-Ag could be detected in the serum of the chimpanzee during the acute phase of the infection. The ELISA for DS-Ag reacted with neither hepatitis A or B virus antigens, nor Epstein-Barr virus or cytomegalovirus. The assay was provisionally evaluated using sera from different groups of patients. Out of 17 patients with posttransfusion hepatitis non-A, non-B, 11 were found positive in the ELISA for DS-Ag (65%). As expected, a relatively high prevalence of DS-Ag (9%) was found in patients with haemophilia, who are regularly treated with blood-clotting factor-concentrates. Antibodies to DS-Ag were found in 48% of these patients. The DS-Ag was found in 8 of 1400 (0.6%) volunteer blood donors, and antibody to DS-Ag in 3% of the sera. Remarkably, a high incidence (41%) of antibodies to DS-Ag was found in prostitutes, suggesting that this antigen may be transmitted by a sexual route. The DS-Ag was pelleted by ultracentrifugation for four hours at 100,000g and was found to have a buoyant density of 1.32 g/cm3 in a CsCl gradient.