Evaluation of an immunoenzyme test (ELISA) for the determination of an Ag/Ab system correlated to non-A, non-B post-transfusion hepatitis

An ELISA for the detection of a Ag/Ab system related to non-A, non-B post-transfusion hepatitis (NANB-PTH) has been developed. A convalescent serum from a patient suffering, 14 month before, of NANB-PTH was used both as capture and detector antibody in a "sandwich" type immunoassay to detect an Ag (Ag-NANB). A "blocking" immunoassay was used, in the same test, to detect the corresponding antibody (Ab-NANB). All patients with NANB-PTH were positive, alternately, for Ag-NANB or Ab-NANB. The Ag was found in the acute phase sera of 3 out of 22 cases of NANB-PTH (13,6%), but in none of 29 acute hepatitis type B,26 acute hepatitis type A,14 NANB sporadic hepatitis, 5 infectious mononucleosis and 8 healthy subjects. 2/3 Ag-NANB positive subjects became chronic carriers of this Ag, whereas the third seroconverted for Ab-NANB after the first two months of their disease. Furthermore, a significant increase of the Ab-NANB titer was observed in the convalescent phase of the disease in 18/20 NANB-PTH. As expected, a relatively high prevalence for Ab-NANB was found in the other groups of patients, suggesting the high diffusion of the agent, but none of these subjects showed a progressive increase of the antibody titer during the course of their disease.