Detection of virus-associated antigen in serum and liver of patients with non-A non-B hepatitis.

In a search for serological markers of non-A non-B(NANB) hepatitis, sera from repeatedly transfused and convalescent patients were assayed by immunodiffusion against sera from 12 patients with early acute NANB hepatitis. A new antigen/antibody system distinct from HBsAg was demonstrated in 8 cases. To assess the specificity of the test, serial sera from 17 patients with acute hepatitis of known aetiology (10 due to hepatitis-B virus, 4 to hepatitis-A virus, 3 to drugs) were tested twice a month, together with sera from 14 NANB patients obtained during a prospective post-transfusion study. NANB antigen (Ag) was detected in at least one sample from 12 of the 14 NANB patients (86%) but in none of the other groups. NANB Ag appeared after or just before elevation of transaminase levels and was cleared before they fell to normal. 4 of 5 patients who showed seroconversion to NANB antibody (Ab) had transient hepatitis. In contrast, the alanine adminotransferase value returned to normal in only 1 of the 5 with persistent NANB antigenaemia during 6 months' follow-up. NANB Ag was also demonstrated by immunodiffusion in liver extracts from patients with chronic NANB hepatitis with antigenaemia. Fluorescein-isothiocyanate-labelled gammaglobulins with strong NANB Ab activity revealed specific nuclear fluorescence in foci of hepatocytes on cryostat sectons of these livers but in none of 6 control human livers. The results suggest that the antigen and antibody are specifically linked to NANB hepatitis of long incubation period.