CHARACTERIZATION OF A LINEAR EPITOPE IN THE NONSTRUCTURAL REGION-4 OFHEPATITIS-C VIRUS WITH REACTIVITY TO SEROCONVERSION ANTIBODIES

Mapping and possible diagnostic meaning of a highly conserved, linear NS4 epitope (NS4/3), located outside the C100-3 antigen within the car boxyl terminal proportion or the NS4 region, with major immunoreactivi ty with specimens of patients with HCV infection from various geograph ic origins is described. Transient, acute-phase IgM anti-HCV NS4/3 was detected coincidentally or earlier than active IgG anti-HCV NS4/3 res ponse with four well-characterized seroconversion panels. GenBank alig nment studies identified patch homologies between the NS4/3 sequence a nd a number of non-HCV proteins, which may explain part of the cross-r eactivity of the NS4/3 epitope. Some of the ''false positive reactivit ies'' of the NS4/3 epitope with asymptomatic blood donors, not being c onfirmed with FDA-approved anti-HCV assays without the NS4/3 epitope, may be explained by recognition of very early seroconversion antibodie s. (C) 1998 Academic Press.