Immunodominant B-cell domains of hepatitis C virus envelope proteins E1 and E2 identified during early and late time points of infection

Background/Aims: We characterized immunoreactive B-cell domains of hepatitis C virus (HCV) envelope proteins E1 and E2 by a peptide ELISA using sera of patients who were infected by the same isolate of HCV (HCV-AD78). Methods: Fifty-four overlapping peptides which corresponded to the sequence of E1 and E2 of isolate HCV-AD78 were used to detect specific antibodies. Three groups of HCV-AD78 related sera were analyzed. Two groups were from sera obtained at early time points of infection (months 4-15) from patients who later resolved infection (group A), or who later developed chronic disease (group B). Group C sera were from later time points of chronic disease. As a control, sera of chronic HCV patients who did not have HCV- AD78 infection were also analyzed (group D). Results: In group A, 25 of the 54 peptides produced OD₄₀₅ above the cut-off, whereas 17 peptides produced such values in group B. Only 10 and 3 peptides yielded such values in groups C and D, respectively. The overall prevalence of antibodies against peptides was high in the early phase of infection (means of 28.7±14.8% and 25.9±14.5% in groups A and B, respectively). At later time points of chronic infection (group C), the overall prevalence was lower (mean 18.6±15.4%). Group D sera produced the lowest overall prevalence (mean 13.2±14.1%). Three peptides, covering aa271-290, aa481-500 and aa551-570, were recognized significantly more frequently (p<0.05) by group A sera than group B sera. Conclusions: We conclude that more linear epitopes of the HCV envelope are recognized with a high prevalence of antibodies, as was suggested previously. However, most B-cell domains of the HCV envelope induce a similarly high antibody response in patients who resolve infection or develop chronic disease.