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.