Immunological evaluation of Escherichia coli-derived hepatitis C virus second envelope protein (E2) variants

: Two variants of the hepatitis C virus (HCV) E2 envelope protein, lacking the C‐terminal domain and comprising amino acids 458–650 (E2A) and 382–605 (E2C), respectively, were efficiently produced in BL21 (DE3) Escherichia coli cells. E2A and E2C were used to immunize mice. The E2C variant induced the maximal mean antibody titer. Anti‐E2C mouse sera reacted mainly with E2 synthetic peptides covering the 70 amino acid N‐terminal region of the E2 protein. Moreover, a panel of anti‐HCV positive human sera recognized only the E2C protein (28.2%) and the synthetic peptide covering the HVR‐1 of the E2 protein (23.1%). These data indicate the existence of an immunologically relevant region in the HVR‐1 of the HCV E2 protein.