Characterization of antigenic epitopes of the ORF2 protein from hepatitis E virus genotype 4.

This study was aimed to characterize antigenic epitopes of a newly identified hepatitis E virus (HEV) Chinese strain of genotype 4. Recombinant capsid protein p166Chn (amino acids 464-629) and six murine monoclonal antibodies (mAbs) against the protein were prepared. The mAbs were evaluated for their ability to neutralize a genotype 4 HEV strain by an in vitro PCR-based HEV neutralization assay. The antigenic epitopes on HEV genotype 4 and other different genotypes of HEV strains were analyzed by ELISA, Western blotting and an additive ELISA assay. All the six mAbs against p166Chn could effectively neutralize HEV in vitro. They strongly reacted with seven different p166 recombinant proteins including p166Chn, p166Bur, p166Mor, p166Pak, p166Mex, p166Us and p166Nz, which were derived from different HEV reference strains of genotypes 1, 2, 3 and 4, respectively. Furthermore, the mAbs recognized the same epitope as indicated by additive ELISA assay. Taken together, our data suggest that there is at least one type-common neutralizing antigenic epitope in ORF2 encoded protein of the newly identified HEV genotype 4.