Localization And Characterization Of The Epitopes Of ORF2-encoded Protein Of The Hepatitis E Virus

Hepatitis E virus (HEV) is responsible for epidemic and sporadic cases of enterically transmitted viral hepatitis, particularly in the developing world. Numerous Hepatitis E outbreaks have occurred in many developing countries, resulting in tens of thousands of people being infected. Hepatitis E most frequently infects young adults. It is seldom fatal, however, mortality rates as high as 20% have been reported for women in the third trimester of pregnancy. Although only a few cases were diagnosed in industrialized countries, anti-HEV antibodies have been found in a significant proportion of blood donors or healthy individuals.HEV is the pathogen of hepatitis E, non-enveloped , approximately 7.5 kb in length. Recently, based on full-length sequence comparisons, HEV can be grouped into four major genotypes and several subtypes. These include genotypes I (include three subtypes, Ia Burma, Ib Pakistan, Ic Morocco), II (Mexico), III(US, the majority of swine) and IV (China, Taiwan),which is discovered in recent years. However , the virus is still not well characterized because that efficient cell culture systems have not been developed and the quantity of virus shed in the feces of infected humans or animals is too small for biochemical characterization.The viral genome contains three partially overlapping open reading frames (ORFs), with ORF2 encoding the putative major structural or capsid protein(ORF2) about 660-aminoacid(aa). There is considerable evidence that antibodies against ORF2 can neutralize HEV. And it is also repoted that a number of antigenic determinants have been identified within ORF2. Our observations suggested that the HEV neutralization epitope(s) may be modeled with variable efficiency by a ORF2 recombinant protein, designated p166, which is 166 aa in length and is located at position 452-617 aa of the HEV ORF2 for the first time. Antibodies obtained against this minimal size protein antigen have been shown to neutralize different HEV strains in the in vitro assay in our previous work. Additionally, antibodies against p166 were found to cross-neutralize three different HEV genotypes, suggesting that a common neutralization epitope(s) may exist within the different HEV genotypes. But up to now, there is no data described where the exact common neutralization epitope(s) that exist within the all of the four different HEV genotypes is.In this study, recombinant DNA containing sequences of four distinct HEV genotypes p166 protein was expressed in Escherichia coli cells. Three monoclonal antibodies (McAbs) were...