Valuable antibody detection method for classifying hepatitis E virus genotypes.

Nucleotide-based methods are conventionally used to classify the hepatitis E virus (HEV) genotypes. A serological enzyme immunoassay (EIA) using open reading frame 3 (ORF3) C-terminal peptides was developed to conveniently and accurately classify and evaluate the genotypes of HEV. The sera of mice immunized with HEV genotype 1, 3, and 4 reacted highly specifically to the peptides of the corresponding genotypes. Most (84.2%) clinical sera infected with HEV genotype 4 were positive for anti-HEV antibodies when tested with the ORF3 peptides of genotype 4, but were negative for genotypes 1 and 3. Monkey and clinical serial sera infected with HEV reacted strongly to the homologous genotype ORF3 peptides. The indirect EIAs were more sensitive, with stronger reactivity, than commercial anti-HEV immunoglobulin G assays when serial sera from monkeys infected with HEV genotype 1 or 4 were tested. All our results indicate that the serological typing EIA assays described in this study are more effective and convenient for the classification of HEV genotypes than molecular approaches, and can be used to screen large numbers of serum samples and differentiate genotypes for the diagnosis of HEV infections.