Open reading frame structure analysis as a novel genotyping tool for hepatitis E virus and the subsequent discovery of an inter-genotype recombinant

Accurate viral genotyping is important. Here I investigate genotypes in hepatitis E virus (HEV) and find that the open reading frame (ORF) structure (the lengths of three ORFs and the overlapping relationships among the ORFs) can be a good criterion for genotyping HEV. An inter-genotype recombinant (GenBank accession no. DQ450072) was revealed by analysing the ORF structure and confirmed by phylogenetic analyses. This discovery of the inter-genotype recombinant indicates that genotyping in HEV should be based on full-length sequences. The Mexican strain which is currently classified as a genotype 2 strain also exhibited the mosaic sequence pattern, although without statistical support.