Hepatitis E virus genotype diversity in eastern China

Abstract

We studied 47 hepatitis E virus (HEV) isolates from hospitalized patients in Nanjing and Taizhou, eastern China. Genotypes 1, 3, and 4 were prevalent; genotype 3 and subgenotype 4b showed a close relationship with the swine strains in eastern China, thus indicating that HEV genotype 3 had infected humans in China.

Figure 1

Phylogenetic tree of hepatitis E virus isolates in eastern China, 2007–2009. The phylogenetic tree was produced with a 348-nt open reading frame 2 sequence alignment of 37 isolates from this study and other 31 reference sequences, using the neighbor-joining method and evaluated by using the interior branch test method with MEGA4 software (www.megasoftware.net). Percentage of bootstrap support is shown by values at the branch nodes of the tree. Only nodes with a bootstrap value >50 are labeled; these values are the result of resampling the data 1,000 times. Black diamonds, isolates identified in the current study; white squares, GenBank sequences with the highest sequence homology to our sequences; ?, genotype 4 strains that could not be subtyped but closely clustered with each other, forming a new subtype. Scale bar indicates nucleotide substitutions per position.

Figure 2

Phylogenetic tree showing alignment of the complete genome of EChZ20 of hepatitis E virus determined in the present study and the referenced genotype 4 isolates with complete genome available in GenBank (A), and the 1,681-nt partial open reading frame 2 sequence of EChN22 and referenced genotype 3 isolates with complete genome available in GenBank (B). The tree was constructed by using the neighbor-joining method and evaluated by using the interior branch test method with MEGA4 software (www.megasoftware.net). Percentage of bootstrap support is indicated at each node. GenBank accession number, source, and country of origin are indicated. Strains identified in this study are indicated by black diamonds. Only partial branches that were sufficient for elucidating the relationship between the study strains and their related strains are shown. Scale bars indicate nucleotide substitutions per site.