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Analysis of the complete genome sequences of one swine and two human hepatitis E virus genotype 4 strains isolated in Beijing, China

Ma, Hongxia, Geng, Yansheng, Li, Zhuo, Harrison, Tim J., Huang, Weijin, Zhao, Chenyan, Wang, Youchun
Infection, genetics, and evolution 2013 v.18 pp. 42-47
Hepatitis E virus, amino acids, genome, genotype, humans, nucleotide sequences, nucleotides, proteins, sequence analysis, swine, China
Full-length sequences were determined and analyzed for two human (MO and W3) and one swine (W2–5) hepatitis E virus (HEV) isolates from Beijing, China. The genomes of the three strains were composed of 7242, 7239, 7239 nucleotides, respectively, excluding the poly (A) tails, and were 84% identical to each other. All were classified into genotype 4. Sequence analysis shows that the 2 human isolates have up to 91–94% nucleotide identity in full length genome with swine strains isolated in China, while the swine isolate share 92% identity with the human strain T1 from Beijing. At the amino acid level, the three strains share 94%, 97% and 89–92% identity in the ORF1, ORF2 and ORF3, proteins respectively. The human strains MO and W3 have the highest identity, 97%, 98–99% and 96–98% in ORFs 1–3, respectively, to swine strains CHN-XJ-SW13 and CHN-XJ-SW33 from Xinjiang, China, while swine strain W2–5 has highest identity with the human strain HE-JA2, 96%, 99% and 91% in ORFs 1–3, respectively. Genotype specific amino acid substitutions were found at a single site in all three ORFs by sequences alignment, and genotype specific short sequences (5–10aa in length) were found in ORF1 and the C-terminus of ORF3. However, no difference was found at any amino acid position that discriminates between human and swine HEVs within genotype 4 for any of the three ORFs. These results indicated that the genotype 4 HEV strains from humans and pigs in China may evolve from the common ancestor.