Full genomic sequence analysis of swine genotype 3 hepatitis E virus isolated from Shanghai.

The full genomic nucleotide sequence of a previously identified genotype 3 hepatitis E virus (HEV), strain SAAS-JDY5, was obtained using RT-PCR and rapid amplification of cDNA ends (RACE). The genome consisted of 7225 nucleotides, excluding a poly-A tail at the 3' terminus, and contained three open reading frames (ORFs), ORF-1, ORF-2 and ORF-3, encoding 1702, 660 and 113 amino acids, respectively. Phylogenetic analysis confirmed that SAAS-JDY5 belonged to genotype 3 HEV and was most closely related to the Japanese isolate wbJYG1 (AB222184). SAAS-JDY5 shared approximately 87% nucleotide similarity to human and swine strains from the United States, compared with 74-75% similarity to Asian (genotype 4) and Mexican strains (genotype 2). Alignment of the SAAS-JDY5 genomic sequence with reference sequences of the same genotype revealed one nucleotide substitution and one deletion at positions 5145 and 7189 (3' UTR), respectively. Moreover, SAAS-JDY5 contained two additional nucleotides (AC) at the very end of the 3'-terminus preceding the poly-A tail of the genome. Comparison of the putative amino acid sequence encoded by the SAAS-JDY5 genome with sequences of other genotype 3 isolates revealed 15 unique amino acid substitutions and one deletion in ORF-1, and three substitutions in ORF-2.