Abstract: To analyze the full length sequence of swCH25, isolated from a pig fecal sample in Xinjiang in 2001, eight overlapping fragments of swCH25 genomes were amplified with reverse transcription nested polymerase chain reaction (RT-nPCR) and the 5′ and 3′ ends were amplified with RACE. The PCR products were cloned into pMD18-T Vector and sequenced. The result showed that its genome consisted of 7 243 nt excluding the poly(A)tail, and contained three ORFs(ORFs1-3) that encoded proteins of 1 707, 674 and 114aa. Sequence analysis revealed that the overall nucleotide sequence identity of swCH25 was 73.5%-75.7% and 83.5%-89.8% with HEV genotypeⅠ-Ⅲ and Ⅳ, respectively. Compared with HEV genotypesⅠ-Ⅲ and Ⅳ，the ORF1 of swCH25 shared 71.6%-74% and 82.3%-89.4% sequence identity at nucleotide level and 80.7%-86.1% and 94.3%-96% identity at amino acid level, the ORF2 shared 78.4%-81.3% and 87.1%-90.9% sequence identity at nucleotide level and 89.7%-93.8% and 97.2%-98.2% identity at amino acid level and the ORF3 shared 84.4%-87.3% and 95.4-96.8% sequence identity at nucleotide level and 74.8%-83.2% and 93.8%-97.4% identity at amino acid level. The phylogenetic tree constructed based on the full genomic sequence confirmed that swCH25 belong to genotype Ⅳ and were most closely related to T1, a prototype human HEV strain of genotype Ⅳ isolated from patients with acute hepatitis in China. This finding further supports the notion that the hepatitis E is a zoonosis.

Key words: Hepatitis E virus, Genotype