Objective: To determine the genotype and phylogenetic characteristics of hepatitis E virus (HEV) strains isolated from the human and swine in Anqing City.
Methods: Twenty seven sera from sporadic hepatitis E patients and 400 commercial swine bile samples were collected in Anqing City. According to the collection time, the bile samples were equally divided into 4 groups which were named group A, B, C and D respectively. Nested reverse transcription polymerase chain reaction (RT-PCR) and DNA sequencing technology were performed to obtain the DNA sequences of HEV RNA Open Reading Frame 2 (ORF2) (150 nt) for all the serum and bile samples. The sample sequences and prototype sequences from the GenBank were aligned and their nucleotide sequence identities were calculated. A phylogenetic tree constructed according to the Bayesian inference method was used to analyze the genotype and phylogenetic relationship between the human and swine HEV strains isolated in Anqing City.
Results: The male-to-female sex ratio of the patients was 2.86:1 and the average age was 56.78 years old. Sixteen out of 27 serum (59.26%) samples were HEV RNA positive. Human HEV strains isolated in Anqing City shared 74.75% - 82.99%, 75.26% - 83.64%, 72.77% - 80.57% and 88.03%-91.63% nucleotide sequence identities with prototype I, II, III and IV HEV strains respectively. HEV RNA was detected in 22 out of 400 bile samples (5.5%). The swine HEV detection rates for group A, B, C and D were 7.00%, 3.00%, 9.00% and 3.00% respectively, showing no significant difference among these groups (χ(2) = 5.20, P = 0.16). Swine HEV strains isolated in Anqing City shared 75.24% - 83.42%, 75.93% - 84.19%, 72.86% - 80.64% and 88.15% - 91.79% nucleotide sequence identities with prototype I, II, III and IV HEV strains respectively. Phylogenetic analysis revealed that all the HEV strains isolated from both the human and swine belonged to genotype IV and scattered in evolutionary branches without significant species aggregation.
Conclusion: It's suggested that genotype IV HEV was the dominant genotype among the human and swine in Anqing City and probably transmitted between them in this area.