Seroprevalence and molecular detection of hepatitis E virus in Yunnan Province, China

In this study, the prevalence and characteristics of hepatitis E virus (HEV) in pigs and the general population in the Yunnan province, China, were evaluated. Nine hundred sixty sera, 95 liver and 60 feces samples were randomly collected from pig farms and abattoirs, in addition 173 human sera were sampled in the provincial capital city for a serological survey and an RT-nPCR assay. The screening results showed that among 621 samples collected from five pig farms, the HEV-specific IgG positive rate ranged from 73.2% to 83.5%, and the overall seroprevalence was 78.9% (490/621). A further analysis revealed that the seroprevalence increased with age. The positive rate of human serum samples was 39.9% (69/173). HEV RNA was detected in five swine feces, six swine liver and one anti-HEV-IgM-positive human serum sample by RT-nPCR. Sequence and alignment of the 348-nt PCR-amplified products of 12 HEV strains identified nine distinct nucleotide sequences. Phylogenetic and molecular evolutionary analysis revealed that these nine sequences shared 84.2% to 100.0% nucleotide sequence identity with each other, with all isolates belonging to genotype 4 HEV and clustering with other Chinese swine and human HEV sequences determined earlier. This study results suggest that the prevalence of genotype 4 HEV is serious, both in pig herds and in the human population, and authorities should pay more attention to the prevalence of HEV in southwest China.