Genetic characteristics of hepatitis E virus isolated from human and swine in Shanghai, 2017–2020

Objective  To analyze the genetic characteristics of hepatitis E virus (HEV) isolated from human and swine samples collected in Shanghai during 2017–2020. Methods  IgM and IgG against HEV were detected with enzyme-linked immunosorbent assay, HEV RNA was detected using qPCR assay, a partial 137-nt sequence of HEV was obtained using nested RT-PCR. Genetic characteristics of HEV isolates were further studied through phylogenetic analysis, including genotype, subtype and nucleotide sequence homology analyses. Results  In this study, 191 human HEV isolates and 8 swine HEV isolates were obtained from serum samples of 525 acute hepatitis E patients and bile samples of 2400 pigs respectively. Phylogenetic analysis revealed that 98.43% of human HEV isolates belonged to genotype 4, including subtypes 4a, 4c, 4d, 4e, 4f and 4g, and 3 human isolates and 4 swine isolates belonged to genotype 3, including subtypes 3b, 3c and 3e. The nucleotide sequences of human and swine isolates shared 93.36%-100% homology. Conclusion  Genotype 4 HEV was predominant in patients. Human genotype 3 HEV isolates were first reported in Shanghai. Human and swine isolates shared high sequence homology, suggesting the possible zoonotic transmission of HEV between swine and humans.