Serological prevalence of hepatitis E virus in domestic animals and diversity of genotype 4 hepatitis E virus in China.

Pigs have been confirmed to be reservoirs of some genotypes of hepatitis E virus (HEV), and other nonhuman species are also likely infected with the virus. To assess the prevalence of HEV infection in domestic animals in China, 3579 serum samples, including 1967 swine, 700 goat, and 912 cattle sera, were collected from 26 provinces across the country and tested for HEV antibodies and antigen using enzyme immunoassays. The results showed that 82.2% of the swine samples, but only 10.4% and 28.2% of cattle and goat sera, were anti-HEV positive respectively. The prevalence of anti-HEV antibody in animals varied from province to province, ranging from 10.9% to 100% in pigs, 0% to 48% in goats, and 0% to 92.9% in cattle. About 1.9% of pigs, 1.6% of goats, and 0.8% of cattle tested in the study were positive for HEV antigen. Some samples, including all HEV antigen-positive samples, were tested for HEV-specific RNA using reverse transcription polymerase chain reaction. Fifteen swine samples, but none from the goats or cattle, were found to be HEV RNA positive. Sequence and phylogenetic analyses classified all the swine HEV isolates into HEV genotype 4, which was further divided into four subgroups. This study demonstrated that HEV infection is widespread in domestic animals, particularly pigs, in China. The HEV genotype infecting pigs in China was genotype 4. However, the isolates displayed considerable genetic diversity.