Comparison of hepatitis E virus genotypes from rabbits and pigs in the same geographic area: No evidence of natural cross-species transmission between the two animals

Domesticated pigs have been shown to be a reservoir of genotypes 3 and 4 hepatitis E virus (HEV). Farmed rabbits were recently recognized as the host of a novel virus, rabbit HEV. In order to determine whether HEV is transmitted naturally between rabbits and pigs, a survey on HEV infections was conducted in rabbits and pigs aged 2-4 months from rabbit and pig farms located near to each other in nine villages in three counties of Hebei Province, China. The overall anti-HEV antibody positivity rates in serum samples of swine and rabbits were 61.7% (58194) and 23.2% (67/289), and the positive rates for HEV RNA were 23.4% (22194) and 10% (29/289), respectively. In addition, 37 of 125 swine fecal samples (29.6%) were HEV RNA positive. The nucleotide sequences of a 304 bp region within HEV ORF2 have identity ranging from 84.5% to 100% among the rabbit isolates and from 82.3% to 100% among the swine isolates. In contrast, the nucleotide identity between the two species groups was only 72-76.6%. Consequently, the two groups were clearly separated in the phylogenetic tree that showed all of the rabbit isolates are closely related to the rabbit HEV reported recently and the swine isolates belong to genotype 4, including subgenotypes 4a, 4c and 4d. The results showed that HEV is highly prevalent in farmed rabbits and pigs in these areas. However, genotype 4 HEV and rabbit HEV are circulating separately in pigs and rabbits in the same area. In conclusion, there was no evidence of cross-species transmission of HEV between pigs and rabbits. The frequency of HEV transmission events between these two animal species is likely low in commercial farms. (C) 2012 Elsevier B.V. All rights reserved.