Comparative study of experimental infection of piglets with a field strain of wild boar HEV, a wild boar HEV strain previously passed in porcine model and a swine HEV strain

Domestic pig and wild boar are reservoirs for hepatitis E virus (HEV). This study aims to investigate the infection of pigs with HEV strains from wild boar and to compare the behaviour of a wild boar strain to a pig strain in vivo. The objective is to contribute to the elucidation of the crossing barrier between wild boar and pig with this zoonotic virus.
A total of 12 specific pathogen free piglets were divided into four groups and orally inoculated respectively with a wild boar HEV strain previously passed in pigs (WbHEV), a wild boar HEV (WbHEVs), a swine HEV (SwHEV) and a negative control group. One pig from each group was euthanized 15 days after inoculation. The remaining pigs were sacrificed on day 56. A serological monitoring by ELISA was realized throughout the experiment, the viral load was determined in different organs by qRT-PCR.
Viral RNA was found in several organs and tissues of the inoculated pigs. Most of the pigs were HEV positive at the 15th day and no clinical signs were observed during infection. Liver enzymes (ALT and AST) remained within the reference values.
This study provides experimental evidence of the swine infection with a strain of HEV isolated from wild boar and previously passed in pig. Furthermore, these data indicate the possibility of the transfer of the virus from wild boar to pig, for example, in the context of outdoor pig breeding.