Comparison of PCR and a Swine Bioassay to Detect Hepatitis E Virus in Pig Tissues and Feces

Swine hepatitis E virus (HEV) was detected by a semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR) in liver tissue and feces but not in skeletal muscle, pancreas, or heart from pigs experimentally infected intravenously with swine hepatitis E virus (swine HEV). Homogenates of liver tissue and suspensions of feces prepared from swine HEV-infected pigs were inoculated intravenously into naïve pigs and induced infection. There was no evidence of transmission of swine HEV to pigs by intravenous route of inoculation with heart or pancreas, or oral route with skeletal muscle homogenates or fecal suspensions prepared from HEV-infected pigs. Results indicate that there is potential for transmission of swine HEV to naïve pigs, and potentially to humans, via pig liver or liver cell xenotransplantation. Failure to detect HEV by RT-PCR in muscle tissue and failure to transmit swine HEV via oral inoculation of muscle tissue suggests that the risk of transmission of HEV in pork meat products is minimal. The route of natural transmission of HEV is thought to be fecal-oral so the failure to transmit HEV via feces suggests that a very high infectious dose is necessary, or there are other routes of transmission. The semiquantitative RT-PCR assay correlates well with that of in vitro swine bioassay.