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

Infection of Pigs with Avian Hepatitis E Virus (HEV)

It is now known that HEV can cross-species barriers. In the present study, we used a pig model to determine if HEV from chickens (avian HEV) or rats (rat HEV) was infectious to pigs. Thirty six, SPF pigs were randomly separated into 4 groups of 9 pigs each. Group 1 served as the sham-inoculated group. Group 2 was inoculated with rat HEV. Group 3 was inoculated with avian HEV. In the rat and avian HEV groups, 6 pigs were inoculated with the corresponding virus and 3 pigs remained uninoculated and served as contact controls. Group 4 was inoculated with the prototype swine HEV. Necropsy of 3 pigs from each group was performed on 7, 21, and 35 days postinoculation (dpi). In the rat and avian HEV groups, 2 inoculated and 1 contact control pigs were necropsied at each time point. Liver and bile from sham-inoculated pigs were negative for HEV throughout the study. Pigs in the sham and rat HEV group remained noninfected. Pigs inoculated with avian HEV and those inoculated with the swine HEV became viremic and shed HEV in feces. Both the avian and swine HEV infected pigs had mild-tomoderate lymphoplasmacytic hepatitis. The findings indicate that avian HEV is transmissible to pigs. This may open new areas of study in the epidemiology of HEV. Pigs may be an excellent model for comparative molecular and pathogenetic studies of different HEV strains

Experimental Inoculation of Growing Pigs with U.S. Strains of Swine and Human Hepatitis E Viruses

U.S. strains of swine and human hepatitis E viruses (HEV) are closely related genetically. We found that swine and human HEV differ in virulence and both induce subclinical, but morphologically discernable, hepatitis in experimentally infected SPF pigs. Experimental inoculation of pigs with human HEV may provide a useful model to study the pathogenesis of hepatitis E virus infection and test efficacy of human HEV vaccines

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.</p