Hepatitis E virus in Norway rats (Rattus norvegicus) captured around pig farm

BACKGROUND: Hepatitis E virus (HEV) transmitted via the oral route through the consumption of contaminated water or uncooked or undercooked contaminated meat has been implicated in major outbreaks. Rats may play a critical role in HEV outbreaks, considering their negative effects on environmental hygiene and food sanitation. Although the serological evidence of HEV infection in wild rodents has been reported worldwide, the infectivity and propagation of HEV in wild rats remain unknown. To investigate if rats are a possible carrier of HEV, we studied wild Norway rats (Rattus norvegicus) that were caught near a pig farm, where HEV was prevalent among the pigs. METHODS: We examined 56 Norway rats for HEV. RNA from internal organs was examined for RT-PCR and positive samples were sequenced. Positive tissue samples were incubated with A549 cell line to isolate HEV. Anti-HEV antibodies were detected by ELISA. RESULTS: Sixteen rats were seropositive, and the HEV RNA was detected in 10 of the 56 rats. Sequencing of the partial ORF1 gene from 7 samples resulted in partially sequenced HEV, belonging to genotype 3, which was genetically identical to the HEV prevalent in the swine from the source farm. The infectious HEVs were isolated from the Norway rats by using the human A549 cell line. CONCLUSIONS: There was a relatively high prevalence (17.9%) of the HEV genome in wild Norway rats. The virus was mainly detected in the liver and spleen. The results indicate that these animals might be possible carrier of swine HEV in endemic regions. The HEV contamination risk due to rats needs to be examined in human habitats

Long-term shedding of hepatitis E virus in the feces of pigs infected naturally, born to sows with and without maternal antibodies.

Pigs are presumed reservoirs for hepatitis E virus (HEV) transmission to humans. To examine infection kinetics, two litters of domestic pigs (A and B, each containing 10 piglets) infected naturally with HEV were studied until pigs were 6 months old. Maternal IgG and IgA antibodies were detected in litter A piglets, but not in litter B ones. All pigs shed HEV in feces when they were 30-110 days old, and 17 developed viremia at 40-100 days of age. Phylogenetic analysis revealed a highly close sequence of HEV genotype 3 in all pigs. The serum levels of specific IgG and IgA were similar in all pigs, although IgA was not detected in the feces. Interestingly, the onset of both viremia and seroconversion was delayed significantly in litter A pigs. The kinetics of fecal virus shedding was similar in both litters; shedding was not detected after the pigs were 120 days old. The differences in the infection kinetics between litters A and B suggested that maternal antibodies delayed the onset of viremia and seroconversion. Quantitative real-time reverse transcriptase-polymerase chain reaction revealed that HEV RNA in feces peaked 10 days after initial shedding of approximately 10(6.0) copies/g. The viral load was much lower in the serum than in the feces. At 200 days of age, HEV RNA was found in the internal organs of 3 out of 13 pigs. These study findings improve the understanding of the dynamics of natural HEV transmission in pigs, which could help in controlling virus transmission from pigs to humans

Infectious prion protein in the filtrate even after 15 nm filtration.

The evaluation of the removal efficacy during manufacturing is important for the risk assessment of plasma products with respect to possible contamination by infectious prions, as recently reported in several papers on the potential for prion transmission through plasma products. Here, we evaluated a virus removal filter which has 15 nm pores. An antithrombin sample immediately prior to nano-filtration was spiked with prion material prepared in two different ways. The removal (log reduction factor) of prion infectivity using animal bioassays was >or=4.72 and 4.00 in two independent filtrations. However, infectivity was detected in both the pellet and supernatant following ultracentrifugation of the 15 nm filtered samples, indicating difficulty in complete removal. The data supports the conclusion that a certain amount of infectious prion protein is present as a smaller and/or soluble form (less than approximately 15 nm in diameter)

Distribution and Propagation of Hepatitis E Virus in Experimentally Infected Swine

HEV infections in human and pigs have been reported in many countries; however, the precise distribution and multiplication of this virus in the host remains poorly understood. In this study, we examined the distribution and multiplication of HEV genotype 3 in two piglets at the early phase of intravenous infection, and also examined the virus distribution in a naturally infected pig. We developed real-time RT-PCR to determine copy numbers of the HEV genome in the sera, feces and organs. HEV-RNA was detected in serum from a pig transiently for 7 days post-inoculation (dpi). The HEV copy numbers in the feces appearing 7 dpi were increased to 3.4x106 copies/g at 14 dpi. In contrast, the higher copy numbers of HEV were widely distributed in the tissue organs from naturally HEV-infected pig. The study showed that intravenously inoculated HEV was distributed in several restricted tissues, such as in the liver and intestine

Sequence Variation in Hepatitis E Virus Genotypes 3 and 4 from Swine Fecal Samples in Japan

Hepatitis E virus (HEV) is a causative agent for hepatitis. HEV is transmitted via the fecal-oral route through contaminated drinking water and induces zoonotic infections through eating uncooked and undercooked meat of deer, wild boar, and swine. In Japan, genotypes 3 (G3) and 4 (G4) are prevalent in domestic swine. Here, we examined the genetic variation among HEVs derived from swine fecal samples in Japan. A total of 320 samples were collected at 32 commercial farm facilities (1 fecal sample from each of 10 pig houses in individual farms). Viral RNA amplification at open reading frame (ORF) 3 was possible in 159 (49.7%) of the fecal samples. For genotyping, the same samples were subjected to amplification at ORF2 and the resulting amplicons were sequenced. The results revealed that all the HEVs in each farm belonged to the same cluster of G3 and G4: G3JP in 8 farms, G3SP in 4 farms, G3US in 6 farms, and G4JP in 2 farms, unclassified G3 in 2 farms, unable to decide due to a low rate of amplification in 5 farms, and no detection in 5 farms. Interestingly, the HEVs from one farm were more homogeneous than those of the same cluster that was derived from other farms. Thus, the efficiency of farm-to-farm transmission of HEVs is likely to be low and HEV seems to have evolved independently at each farm in Japan