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

Yuta Kanai14, Satoshi Miyasaka1, Sachiko Uyama1, Sachiyo Kawami1, Yuko Kato-Mori1, Muneo Tsujikawa3, Mikihiro Yunoki3, Shoko Nishiyama1, Kazuyoshi Ikuta2 and Katsuro Hagiwara1*

Author Affiliations

1 School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Hokkaido 069-8501, Japan

2 Department of Virology, Research Institute for Microbial Diseases, Osaka University, Osaka 565-0871, Japan

3 Infectious Pathogen Research Group, Osaka Research Laboratory, Research & Development Division, Benesis Corporation, Osaka 541-8505, Japan

4 Present Address: Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK

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BMC Research Notes 2012, 5:4  doi:10.1186/1756-0500-5-4

Published: 5 January 2012

Abstract

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.