First detection and characterization of rat hepatitis E Virus (HEV-C1) in Japan

Rat hepatitis E virus (HEV-C1) in the Orthohepevirus C species has been reported to cause zoonotic infection and hepatitis in humans. HEV-C1 strains have been detected from wild rats in many countries in Europe, Asia, and North America. However, in Japan, no HEV-C1 strains have been identified. In the present study, 5 (1.2%) of 428 wild rats (Rattus norvegicus or R. rattus) were positive for anti-HEV-C1 IgG. Although all 428 rat sera were negative for HEV-C1 RNA, it was detectable in 20 (19.8%) of 101 rat fecal samples collected on a swine farm, where HEV (genotype 3b, HEV-3b) was prevalent and wild rats were present. In addition, HEV-C1 RNA was detectable in the intestinal contents and liver tissues of 7 (18.9%) of 37 additional rats captured on the same farm. The HEV-C1 strain (ratEJM1703495L) obtained in this study shared only 75.8-84.7% identity with reported HEV-C1 strains over the entire genome but propagated efficiently in cultured cells. HEV-3b strains were detected in the rats' intestinal contents, with 97.3-99.5% identity to those in pigs on the same farm, but were undetectable in rat liver tissues, suggesting that wild rats do not support the replication of HEV-3b of swine origin.