Case Report High genomic similarity between European type hepatitis E virus subgenotype 3e strains isolated from an acute hepatitis patient and a wild boar in Mie, Japan Hiroshi Okano, 1 † Tatsunori Nakano, 2 † Kazushi Sugimoto, 3 Kazuaki Takahashi, 4 Shigeo Nagashima, 6 Masaharu Takahashi, 6 Masahiro Arai 4,5 and Hiroaki Okamoto 6 1 Department of Gastroenterology, Suzuka General Hospital, 2 Department of Internal Medicine, Fujita Health University Nanakuri Sanatorium, 3 Department of Laboratory Medicine, Mie University School of Medicine, Mie, 4 Department of Medical Sciences, 5 Department of Gastroenterology, Toshiba General Hospital, Tokyo, and 6 Division of Virology, Department of Infection and Immunity, Jichi Medical University School of Medicine, Tochigi, Japan A 67-year-old male living in Tsu city, Mie prefecture, Japan was referred to our hospital for further examination of acute liver injury and was diagnosed as having clinical hepatitis E virus (HEV) infection in January 2010. The HEV strain (HE-JA11-1701) isolated from the patient belonged to genotype 3 and European-type subgenotype 3e. It was presumed that the patient had been infected from a wild boar (Sus scrofa leu- comystax) because he consumed meat/viscera from a wild boar that he had captured himself as a hunter approximately 2 months before disease onset. A specimen of the boar meat/ viscera that the patient had ingested was not available. However, the HE-JA11-1701 strain was 99.8% identical within the 412-nucleotide sequence of the open reading frame 2 region to a HEV strain (JBOAR012-Mie08) that had been recov- ered from a wild boar captured near the patient’s hunting area in 2008. A phylogenetic analysis confirmed that the two HEV strains had a close genetic relationship and were segre- gated into subgenotype 3e, supported by a high bootstrap value of 99%. Of note, the HE-JA11-1701 and JBOAR012-Mie08 strains were remotely related to the 3e strains reported in Japan and European countries, with a nucleotide difference of 7.9–13.9%, reinforcing the uniqueness of the 3e strains obtained in the present study. These results strongly support our speculation that the patient developed acute hepatitis E via consumption of HEV-infected boar meat/viscera. Genetic analyses of HEV strains are useful for tracing infectious sources in sporadic cases of acute hepatitis E. Key words: hepatitis E virus, Japan, nucleotide sequence, subgenotype 3e, wild boar INTRODUCTION H EPATITIS E VIRUS (HEV) is transmitted via the fecal–oral route through the consumption of con- taminated water or food. HEV infection had long been considered to be restricted to developing countries where sanitation conditions are suboptimal. However, HEV is now recognized to be an important pathogen of acute hepatitis in industrialized countries. Both HEV and hepatitis caused by HEV appear to exist virtually everywhere worldwide. 1 In Japan, autochthonous HEV strains were first recovered in 2001 from a Japanese patient with sporadic acute hepatitis E who had no history of traveling abroad and from domesticated pigs independently. 2,3 Zoonotic food-borne transmission of HEV via the ingestion of meat or viscera of infected animals including pigs, wild boar and deer is the main route of HEV transmission in Japan, 4–6 where transfusion-transmitted HEV infection is reported to rarely occur. 7,8 However, infectious source(s)/route(s) remain unknown in nearly half of hepatitis E cases in Japan. 4 Four major genotypes of HEV that infect humans have been identified thus far. 9 Unlike genotypes 1 and 2 that are responsible for the majority of HEV infections in Correspondence: Dr Hiroshi Okano, Department of Gastroenterology, Suzuka General Hospital, 1275-1253 Yasuduka-cho, Suzuka, Mie 513-8630, Japan. Email: oohh1969@yahoo.co.jp †These authors contributed equally to this work. Received 5 April 2013; revision 24 April 2013; accepted 25 April 2013. Hepatology Research 2013 doi: 10.1111/hepr.12155 © 2013 The Japan Society of Hepatology 1