title: Molecular tracing of Japan-indigenous hepatitis E viruses.
abstract: The ancestor(s) of apparently Japan-indigenous strains of Hepatitis E virus (HEV) was probably of foreign origin, but it remains unclear when and from where it made inroads. In this study, 24 genotype 3 and 24 genotype 4 HEV strains recovered in Japan each showed a significant cluster, clearly distinct from those of foreign strains, in the phylogenetic tree constructed from an 821 nt RNA polymerase gene fragment. The evolutionary rate, approximately 0.8 x 10(-3) nucleotide substitutions per site per year, enabled tracing of the demographic history of HEV and suggested that the ancestors of Japan-indigenous HEV had made inroads around 1900, when several kinds of Yorkshire pig were imported from the UK to Japan. Interestingly, the evolutionary growth of genotype 3 in Japan has been slow since the 1920s, whereas genotype 4 has spread rapidly since the 1980s. In conclusion, these data suggest that the indigenization and spread of HEV in Japan were associated with the popularization of eating pork.
authors.affiliation: Department of Clinical Molecular Informative Medicine, Nagoya City University Graduate School of Medical Sciences, Kawasumi, Mizuho, Nagoya 467-8601, Japan.
authors.forename: Yasuhito
authors.initials: Y
authors.lastname: Tanaka
authors.affiliation: Department of Medical Sciences, Toshiba General Hospital, Tokyo 140-8522, Japan.
authors.forename: Kazuaki
authors.initials: K
authors.lastname: Takahashi
authors.affiliation: Department of Clinical Molecular Informative Medicine, Nagoya City University Graduate School of Medical Sciences, Kawasumi, Mizuho, Nagoya 467-8601, Japan.
authors.forename: Etsuro
authors.initials: E
authors.lastname: Orito
authors.affiliation: Department of Hepatology, Sapporo Kosei General Hospital, Sapporo 060-0033, Japan.
authors.forename: Yoshiyasu
authors.initials: Y
authors.lastname: Karino
authors.affiliation: Center for Gastroenterology, Teine Keijinkai Hospital, Sapporo 006-8555, Japan.
authors.forename: Jong-Hon
authors.initials: JH
authors.lastname: Kang
authors.affiliation: First Department of Internal Medicine, Iwate Medical University, Iwate 020-8505, Japan.
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Suzuki
authors.affiliation: Department of Gastroenterology and Hepatology, Saitama Medical University, Saitama 350-0495, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Matsui
authors.affiliation: Department of Internal Medicine, Kokuho Central Hospital, Nara 636-0302, Japan.
authors.forename: Akiko
authors.initials: A
authors.lastname: Hori
authors.affiliation: Department of Internal Medicine, Tottori Red Cross Hospital, Tottori 680-8517, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Matsuda
authors.affiliation: Transfusion Section, University of the Ryukyus School of Medicine, Okinawa 903-0215, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Sakugawa
authors.affiliation: Division of Gastroenterology and Hepatology, Musashino Red Cross Hospital, Tokyo 180-8610, Japan.
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Asahina
authors.affiliation: Department of Gastroenterology, Juntendo University School of Medicine, Urayasu Hospital, Chiba 279-0021, Japan.
authors.forename: Tsuneo
authors.initials: T
authors.lastname: Kitamura
authors.affiliation: Department of Clinical Molecular Informative Medicine, Nagoya City University Graduate School of Medical Sciences, Kawasumi, Mizuho, Nagoya 467-8601, Japan.
authors.forename: Masashi
authors.initials: M
authors.lastname: Mizokami
authors.affiliation: Department of Medical Sciences, Toshiba General Hospital, Tokyo 140-8522, Japan.
authors.forename: Shunji
authors.initials: S
authors.lastname: Mishiro
mesh_terms: D000818:Animals; D012321:DNA-Directed RNA Polymerases / Q000235:genetics; D019143:Evolution, Molecular; D016751:Hepatitis E / Q000453:epidemiology* / Q000821:virology; D016752:Hepatitis E virus / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008969:Molecular Sequence Data; D017422:Sequence Analysis, DNA; D013552:Swine / Q000821:virology; D013553:Swine Diseases / Q000453:epidemiology* / Q000821:virology
chemical_list: D012321:DNA-Directed RNA Polymerases