Molecular tracing of Japan-indigenous hepatitis E viruses.
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.
Tanaka
Yasuhito
Y
Department of Clinical Molecular Informative Medicine, Nagoya City University Graduate School of Medical Sciences, Kawasumi, Mizuho, Nagoya 467-8601, Japan.
Takahashi
Kazuaki
K
Department of Medical Sciences, Toshiba General Hospital, Tokyo 140-8522, Japan.
Orito
Etsuro
E
Department of Clinical Molecular Informative Medicine, Nagoya City University Graduate School of Medical Sciences, Kawasumi, Mizuho, Nagoya 467-8601, Japan.
Karino
Yoshiyasu
Y
Department of Hepatology, Sapporo Kosei General Hospital, Sapporo 060-0033, Japan.
Kang
Jong-Hon
JH
Center for Gastroenterology, Teine Keijinkai Hospital, Sapporo 006-8555, Japan.
Suzuki
Kazuyuki
K
First Department of Internal Medicine, Iwate Medical University, Iwate 020-8505, Japan.
Matsui
Atsushi
A
Department of Gastroenterology and Hepatology, Saitama Medical University, Saitama 350-0495, Japan.
Hori
Akiko
A
Department of Internal Medicine, Kokuho Central Hospital, Nara 636-0302, Japan.
Matsuda
Hiroyuki
H
Department of Internal Medicine, Tottori Red Cross Hospital, Tottori 680-8517, Japan.
Sakugawa
Hiroshi
H
Transfusion Section, University of the Ryukyus School of Medicine, Okinawa 903-0215, Japan.
Asahina
Yasuhiro
Y
Division of Gastroenterology and Hepatology, Musashino Red Cross Hospital, Tokyo 180-8610, Japan.
Kitamura
Tsuneo
T
Department of Gastroenterology, Juntendo University School of Medicine, Urayasu Hospital, Chiba 279-0021, Japan.
Mizokami
Masashi
M
Department of Clinical Molecular Informative Medicine, Nagoya City University Graduate School of Medical Sciences, Kawasumi, Mizuho, Nagoya 467-8601, Japan.
Mishiro
Shunji
S
Department of Medical Sciences, Toshiba General Hospital, Tokyo 140-8522, Japan.
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
D012321:DNA-Directed RNA Polymerases