Molecular tracing of Japan-indigenous hepatitis E viruses Tanaka, Yasuhito and Takahashi, Kazuaki and Orito, Etsuro and Karino, Yoshiyasu and Kang, Jong-Hon and Suzuki, Kazuyuki and Matsui, Atsushi and Hori, Akiko and Matsuda, Hiroyuki and Sakugawa, Hiroshi and Asahina, Yasuhiro and Kitamura, Tsuneo and Mizokami, Masashi and Mishiro, Shunji,, 87, 949-954 (2006), doi = https://doi.org/10.1099/vir.0.81661-0, publicationName = Microbiology Society, issn = 0022-1317, 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 0·8×10−3 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., language=, type=