Molecular Evolutionary Analysis of the Influenza AH1N1pdm, May–September, 2009: Temporal and Spatial Spreading Profile of the Viruses in JapanReport as inadecuate




Molecular Evolutionary Analysis of the Influenza AH1N1pdm, May–September, 2009: Temporal and Spatial Spreading Profile of the Viruses in Japan - Download this document for free, or read online. Document in PDF available to download.

Background

In March 2009, pandemic influenza AH1N1 AH1N1pdm emerged in Mexico and the United States. In Japan, since the first outbreak of AH1N1pdm in Osaka and Hyogo Prefectures occurred in the middle of May 2009, the virus had spread over 16 of 47 prefectures as of June 4, 2009.

Methods-Principal Findings

We analyzed all-segment concatenated genome sequences of 75 isolates of AH1N1pdm viruses in Japan, and compared them with 163 full-genome sequences in the world. Two analyzing methods, distance-based and Bayesian coalescent MCMC inferences were adopted to elucidate an evolutionary relationship of the viruses in the world and Japan. Regardless of the method, the viruses in the world were classified into four distinct clusters with a few exceptions. Cluster 1 was originated earlier than cluster 2, while cluster 2 was more widely spread around the world. The other two clusters clusters 1.2 and 1.3 were suggested to be distinct reassortants with different types of segment assortments. The viruses in Japan seemed to be a multiple origin, which were derived from approximately 28 transported cases. Twelve cases were associated with monophyletic groups consisting of Japanese viruses, which were referred to as micro-clade. While most of the micro-clades belonged to the cluster 2, the clade of the first cases of infection in Japan originated from cluster 1.2. Micro-clades of Osaka-Kobe and the Fukuoka cases, both of which were school-wide outbreaks, were eradicated. Time of most recent common ancestor tMRCA for each micro-clade demonstrated that some distinct viruses were transmitted in Japan between late May and early June, 2009, and appeared to spread nation-wide throughout summer.

Conclusions

Our results suggest that many viruses were transmitted from abroad in late May 2009 irrespective of preventive actions against the pandemic influenza, and that the influenza AH1N1pdm had become a pandemic stage in June 2009 in Japan.



Author: Teiichiro Shiino , Nobuhiko Okabe, Yoshinori Yasui, Tomimasa Sunagawa, Makoto Ujike, Masatsugu Obuchi, Noriko Kishida, Hong Xu, E

Source: http://plos.srce.hr/



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