Genetic Analysis of Human Norovirus Strains in Japan in 2016–2017

作者：Koo Nagasawa, Yuki Matsushima, Takumi Motoya, Fuminori Mizukoshi, Yo Ueki, Naomi Sakon, Koichi Murakami, Tomomi Shimizu, Nobuhiko Okabe, Noriko Nagata, Komei Shirabe, Hiroto Shinomiya, Wataru Suzuki, Makoto Kuroda, Tsuyoshi Sekizuka, Yoshiyuki Suzuki, Akihide Ryo, Kiyotaka Fujita, Kazunori Oishi, Kazuhiko Katayama, Hirokazu Kimura · 发表于：Frontiers in Microbiology · 年份：2018 · DOI：10.3389/fmicb.2018.00001 · 被引用次数：1265 · 研究领域：Viral gastroenteritis research and epidemiology、Respiratory viral infections research、Animal Virus Infections Studies

In the 2016/17 winter season in Japan, HuNoV GII.P16-GII.2 strains (2016 strains) emerged and caused large outbreaks of acute gastroenteritis. To better understand the outbreaks, we examined the molecular evolution of the VP1 gene and RdRp region in 2016 strains from patients by studying their time-scale evolutionary phylogeny, positive/negative selection, conformational epitopes, and phylodynamics. The time-scale phylogeny suggested that the common ancestors of the 2016 strains VP1 gene and RdRp region diverged in 2006 and 1999, respectively, and that the 2016 strain was the progeny of a pre-2016 GII.2. The evolutionary rates of the VP1 gene and RdRp region were around 10−3 substitutions/site/year. Amino acid substitutions (position 341) in an epitope in the P2 domain of 2016 strains were not found in pre-2016 GII.2 strains. Bayesian skyline plot analyses showed that the effective population size of the VP1 gene in GII.2 strains was almost constant for those 50 years, although the number of patients with NoV GII.2 increased in 2016. The 2016 strain may be involved in future outbreaks in Japan and elsewhere.