栃木県保健環境センター年報 第 23 号（2018）

Front Microbiol. 2018 Jan 18;9:1. doi: 10.3389/fmicb.2018.00001. eCollection 2018.

Genetic Analysis of Human Norovirus Strains in Japan in 2016-2017.
Nagasawa K1,2 , Matsushima Y 3, Motoya T 4 , Mizukoshi F5 , Ueki Y 6 , Sakon N 7 , Murakami K1 , Shimizu T 3,Okabe N 3 , Nagata N 4, Shirabe K8 , Shinomiya H 9 , Suzuki W 10 , Kuroda M 11 , Sekizuka T 11 , Suzuki Y 12 ,Ryo A 13 , Fujita K14 , Oishi K1 , Katayama K15 , Kimura H 1,13,14 .
1 Infectious Disease Surveillance Center, National Institute of Infectious Diseases, Musashimurayama, Japan.
2 Department of Pediatrics, Graduate School of Medicine, Chiba University, Chiba, Japan.
3 Division of Virology, Kawasaki City Institute for Public Health, Kawasaki, Japan.
4 Division of Virology, Ibaraki Prefectural Institute of Public Health, Mito, Japan.
5 Department of Microbiology, Tochigi Prefectural Institute of Public Health and Environmental Science, Utsunomiya, Japan.
6 Division of Virology, Department of Microbiology, Miyagi Prefectural Institute of Public Health and Environment, Sendai, Japan.
7 Department of Microbiology, Osaka Institute of Public Health, Osaka, Japan.
8 Yamaguchi Prefectural Institute of Public Health and Environmen t, Yamaguchi, Japan.
9 Department of Microbiology, Ehime Prefectural Institute of Public Health and Environmental Science, Matsuyama, Japan.
10 Eiken Chemical Co., Ltd., Biochemical Research Laboratory I Department -I, Shimotsuga, Japan.
11 Pathogen Genomics Center, National Institute of Infectious Diseases, Shinjuku, Japan.
12 Division of Biological Science, Department of Information and Basic Science, Graduate School of Natural Sciences, Nagoya C ity
University, Nagoya, Japan.
13 Department of Microbiology, Yokohama City University School of Medicine, Yokohama, Japan.
14 School of Medical Technology, Faculty of Health Science, Gunma Paz University, Takasaki, Japan.
15 Laboratory of Viral Infection I, Kitasato Institute for Life Sciences, Graduate School of Infection Control Sciences, Kitasato
University, Minato, Japan.

Abstract
In the 2016/2017 winter season in Japan, HuNoV GII.P16-GII.2 strains (2016 strains) emerged andcaused large outbreaks of acute gastroenteritis. To better understand the outbreaks, we examined themolecular evolution of the VP1 gene and RdRp region in 2016 strains from patients by studying theirtime-scaleevolutionary

phylogeny,

positive/negative

selection,

conformationalepitopes,andphylodynamics. The time-scale phylogeny suggested that the common ancestors of the 2016 strains VP1gene and RdRp region diverged in 2006 and 1999, respectively, and that the 2016 strain was the progenyof 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 thenumber of patients with NoV GII.2 increased in 2016. The 2016 strain ma y be involved in future
outbreaks in Japan and elsewhere.
KEYWORDS: RNA-dependent RNA polymerase; capsid; epitope mapping; molecular evolution;
norovirus; phylogeny- 157 -

栃木県保健環境センター年報 第 23 号（2018）

PMID: 29403456

Jpn J Infect Dis. 2018 Mar 22;71(2):172-173. doi: 10.7883/yoken.JJID.2017.264. Epub 2018 Feb 28.

A Food Poisoning Outbreak Due to Food Handler-AssociatedContamination with the Human Norovirus GII.P16-GII.2 Variant Strain inItalian Cuisine in Tokyo during the 2016/17 Winter Season.
Somura Y 1 , Mizukoshi F2 , Nagasawa K3 , Kimoto K1 , Oda M 1 , Shinkai T 1 , Murakami K3 , Sadamasu K1 ,Katayama K4 , Kimura H 3 .
1 Department of Microbiology, Tokyo Metropolitan Institute of Public Health.
2 Department of Microbiology, Tochigi Prefectural Institute of Public Health and Environmental Science.
3 Infectious Disease Surveillance Center, National Institute of Infectious Di seases.
4 Laboratory of Viral infection I, Kitasato Institute for Life Sciences Graduate School of Infection Control Sciences,Kitasato University.

KEYWORDS:

Norovirus; food poisoning outbreak; variant

PMID: 29491240- 158 -