Molecular Epidemiological Characteristics of Gastroenteritis Outbreaks Caused by Norovirus GII.4 Sydney [P31] Strains — China, October 2016–December 2020

Abstract

Introduction: Human noroviruses are the leading cause of acute viral gastroenteritis (AGE) worldwide in all age groups. GII.4 strains have been the predominant genotype circulating globally over the last 2 decades and since 2012. GII.4 Sydney viruses have emerged and caused the majority of AGE outbreaks worldwide.Methods: Data from norovirus outbreaks from the laboratory-based surveillance of norovirus outbreaks in China (CaliciNet China) between October 2016-December 2020 were analyzed.Results: During October 2016-December 2020, 1,954 norovirus outbreaks were reported, and positive fecal samples from 1,352 (69.19%) outbreaks were genotyped. GII.4 Sydney [P31] viruses accounted for 2.

Molecular epidemiology analysis of symptomatic and asymptomatic norovirus infections in Chinese infants

“…Our study found that the mutation frequency of ORF2 region was higher than RdRp region of the ORF1, especially in the P2 subdomain. The amino acid mutations of the VP1 protein identified in our study (amino acid positions 309, 373, 414) corresponded to the same characteristics identified by another Chinese group, and the remaining amino acid mutation sites were located at or near the amino acids identified by this group [ 55 ]. Most of these mutations are located at or near the epitope region of the P2 sub-domain.…”

“…The phylogenetic tree suggested that GII.4[P31] strains isolated from our study have a close genetic distance with previously circulating strains in Shanghai, Beijing, Zhengzhou and Guangzhou in 2016–2020. This finding proves that GII.4[P31] strains have circulated in the mainland China before 2016 [ 54 , 55 ]. The GII.4[P16] strain in our study was similar to the viruses circulating in Beijing in 2019–2020, and strains detected in Thailand in 2019–2020.…”

Emergence of GII.4 Sydney[P16]-like Norovirus-Associated Gastroenteritis, China, 2020–2022

“…GII.4 Sydney[P16] norovirus has advantageous epidemic potential because of viral fitness from its recombinant components: emerging GII.P16 polymerase and persistently mutating GII.4 VP1 ( 11 , 12 ). Although GII.4 Sydney[P16] norovirus prevalence has rarely been reported in China ( 13 ), its advantageous qualities raise concerns about the virus possibly causing an epidemic. To monitor epidemiologic and genetic data from GII.4 Sydney[P16] norovirus in China, we performed laboratory-based surveillance of noroviruses among children with AGE in Shanghai.…”

Molecular epidemiology and genetic diversity of norovirus among hospitalized patients with acute gastroenteritis in Shandong, China, 2016–2018

“…Cluster Ⅲ included the NoV strains circulated in the Western Pacific Region—China, Japan, Vietnam, South Korea, and Russia 27,28 . Our GⅡ.3 strains all clustered into Cluster Ⅲ. The Sydney_2012 clade was the latest variant for G.4 and has been circulating globally with a high incidence in the last decade 29 . Our GII.4 strains clustered within the Sydney_2012 clade. VP1‐specific phylogeny of GII.17 strains also showed six genetic clades: Lineage I (1978), Lineage II (2002), Lineage III (2005−2007), Lineage IV (2008−2009), Lineage V (2013−2014), and Lineage VI (2014−2015).…”

“…• The Sydney_2012 clade was the latest variant for G.4 and has been circulating globally with a high incidence in the last decade. 29 Our GII.4 strains clustered within the Sydney_2012 clade. spread to many countries, including China, Japan, and Italy.…”