An increasing prevalence of non-GII.4 norovirus genotypes in acute gastroenteritis outbreaks in Huzhou, China, 2014-2018
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ORIGINAL ARTICLE
An increasing prevalence of non‑GII.4 norovirus genotypes in acute gastroenteritis outbreaks in Huzhou, China, 2014‑2018 Liping Chen1 · Deshun Xu1 · Xiaofang Wu1 · Guangtao Liu1 · Lei Ji1 Received: 8 January 2020 / Accepted: 27 February 2020 © Springer-Verlag GmbH Austria, part of Springer Nature 2020
Abstract Since 2014, novel non-GII.4 norovirus (NoV) genotypes continue to be reported as the main cause of outbreaks worldwide. In this study, we analyzed the epidemiological and genetic features of NoV outbreaks from July 2014 to June 2018 in Huzhou, China. A total of 450 stool samples collected from 51 AGE outbreaks were tested for NoVs by real-time RT PCR. Partial polymerase and capsid sequences of NoV-positive samples were amplified and sequenced for phylogenetic analysis. NoVs were found to be responsible of 84.3% of AGE outbreaks in Huzhou over the past 5 years. Most NoV outbreaks were reported in the cool months (November-March) and occurred in primary schools and kindergartens. Changes in the diversity of genotypes and the distribution of predominant types were observed in recent years. At least eight genotypes were identified, and 91.9% of the genotyped outbreaks were caused by non-GII.4 strains. The top three circulating genotypes during the study period were GII.2[P16], GII.3[P12], and GII.17[P17]. The predominant NoV genotypes in outbreaks have changed from GII.4 variants to GII.17[P17] in 2014-2015, GII.3[P12] in 2015-2016, and then GII.2[P16] in 2016-2018. Non-GII.4 NoVs play an increasingly important role in outbreaks in Huzhou. Continuous surveillance is needed to monitor the emergence of novel NoV strains and help control NoV outbreaks in the next epidemic season.
Introduction Noroviruses (NoVs) are now recognized as the leading cause of viral acute gastroenteritis (AGE) in people of all ages worldwide. Globally, NoVs are estimated to be associated with 50% of all-cause AGE outbreaks and 18% of sporadic cases of AGE [1, 2]. Due to their low infectious dose, prolonged asymptomatic shedding, environmental stability and substantial strain diversity, NoVs are highly infectious and can be easily transmitted from person to person [1]. Outbreaks often occur in semi-closed settings, such as cruise ships, health care settings and schools, that favor person-toperson spread [3]. As a member of the family Caliciviridae, NoV possesses a single-stranded positive-sense RNA genome of 7.7 kb divided into three open reading frames (ORFs) [4]. ORF1 encodes a large polyprotein that is post-translationally Handling Editor: Reimar Johne. * Lei Ji [email protected] 1
Huzhou Center for Disease Control and Prevention, 999 Changxing Road, Huzhou 313000, Zhejiang, China
cleaved into seven nonstructural proteins, including RNAdependent RNA polymerase (RdRp). ORF2 and ORF3 encode the major capsid protein VP1and minor capsid protein VP2, respectively [5]. Based on their complete VP1 amino acid sequences, NoVs can be classified genetically into ten different genogroups (GI to GX), but only GI, GII, GIV, GV
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