Abstract
Infection caused by noroviruses (NoVs) is one of the most important causes of acute gastroenteritis in humans worldwide. To gain insight into the epidemiology of and genetic variation in NoV strains, stool samples collected from 18 outbreaks of acute gastroenteritis in Huzhou, China, between January 2008 and December 2012 were analyzed. Samples were tested for NoVs by real-time RT-PCR. Partial sequences of the RNA- dependent RNA polymerase (RdRp) and capsid gene of the positive samples were amplified by RT-PCR, and the PCR products were sequenced and used for phylogenetic analysis. NoVs were found to be responsible of 88.8% of all nonbacterial acute gastroenteritis outbreaks in Huzhou over the last 5 years. Genogroup II outbreaks largely predominated and represented 93% of all outbreaks. A variety of genotypes were found among genogroups I and II, including GI.4, GI.8, GII.4, and GII.b. Moreover, phylogenetic analyses identified two recombinant genotypes (polymerase/capsid): GI.2/GI.6 and GII.e/GII.4 2012 Sydney. GII.4 was predominant and involved in 8/10 typed outbreaks. During the study period, GII.4 NoV variants 2006b, New Orleans 2009, and Sydney 2012 were identified. This is the first report of the detection of GII.4 New Orleans 2009 variant, GII.e/GII.4 Sydney 2012 recombinant in outbreaks of acute gastroenteritis in China.
Highlights
Noroviruses (NoVs) are the major cause of outbreaks and sporadic cases of nonbacterial acute gastroenteritis in all age groups in both developing and developed countries
NoVs are single-stranded, positive-sense RNA viruses that belong to the Caliciviridae family and possess a polyadenylated RNA genome of 7.3–7.7 kb containing three overlapping open reading frames (ORFs) [2]
From January 2008 to December 2012, 155 stool specimens from 18 nonbacterial acute gastroenteritis outbreaks in the Huzhou area were examined by reverse transcription (RT)-qPCR Real-time PCR (qPCR) that detects NoVs in a genogroup-specific manner
Summary
Noroviruses (NoVs) are the major cause of outbreaks and sporadic cases of nonbacterial acute gastroenteritis in all age groups in both developing and developed countries. NoVs are genetically highly diverse and can be grouped into five genogroups (GI through GV), which are further divided into at least 34 genotypes based on genetic differences in the capsid gene [4]. The high degree of genetic diversity of NoVs can be attributed to both point mutations during genome replication and RNA recombination between co-circulating strains. Recombination of NoV genomes is believed to occur in nature at high frequency. The majority of NoV recombinants have breakpoints located either within or close to the ORF1-ORF2 junction, which causes more genetic divergence of NoVs [8,9]
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