Abstract
BackgroundNorovirus (NoV) is a major cause of viral acute gastroenteritis (AGE) in children worldwide. Epidemiological analysis with respect to the virus strains is limited in China. This study aimed to investigate the prevalence, patterns, and molecular characteristics of NoV infection among children with AGE in China.MethodsA total 4848 stool samples were collected from children who were admitted with AGE in Tianjin Children’s Hospital from August 2018 to July 2020. NoV was preliminarily detected using real-time reverse transcription polymerase chain reaction (RT-PCR). Partial sequences of the RNA-dependent RNA polymerase (RdRp) and capsid genes of positive samples were amplified by conventional RT-PCR and then sequenced. The NoV genotype was determined by online Norovirus Typing Tool Version 2.0, and phylogenetic analysis was conducted using MEGA 6.0.ResultsThe prevalence of NoV was 26.4% (1280/4848). NoV was detected in all age groups, with the 7–12 months group having the highest detection rate (655/2014, 32.5%). NoV was detected during most part of the year with higher frequency in winter than other seasons. Based on the genetic analysis of RdRp, GII. Pe was the most predominant genotype detected at 70.7% (381/539) followed by GII.P12 at 25.4% (137/539). GII.4 was the most predominant capsid genotype detected at 65.3% (338/518) followed by GII.3 at 26.8% (139/518). Based on the genetic analysis of RdRp and capsid sequences, the strains were clustered into 10 RdRp–capsid genotypes: GII.Pe-GII.4 Sydney 2012 (65.5%), GII.P12-GII.3 (27.2%), GII.P16-GII.2 (1.8%), GII.P12-GII.2 (0.2%), GII.P17-GII.17 (1.1%), GII.Pe-GII.3 (1.8%), GII.Pe-GII.2 (1.1%), GII.Pe-GII.1 (0.4%), GII.16-GII.4 Sydney 2012 (0.7%), and GII.P7-GII.6 (0.2%). The predominant NoV genotypes changed from GII.Pe-GII.4 Sydney 2012 and GII.P12-GII.3 between August 2018 and July 2019 to GII.Pe-GII.4 Sydney 2012 and GII.P16-GII.2 between August 2019 and July 2020. The patients with GII.Pe-GII.4 Sydney 2012 genotype were more likely to suffer from vomiting symptom than those with GII.P12-GII.3.ConclusionsNoV is an important pathogen responsible for viral AGE among children in China. GII.Pe-GII.4 Sydney 2012 and GII.P12-GII.3 were major recombinant genotypes. Knowledge of circulating genotypes and seasonal trends is of great importance for disease prevention and surveillance.
Highlights
Norovirus (NoV) is a major cause of viral acute gastroenteritis (AGE) in children worldwide
The NoV genotype was determined by only RNA-dependent RNA polymerase (RdRp) (ORF1) or VP1 (ORF2) gene sequence
More and more researchers found that NoV often undergoes recombination at the ORF1–ORF2 junction, which leads to a single virus strain clustering under different genotypes when different genomic regions are used for sequencing [7, 8]
Summary
Norovirus (NoV) is a major cause of viral acute gastroenteritis (AGE) in children worldwide. Its symptoms include nausea, vomiting, diarrhea, abdominal pain, dehydration, and fever [1] While these symptoms can be self-limiting among healthy people, elderly and immunocompromised individuals often develop severe illness [2]. Capsid protein VP1 and RdRp sequences are the basis of current genetic classification of NoV [5]. More and more researchers found that NoV often undergoes recombination at the ORF1–ORF2 junction, which leads to a single virus strain clustering under different genotypes when different genomic regions are used for sequencing [7, 8]. Genotyping of NoV should ideally be based on sequencing of the capsid and RdRp
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