Molecular epidemiology of genogroup II norovirus infection among hospitalized children with acute gastroenteritis in Suzhou (Jiangsu, China) from 2010 to 2013

Molecular epidemiology of norovirus infections in children with acute gastroenteritis in 2017-2019 in Tianjin, China

Norovirus (NoV) is the leading cause of acute gastroenteritis (AGE) worldwide. Globally, the GII.4 Sydney 2012 strain has predominated since 2012, although GII.4 variant strains have caused AGE outbreaks in China. Recent patterns of NoV genotype distributions in 6011 children with AGE in Tianjin, China were investigated. NoV was detected using real-time reverse-transcriptase polymerase chain reaction and sequencing of partial sequences of the viral capsid gene. NoV genotypes were determined, and phylogenetic analysis was conducted. Epidemiological and clinical data were compared between children infected with different NoV genotypes. NoV was detected in 27.6% of the specimens tested. GII.4 strains comprised 49.4% infections, followed by GII.3 at 39.9%. Genotypes GII.2, GII.13, GII.17, GII.1, GII.6, and GII.14 were also detected. NoV was detected during most of the year, with a peak season of cases in the winter. Diarrhea, vomiting, fever, abdominal pain, and dehydration were present in patients with NoV infection. The main genotypes were GII.4 and GII.3, with a slight increase in GII.2, beginning in March 2017. Among the GII.4 strains, GII.4 Sydney 2012 was the only epidemic strain in Tianjin. Patients with GII.4 genotypes were more likely to present with diarrhea and vomiting than those with GII.3. Children with GII. Others were prone to suffered from dehydration and abdominal pain than those with GII.3. NoV GII has become the main cause of viral AGE in Tianjin, China. The predominant genotypes of NoV were GII.4 and GII.3. Identification of emerging genotypes is crucial for the prevention and control of NoV-caused AGE.

Epidemiology and evolution of Norovirus in China

Norovirus (NoV) has been recognized as a leading cause of gastroenteritis worldwide. This review estimates the prevalence and genotype distribution of NoV in China to provide a sound reference for vaccine development. Studies were searched up to October 2020 from CNKI database and inclusion criteria were study duration of at least one calendar year and population size of >100. The mean overall NoV prevalence in individuals with sporadic diarrhea/gastroenteritis was 16.68% (20796/124649, 95% CI 16.63-16.72), and the detection rate of NoV was the highest among children. Non-GII.4 strains have replaced GII.4 as the predominant caused multiple outbreaks since 2014. Especially the recombinant GII.P16-GII.2 increased sharply, and virologic data show that the polymerase GII.P16 rather than VP1 triggers pandemic. Due to genetic diversity and rapid evolution, predominant genotypes might change unexpectedly, which has become major obstacle for the development of effective NoV vaccines.

Molecular epidemiology and genetic diversity of norovirus among hospitalized children with acute gastroenteritis in Tianjin, China, 2018-2020

Background

Norovirus (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.

Methods

A 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.

Results

The 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.

Conclusions

NoV 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.

Global prevalence and genotype distribution of norovirus infection in children with gastroenteritis: A meta-analysis on 6 years of research from 2015 to 2020

In the post rotavirus vaccine era, norovirus (NoV) plays an increasingly important role in epidemic and sporadic gastroenteritis among children. This study was designed to provide an updated meta-analytic review of the prevalence of NoV among paediatric patients with gastroenteritis and to clarify the relationship between NoV infection and gastroenteritis. Systematic searches of the literature for potentially relevant studies were carried out from 1 January 2015 to 29 May 2020. The inverse variance method was chosen for weighting of the studies, and the random-effects model was used to analyse data. To determine the association between NoV infection and gastroenteritis in children, pooled odds ratio (OR) and its 95% confidence interval (CI) were computed for case-control studies. The pooled prevalence of NoV infection among 12,0531 children with gastroenteritis from 45 countries across the world was 17.7% (95% CI: 16.3%-19.2%). There were 28 studies with a case-control design, and the pooled prevalence of NoV infection among 11,954 control subjects was 6.7% (95% CI: 5.1%-8.8%). The pooled OR of the association of NoV infection and gastroenteritis was 2.7 (95% CI: 2.2-3.4). The most common NoV genotypes were GII.4 (59.3%) and GII.3 (14.9%). The highest frequency of NoV was found in the age group below 1 year. Our findings indicated a substantial burden of gastroenteritis caused by NoV globally, with GII.4 and GII.3 the major genotypes responsible for the majority of NoV-associated gastroenteritis cases among children. Younger age and male sex can be considered risk factors for NoV-associated gastroenteritis among children.

Norovirus strains in patients with acute gastroenteritis in rural and low-income urban areas in northern Brazil

From 2010-2016, a total of 251 stool samples were screened for norovirus using next-generation sequencing (NGS) followed by phylogenetic analysis to investigate the genotypic diversity of noroviruses in rural and low-income urban areas in northern Brazil. Norovirus infection was detected in 19.9% (50/251) of the samples. Eight different genotypes were identified: GII.4_Sydney[P31] (64%, 32/50), GII.6[P7] (14%, 7/50), GII.17[P17] (6%, 3/50), GII.1[P33] (6%, 3/50), GII.3[P16] (4%, 2/50), GII.2[P16] (2%, 1/50), GII.2[P2] (2%, 1/50), and GII.4_New Orleans[P4] (2%, 1/50). Distinct GII.6[P7] variants were recognized, indicating the presence of different co-circulating strains. Elucidating norovirus genetic diversity will improve our understanding of their potential health burden, in particular for the GII.4_Sydney[P31] variant.

Molecular epidemiology of GII noroviruses in outpatients with acute gastroenteritis in Shandong Province, China

Noroviruses have been recognized as the most important causative agents of acute gastroenteritis. The present study was carried out to investigate the molecular epidemiological features of genotype II (GII) norovirus in outpatients with acute gastroenteritis in Shandong province in China from July 2017 to June 2018. In total, 151 (10.30%) samples were positive for NoV GII strains by RT-PCR. Eight genotypes were detected: GII.2, GII.3, GII.4, GII.6, GII.7, GII.12, GII.13 and GII.17. GII.4 (43.71%) was the most prevalent genotype, and the dominant strains belonged to the group of Sydney-2012 strains. GII.17 (27.15%), which has become the main cause of outbreaks of acute gastroenteritis in China, also accounted for a high proportion. Meanwhile, three recombinant types (GII.P17-GII.7, GII.P3-GII.4 and GII.P12-GII.4) were observed and authenticated using Simplot software. The results showed that GII norovirus was the main cause of acute gastroenteritis in Shandong province. GII.4 and GII.17 were the dominant genotypes. Continuous observation and identification of emerging genotypes are necessary for understanding the evolution of the virus, control of infection, and development of vaccines.

Genetic diversity and epidemiology of Genogroup II noroviruses in children with acute sporadic gastroenteritis in Shanghai, China, 2012-2017

BACKGROUND

Noroviruses (NoVs) are considered an important cause of acute gastroenteritis (AGE) across all age groups, especially in children under 5 years of age. We investigated the epidemiology of noroviruses in outpatient children from the Children's Hospital of Fudan University in Shanghai, China.

METHODS

Stool specimens were collected between January 2012 and December 2017 from 1433 children under 5 years of age with acute gastroenteritis. All samples were analysed by conventional reverse transcription-polymerase chain reaction (RT-PCR) for genogroup II NoVs amplifying both the RNA-dependent RNA polymerase (RdRp) and partial capsid genes. The Norovirus Genotyping Tool v.2.0 ( https://www.rivm.nl/mpf/typingtool/norovirus/ ) was used for genotyping the strains, and phylogenetic analyses were conducted by MEGA 6.0.

RESULTS

From 2012 to 2017, GII NoVs were detected in 15.4% (220/1433) of the samples, with the highest detection rate in children aged 7-12 months (19.2%, 143/746). The seasons with the highest prevalence of GII NoVs infection were autumn and winter. Based on genetic analysis of RdRp, GII.Pe (74.5%%, 137/184) was the most predominant RdRp genotype from 2013 to 2017, while GII.P4 played a dominant role in 2012 (55.6%, 21/36). Among the capsid genotypes, the most prevalent NoV genotype from 2012 to 2017 was GII.4 (74.1%, 163/220). On the basis of genetic analysis of RdRp and capsid sequences, the strains were clustered into - 19 RdRp/capsid genotypes, and 12 of them were discordant, such as GII.Pe/GII.4-Sydney_2012, GII.P12/GII.3, GII.P7/GII.6, GII.Pe/GII.3, and GII.P16/GII.2. Starting with 2013, GII.Pe/GII.4-Sydney_2012 had completely replaced the pandemic GII.P4-2006b/GII.4-2006b subtype and was detected in children across all age groups.

CONCLUSIONS

The present study shows high detection rates and the genetic diversity of circulating NoV GII genotypes in paediatric AGE samples from Shanghai. The findings emphasize the importance of continuous molecular surveillance of emerging NoV strains.

Norovirus RNA in serum associated with increased fecal viral load in children: Detection, quantification and molecular analysis

Worldwide, norovirus (NoV) is a major cause of acute gastroenteritis (AGE) responsible for pandemics every ~3 years, and over 200,000 deaths per year, with the majority in children from developing countries. We investigate the incidence of NoV in children hospitalized with AGE from Belém, Pará, Brazil, and also correlated viral RNA levels in their blood and stool with clinical severity. For this purpose, paired stool and serum samples were collected from 445 pediatric patients, ≤9 years between March 2012 and June 2015. Enzyme-linked immunosorbent assay (EIA) was used to detect NoV in stool and reverse transcription quantitative PCR (RT-qPCR) used to quantify NoV RNA levels in sera (RNAemia) and in the positive stool. Positives samples were characterized by the partial ORF1/2 region sequence of viral genome. NoV antigen was detected in 24.3% (108/445) of stool samples, with RNAemia also present in 20.4% (22/108). RNAemia and a high stool viral load (>10⁷ genome copies/gram of faeces) were associated with longer hospitalizations. The prevalent genotypes were GII.4 Sydney_2012 (71.6%-58/81) and New Orleans_2009 (6.2%-5/81) variants. Eight other genotypes belonging to GII were detected and four of them were recombinant strains. All sera were characterized as GII.4 and shared 100% similarity with their stool. The results suggest that the dissemination of NoV to the blood stream is not uncommon and may be related to increased faecal viral loads and disease severity.

Norovirus recombinants: recurrent in the field, recalcitrant in the lab - a scoping review of recombination and recombinant types of noroviruses

Noroviruses are recognized as the major global cause of sporadic and epidemic non-bacterial gastroenteritis in humans. Molecular mechanisms driving norovirus evolution are the accumulation of point mutations and recombination. Intragenotypic recombination has long been postulated to be a driving force of GII.4 noroviruses, the predominant genotype circulating in humans for over two decades. Increasingly, emergence and re-emergence of different intragenotype recombinants have been reported. The number and types of norovirus recombinants remained undefined until the 2007 Journal of General Virology research article 'Norovirus recombination' reported an assembly of 20 hitherto unclassified intergenotypic norovirus recombinant types. In the intervening decade, a host of novel recombinants has been analysed. New recombination breakpoints have been described, in vitro and in vivo studies supplement in silico analyses, and advances have been made in analysing factors driving norovirus recombination. This work presents a timely overview of these data and focuses on important aspects of norovirus recombination and its role in norovirus molecular evolution. An overview of intergenogroup, intergenotype, intragenotype and 'obligatory' norovirus recombinants as detected via in silico methods in the field is provided, enlarging the scope of intergenotypic recombinant types to 80 in total, and notably including three intergenogroup recombinants. A recap of advances made studying norovirus recombination in the laboratory is given. Putative drivers and constraints of norovirus recombination are discussed and the potential link between recombination and norovirus zoonosis risk is examined.

Prevalence and genetic diversity of norovirus genogroup II in children less than 5 years of age with acute gastroenteritis in Tehran, Iran

Viral gastroenteritis is a major public health problem worldwide. In Iran, very limited studies have been performed with regard to the epidemiology of noroviruses. This study aimed to evaluate the prevalence and molecular epidemiology of GII noroviruses in hospitalized children less than 5 years of age with acute gastroenteritis (AGE). A total of 210 stool specimens were collected from Ali Asghar Children's Hospital and Bahrami Children's Hospital in Tehran, from June 2015 to June 2016. The samples were screened by real-time RT-PCR for genogroup II (GII). Positive samples were genotyped by semi-nested PCR followed by Sanger sequencing and phylogenetic analysis. Norovirus was identified in 36 (17.1%) of 210 specimens. Based on genetic analysis of RdRp and capsid sequences, the strains were clustered into eight RdRp-capsid genotypes: GII.P4-GII.4 Sydney_2012 (41.7%), GII.Pe-GII.4 Sydney_2012 (30.6%), GII.P21-GII.3 (13.9%), GII.P16-GII.4 Sydney_2012 (2.8%), GII.P16-GII.12 (2.8%), GII.P2-GII.4 Sydney_2012 (2.8%), GII.P7-GII.7 (2.8%) and GII.P2-GII.2 (2.8%). We determined several different co-circulating norovirus genotypes in children < 5 years of age with AGE in our hospital in Tehran, Iran. Continued molecular surveillance of noroviruses, including typing of both RdRp and capsid genes, is important for monitoring emerging strains in our continued efforts to reduce the overall burden of norovirus disease.

Molecular epidemiology and temporal evolution of norovirus associated with acute gastroenteritis in Amazonas state, Brazil

BACKGROUND

Globally, Norovirus (NoV) is considered the most common cause of diarrheal episodes across all age groups. Despite its wide genetic diversity, the GII.4 strain is the most predominant and has been associated with epidemics worldwide. In this study, we characterized sporadic cases of diarrhea from NoV-positive children, during a five-year period (2010-2014).

METHODS

A total of 250 NoV-positive samples identified by an enzyme immunoassay (EIA) were subjected to RT-PCR and partial nucleotide sequencing for polymerase and capsid genes. Phylogenetic analysis was performed to identify NoV genotypes using the binary classification. In addition, sequences from the P2 subdomain (capsid) gene of GII-4 variants were characterized by evolutionary analyses, using the MCMC method implemented in the BEAST package. A 3D structure was built using protein modeling.

RESULTS

Phylogenetic analysis demonstrated a predominance of genotype GII.4 (52.4% - 99/189), variants New Orleans_2009 and Sydney_2012 followed by GII.P7/GII.6 with 6.3% (12/189). Amino acid analyses of the GII.4 strains showed several important amino acid changes. A higher evolutionary rate was found, 7.7 × 10^- 3 in the Sydney variant and 6.3 × 10^- 3 in the New Orleans. Based in evolutionary analysis the time to the most recent common ancestor (TMRCA) has been calculated as estimates of the population divergence time. Thus, TMRCA for New Orleans and Sydney variant were 2008.7 and 2010.7, respectively. Also, we observed a lineage of transition between New Orleans and Sydney.

CONCLUSION

This study describes the different strains of norovirus isolated from Amazonas state in Brazil during a five-year period. Considering that NoV are capable of changing their antigenic epitopes rapidly, a continuous surveillance is important to monitor the occurrence and changes of the NoV in the community through epidemiological studies. These results contribute to the understanding of NoV molecular epidemiology and its evolutionary dynamics in Amazonas state, Brazil.