Molecular evolution of GII.P17-GII.17 norovirus associated with sporadic acute gastroenteritis cases during 2013-2018 in Zhoushan Islands, China.

In this study, we investigated the molecular characteristics and spatio-temporal dynamics of GII.P17-GII.17 norovirus in Zhoushan Islands during 2013-2018. We collected 1849 samples from sporadic acute gastroenteritis patients between January 2013 and August 2018 in Zhoushan Islands, China. Among the 1849 samples, 134 (7.24%) samples were positive for human norovirus (HuNoV). The complete sequence of GII.17 VP1 gene was amplified from 31 HuNoV-positive samples and sequenced. A phylogenetic tree was constructed based on the full-length sequence of the VP1 gene. Phylogenetic analysis revealed that the GII.17 genotype detected during 2014-2018 belongs to the new GII.17 Kawasaki variant. Divergence analysis revealed that the time of the most recent common ancestor (TMRCA) of GII.17 in Zhoushan Islands was estimated to be between 1997 and 1998. The evolutionary rate of the VP1 gene of the GII.17 genotype norovirus was 1.14 × 10-3 (95% HPD: 0.62-1.73 × 10-3) nucleotide substitutions/site/year. The spatio-temporal diffusion analysis of the GII.17 genotype identified Hong Kong as the epicenter for GII.17 dissemination. The VP1 gene sequence of Zhoushan Island isolates correlated with that of Hong Kong and Japan isolates.

Genetic Diversity of Sapoviruses among Inpatients in Germany, 2008-2018.

Sapovirus enteric disease affects people of all ages across the globe, in both sporadic cases and outbreak settings. Sapovirus is seldom assessed in Germany and its epidemiology in the country is essentially unknown. Thus, sapovirus occurrence and genetic diversity were studied by real-time reverse transcription polymerase chain reaction (RT-PCR) and partial sequencing of major viral structural protein (VP1) gene in two different sets of stool samples: 1) a selection of 342 diarrheal stools collected from inpatient children during 2008-2009, and 2) 5555 stool samples collected during 2010-2018 from inpatients of all age groups with gastrointestinal complaints. Results showed year-round circulation of sapoviruses, with peaks during cooler months. In total, 30 samples (8.8%) of the first and 112 samples of the second set of samples (2.0%) were sapovirus positive. Capsid gene sequencing was successful in 134/142 samples (94.4%) and showed circulation of all known human pathogenic genogroups. Genotype GI.1 predominated (31.8%), followed by GII.1 (16.7%), GII.3 (14.5%), GI.2 (13.8%) and GV.1 (12.3%). Additionally, minor circulation of GI.3, GI.6, GII.2, GII.4, GII.6 and GIV.1 was shown. Consequently, sapovirus diagnostics need broadly reactive RT-PCR protocols and should particularly be considered in infants and young children. Further studies from other sampling sites are essential to extend our knowledge on sapovirus epidemiology in Germany.

Recombinant GII.Pe-GII.4 Norovirus, Thailand, 2017-2018.

During June 2017-December 2018, norovirus was responsible for 10.9% of acute gastroenteritis cases in Thailand. Genogroup I (GI) was found in 14% of samples, of which 12 were co-infected with genogroup II (GII). In 35.8% of samples, GII.Pe-GII.4 Sydney predominated. Diverse recombinant strains of GI and GII norovirus co-circulated year-round.

Norovirus outbreaks in Beijing, China, from 2014 to 2017.

OBJECTIVES: Noroviruses are a leading cause of acute gastroenteritis (AGE) outbreaks worldwide. This study examined the epidemiology and genetic characteristics of norovirus outbreaks in Beijing, China. METHODS: Epidemiological data and fecal specimens were collected through the AGE outbreak surveillance system in Beijing. GI and GII genogroup noroviruses were detected and genotyped. The data were analyzed using descriptive statistics. RESULTS: Between September 2014 and August 2017, 762 AGE outbreaks were reported in Beijing, of which 661 (86.7%) were laboratory-confirmed as norovirus. Most norovirus outbreaks were reported during the spring (66.9%, 442/661), occurred in kindergartens and elementary schools (92.3%, 610/661), and were caused by GII genogroup noroviruses (95.6%; 632/661). The genotypes of the norovirus strains were determined in 468 outbreaks, and GII.P16-GII.2 and GII.P17-GII.17 strains were the most commonly identified. GII.P17-GII.17 and GII.P16-GII.2 strains predominated in 2014-2015 and 2016-2017 outbreaks, respectively. GII.P16-GII.2 noroviruses were responsible for a steep increase in AGE outbreaks in Beijing: 549 norovirus outbreaks were reported from 2016 to 2017, 9.2 times the number that occurred during the previous year. CONCLUSIONS: Norovirus causes a large disease burden in Beijing, and the prevalence of non-GII.4 noroviruses presents a new challenge for the development of vaccines.

Recombinant noroviruses detected in Mid-West region of Brazil in two different periods 2009-2011 and 2014-2015: Atypical breakpoints of recombination and detection of distinct GII.P7-GII.6 lineages.

Noroviruses are an important cause of acute gastroenteritis. The high incidence of norovirus is a reflection of its great genomic and antigenic variability resultant of evolutionary mechanisms, such as recombination. Herein, the main objective of this study was to characterize partially two regions of norovirus genome (RdRp and VP1) from fecal samples, collected in two different time periods (2009-2011 and 2014-2015) in the Mid-West region of Brazil. Twenty samples were sequenced and characterized (GI.P5-GI.5, GII.P16-GII.3, GI.P7-GI.7, GII.Pe-GII.4 and GII.P7-GII.6). Sequences of GII.Pe-GII.4 genotype were also characterized as Sydney 2012 variant. Genotypes GII.P7-GII.6, GII.P16-GII.3 and GII.Pe-GII.4 (16/20-80%) were identified as norovirus recombinants by phylogeny and bioinformatic analyzes. The GII.P7-GII.6 (62.5%) and GII.Pe-GII.4 (25%) genotypes had recombination point's upstream ORF1/2 overlapping region, whereas GII.P16-GII.3 (12.5%) genotype had the recombination point in the overlapping region. Furthermore, the GII.P7-GII.6, from samples collected in 2009-2011 had different recombinant points than the GII.P7-GII.6 from samples obtained in 2014-2015, forming two different clusters in the phylogenetic analysis. Our study brings information on the circulation of recombinant norovirus genotypes in Mid-West of Brazil, including recombinants with atypical recombination breakpoints, and provides evidence for the circulation of different lineages of the same recombinant genotype.

Pediatric norovirus GII.4 infections in Nicaragua, 1999-2015.

OBJECTIVES: Investigate clinical and epidemiological factors of pediatric GII.4 norovirus infections in children with acute gastroenteritis (AGE) in Nicaragua between 1999 and 2015. METHODS: We retrospectively analyzed laboratory and epidemiologic data from 1,790 children≤7years with AGE from 6 hospitals in Nicaragua (n=538), and 3 community clinics (n=919) and households (n=333) in León, between 1999 and 2015. Moreover, asymptomatic children from community clinics (n=162) and households (n=105) were enrolled. Norovirus was detected by real-time PCR and genotyped by sequencing the N-terminal and shell region of the capsid gene. RESULTS: Norovirus was found in 19% (n=338) and 12% (n=32) of children with and without AGE, respectively. In total, 20 genotypes including a tentatively new genotype were detected. Among children with AGE, the most common genotypes were GII.4 (53%), GII.14 (7%), GII.3 (6%) and GI.3 (6%). In contrast, only one (1.4%) GII.4 was found in asymptomatic children. The prevalence of GII.4 infections was significantly higher in children between 7 and 12months of age. The prevalence of GII.4 was lowest in households (38%), followed by community clinics (50%) and hospitals (75%). Several different GII.4 variants were detected and their emergence followed the global temporal trend. CONCLUSIONS: Overall our study found the predominance of pediatric GII.4 norovirus infections in Nicaragua mostly occurring in children between 7 and 12months of age, implicating GII.4 as the main norovirus vaccine target.

Global Spread of Norovirus GII.17 Kawasaki 308, 2014-2016.

Analysis of complete capsid sequences of the emerging norovirus GII.17 Kawasaki 308 from 13 countries demonstrated that they originated from a single haplotype since the initial emergence in China in late 2014. Global spread of a sublineage SL2 was identified. A new sublineage SL3 emerged in China in 2016.

Norovirus GII.17 as Major Epidemic Strain in Italy, 2015-16.

In winter 2015-16, norovirus GII.17 Kawasaki 2014 emerged as a cause of sporadic gastroenteritis in children in Italy. Median patient age was higher for those with GII.17 than GII.4 infection (55 vs. 24 months), suggesting limited cross-protection for older children.

Genotype diversity and molecular evolution of noroviruses: A 30-year (1982-2011) comprehensive study with children from Northern Brazil.

A chronologically comprehensive 30-year study was conducted that involved children living in Belém, in the Amazon region of Northern Brazil, who participated in eight different studies from October 1982 to April 2011. The children were followed either in the community or in health units and hospitals in order to identify the norovirus genotypes involved in infections during this time. A total of 2,520 fecal specimens were obtained and subjected to RT-PCR and nucleotide sequencing for regions A, B, C, D and P2 of the viral genome. An overall positivity of 16.9% (n = 426) was observed, and 49% of the positive samples were genotyped (208/426), evidencing the presence of several genotypes as follows: Polymerase gene (GI.P4, GII.Pa, GII.Pc, GII.Pe, GII.Pg, GII.Pj, GII.P3, GII.P4, GII.P6, GII.P7, GII.P8, GII.P12, GII.P13, GII.P14, GII.P21, GII.P22), and VP1 gene (GI.3, GI.7, GII.1, GII.2, GII.3, GII.4, GII.6, GII.7, GII.8, GII.10, GII.12, GII.14, GII.17, GII.23). The GII.P4/GII.4 genotype determined by both open reading frames (ORFs) (partial polymerase and VP1 genes) was found for 83 samples, and analyses of the subdomain P2 region showed 10 different variants: CHDC (1970s), Tokyo (1980s), Bristol_1993, US_95/96, Kaiso_2003, Asia_2003, Hunter_2004, Yerseke_2006a, Den Haag_2006b (subcluster "O") and New Orleans_2009. Recombination events were confirmed in 47.6% (n = 20) of the 42 samples with divergent genotyping by ORF1 and ORF2 and with probable different breakpoints within the viral genome. The evolutionary analyses estimated a rate of evolution of 1.02 x 10-2 and 9.05 x 10-3 subs./site/year using regions C and D from the VP1 gene, respectively. The present research shows the broad genetic diversity of the norovirus that infected children for 30 years in Belém. These findings contribute to our understanding of noroviruses molecular epidemiology and viral evolution and provide a baseline for vaccine design.

Recombinant GII.P16-GII.2 Norovirus, Taiwan, 2016.

In Taiwan, acute gastroenteritis outbreaks caused by a new norovirus genotype GII.2 increased sharply toward the end of 2016. Unlike previous outbreaks, which often involved restaurants, GII.2 outbreaks mainly occurred in schools. Phylogenetic analysis indicates that these noroviruses are recombinant GII.P16-GII.2 strains.

Association of GII.P16-GII.2 Recombinant Norovirus Strain with Increased Norovirus Outbreaks, Guangdong, China, 2016.

An unusual prevalence of recombinant GII.2 noroviruses (GII.P16-GII.2) in Guangdong, China, at the end of 2016 caused a sharp increase in outbreaks of acute gastroenteritis. This event was another non-GII.4 epidemic that emerged after the GII.17 viruses in 2014 and 2015 and warrants global surveillance.

Norovirus GII.P16/GII.2-Associated Gastroenteritis, China, 2016.

During October-December 2016, the number of norovirus outbreaks in China increased sharply from the same period during the previous 4 years. We identified a recombinant norovirus strain, GII.P16-GII.2, as the cause of 44 (79%) of the 56 outbreaks, signaling that this strain could replace the predominant GII.4 viruses.

The molecular epidemiology of norovirus outbreaks in Victoria, 2014 to 2015
.

Noroviruses are a leading cause of outbreaks of gastroenteritis. This study examined the incidence and molecular characteristics of norovirus outbreaks in healthcare and non-healthcare settings in Victoria, Australia, over 2 years (2014-2015). Norovirus was detected in 65.7% and 60.4% of gastroenteritis outbreaks investigated for the years 2014 and 2015 respectively. There was a significant decline in the number of norovirus outbreaks in the period 2014 to 2015 although in both years norovirus outbreaks peaked in the latter part of the year. Norovirus Open Reading Frame (ORF) 2 (capsid) genotypes identified included GI.2, GI.3, GI.4, GI.5, GI.6, GI.9, GII.2, GII.3, GII.4, GII.6, GII.7, GII.8, GII.13 and GII.17. GII.4 was the most common genotype detected. In addition, the following ORF 1/ORF 2 recombinant forms were confirmed: GII.P4_NewOrleans_2009/GII.4_Sydney_2012, GII.P12/GII.3, GII.Pb (GII.21)/GII.3, GII.Pe/GII.2 and GII.Pe/GII.4_Sydney_2012. A significant decline was noted in the chief norovirus strain GII.Pe/GII.4_Sydney_2012 between 2014 and 2015 but there was a re-emergence of a GII.P4_ NewOrleans _2009 norovirus strain. Outbreaks involving the GII.P17/GII.17 genotype were also detected for the first time in Victoria. GI genotypes circulating in Victoria for the 2 years 2014 and 2015 underwent a dramatic change between the 2 years of the survey. Many genotypes could occur in both healthcare and non-healthcare settings although GI.3, GII.6, and GII.4 were significantly more common in healthcare settings. The study emphasises the complex way in which norovirus circulates throughout the community.

Incidence of Norovirus-Associated Diarrhea, Shanghai, China, 2012-2013.

We conducted sentinel-based surveillance for norovirus in the Pudong area of Shanghai, China, during 2012-2013, by analyzing 5,324 community surveys, 408,024 medical records, and 771 laboratory-confirmed norovirus infections among 3,877 diarrhea cases. Our analysis indicated an outpatient incidence of 1.5/100 person-years and a community incidence of 8.9/100 person-years for norovirus-associated diarrhea.

Caliciviruses in hospitalized children, São Luís, Maranhão, 1997-1999: detection of norovirus GII. 12

ABSTRACT Gastroenteritis is one of the most common diseases during childhood, with norovirus (NoV) and sapovirus (SaV) being two of its main causes. This study reports for the first time the incidence of these viruses in hospitalized children with and without gastroenteritis in São Luís, Maranhão. A total of 136 fecal samples were tested by enzyme immunoassays (EIA) for the detection of NoV and by reverse transcription-polymerase chain reaction (RT-PCR) for detection of both NoV and SaV. Positive samples for both agents were subjected to sequencing. The overall frequency of NoV as detected by EIA and RT-PCR was 17.6% (24/136) and 32.6% (15/46), respectively in diarrheic patients and 10.0% (9/90) in non-diarrheic patients (p < 0.01). Of the diarrheic patients, 17% had fever, vomiting and anorexia, and 13% developed fever, vomiting and abdominal pain. Of the 24 NoV-positive samples, 50% (12/24) were sequenced and classified as genotypes GII.3 (n = 1), GII.4 (6), GII.5 (1), GII.7 (2), GII.12 (1) and GII.16 (1). SaV frequency was 9.8% (11/112), with 22.6% (7/31) in diarrheic patients and 4.9% (4/81) in nondiarrheic (p = 0.04) ones. In diarrheic cases, 27.3% had fever, vomiting and anorexia, whereas 18.2% had fever, anorexia and abdominal pain. One SaV-positive sample was sequenced and classified as GII.1. These results show a high genetic diversity of NoV and higher prevalence of NoV compared to SaV. Our data highlight the importance of NoV and SaV as enteropathogens in São Luís, Maranhão.

Caliciviruses in hospitalized children, São Luís, Maranhão, 1997-1999: detection of norovirus GII.12.

Gastroenteritis is one of the most common diseases during childhood, with norovirus (NoV) and sapovirus (SaV) being two of its main causes. This study reports for the first time the incidence of these viruses in hospitalized children with and without gastroenteritis in São Luís, Maranhão. A total of 136 fecal samples were tested by enzyme immunoassays (EIA) for the detection of NoV and by reverse transcription-polymerase chain reaction (RT-PCR) for detection of both NoV and SaV. Positive samples for both agents were subjected to sequencing. The overall frequency of NoV as detected by EIA and RT-PCR was 17.6% (24/136) and 32.6% (15/46), respectively in diarrheic patients and 10.0% (9/90) in non-diarrheic patients (p<0.01). Of the diarrheic patients, 17% had fever, vomiting and anorexia, and 13% developed fever, vomiting and abdominal pain. Of the 24 NoV-positive samples, 50% (12/24) were sequenced and classified as genotypes GII.3 (n=1), GII.4 (6), GII.5 (1), GII.7 (2), GII.12 (1) and GII.16 (1). SaV frequency was 9.8% (11/112), with 22.6% (7/31) in diarrheic patients and 4.9% (4/81) in nondiarrheic (p=0.04) ones. In diarrheic cases, 27.3% had fever, vomiting and anorexia, whereas 18.2% had fever, anorexia and abdominal pain. One SaV-positive sample was sequenced and classified as GII.1. These results show a high genetic diversity of NoV and higher prevalence of NoV compared to SaV. Our data highlight the importance of NoV and SaV as enteropathogens in São Luís, Maranhão.

Surveillance of norovirus in Portugal and the emergence of the Sydney variant, 2011-2013.

This report presents the results of the national surveillance system of diarrhea etiology of the National Institute of Health of Portugal concerning norovirus (NoV) during a two-year period, May 2011-2013. Of the total 580 stool samples collected from patients hospitalized for acute diarrhea in 13 Hospitals of Portugal, 67 (11.6%) tested positive for NoV. From May 2011 to March 2012 the GII.4 variant New Orleans 2009 was the most predominant strain having been replaced by the new GII.4 variant Sydney 2012 since then till the end of the survey. To our knowledge this is the first study showing the circulation of GII.4 as the norovirus strain most commonly associated to gastroenteritis and the first to report the replacement of GII.4 New Orleans by GII.4 Sydney 2012 variant in Portugal.

Virus Genotype Distribution and Virus Burden in Children and Adults Hospitalized for Norovirus Gastroenteritis, 2012-2014, Hong Kong.

We conducted a 2-year hospital-based study on norovirus gastroenteritis among children and adults between August 2012 and September 2014. A total of 1,146 norovirus cases were identified. Young children (aged ≤ 5 years) accounted for a majority (53.3%) of cases. Hospitalization incidence exhibited a U-shaped pattern with the highest rate in young children (1,475 per 100,000 person-years), followed by the elderly aged > 84 years (581 per 100,000 person-years). A subset (n = 395, 34.5%) of cases were selected for norovirus genotyping and noroviral load measurement. Non-GII.4 infections were more commonly observed in young children than in older adults (aged > 65 years) (20.5% versus 9.2%; p < 0.05). In young children, the median noroviral load of GII.4 and non-GII.4 cases was indistinguishably high (cycle threshold value, median [interquartile range]: 16.6 [15.2-19.3] versus 16.6 [14.9-21.6]; p = 0.45). Two age-specific non-GII.4 genotypes (GII.3 and GII.6) were identified among young children. These findings may have implications in norovirus vaccination strategy.

Incidence of Medically-Attended Norovirus-Associated Acute Gastroenteritis in Four Veteran's Affairs Medical Center Populations in the United States, 2011-2012.

An estimated 179 million acute gastroenteritis (AGE) illnesses occur annually in the United States. The role of noroviruses in hospital-related AGE has not been well-documented in the U. S. We estimated the population incidence of community- acquired outpatient and inpatient norovirus AGE encounters, as well as hospital-acquired inpatient norovirus AGE among inpatients at four Veterans Affairs (VA) Medical Centers (VAMCs). Fifty (4%) of 1,160 stool specimens collected ≤7 days from symptom onset tested positive for norovirus. During a one year period, the estimated incidence of outpatient, community- and hospital-acquired inpatient norovirus AGE was 188 cases, 11 cases, and 54 cases/ 100,000 patients, respectively. This study demonstrates the incidence of outpatient and community- and hospital-acquired inpatient norovirus AGE among the VA population seeking care at these four VAMCs.

Norovirus genotype profiles associated with foodborne transmission, 1999-2012.

Worldwide, noroviruses are a leading cause of gastroenteritis. They can be transmitted from person to person directly or indirectly through contaminated food, water, or environments. To estimate the proportion of foodborne infections caused by noroviruses on a global scale, we used norovirus transmission and genotyping information from multiple international outbreak surveillance systems (Noronet, CaliciNet, EpiSurv) and from a systematic review of peer-reviewed literature. The proportion of outbreaks caused by food was determined by genotype and/or genogroup. Analysis resulted in the following final global profiles: foodborne transmission is attributed to 10% (range 9%%-11%) of all genotype GII.4 outbreaks, 27% (25%-30%) of outbreaks caused by all other single genotypes, and 37% (24%%-52%) of outbreaks caused by mixtures of GII.4 and other noroviruses. When these profiles are applied to global outbreak surveillance data, results indicate that ≈14% of all norovirus outbreaks are attributed to food.