Genotype GII Research Articles

Molecular and clinical epidemiology of norovirus outbreaks in Spain during the emergence of GII.4 2012 variant

BackgroundNorovirus (NoV) is the most common cause of acute nonbacterial gastroenteritis outbreaks worldwide, but the impact of NoV infections in Spain remains underestimated. ObjectivesThis study aimed to determine the prevalence and genetic diversity of NoVs causing outbreaks of acute gastroenteritis in Northeastern Spain (Catalonia) during 2010–2012, and to compare clinical features and levels of viral shedding of the most prevalent GII.4 2012 variant with its predecessor. Study designNoVs were screened and genotyped in stools from gastroenteritis outbreaks. Genetic diversity over a region covering 50% of VP1, and viral loads were analyzed in stools belonging to GII.4 2009 and 2012 variants. ResultsMore than 50% of outbreaks were caused by genotype GII.4, although outbreaks caused by multiple strains, GII.6 and GII.1 were also prevalent. During 2012, GII.4 2012 strains clearly replaced GII.4 2009 strains. The first 2012 strain was detected in February 2011, representing the earliest isolate reported worldwide. Epidemiological features of GII.4 2012 and GII.4 2009 outbreaks were comparable, as well as levels of viral shedding in stools. Finally, analysis of the capsid gene showed a higher amino acid variability and diversification in GII.4 2012, affecting sites located at the P2 domain, but also in the shell domain. ConclusionsClinical features of outbreaks caused by different genotypes circulating in Spain, including outbreaks caused by GII.4 2012 and GII.4 2009 strains, were comparable. Although shed at similar levels than GII.4 2009 strains, GII.4 2012 strains have clearly replaced the previous predominant strain.

Investigation and control of a Norovirus outbreak of probable waterborne transmission through a municipal groundwater system.

During March 2011 an outbreak of gastroenteritis occurred in Santo Stefano di Quisquina, Agrigento, Sicily, Italy. Within two weeks 156 cases were identified among the 4,965 people living in the municipality. An epidemiological investigation was conducted to characterize the outbreak and target the control measures. A case was defined as a person developing diarrhea or vomiting during February 27-March 13, 2011. Stool specimens were collected from 12 cases. Norovirus (NoV) genotype GII.4 variant New Orleans 2009 was identified in stool samples from 11 of 12 cases tested (91.7%). Epidemiological investigations suggested a possible association with municipal drinking water consumption. Water samples from the public water system were tested for NoV and a variety of genotypes were detected during the first 3 months of surveillance, including GII.4 strains belonging to different variants from that involved in the gastroenteritis outbreak. Contamination of the well and springs supplying the public water network was eventually thought to be the source of the NoV contamination.

Association between Norovirus and Rotavirus Infection and Histo-Blood Group Antigen Types in Vietnamese Children

Norovirus and rotavirus are the two most important causes of acute gastroenteritis in children worldwide. Both norovirus and rotavirus recognize human histo-blood group antigens (HBGAs), and multiple binding patterns for HBGAs have been reported. To explore the role of HBGAs in host susceptibility to norovirus and rotavirus, we conducted a cross-sectional study in children hospitalized with diarrhea in northern Vietnam from September 2010 through September 2012. Of 260 children with paired stool and saliva samples, 158 (61%) were classified as HBGA secretors (Lea-b+), 31 (12%) were nonsecretors (Lea+b-), and 71 (27%) were partial secretors (Lea+b+). Norovirus was detected in 50 patients (19%), with viral genotypes GII.3 (n=28) and GII.4 (n=22) being the most common. All children infected with norovirus strains of genotype GII.4 were either HBGA secretors or partial secretors. Of the 28 GII.3 cases, 12 involved HBGA secretors, 11 partial secretors, and 5 nonsecretors. A total of 85 children tested positive for rotavirus, 74 of whom were infected with genotype P[8], 5 with P[4], and 6 with P[6]; all were HBGA secretors or partial secretors. This is the first epidemiological study demonstrating in a population that HBGA phenotype is a key susceptibility factor for both norovirus and rotavirus infections in children.

Detection of the pandemic norovirus variant GII.4 Sydney 2012 in Rio Branco, state of Acre, northern Brazil

Noroviruses (NoVs) are important cause of gastroenteritis in humans worldwide. Genotype GII.4 is responsible for the majority of outbreaks reported to date. This study describes, for the first time in Brazil, the circulation of NoV GII.4 variant Sydney 2012 in faecal samples collected from children aged less than or equal to eight years in Rio Branco, state of Acre, northern Brazil, during July-September 2012.

Norovirus Variant GII.4/Sydney/2012, Bangladesh

To the Editor: Noroviruses (NoVs) are the most common cause of foodborne and waterborne outbreaks of gastroenteritis in persons from all age groups in industrialized and developing countries (1). Although NoV outbreaks occur throughout the year, activity increases in the winter months, especially in the countries with a temperate climate. As expected, during the last few months of 2012, outbreaks of NoV gastroenteritis markedly increased in Europe and the United States (2–4). These increases corresponded with the emergence of a variant of genotype GII.4, Sydney/2012, which was first reported from Australia in March 2012 and, subsequently, in the United States, Belgium, Denmark, Scotland, and Japan (2,5–7). We identified the NoV GII.4 variant Sydney/2012 through hospital surveillance on diarrhea etiology in Bangladesh in December 2011 and then throughout 2012. These strains came from 3 hospitals in Dhaka, Matlab, and Mirzapur, where ≈150,000 patients with diarrhea are treated annually. We randomly selected 795 fecal specimens from patients of all ages who sought treatment for diarrhea in these hospitals during 2010–2012 and detected NoV RNA in 90 (33.6%), 72 (27.9%), and 92 (34.2%) samples in 2010, 2011, and 2012, respectively, by performing real-time PCR (8). For characterization, we amplified and sequenced 108 samples on the basis of the capsid genes (9). Ages of diarrhea patients with NoV infection ranged from 1 month to 91 years (median 15 months; mean 11.9 years). Most (66%) NoV-positive patients were 18 years of age). NoVs were detected throughout the year, and no clear seasonal peaks were observed. Overall, GII was the most predominant genogroup (66.1%), followed by GI (18.1%) and GIV (3.9%). Mixed infections were detected in 11.8% of samples. We observed a high diversity in the GII genogroup and identified at least 11 different genotypes within the group, in which GII.4 constituted 30.1% of all GII strains. Until December 2011, the GII.4 variant NewOrleans/2009 was the most predominant strain (Figure). However, the new GII.4 variant, Sydney/2012, replaced the old variant and appeared as the dominant strain in 2012. We constructed a phylogenetic tree on the basis of 1,026 bases around the junction region of pol and cap genes, and it revealed that the newly identified variant has evolved from previous NoV GII.4 variants Apeldoorn/2007 and NewOrleans/2009 (data not shown). Figure Distribution of 108 norovirus (NoV) genotypes in Bangladesh, 2010–2012. Bar chart shows the percentage of NoV genotypes. Mixed genotypes comprise NoV GI and GII. GI comprises GI.1, GI.3, GI.4, GI.5, and GI.9. GII.others comprises GII.2, GII.3, ... NoVs, old and new, remain a substantial threat to human health, with a new variant emerging every 2–3 years. The Sydney/2012 strain appears to have replaced the previously predominant strain, but its clinical effects and epidemiology are largely unknown and warrant further investigation.

Host Genetic Factors Affect Susceptibility to Norovirus Infections in Burkina Faso

Norovirus (NoV) constitutes the second most common viral pathogen causing pediatric diarrhea after rotavirus. In Africa, diarrhea is a major health problem in children, and yet few studies have been performed regarding NoV. The association of histo-blood group antigens (HBGA) and susceptibility to NoV infection is well established in Caucasian populations with non-secretors being resistant to many common NoV strains. No study regarding HBGA and NoV susceptibility has yet been performed in Africa. We collected 309 stool and 208 saliva samples from diarrheal children in Ouagadougou, Burkina Faso; May 2009 to March 2010. NoV was detected using real-time PCR, and genotyped by sequencing. Saliva samples were ABO, Lewis and secretor phenotyped using in house ELISA assays. NoV was detected in 12% (n = 37) of the samples. The genotype diversity was unusually large; overall the 37 positive samples belonged to 14 genotypes. Only children <2 years of age were NoV positive and the GII.4 NoVs were more frequent in the late dry season (Jan-May). NoV infections were observed less in children with the secretor-negative phenotype or blood group A (OR 0.18; p = 0.012 and OR 0.31; p = 0.054; respectively), with two non-secretors infected with genotypes GII.7 and GII.4 respectively. Lewis-negative (Lea−b−) children, representing 32% of the study population, were susceptible to GII, but were not infected with any NoV GI. GII.4 strains preferentially infected children with blood group B whereas secretor-positive children with blood group O were infected with the largest variety of genotypes. This is the first study identifying host genetic factors associated with susceptibility to NoV in an African population, and suggests that while the non-secretor phenotype provides protection; the Lewis b antigen is not necessary for GII infection.

Different norovirus genotypes in patients with gastroenteritis in Kuwait

Norovirus is a leading cause of acute gastroenteritis worldwide. The importance of this virus infection in Kuwait is not known. Eight out of 100 stool samples (8.0%) from children up to 5 years of age with gastroenteritis studied during 2006-2007 from one hospital, and 6 out of 70 stool samples (8.5%) from similar children studied from another hospital during 2010-2011 were positive for norovirus by RT-PCR. Out of these 170 samples studied from both hospitals, 10 samples were positive for norovirus when tested by ELISA. Phylogenetic tree analysis of norovirus strains showed that 50% of the norovirus strains belonged to genotype GII.4, and the predominant strain was GII.4 2006b. Other detected genotypes were GII.12, GII.b, GII.3, GII.8, and GII.7. This study highlights the importance of screening for norovirus infection in acute gastroenteritis and having a reporting system to understand better the epidemiology of norovirus infection in Kuwait.

Norovirus contamination levels in ground water treatment systems used for food-catering facilities in South Korea.

This study aimed to inspect norovirus contamination of groundwater treatment systems used in food-catering facilities located in South Korea. A nationwide study was performed in 2010. Water samples were collected and, for the analysis of water quality, the temperature, pH, turbidity, and residual chlorine content were assessed. To detect norovirus genotypes GI and GII, RT-PCR and semi-nested PCR were performed with specific NV-GI and NV-GII primer sets, respectively. The PCR products amplified from the detected strains were then subjected to sequence analyses. Of 1,090 samples collected in 2010, seven (0.64%) were found to be norovirus-positive. Specifically, one norovirus strain was identified to have the GI-6 genotype, and six GII strains had the GII, GII-3, GII-4, and GII-17 genotypes. The very low detection rate of norovirus most likely reflects the preventative measures used. However, this virus can spread rapidly from person to person in crowded, enclosed places such as the schools investigated in this study. To promote better public health and sanitary conditions, it is necessary to periodically monitor noroviruses that frequently cause epidemic food poisoning in South Korea.

Virus infections among young children—the first year of the INDIS study

The frequencies of early childhood infections were studied in healthy children with increased genetic risk for type 1 diabetes participating in the ongoing prospective high intensive infection follow-up Study, INDIS, started in 2009 in Turku, Finland. Here the results obtained from 160 stool to 160 nasal swab specimens collected in parallel at times of infectious symptoms in 2009-2010 from 45 children at the age of 24 months or younger are reported. The specimens were analyzed for enteric (human enterovirus, norovirus, rotavirus, sapovirus, astrovirus) and respiratory RNA viruses (human enterovirus and rhinovirus) common in early childhood, respectively, using highly validated virus-specific real-time PCR methods. According to the results 96% of the children had at least one virus infection during the study period and one or several viral agents were detected in 76% of sample sets. The most prevalent viral agents were human rhinovirus, enterovirus, parechovirus, and norovirus (genotype GII) with positive specimens 57.5%, 28.8%, 19.4%, and 6.9%, respectively. Other intestinal viruses were found in less than 2% of stool specimens. Single infections covered 40.0% of the specimens while multiple infections with two or more infectious agents were detected in 36.3% of specimens and altogether 11 combinations of viruses were included in the mixed infections. Although human enterovirus is known to be a frequent finding in stool specimens, especially during early childhood, it was found in this study more frequently in nasal swab specimens. Whether this is true, more general, in countries with the high hygiene level remains to be shown.

Incidence and Characteristics of Sporadic Norovirus Gastroenteritis Associated with Hospitalization of Children Less Than 5 Years of Age in Israel

The incidence of sporadic GII norovirus gastroenteritis associated with hospitalization was examined among 515 children aged <5 years in a prospective study in Israel. Using real-time polymerase chain reaction, norovirus was detected in stools of 89 (17.3%) children, yielding an estimated incidence of 3.3 per 1000 children. Genotypes GII.3 (40.4%) and GII.4a (21.3%) predominated, though year-to-year variation was observed.

First detection of human sapoviruses in river water in South Africa

Over a 2-year period, from January 2009 to December 2010, water samples were collected from three rivers (Klip, Rietspruit and Suikerbosrand) in the Vaal River System, South Africa. Enteric viruses were recovered by a glass wool adsorption-elution method and concentrated using polyethylene glycol/sodium chloride precipitation. Sapoviruses (SaVs) were detected using published sapovirus (SaV)-specific primers and Taqman probes in a two-step real-time reverse transcription-polymerase chain reaction assay. Based on sequence analysis of the 5'-end of the capsid gene, SaVs were genotyped. In 2009, SaVs were detected in 39% (15/38) of samples from the Klip river, 83% (5/6) from the Rietspruit and 14% (1/7) of samples from the Suikerbosrand river. In 2010, SaVs were detected in 54% (14/26) of Klip river samples, 92% (11/12) from the Rietspruit and 20% (2/10) of samples from the Suikerbosrand river. SaV strains identified in the water samples were characterised into several GI and GII genotypes. The presence of SaVs in these rivers indicates human faecal contamination which may pose a potential health risk to persons exposed to these water sources during domestic or recreational activities.

Pattern of activation of human antigen presenting cells by genotype GII.4 norovirus virus-like particles

BackgroundVirus-like particles (VLPs) from an Italian GII.4 norovirus strain were used to investigate activation and maturation of circulating antigen presenting cells (APCs) of human origin.MethodsPeripheral blood mononuclear cells (PBMCs) isolated from five healthy subjects were pulsed ex vivo with VLPs, and stained with a set of monoclonal antibodies (MAbs) for phenotypic analysis by flow cytometry. Cytokine release in cell supernatants was investigated by ELISA.ResultsNorovirus VLPs induced activation and maturation of circulating APCs derived from the five donors, as well as production of IL-6, IFN-γ and TNF-α cytokines.ConclusionsThe present results suggest that VLPs can activate antigen presenting cells for an efficient induction of the adaptive immune response.

Human calicivirus diversity in wastewater in South Africa

To investigate the diversity of human caliciviruses (HuCVs) in wastewater from small- to medium-sized communities in five provinces of South Africa (SA). Wastewater samples (51) were screened for norovirus (NoV) GI, GII, GIV and sapovirus (SaV) using real-time reverse transcription (RT)-PCR. Partial capsid nucleotide sequences were analysed for genotyping. At least one HuCV was detected in 42 samples (82%) with NoV GI being detected in 15 (29%), NoV GII in 32 (63%) and SaV in 37 (73%) samples. NoV GIV was not detected. Five NoV GI genotypes (GI.1, GI.3, GI.4, GI.8 and GI.unassigned), eight NoV GII genotypes (GII.2, GII.3, GII.4, GII.6, GII.7, GII.12, GII.13 and GII.17) and six SaV genotypes (GI.2, GI.3, GI.6, GI.7, GII.1 and GII.2) were characterized. Many NoV and SaV genotypes were detected in wastewater, demonstrating a high genetic diversity of HuCVs in the surrounding communities. Caliciviruses were characterized from several provinces in SA, indicating widespread occurrence in the country. This study provides valuable new data on CVs circulating in SA, including the first data on SaV strains from wastewater in Africa. Environmental surveillance is especially important in countries like SA where outbreak reporting systems or routine HuCV surveillance is lacking.

The presence of Genogroup II Norovirus in Retail Shellfish from Seven Coastal Cities in China

Noroviruses (NoVs) are commonly occurring pathogens that cause gastroenteritis. Outbreaks of viral diseases have often been ascribed to the consumption of contaminated shellfish. Our objective was to evaluate the presence and contamination levels of NoV in shellfish sold at seafood markets in China. We tested 840 shellfish samples (Crassostrea gigas, Mytilus edulis, Azumapecten farreri, SinoNoVacula constricta, Scapharca subcrenata, Ruditapes philippinarum) that were collected from seven cities around the Yellow and Bohai Seas in China between December 2009 and November 2011. We used real-time RT-PCR to detect NoV in purified concentrates from the stomach and digestive diverticula of these shellfish. NoV was detected in 19.35 % (N = 155), 16.67 % (N = 114), 5.70 % (N = 158), 8.82 % (N = 136), 13.74 % (N = 131), and 16.44 % (N = 146) of oyster, mussel, scallop, razor clam, ark shell, and clam samples, respectively. The average detection rate was 13.33 % (112/840). Nucleotide sequencing of the NoV RT-PCR products demonstrated that all strains belonged to NoV genotype GII.12, except two that belonged to GI.3. More than 10² copies of the NoV genome were detected in 69 of 112 positive shellfish samples. Our results suggest that ~13 % of shellfish harbor NoV, and GII.12 NoV is the primary strain in shellfish purchased at markets in seven coastal cities in China.

Norovirus infection in children admitted to hospital for acute gastroenteritis in Belém, Pará, Northern Brazil

Noroviruses are the leading cause of epidemic, non-bacterial outbreaks of acute gastroenteritis, and are also a major cause of sporadic acute gastroenteritis in infants. The aim of the present study was to identify norovirus infections in children not infected by rotavirus admitted to hospital for acute gastroenteritis in Belém. A total of 348 fecal specimens were obtained from children with diarrhea aged less than 5 years, all of whom had tested negative for rotavirus, between May 2008 and April 2010. Fecal samples were screened for norovirus antigen using enzyme-immunoassay (EIA). Specimens were subjected to reverse-transcription polymerase chain reaction (RT-PCR) using the primers Mon432/434-Mon431/433 for detection of the GI and GII norovirus strains, respectively. Based on both methods, the overall norovirus positivity rate was 36.5% (127/348). Of the 169 samples collected in the first year, 44.4% (n = 75) tested positive for norovirus using both methods, 35.5% (n = 60) by EIA and 40.8% (n = 69) by RT-PCR. Using RT-PCR as a reference standard, a sensitivity of 78.3%, specificity of 94%, and agreement of 87.6% were recorded. Genome sequencing was obtained for 22 (31.9%) of the 69 positive samples, of which 90.9% (20/22) were genotype GII.4d and 9.1% (2/22) were genotype GII.b. Norovirus infection was most frequent in children under 2 years of age (41.5%-115/277). The peak incidence (62.1%) of norovirus-related acute gastroenteritis in these patients (not infected by rotavirus) was observed in February 2010. These findings emphasize the importance of norovirus as a cause of severe acute gastroenteritis among children in Belém, Pará, Northern Brazil.

The Importance of Intergenic Recombination in Norovirus GII.3 Evolution

Norovirus genotype II.3 (GII.3) strains are a major cause of sporadic gastroenteritis. Intergenic recombination between the capsid and RNA-dependent RNA polymerase (RdRp) genes is common and results in the acquisition of an alternative RdRp genotype. This study aimed to explore the evolution of the GII.3 capsid gene, focusing on the influence of intergenic recombination. The capsid genes from six GII.3 norovirus strains, collected from Australian children between 2001 and 2010, were sequenced and aligned with 66 GII.3 capsid sequences from GenBank, spanning 1975 to 2010. The GII.3 capsid gene evolved at a rate of 4.16 × 10(-3) to 6.97 × 10(-3) nucleotide substitutions/site/year from 1975 to 2010 and clustered into five temporally sequential lineages. Clustering of the GII.3 capsid gene sequences was associated with intergenic recombination and switches between RdRp genotypes GII.3, GII.a, GII.b, GII.12, and an undefined ancestral RdRp. Comparison of the substitution rate of the GII.3 and GII.b RdRps suggested that RdRp switching allows a higher evolutionary rate, leading to increased genetic diversity and adaptability. Alignment of GII.3 capsid sequences revealed 36 lineage-specific conserved amino acid substitutions, four of which were under positive selection. Many conserved substitutions were within predicted antibody binding regions and close to host attachment factor binding sites. In conclusion, evolution of GII.3 noroviruses was primarily driven by intergenic recombination. The acquisition of new RdRps may lead to a faster mutation rate and increased genetic diversity, improving overall GII.3 fitness.

金コロイドを用いた新規イムノクロマト法による便中ノロウイルス検出試薬の有用性

We evaluated the usefulness of ImmunoCatch-Noro (Eiken Chemical Co., Ltd.) (IC-A), a newly developed immunochromatography kit using Au colloid, for the detection of norovirus in stool specimens collected from patients with acute gastroenteritis during the three-year period from 2008-2011. When a total of 316 specimens were tested by RT-PCR and direct sequencing of the PCR products, norovirus was detected in 198 specimens (62.7%), including nine genotypes (GI/2, GI/4, GI/8, GII/1, GII/2, GII/3, GII/4, GII/6 and GII/ 13). The most frequently isolated genotypes were GII/3 (64), GII/2 (59) and GII/4 (58), accounting for about 90% of the positive specimens. As compared to RT-PCR, the sensitivity, specificity and concordance rate of IC-A were 87.4% (173/198), 100% (118/118) and 92.1% (291/316), respectively. Twenty-five positive specimens that were positive by RT-PCR were negative by IC-A, however there were no false-positive results of IC-A. On the other hand, the commercially available immunochromatography kit (IC-B), which was tested for comparison, had a sensitivity, specificity and concordance rate of 59.6% (118/198), 96.6% (114/118) and 73.4% (232/316), respectively, containing 80 false-negative and four false-positive specimens. All of the 118 specimens positive by both IC-B and RT-PCR were also interpreted as positive by IC-A. The detection rates of the predominant genotypes (GII/2, GII/3 and GII/4) by IC-A were 88.1%, 87.5% and 89.7%, respectively. In contrast, those by IC-B were only 32.2%, 67.2% and 81.0%, respectively. These results show that IC-A had adequate sensitivity and cross-reactivity for a wide range of GI and GII genotypes, and also had high specificity. In conclusion, IC-A is a useful rapid-diagnostic kit for the detection of norovirus, however, its current application is limited for stool specimens.

Norovirus GII.4 virus-like particles recognize galactosylceramides in domains of planar supported lipid bilayers.

A sticky situation: Domain-dependent recognition of the glycosphingolipid galactosylceramide by norovirus-like particles (see picture; red/yellow) is shown using supported lipid bilayers (purple) as model membranes. Optimal ligand presentation is found to promote strong binding to GalCer. This presentation can be found at the edges of the glycosphingolipid-enriched domains (green) and binding is repressed in the absence of these domains.

Characterization of norovirus infections in Seoul, Korea

The present study has determined the detection rate of norovirus (NoV) with acute gastroenteritis (AGE) in hospitalized children and describes the molecular epidemiology of NoV circulating in Seoul, Korea. Six hundred and eighty-three (9.8%) of samples were positive for NoV. Of these, the NoV GII genogroup was the most commonly found, with a prevalence of 96.2% (683 of 710). Only 27 samples were positive for the NoV GI genogroup. Ten kinds of GI genotype (GI/1, GI/2, GI/3, GI/4, GI/5, GI/6, GI/7, GI/9, GI/12, and GI/13) and eight kinds of GII genotype (GII/2, GII/3, GII/4, GII/8, GII/14, GII/15, GII/16, and GII/17) were identified in children with AGE during the years 2008-2011.

A preliminary study on Norovirus variant for GII.4 in Guiyang regions

Objective To study the composition of variant and point mutations of Norovirus GⅡ.4 in Guiyang regions.Methods From June to November 2010,cases information and fecal specimens were collected from guard-hospitals in Guiyang regions,who had caught the acute-gastroenteritis.Noroviruses in specimens were detected by a real-time reverse transcription polymerase chain reaction(real-time RT-PCR),and then partial genotyped norovirus-positive clinical samples (in random) were cloned and sequenced in VP1 gene code.Furthermore,the gene sequences were compared with the published variants at home and abroad of norovirus(GⅡ.4),including the phylogenetic analyses of genomes and variation of amino acids within individual sites.Results Those 267 specimens were GⅡ-norovirus-positive(62.68％) in 426 clinical samples.There were nine GⅡ.4-norovirus-positive VP1 gene-sequences available,and two subtype-norovirus variants (GⅡ.4 2008a and G Ⅱ.4 2008b variant) were epidemic in 2010,Guizhou province.The homology between and in subgroups were 95.90％-96.72％ and 99.45％-100％.Two amino acids within individual sites were apt to mutate.Conclusion Norovirus GⅡ genotype were predominant in summer and fall acute gastroenteritis in 2010 for Guiyang regions,and the variants were diversity. Key words: Norovirus(NoVs); GⅡ.4 genotype; VP1 gene; Variant