Molecular epidemiology of noroviruses associated with sporadic gastroenteritis in children in Novosibirsk, Russia, 2003-2012.

Noroviruses (NoVs) are an important cause of acute gastroenteritis worldwide. To monitor the molecular epidemiology of NoVs genogroup II (GII) in Novosibirsk, Russia, a total of 10,198 stool samples from young children hospitalized with acute gastroenteritis and two asymptomatic comparison groups were collected from 2003 to 2012. All samples were screened for the presence of NoV GII, rotavirus, and astrovirus by RT-PCR. The prevalence of NoV in gastroenteritis cases was 13.1%, varying from 7.1% to 21.3% in different seasons. Rotavirus and/or astrovirus were detectable in 25% of the NoV-positive samples. NoV was detected throughout the year with a seasonal increase during winter months. Based on sequence analysis of regions D and/or C within the VP1 gene, 892 identified NoV strains were divided into nine genotypes—GII.3 (51%), GII.4 (44%), GII.6 (2%), as well as GII.1, GII.2, GII.5, GII.7, GII.16, and GII.21 (totally, 3%). The prevalence of NoV in the comparison groups was considerably lower (∼2.5%); only GII.4 (n = 6), GII.21 (n = 2) and GII.1 (n = 1) genotypes were revealed. Based on phylogenetic analysis of the ORF1/ORF2 junction region sequences, GII.P21/GII.3 recombinant and GII.P4/GII.4 were prevalent genotypes (totally, 93%) and their ratio changed every season. The median age of children with NoV infection was 6.6 months (range, <1-35 months), but it was different depending on NoV genotype. Children infected with the NoV GII.3 were younger (median 6.2 months) than GII.4-positive patients (median 9.1 months). This is the first long-term systematic study of NoV molecular epidemiology in Russia.

Zhirakovskaia EV ，Tikunov AY ，Bodnev SA ，Klemesheva VV ，Netesov SV ，Tikunova NV ... -  《-》

Molecular epidemiology of norovirus strains in Paraguayan children during 2004-2005: description of a possible new GII.4 cluster.

Noroviruses (NoV) have been shown to be an important cause of morbidity and mortality in children worldwide, only second after Group A rotaviruses (RVA). In Paraguay, acute gastroenteritis (AGE) is the third cause of mortality in children ≤5 years old. To analyze the presence and diversity of NoV in Paraguayan children ≤5 years old presenting AGE. Three hundred seventy eight fecal samples, negative for pathogenic bacteria and RVA, were collected from children admitted as ambulatory and hospitalized patients in a large private hospital from Asuncion, Paraguay from 2004 to 2005. The presence and diversity of NoV was determined by two different RT-PCR strategies and nucleotide sequencing. One hundred and sixty one samples were positive for NoV by partial amplification of the viral polymerase gene (RdRp). No seasonality or differences in the viral prevalence for the different age-groups were detected. GII and GI NoVs were associated to 58% and 42% of the infections, respectively. The genotype was determined in 18% (29/161) NoV-positive samples. The genotypes detected were: GII.4 (18%), GII.17 (18%), GII.6 (14%), GII.7 (14%), GII.3 (10%), GII.5 (3%), GII.8 (3%), GII.16 (3%), GI.3 (14%) and GI.8 (3%). Amplification of the ORF2 from the GII.4 strains showed the presence of a new GII.4 variant. The results showed a continuous circulation of NoV in children throughout the two years of study and an extensive diversity of genotypes co-circulating, highlighting the need for better surveillance of NoV in Paraguayan children.

Galeano ME ，Martinez M ，Amarilla AA ，Russomando G ，Miagostovich MP ，Parra GI ，Leite JP ... -  《-》

High prevalence and genetic diversity of noroviruses among children with sporadic acute gastroenteritis in Nanning City, China, 2010-2011.

A molecular epidemiological study of Norovirus (NoV) infections in children aged <5 years was conducted in the outpatient department of a hospital between January 2010 and December 2011 in Nanning City, Guangxi Zhuang Autonomous Region of China. Fecal samples were collected from 354 pediatric patients with acute gastroenteritis, and were screened for the presence of NoV with one-step real-time reverse-transcription polymerase chain reaction (RT-PCR). NoV genogroup II (GII) was detected in 28.5% (101/342) of samples, but no NoV GI was found. Eighty-four of the NoV GII strains were successfully sequenced, and they were clustered into seven genotypes: GII.4 (77.4%), GII.2 (8.3%), GII.14 (4.8%), GII.7 (3.6%), GII.3 (2.4%), GII.6 (2.4%), and GII.12 (1.2%). The predominant GII.4 variant in circulation was variant 2006b (92.3%). Importantly, the emergence of variant GII.4 2010 was detected. NoV was detected throughout the year, but mainly during the cold months. The highest prevalence of NoV was detected in young children aged <2 years. The NoV detection rates did not differ significantly in males and females. This is the first report to demonstrate the high prevalence and genetic diversity of NoVs in children with sporadic acute gastroenteritis in Nanning. Our study findings indicate the need for continual surveillance to monitor epidemiological changes and potential new variants of these viruses.

Tan D ，Deng L ，Wang M ，Li X ，Ma Y ，Liu W ... -  《-》

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

Noroviruses (NoVs) are the most common cause of acute gastroenteritis in both sporadic and outbreak cases. Genotyping and recombination analyses were performed in order to help getting more knowledge of the distribution and genetic diversity of NoVs in Suzhou, located in Jiangsu province of China. All stool samples were collected from hospitalized children younger than 5 years old with acute gastroenteritis. For genotyping, the open reading frame (ORF) 1 and ORF2 were partially amplified and sequenced. 26.9% of stool samples were positive for genogroup II NoVs. The most common genotype was GII.4 and its variants included Den Haag-2006b, New Orleans-2009, and Sydney-2012. The Den Haag-2006b variants predominated during 2010-2012. In 2013, it was replaced by the Sydney-2012 variant. The second most common genotype was GII.12/GII.3. NoVs could be detected throughout the year, with GII.4 and GII.12/GII.3 coexisting during the cold months, and GII.4 was the main genotype during the warm months. The highest prevalence of NoV was detected in young children aged <24 months. Patients infected with GII.4 had a higher chance of getting moderate fever than other NoV-positive patients, while those infected with GII.12/GII.3 tended to have a mild degree of fever. NoV is an important pathogen responsible for viral gastroenteritis among children in Suzhou. Analyses of NoV circulating between 2010 and 2013 revealed a change of predominant variant of NoV GII.4 in each epidemic season and intergenotype recombinant strains represented an important part.

Fu JG ，Ai J ，Zhang J ，Wu QB ，Qi X ，Ji H ，Jin M ，Liu C ，Wang SJ ，Shan J ，Bao CJ ，Tang FY ，Zhu YF ... -  《-》

Emergence and predominance of norovirus GII.17 in Huzhou, China, 2014-2015.

Han J ，Ji L ，Shen Y ，Wu X ，Xu D ，Chen L ... -  《Virology Journal》