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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.

Background New emerging strains of noroviruses (NoVs) often increase acute gastroenteritis (AGE) outbreaks worldwide. Objective We analyzed the epidemiological features and genotypic patterns of NoVs in AGE outbreaks. Study design To elucidate the public health impact of NoVs during AGE outbreaks in South Korea, a molecular and epidemiological investigation was performed with 318 AGE outbreaks reported from the Gyeonggi province of South Korea during the period from 2006 to 2013. Results NoVs were associated with 102 (32.1%) of the AGE outbreaks. Epidemiological data revealed that the majority of NoV outbreaks were in the student group (47.1%), and the majority of AGE patients were identified in schools (68.8%). NoV genogroup (G) II strains were associated with 94 (92.2%) of the NoV outbreaks, and GII.4 strains were predominantly associated with 57.6% ( n = 49) of NoV GII outbreaks. Four GII.4 variants (2006b, 2007, 2009 and 2012 variants) emerged and showed different contributions to NoV outbreak activity. The 2006b variant was predominantly associated with NoV outbreaks during the early years of the study period, and was subsequently displaced by the New Orleans 2009 variant, and most recently by the Sydney 2012 variant. In addition, the GII.2, GII.14, and GII.17 strains have recently been often associated with NoV AGE outbreaks. Conclusions The emergence of new NoV GII.4 variants significantly affected the NoV outbreak activity in South Korea during the period from 2006 to 2013. The surveillance for new emerging strains affecting NoV outbreak activity should be intensified to develop an adequate policy to prevent further NoV outbreaks. [ABSTRACT FROM AUTHOR]

During a 5-year (2007–2011) surveillance period a total of 435 (15·34%) of 2834 stool specimens from children aged <14 years with acute gastroenteritis tested positive for norovirus and 217 strains were characterized upon partial sequence analysis of the polymerase gene as either genogroup (G)I or GII. Of the noroviruses, 99·2% were GII with the GII.P4 genotype being predominant (80%). GII.P4 variants (Yerseke 2006a, Den Haag 2006b, Apeldoorn 2008, New Orleans 2009) emerged sequentially during the study period. Sequence analysis of the capsid gene of 57 noroviruses revealed that 7·8% were recombinant (ORF1/ORF2) viruses including GII.P7_GII.6, GII.P16_GII.3, GII.P16_GII.13, GII.Pe_GII.2, and GII.Pe_GII.4, never identified before in Italy. GII.P1_GII.1, GII.P2_GII.1, GII.P3_GII.3 and GII.P6_GII.6 strains were also detected. Starting in 2011 a novel GII.4 norovirus with 3–4% nucleotide difference in the polymerase and capsid genes from variant GII.4 New Orleans 2009 was monitored in the local population. Since the epidemiology of norovirus changes rapidly, continuous surveillance is necessary to promptly identify the onset of novel types/variants. [ABSTRACT FROM PUBLISHER]

Norovirus is one of the major causes of non-bacterial gastroenteritis in humans. The aim of this study was to analyze the amino acid variation of open reading frame 2 of GII.4 variants in South Korea during the period from November 2006 to December 2012. Sixty-nine complete nucleotide sequences of open reading frame 2 were obtained from 113 GII.4 strains. The GII.4 2006b variants were detected predominantly between 2006 and 2009; however, new GII.4 variants, which were termed the 2010 variant and the 2012 variant, emerged in 2010 and 2012, respectively. The number of GII.4 2006b variants steadily decreased until 2012, whereas the number of gastroenteritis cases caused by the new variants increased between 2010 and 2012. The amino acid sequence in the ORF2 region obtained in this study was compared with other GII.4 variants isolated in various countries. Amino acid variations were observed primarily at epitope sites and the surrounding regions. Amino acids 294, 359, 393, and 413 of the P2 subdomain were the most variable sites among the GII.4 variants. The information in this study can be useful in basic research to predict the emergence and determine the genetic functions of new GII.4 variants. [ABSTRACT FROM AUTHOR]

The incidence of noroviral gastroenteritis has increased dramatically in recent years, and norovirus (NoV) genogroup II.4 (GII.4) is associated with outbreaks worldwide. The NoV genotypes and their clinical relevance in children hospitalized with acute gastroenteritis between 2006 and 2011 in northern Taiwan were evaluated in this study. NoV sequences were amplified from 47 clinical specimens and phylogenetic analysis was performed. Based on noroviral capsid protein (VP1) and RNA dependent RNA polymerase (RdRp) phylogeny, circulating NoV could be divided into GII.2, GII.3, GII.12, and GII.4 and GII.16, GII.12, GII.g, and GII.4; respectively. The GII.4 subtype was predominant and could be divided further into the 2004 (Hunter), 2006b, and 2010 (New Orleans) subtypes. Regarding clinical manifestations, convulsive disorder occurred only in cases caused by NoV GII.4 2006b. Patients affected by NoV GII.4 2006b presented with a higher frequency of diarrhea ( P = 0.0204), longer duration of diarrhea ( P = 0.0215), more frequent hypoglycemia ( P = 0.038), and electrolyte imbalance ( P = 0.0487) than acute gastroenteritis caused by NoV GII.4 2010. Structural analysis showed that the amino acid changes in viral VP1 between GII.4 2006b and 2010 subtype were located mainly in the protruding domain 2 (P2 domain). In conclusion, the NoV GII.4 variants 2006b and 2010 were the main causes of acute gastroenteritis in hospitalized children in northern Taiwan during 2006-2011. The clinical presentations and structural changes in VP1 of the two NoV GII.4 variants should be evaluated in the future. J. Med. Virol. 86:335-346, 2014. © 2013 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Background: The global emergence of norovirus (NoV) GII.4 variants has raised public concerns in the world including South Korea since 1996., Objective: We analyzed seasonality and genotypic pattern for sporadic cases by norovirus GII-4 variants., Study Design: To determine the epidemic status of GII.4 variants in South Korea during 2006-2013, 7301 fecal specimens were collected from children who were younger than 5 years and had sporadic acute gastroenteritis (AGE)., Results: During the study period, NoVs were the most prevalent viral agent, detected in 877 (12.0%) of the 7301 fecal specimens from children with sporadic AGE. NoV GII strains predominantly accounted for 97.6% of all sporadic NoV infections. NoV GII.4 was the most prevalent genotype and comprised 67.6% of the NoV GII strains. However, seasonal prevalence of GII.4 strains varied depending on the spread of GII.4 variants. GII.4-2006b variant most predominantly circulated from 2006-2007 to 2009-2010 and persisted during other seasons. GII.4-2009 variant was first detected in January 2010 and predominant in 2011-2012. However, it was rapidly displaced by GII.4-2012 variant, which emerged in May 2012 and substantially circulated in 2012-2013., Conclusions: The frequent emergence and rapid spread of GII.4 variants significantly affect the magnitude of sporadic NoV infections in children. Hence, to minimize the disease burden of NoV infections, GII.4 strains should be considered as a primary target for vaccine development against NoVs., (Copyright © 2014 Elsevier B.V. All rights reserved.)