Molecular epidemiology of noroviruses in children in South Greece, 2013‐2015

Noroviruses constitute the leading cause of acute, nonbacterial gastroenteritis that affects both children and adults in healthcare and community settings. The current study attempted to provide insight on the molecular epidemiology of noroviruses in children in South Greece. Genotypic characterization of 69 norovirus strains detected in stool samples from children with gastroenteritis during a period of 30 months (January 2013 to June 2015) was performed on the basis of ORF2 (VP1 capsid) gene sequences. The results revealed the circulation of a diverse variety of norovirus genotypes. GII.4 was the predominant genotype (74%), followed by GII.2 (8.7%), GII.3 (5.8%), GII.6 (2.9%), GI.2 (2.9%), and four strains identified as GII.1, GII.7, GII.8, and GII.13, respectively. Phylogenetic analysis showed that most of the strains were closely associated with norovirus strains that circulated globally either in outbreaks and sporadic cases of gastroenteritis or in the environment during the last 4 years. Οf the GII.4 strains, 80.4% were detected between January 2013 and February 2014, indicating a possible ongoing epidemic. The incidence of other genotypes remained constant throughout the study period. Genotypic and phylogenetic analysis showed the predominance of the “Sydney 2012” variant among the GII.4 strains, whereas one GII.4 strain was identified as a “New Orleans 2009” variant. Five GII.4 strains showed significant nucleotide and amino acid sequence divergence from either the “Sydney 2012” or the “New Orleans 2009” variant, and these divergent strains might represent an emerging GII.4 variant.     

Detection and molecular characterization of noroviruses and sapoviruses in children admitted to hospital with acute gastroenteritis in Vietnam

Noroviruses (NoV) and sapoviruses (SaV) are recognized as important causes of acute gastroenteritis in children worldwide. In this study, the prevalence and genetic variability of NoV and SaV were determined in hospitalized children <5 years of age with acute gastroenteritis in Hanoi, Vietnam. A total of 501 fecal specimens collected between November-2007 and October-2008, that previously had been tested for rotavirus (RV), were tested for NoV and SaV by realtime RT-PCR. Positive samples were genotyped by conventional RT-PCR followed by sequencing. GII NoV was detected in 180 (36%) and SaV in 7 (1.4%) of the samples. NoV was detected year-round ranging from 9.5% in April to 81.5% in September among RV negative samples. NoV GII.4 Minerva (2006b) was the dominant genotype (93%) with a few other genotypes detected including GII.3 (4.4%), GII.13 (1.7%), and GII.2 (0.6%) but no GI strains. Only GI and GII SaV strains were detected in this study. No difference in NoV prevalence between age groups was noted. Frequency of vomiting or fever was similar between children with NoV and RV infection, yet, NoV caused diarrhea with longer duration. In conclusion, NoV is the second most frequent cause of diarrhea in hospitalized children in North Vietnam.     

Detection and characterisation of human astroviruses in children with acute gastroenteritis in Blantyre,Malawi

In a 2-year hospital-based study of paediatric gastroenteritis in Blantyre, Malawi, astroviruses were detected by enzyme immunoassay in 15 (1.9%) of 786 inpatients and in 9 (2.3%) of 400 outpatients. Greater disease severity was noted in children coinfected with human immunodeficiency virus (HIV). Six human astrovirus (HAstV) genotypes were identified, including HAstV-1 (25%), HAstV-2 (21%), HAstV-3 (25%), HAstV-4 (13%), HAstV-5 (4%), and HAstV-8 (13%). Although astroviruses are not major causes of gastroenteritis among children admitted to hospital in Blantyre, concomitant HIV infection appears to be a risk factor for increased severity of disease.     

Molecular epidemiology of norovirus infection among children with acute gastroenteritis in Shanghai,China, 2001–2005

Norovirus is one of the major causes of outbreaks and sporadic cases of acute gastroenteritis in young children worldwide. Obtaining local baseline information regarding this virus is important for developing and evaluating prevention strategies of norovirus transmission in children. The age, seasonal distribution and circulating genotypes of norovirus in Shanghai, China, between 2001 and 2005 were determined. Of 5411 stool specimens collected from children under 5 years of age who were hospitalized with acute gastroenteritis 3,975 were rotavirus‐negative, indicating the presence of another causative agent. From these specimens, 484 were selected at random for genotyping, and 45 were norovirus‐positive. Norovirus infection was detected in all age groups, but infants less than 6 months old showed the lowest prevalence (5.4%). Norovirus infections peaked from August to November. Among the 37 identified norovirus strains, 2 were GII‐3, 2 were GII‐7, and 33 were GII‐4 genotypes. This study demonstrated the impact of norovirus infection causing acute gastroenteritis in hospitalized children and the importance of vaccination against norovirus diarrhea in Shanghai, China. J. Med. Virol. 81:1826–1830, 2009. © 2009 Wiley‐Liss, Inc.     

Genetic relatedness of noroviruses identified in sporadic gastroenteritis in children and gastroenteritis outbreaks in northern Alberta

We compared the proportion and genotype distribution of norovirus (NoV) identified in sporadic acute gastroenteritis in children younger than 7 years old with the NoV strains found in outbreaks from January 2003 through April 2004 in northern Alberta, Canada. Eight genogroup I (GI) and 133 GII NoV cases were detected in 1,166 cases of acute sporadic childhood gastroenteritis with a monthly detection rates varying from 6.0% to 20.4% and no sporadic gastroenteritis case in October 2003. Seventy-eight outbreaks (65%) tested positive for NoV during the study period with an obvious winter predominance and no NoV outbreaks in August, September, and October 2003. Three GI and 51 GII strains from the sporadic childhood gastroenteritis cases and seven GI and 37 GII strains from gastroenteritis outbreaks were sequenced and analyzed. Strains belonging to the GII.4 cluster predominated in outbreaks (68%) while the strains in sporadic childhood gastroenteritis demonstrated significant heterogeneity with the majority belonging to the GII.3 cluster (36%). Further analysis of NoV strains from 34 sporadic childhood gastroenteritis cases and 38 gastroenteritis outbreaks in chronologically and geographically related groups failed to demonstrate clear link between strains circulating in the setting of sporadic childhood gastroenteritis and those found in outbreaks.     

Molecular characterization of astrovirus infection in children with diarrhea in Beijing, 2005–2007

Human astroviruses (HAstVs) have been recognized as one of the major causes of acute gastroenteritis in children. To provide more insight into the prevalence of HAstV gastroenteritis in China, 664 fecal samples were collected from children affected with acute gastroenteritis in Beijing from March 2005 to November 2007. The samples were analyzed genetically. All eight serotypes (genotypes) of HAstVs were screened using RT‐PCR assays targeting the ORF2 region in the study. The assays detected HAstVs in 52 (7.8%) of the patients, with HAstV‐1 (50/52) being the dominant genotype during the study period. Two minor genotypes, HAstV‐6 and HAstV‐3, were also detected. Partial sequencing of the 50 HAstV‐1 strains showed that the homology of the nucleotide sequence of the ORF1a region between these strains was 88.4–100%, whereas the homology of the amino acid sequences was 95.6–100%. In the ORF2 partial region, the nucleotide identities ranged from 91.5% to 100%, and amino acid identities ranged from 97.3% to 100%. The identity of the whole genome sequence between four randomly examined HAstV‐1 strains was 91–99%. No recombination events were observed in HAstVs in this study. The findings of this study will provide baseline data for HAstVs surveillance and control. J. Med. Virol. 82:415–423, 2010. © 2010 Wiley‐Liss, Inc.     

Molecular detection and characterization of noroviruses from children in Botswana

Stool specimens were collected from 100 children in Botswana. RT‐PCR analysis detected noroviruses (NoVs) in 24% of samples tested. Genogroup I and genogroup II strains were identified. There was no association between NoV detection and age or gender. This study is the first indication that NoVs circulate widely in Botswana. J. Med. Virol. 82:321–324, 2010. © 2009 Wiley‐Liss, Inc.     

Detection of GII‐4/2006b variant and recombinant noroviruses in children with acute gastroenteritis,South Korea

Norovirus (NoV), a single‐stranded, positive RNA virus, is an important etiologic agent of acute gastroenteritis in children worldwide. In this study, a total of 434 fecal samples collected from 434 children with acute gastroenteritis in Seoul, between September 2007 and July 2008 were tested to determine the molecular epidemiology of NoVs and characterize recombinant strains by using RT‐PCR followed by sequencing. Of the 434 specimens, NoV, rotavirus, and adenovirus were detected in 155 (35.8%), 72 (16.6%), and 19 specimens (4.3%), respectively. NoV GI was detected in 7 specimens (1.6%) and GII in 148 (34.1%) specimens. Phylogenetic analysis of capsid sequences in the GII‐positive specimens revealed the presence of the following strains: GII‐4, 111 (75.0%); GII‐3, 35 cases (23.6%); GII‐6b, 1 case; and GII‐16, 1 case. Most of the GII‐4 strains were grouped with the GII‐4/2006b variant with 98–100% nucleotide identity. Eleven strains were identified as recombinant (GII‐4/GII‐3 in 10 cases and GII‐b polymerase/GII‐16 capsid in 1 case) by sequencing based on the RdRP and capsid genes. The putative recombination point in the recombinant strains was the ORF‐1/ORF2 overlap, located at nucleotide 5,046 with reference to Lordsdale. In conclusion, GII‐4/2006b variants were detected predominantly and a new recombinant strain (GII‐4/GII‐3) was found in the Korean children with gastroenteritis. Continuous monitoring of the genetic diversity of NoVs is important to determine the trend of the predominant genotype and new recombinant strain. J. Med. Virol. 82:146–152, 2010. © 2009 Wiley‐Liss, Inc.