Genetic diversity of noroviruses in Taiwan between November 2004 and March 2005

Wu, Fang‐Tzy; Oka, Takahiro; Katayama, Kazuhiko; Wu, Hui; Jiang, Donald Dah-Shyong; Miyamura, Tatsuo; Takeda, Naokazu; Hansman, Grant S.

doi:10.1007/s00705-005-0717-4

Cited by 28 publications

(29 citation statements)

References 24 publications

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“…GII/4 strains were detected in 20 of 55 (36%) outbreaks, followed by GII/3, which was detected in 7 of 55 outbreaks. We also found that noroviruses belonging to GII/4 were the dominant cause of outbreaks in Taiwan (32). In a number of norovirus GII-associated outbreaks (9 of 50 outbreaks), different norovirus genotypes were detected in specimens from symptomatic and asymptomatic food handlers from the same food-catering setting.…”

Section: Discussionmentioning

confidence: 68%

Norovirus Infections in Symptomatic and Asymptomatic Food Handlers in Japan

Ozawa¹,

et al. 2007

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Noroviruses are the leading cause of outbreaks of gastroenteritis in the world. At present, norovirus genogroup II, genotype 4 (GII/4), strains are the most prevalent in many countries. In this study we investigated 55 outbreaks and 35 sporadic cases of norovirus-associated gastroenteritis in food handlers in foodcatering settings between 10 November 2005 and 9 December 2006 in Japan. Stool specimens were collected from both symptomatic and asymptomatic individuals and were examined for norovirus by real-time reverse transcription-PCR; the results were then confirmed by sequence analysis. Norovirus was detected in 449 of 2,376 (19%) specimens. Four genogroup I (GI) genotypes and 12 GII genotypes, including one new GII genotype, were detected. The GII/4 sequences were predominant, accounting for 19 of 55 (35%) outbreaks and 16 of 35 (46%) sporadic cases. Our results also showed that a large number of asymptomatic food handlers were infected with norovirus GII/4 strains. Norovirus GII had a slightly higher mean viral load (1 log unit higher) than norovirus GI, i.e., 3.81 ؋ 10 8 versus 2.79 ؋ 10 7 copies/g of stool. Among norovirus GI strains, GI/4 had the highest mean viral load, whereas among GII strains, GII/4 had the highest mean viral load (2.02 ؋ 10 8 and 7.96 ؋ 10 9 copies/g of stool, respectively). Importantly, we found that asymptomatic individuals had mean viral loads similar to those of symptomatic individuals, which may account for the increased number of infections and the predominance of an asymptomatic transmission route.The positive-sense polyadenylated single-stranded RNA virus family Caliciviridae contains four genera: Norovirus, Sapovirus, Lagovirus, and Vesivirus (1). The prototype strain of human norovirus is the Norwalk virus (NV/Human/US/1968), which was first discovered in an outbreak of gastroenteritis in an elementary school in Norwalk, OH, in 1968 (15). Noroviruses are the leading cause of outbreaks of gastroenteritis in the world; they cause outbreaks in various settings, including hospitals, cruise ships, schools, and restaurants (2,9,12,15,23,24,29). In addition, noroviruses have been detected in environmental samples (e.g., treated and untreated sewage) as well as in contaminated foods such as oysters, shellfish, sandwiches, salads, raspberries, and even ice (7,18,19,26). Numerous molecular epidemiological studies have revealed a global distribution of these viruses (25,27,31).The most widely used method of detecting noroviruses is reverse transcription-PCR (RT-PCR), which has high sensitivity; also, the products can be used for further genetic analysis. Real-time RT-PCR assays have also been developed; they are sensitive, broadly reactive, and rapid for the detection of human noroviruses in clinical stool specimens and environmental samples (13,14,21).As the detection methods become more and more sensitive, the numbers of genogroups and genotypes are expected to increase. One emerging characteristic is that strains have been found to persist in one geographical region, only to disapp...

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Section: Discussionmentioning

confidence: 68%

Norovirus Infections in Symptomatic and Asymptomatic Food Handlers in Japan

Ozawa¹,

et al. 2007

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“…The recent global increase in NoV activity is due to the emergence of a new GII-4 variant. Pandemics caused by several GII-4 variants such as the 95/96, 2002, 2004, and 2006 variants reported by previous studies [Kageyama et al, 2004;Wu et al, 2006;Siebenga et al, 2007;Tu et al, 2007;Buesa et al, 2008;Hukuda et al, 2008;Racnakunda et al, 2008]. The variance of this genotype is considered to be due to an evolution driven by herd immunity or colonial expansion from quasispecies [Lindesmith et al, 2008;Carlsson et al, 2009].…”

Section: Discussionmentioning

confidence: 91%

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

Chung

Han

Park

et al. 2009

Journal of Medical Virology

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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.

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“…These had previously been examined using nested RT-PCR, and sequence analysis identified seven positive SaV specimens: two GI (Sydney31 and Sydney40), three GII (Sydney53, Sydney77, and Sydney4106), one GIV (Sydney3), and one GV (Sydney4402), while the remaining 88 specimens were negative for norovirus (NoV), rotavirus, astrovirus, and adenovirus [Hansman et al, 2006c]. We also used 138 clinical stool specimens collected from 12 outbreaks of gastroenteritis in Taiwan that were shown to contain 4 NoV GI, 26 NoV GII, 1 rotavirus, 4 adenovirus, and 1 astrovirus [Wu et al, 2006].…”

Section: Stool Specimensmentioning

confidence: 99%

Detection of human sapovirus by real‐time reverse transcription‐polymerase chain reaction

Oka

Katayama

Hansman

et al. 2006

Journal of Medical Virology

235

183

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Sapovirus (SaV) is an agent of gastroenteritis for humans and swine, and is divided into five distinct genogroups (GI-GV) based on its capsid gene sequences. Typical methods of SaV detection include electron microscopy (EM), enzyme-linked immunosorbent assay (ELISA), and reverse transcription-polymerase chain reaction (RT-PCR). A novel TaqMan-based real-time RT-PCR assay was developed that is sensitive and has the ability to detect the broad range of genetically diverse human SaV strains. A nucleotide alignment of 10 full-length SaV genome sequences was subjected to similarity plot analysis, which indicated that the most conserved site was the polymerase-capsid junction in open reading frame 1 (ORF1). Based on multiple alignments of the 27 available sequences encoding this junction, we designed sets of primers and TaqMan MGB probes that detect human SaV GI, GII, GIV, and GV sequences in a single tube. The reactivity was confirmed with SaV GI, GII, GIV, and GV control plasmids, and the efficiency ranged from 2.5 x 10(7) to 2.5 x 10(1) copies per tube. Analysis using clinical stool specimens revealed that the present system was capable of detecting SaV GI, GII, GIV, and GV sequences, and no cross-reactivity was observed against other enteric viruses, including norovirus (NoV), rotavirus, astrovirus, and adenovirus. This is the first real-time RT-PCR system that could detect all genogroups of human sapoviruses.

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Genetic diversity of noroviruses in Taiwan between November 2004 and March 2005

Cited by 28 publications

References 24 publications

Norovirus Infections in Symptomatic and Asymptomatic Food Handlers in Japan

Norovirus Infections in Symptomatic and Asymptomatic Food Handlers in Japan

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

Detection of human sapovirus by real‐time reverse transcription‐polymerase chain reaction

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