• Journal of Microbiology
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• v.44 no.4
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• pp.403-408
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• 2006

The purpose of this study was to determine the efficacy of a nucleic acid sequence-based amplification (NASBA) method of detecting noroviruses in artificially and naturally contaminated shellfish. We used 58 fecal samples that tested positive for noroviruses with electron microscopy (EM) to develop an NASBA assay for these viruses. Oligonucleotide primers targeting the polymerase coding region were used to amplify the viral RNA in an isothermal process that resulted in the accumulation of RNA amplicons. These amplicons were detected by hybridization with digoxigenin-labeled oligonucleotide probes that were highly specific for genogroup I (GI) and genogroup II (GII) of noroviruses. The expected band of 327bp appeared in denaturing agarose gel without any nonspecific band. The specific signal for each amplicon was obtained through Northern blotting in many repeats. All fecal samples of which 46(79.3%) belonged to GII and 12(20.6%) belonged to GI were positive for noroviruses by EM and by NASBA. Target RNA concentrations as low as 5pg/ml were detected in fecal specimens using NASBA. When the assay was applied to artificially contaminated shellfish, the sensitivity to nucleic acid was 100pg/1.5g shellfish tissue. The potential use of this assay was also confirmed in naturally contaminated shellfish collected from different ponds in Guangzhou city of China, of which 24 (18.76%) out of 128 samples were positive for noroviruses; of these, 19 (79.6%) belonged to GII and 5 (20.4%) belonged to GI. The NASBA assay provided a more rapid and efficient way of detecting noroviruses in fecal samples and demonstrated its potential for detecting noroviruses in food and environmental samples with high specificity and sensitivity.

• Journal of Microbiology
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• v.45 no.1
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• pp.48-52
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• 2007

A new procedure for the concentration of nonoviruses from water samples has been developed. This procedure (calcium flocculation-citrate dissolution method) uses the following steps: virus flocculation formed by treatment with 1 M $CaCl_2$ and 1 M $Na_2HPO_4$, virus release by sodium citrate dissolution (0.3 M Na citrate, pH 3.5), and virus re-concentration by ultrafiltration. When reverse transcription (RT)-PCR was performed after the procedure, the overall detection sensitivity for seeded noroviruses in a one liter drinking water sample was as low as 1 RT-PCR unit, which is equal to a $10^{-6}$ dilution of the virus sample. This approach showed at least a 5-fold-higher sensitivity than the current method with its three steps of adsorption-elution-concentration. The newly developed procedure was used to test different brands of bottled drinking water from China for putative contamination with noroviruses. A total of 144 samples were analyzed; all of the samples were negative for norovirus specific nucleic acids.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.15 no.1
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• pp.1-7
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• 2012

Noroviruses (NoVs) are one major etiologic agent in acute gastroenteritis (AGE) in all ages and are the primary cause of food-borne gastroenteritis worldwide. GII-4 NoVs has predominated since 1990s, and novel recombinant strains have been reported worldwide. Researchers face difficulties in making vaccines and therapeutic agents against NoVs due to the lack of cell culture and animal-model systems and the rapid emergence of novel variant strains. Recently, a randomized clinical trial for intranasal NoVs vaccine has been reported, which casts a light in the way of vaccine production. This review discusses the recent findings on the structure, immunity, and vaccination of NoVs.

• Journal of Environmental Health Sciences
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• v.38 no.1
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• pp.57-65
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• 2012

Objectives: For our survey of the incidence of norovirus infections and the genogroup distribution of norovirus in Seoul, Republic of Korea, we evaluated through regular surveillance the prevalence of norovirus infections in patients with acute gastroenteritis occurring in Seoul from January 2007 to July 2011. Methods: For norovirus detection, we conducted epidemiological analyses on the basis of the junction of ORF1 and ORF2 (approximately 314 bp). 11,202 fecal specimens were collected from patients in Seoul with acute gastroenteritis between January 2007 and July 2011 and then tested for the presence of NoV via reverse transcription (RT) - polymerase chain reaction (PCR). Results: 16.6% (1,861/11,202) of the fecal specimens were determined to be positive for noroviruses. The incidences of norovirus infection in Seoul in the case of acute gastroenteritis with regular surveillance were 28.0% in 2007, 14.6% in 2008, 9.1% in 2009, 14.1% in 2010, and 12.9% in 2011, which shows that noroviruses constituted a major causative agent of acute gastroenteritis. Also, the incidence of noroviral infection in patients with acute gastroenteritis increased after the large-scale new influenza in 2009. Conclusions: The genetic characteristics of norovirus and the epidemiologic patterns of a viral pathogen in acute gastroenteritis patients may provide potentially effective data for epidemiological studies in Seoul, Korea.

• Preventive Nutrition and Food Science
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• v.12 no.2
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• pp.126-130
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• 2007

Noroviruses, members of the family Caliciviridae, are often found in shellfish grown in polluted water and are emerging as a leading cause of foodborne disease worldwide. As the presence of norovirus in food commodities becomes an important medical and social issue, there are increasing needs for designing improved detection methods for the virus. In this study, we tested the Agilent 2100 Bioanalyzer for the analysis of norovirus DNA amplified from oyster samples. Microchip electrophoresis provided us with more accurate information, compared to conventional agarose gel electrophoresis, in the resolution and quantification of amplified products. The development of an improved method for food-associated noroviruses would contribute to a rapid identification of contaminated food and improve our understanding of the modes of food contamination and norovirus transmission.

• Proceedings of the Korean Society of Food Hygiene and Safety Conference
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• 2006.05a
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• pp.73-96
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• 2006

$\square$ A nationwide surveillance including 17 provincial labs has been established $\square$ Noroviruses are involved in recent viral gastroenteritis outbreaks and sproradic viral gastroenteritis cases in Korea $\square$ Analysis of RDRP and capsid regions of norovirus strains shows that various genotypes were circulated in Korea $\square$ Early detection of outbreaks cases (2004 Jeju-cause of epidemic) $\square$ New variant or emerging strain detection: variant GII4 and GIIb $\square$ Detection of Sapoviruses from AGE patients in 2003-4

• Journal of Environmental Science International
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• v.23 no.2
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• pp.219-229
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• 2014

The occurrence trends and moleculargenetic characteristics of noroviruses detected from gastroenteritis patients in Jeju from 2008 to 2010 were investigated. In addition, the norovirus contamination and its characteristics of groundwaters in Jeju were examined. The incidence caused by norovirus in viral gastroenteritis patients has increased every year and was higher in male than in female. The patients caused by norovirus occurred throughout all months. The incidences started to increase from November, were very high from December to February, started to decrease from March, and were very low from June to September. The patients caused by norovirus occurred throughout all ages, however, the infants below 5 years were the most susceptible to norovirus infection and the age group from teens to forties were the most insensitive to norovirus infection. The sequencing analysis showed that 18 genotypes (8 genogroup I (GI) and 10 genogroup II (GII)) were detected, the incidences caused by GI and GII were 11.5% and 88.5%, respectively, and predominant genotype was GII-4 (70.5%), which was the major genotype giving rise to norovirus incidences in Jeju, together with GII-3 (6.1%) and GI-4 (4.1%). Among 20 groundwaters sampled at 9 wells (4 non-drinking water wells and 5 drinking water wells), noroviruses were detected from 2 groundwaters sampled at one non-drinking water well and their genotypes were GI-5 and GI-8.

• Journal of Microbiology and Biotechnology
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• v.27 no.4
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• pp.816-824
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• 2017

Human noroviruses are widespread and contagious viruses causing nonbacterial gastroenteritis. Real-time reverse transcription quantitative PCR (real-time RT-qPCR) is currently the gold standard for the sensitive and accurate detection of these pathogens and serves as a critical tool in outbreak prevention and control. Different surveillance teams, however, may use different assays, and variability in specimen conditions may lead to disagreement in results. Furthermore, the norovirus genome is highly variable and continuously evolving. These issues necessitate the re-examination of the real-time RT-qPCR's robustness in the context of accurate detection as well as the investigation of practical strategies to enhance assay performance. Four widely referenced real-time RT-qPCR assays (Assays A-D) were simultaneously performed to evaluate characteristics such as PCR efficiency, detection limit, and sensitivity and specificity with RT-PCR, and to assess the most accurate method for detecting norovirus genogroups I and II. Overall, Assay D was evaluated to be the most precise and accurate assay in this study. A ZEN internal quencher, which decreases nonspecific fluorescence during the PCR, was added to Assay D's probe, which further improved the assay performance. This study compared several detection assays for noroviruses, and an improvement strategy based on such comparisons provided useful characterizations of a highly optimized real-time RT-qPCR assay for norovirus detection.

• Korean Journal of Microbiology
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• v.44 no.2
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• pp.135-139
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• 2008

Fecal specimens from acute gastroenteritis in Seoul from 2004 to 2007 were collected and then tested for the presence of norovirus by RT-PCR. 258 noroviruses were subjected to be futher characterized to sequencing analysis. The sequencing analysis showed that thirteen genotypes were detected (GII.1, GII.2, GII.3, GII.4, GII.5, GII.6, GII.8, GII.10, GII.l2, GII.13, GII.l5, GII.l6, GII.l7) and predominant genotype was GII.4 (76.7%) in the cases of norovirus detected sporadic acute gastroenteritis in Seoul. By this molecular investigation, genotypic distribution associated with norovirus infections will be used for control and prevention of norovirus related diseases.

• Journal of Microbiology and Biotechnology
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• v.25 no.12
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• pp.2106-2109
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• 2015

The synergy effect of trisodium phosphate (TSP) and ethanol against murine norovirus 1 (MNV-1), as a surrogate for human noroviruses, on fresh produces was evaluated. More than 2% (w/v) of TSP effectively inactivated MNV-1. The single treatment of 1% TSP or 30% ethanol for 30 min was not effective on MNV-1; however, cotreatment showed inactivation of MNV-1 on stainless steel and the produces of lettuce and bell pepper under 15 min. The results suggest that cotreatment of TSP and ethanol at a low concentration and a short time of exposure might be useful for the reduction of norovirus in some produce.