• 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.

• Food Science and Biotechnology
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• v.17 no.5
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• pp.925-930
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• 2008

Norovirus has become the most common cause of human gastroenteritis in developed countries. Detection procedures of foodborne viruses from foods require several steps. The concentration step using polyethylene glycol (PEG) is time-consuming and the detection efficiency of reverse transcription-polymerase chain reaction (RT-PCR) is affected by inhibitors from food components. In this study, a rapid detection method based on buoyant density centrifugation was developed to replace the time-consuming chloroform-polyethylene glycol-Tris Tween method. Feline calicivirus that belongs to the family Caliciviridae was used as a surrogate model for norovirus. After artificial inoculation of feline calcivirus (FCV) to oyster and lettuce, 830 ${\mu}L$ of homogenized sample suspension was layered on the top of 670 ${\mu}L$ 20% percoll and centrifuged. Then RNA extraction step was proceeded with the supernatant. By varying several physical conditions, the detection limits were lowered to $2.4{\times}10^2$ PFU per 1 g in oyster and $2.4{\times}10^0$ PFU per 1 g in lettuce. The protocol obtained in this study could be used to develop new detection method for norovirus in foods.

• 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.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.27 no.2
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• pp.95-103
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• 2024

Purpose: Diarrhea is one of the leading causes of mortality in children living in developing countries. The etiology of acute diarrhea in each healthcare center varies depending on place, time, and population. This study aimed to identify pathogen patterns in human immunodeficiency virus (HIV)-infected and non-HIV children suffering from acute diarrhea, using multiplex real time reverse transcriptase polymerase chain reaction (RT-PCR), in an Indonesian tertiary hospital. Methods: This cross-sectional study was conducted at Dr. Cipto Mangunkusumo National Hospital from March 2019 to April 2020. Results: The study showed that multiplex RT-PCR results were positive in 58.9% of the specimens, with more positive results in HIV-infected children than in non-HIV-infected children (70% vs. 54.7%). Altogether 72 enteropathogens were detected from all specimens. Enteropathogens in non-HIV children with acute diarrhea consisted of bacteria (70.6%) and viruses (29.4%) with a predominance of enteroaggregative Escherichia coli (25.4%), followed by Campylobacter spp. (11.8%), enteropathogenic E. coli (9.8%), Norovirus GII (7.8%), and Clostridium difficile (7.8%). Enteropathogens in HIV-infected children consisted of viruses (57.1%), bacteria (28.6%), and parasites (14.3%) comprising Norovirus GII (24%), Cryptosporidium spp. (14.3%), Campylobacter spp. (14.3%), Norovirus GI (14.3%), and Astrovirus (14.3%). Cryptosporidium spp. was the only parasite found in this study and was found only in HIV-infected children. In non-HIV children with acute diarrhea, most pathogens were invasive bacteria, while in HIV-infected children, more viral and parasite infections occurred, primarily caused by opportunistic pathogens. Conclusion: The pattern of enteropathogens can help clinicians determine further examinations and appropriate empirical antimicrobial therapy for the patient.

• Food Science of Animal Resources
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• v.41 no.1
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• pp.1-7
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• 2021

This mini review focuses on foodborne illnesses and outbreaks caused by food-producing animals because statistical information of the foodborne illnesses is important in human health and food industry. Contaminated food results in 600 million cases of foodborne diseases and 420,000 deaths worldwide every year. The world population is currently 7.8 billion, and 56 million people die every year; of these, every year, 7.69% of people experience foodborne diseases, and 7.5% of annual deaths (56 million deaths) was died by foodborne illness in the world. A majority of such patients are affected by norovirus and Campylobacter. Listeria monocytogenes is the most fatal. In the United States, except for those caused by Campylobacter, the number of foodborne diseases did not decrease between 1997 and 2017, and cases caused by Toxoplasma gondii are still being reported (9 cases in 2017). The percentage of foodborne illnesses caused by food-producing animals was 10.4%-14.1% between 1999 and 2017 in the United States. In Europe, foodborne illnesses affect 23 million people every year and cause approximately 5,000 deaths. Europe has more Campylobacter- and Salmonella-related cases than in other countries. In Australia, the highest number of cases are due to Campylobacter, followed by Salmonella. In Korea, Escherichia coli followed by norovirus. Campylobacter- and Clostridium perfringens-related cases have been reported in Japan as well. This review suggests that Campylobacter, Salmonella, L. monocytogenes, and E. coli, which are usually isolated from animal-source food products are associated with a high risk of foodborne illnesses.

• Biomolecules & Therapeutics
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• v.30 no.1
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• pp.64-71
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• 2022

Norovirus (NV) is the most common cause of viral gastroenteritis, with the potential to develop into a fatal disease in those who are immuno-compromised, and effective vaccines and treatments are still non-existent. In this study, we aimed to elucidate the molecular mechanism of the previously identified NV replication inhibitor utilizing a vinyl-stilbene backbone, AC-1858. First, we confirmed the inhibition of the NV RNA replication by a structural analog of AC-1858, AC-2288 with its exclusive cytoplasmic sub-cellular localization. We further validated the induction of one specific host factor, the phosphorylated form of heat shock factor (HSF)-1, and its increased nuclear localization by AC-1858 treatment. Finally, we verified the positive and negative impact of the siRNA-mediated downregulation and lentivirus-mediated overexpression of HSF-1 on NV RNA replication. In conclusion, these data suggest the restrictive role of the host factor HSF-1 in overall viral RNA genome replication during the NV life cycle.

• Pediatric Infection and Vaccine
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• v.18 no.1
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• pp.40-47
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• 2011

Purpose : Norovirus infection, a common cause of community-acquired gastroenteritis, can also lead to severe illness in immunocompromised patients. We investigated clinical manifestations of norovirus infection in pediatric cancer patients. Methods : Stool specimens were collected from pediatric patients with gastrointestinal symptoms between November 2008 and September 2009 at Samsung Medical Center, Seoul, Korea. Norovirus infection was identified by reverse-transcription polymerase chain reaction (RT-PCR). A retrospective chart review was performed in pediatric cancer patients who were diagnosed with norovirus infection. Results : Ten patients were diagnosed with norovirus infection by RT-PCR in stool samples. The median age was 0.83 years (range 0.25-5.5 years) and the male to female ratio was 1.5:1 (6 males and 4 females). Underlying diseases were hematologic malignancies (4/10, 40%), neuroblastoma (4/10, 40%), and brain tumors (2/10, 20%). Three patients were infected before hematopoietic cell transplantation (HCT) and four patients after HCT. All patients had diarrhea (10/10, 100%), with a median frequency of diarrhea of 8.5 times/day (range 4-22 times/day). Median virus shedding duration was 72.5 days (range 19-299 days). Four patients with pneumatosis intestinalis were conservatively treated with bowel rest and total parenteral nutrition. One patient with severe diarrhea and bloody stool had concomitant chronic gut graft-versus-host disease (GVHD). Norovirus infection-related mortality was not observed. Conclusion : Norovirus infection can cause significant clinical manifestations with prolonged viral shedding in immunocompromised patients. Norovirus should be considered in pediatric cancer patients with severe gastrointestinal symptoms.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.9 no.2
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• pp.139-146
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• 2006

Purpose: Human astrovirus (HAstV) is known to be an important etiologic agent of acute gastroenteritis in infants worldwide. However, the prevalence of HAstV infection varies according to geographic region and patient age. The purpose of our study was to investigate the incidence of HAstV infection among hospitalized children at a tertiary hospital in Seoul. Methods: Fecal samples were collected from hospitalized children up to five years of age with acute gastroenteritis. A total of 812 fecal samples were collected from hospitalized children with acute gastroenteritis between February 2004 and January 2005. Fecal specimens were screened for rotavirus, enteric adenovirus and norovirus by enzyme immunoassay (EIA) or reverse transcriptase polymerase chain reaction (RT-PCR). HAstV positive samples were characterized by RT-PCR. Results: Rotavirus was detected in 16.9% (138/812), norovirus in 11.6% (94/812), and adenovirus in 4.0% (33/812) of the study population. HAstV was detected in 4.0% (33/812) samples by RT-PCR. The age distribution of HAstV positive patients was as follows: <12 month old, 82.0% (27/33); 1~2 years old, 6.0% (2/33); 2~5 years old, 12.0% (4/33). The seasonal distribution of HAstV positive samples was as follows; April (3), May (5), June (4), August (12), September (4), October (2), November (2), and December (1). The peak rate of HAstV infection was observed during the summer season, 2004. A mixed infection of viral agents was confirmed in 2.7% (22 /812) of the study population, most commonly with rotavirus and norovirus, and with rotavirus and HAstV. Genotype 1 was the predominant type (91%, 20/22) and genotype 8 was detected in two cases. Conclusion: The prevalence of HAstV infection was 4.0% in hospitalized children with acute gastroenteritis, and was especially high in infants. HAstV can be considered as an important etiologic agent of gastroenteritis in children.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.49 no.4
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• pp.454-459
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• 2016

Pre- or post-harvest processing is required to mitigate the risk of norovirus infection mediated by shellfish or seafood. We investigated the environmental resistance of human norovirus (HuNoV) under various conditions of temperature, salinity, and pH in seawater. Male-specific coliphage (MSC) was as the reference virus for all tests. At 4℃, HuNoV GII4 spiked into seawater was continually detected by RT-PCR for 35 days, regardless of salinity or pH level. It maintained nearly stable concentrations, meaning HuNoV can sustain a viral population in seawater long enough to be accumulated by shellfish and other filter feeders during winter. MSC was also stable at 4℃ although viral infectivity dropped sharply after 28 days. The effects of salinity and pH on MSC were indistinct. At 25℃ the detectable period of HuNoV GII4 by RT-PCR in seawater decreased to about one-third or half of the period at 4℃. High salinity (32 psu) and alkaline pH (8.5) were also unfavorable for sustaining HuNoV abundance at 25℃ in seawater. The resistance patterns of MSC to high temperature, high salinity, and alkaline pH were more dramatic and viral infectivity decreased over time, almost in direct proportion to experimental days. MSC was undetectable after 12 days under all salinities and pH levels at 25℃.

• Journal of Life Science
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• v.21 no.6
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• pp.845-850
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• 2011

Norovirus (NoV) causes major acute non-bacterial gastroenteritis in humans. NoV genus is a member of the family Caliciviridae, which is transmitted by contaminated food and water or from human to human. Many genotypes of genogroups I and II have been reported because of their high genetic diversity. To obtain molecular epidemiological information on gastroenteritis sporadic cases in Busan, Korea, we analyzed the nucleotide sequences of NoV strains detected during 2008~2010. We performed one step RT-PCR amplifying the open reading frame (ORF) 2 (capsid region) followed by semi-nested PCR. Fecal samples were collected from 4,071 acute gastroenteritis, and genotypes of the 421 positive samples were determined by sequence analysis. Based on partial sequence of capsid region, 7 NoV were categorized into genogroup I and 13 into genogroup II. Prevalent genotypes among gastroenteritis patients within Busan were GII.4, GI.6, GII.5 in 2008~2010. The results of this study will contribute to the currently available epidemiological data and improve public health and hygiene via development of diagnostic methods and sustainable surveillance.