• Fisheries and Aquatic Sciences
• /
• v.24 no.1
• /
• pp.10-18
• /
• 2021

Norovirus (NoV) prevalence was investigated in 100 sewage samples collected from 35 individual septic tanks around the drainage basin of Jaran Bay, Korea in January, May, and July of 2017. Genotypes and diversity of NoV strains detected in sewage samples were also assessed using the conventional RT-PCR and phylogenetic analysis. NoV GI or GII were detected in 22 (22.0%) and 24 (24.0%) samples, respectively. Thirteen genotypes were identified with three dominant genotypes (GI.9, GII.5 and GII.17) and GII.17 showed relatively higher prevalence during the survey period. GII.17 strains were clustered into recombinant type variant or NoV GII.17 Kawasaki variant. NoV GII.17 strains were considered emergent epidemic variants with widespread circulation. NoV surveillance strategy should include both environmental (sewage) and clinical data to reveal minor NoV genotypes likely cause of asymptomatic or underreported infections in the local population.

• Microbiology and Biotechnology Letters
• /
• v.50 no.1
• /
• pp.126-134
• /
• 2022

Norovirus (NoV) is an important pathogen causing acute gastroenteritis worldwide. The purpose of the present study was the molecular characterization of NoV. A total of 408 stool specimens collected from hospitalized children associated with acute gastroenteritis in Chiang Rai, Thailand, 2015-2017 were investigated for the presence of NoVs by RT-PCR. NoV GII was detected in 32 samples (7.8%). Five distinct genotypes were identified, including GII.4 (13/32, 40.6%), GII.3 (11/32, 34.3%), GII.17 (4/32, 12.5%), GII.2 (2/32, 6.3%), and GII.14 (2/32, 6.3%). NoV infection occurred mostly in young children under 3 years of age (31/32, 96.9%) and showed the main peak in summer months from March to April (18/32, 56.3%). Phylogenetic analysis revealed that all 13 GII.4 strains clustered with GII.4 Sydney 2012 variant. Representative GII.3 strains were analyzed as a recombinant GII.3P[12] strain. Several amino acid differences were found in the antigenic epitopes and antibody binding sites of the VP1 capsid of the GII.3P[12]. Homology modeling of the P domain of the GII.3P[12] strain demonstrated that 10/13 amino acid differences were predicted to be located on the surface-exposed area of the capsid structure. These amino acid changes might affect the infectivity and the antigenicity of the recombinant GII.3P[12]. The prevalence of GII.4 Sydney 2012 and recombinant GII.3P[12] strains indicates the genetic diversity of circulating NoVs in Thailand, emphazing the importance of continuous surveillance to mornitor newly emerging NoV strains in the future.

• Journal of Food Hygiene and Safety
• /
• v.32 no.6
• /
• pp.455-459
• /
• 2017

Norovirus (NoV) is the most common cause of acute gastroenteritis in all age groups worldwide. In this study, prevalence of asymptomatic norovirus infection was investigated in food handler being employed at food catering facilities in South Korea. A total of 2,729 fecal specimens from asymptomatic food handlers were analyzed, and 1.06% of food handlers (29/2,729) had asymptomatic NoV infection. Of these, 17.2% (5/29) were positive for NoV GI and 82.7% (24/29) were positive for NoV GII. Especially, sequencing and phylogenetic analysis showed that GII-4 was the most prevalent genotype and a large number of asymptomatic food handlers were infested with norovirus GII-4 strains. The results of this study show that asymptomatic food handlers may be potential transmission sources for NoV infection. These results emphasize the need for training of food catering employees about norovirus prevention. Asymptomatic norovirus infection should receive more attention.

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

• Pediatric Infection and Vaccine
• /
• v.27 no.2
• /
• pp.90-101
• /
• 2020

Purpose: The multiplex reverse transcriptase-polymerase chain reaction (RT-PCR) test developed recently can help detect enteric pathogens of acute gastroenteritis (AGE). This study aimed to investigate the epidemiology of pathogens in children with AGE using the multiplex RT-PCR. Methods: From May 2015 to June 2018, multiplex RT-PCR tests were performed to identify pathogens in the feces of pediatric patients diagnosed with AGE at a secondary hospital in Seoul, Korea. Results: Of the 1,366 stool samples examined for viral pathogens, 483 (35.3%) tested positive for ≥1 pathogen. Group A rotavirus (RV) was detected in 106 cases (7.8%). The positivity rate increased annually from 3.0% (8/263) to 16.7% (48/288) and surged in 2018 (P<0.001). Norovirus (NoV) GII was the most common viral pathogen (263/1,366, 19.3%), and the positivity rate did not increase during the 3 years. Of the 304 stool samples tested for bacterial pathogens, Campylobacter spp. was the most common bacterial pathogen (32/304, 10.5%), followed by Clostridium difficile (22/304, 7.2%) and Salmonella spp. (17/304, 5.6%). The positivity rate of these bacterial pathogens did not change significantly during the study period. Conclusions: NoV GII is the main pathogen in childhood AGE since the introduction of RV vaccine, yet the number of rotavirus-infected patients increased during our study, especially in 2018. Therefore, further research is needed including the possibility of emergence of novel RV strains. Campylobacter spp. is the predominant cause of bacterial AGE in children. For proper treatment, the clinical characteristics of the bacteria should be taken into consideration, and continuous monitoring is necessary.