• Korean Journal of Veterinary Research
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• v.38 no.2
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• pp.336-344
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• 1998

Eight monoclonal antibodies(MAbs) against the transmissible gastroenteritis virus (TGEV) were produced and characterized. Four of the MAbs were produced against a reference TGEV, Purdue strain(P115) and the others were produced against the Korean vaccine virus, Pyungtaek strain. Only one MAb(5C8) produced against P115 had neutralizing activity and was found to be E2 protein-specific. The other seven MAbs(4E2, 4G8, 5H6, 1F8, 2C6, 5H5, and 3A6) had specificity of nucleocapsid protein and no neutralizing activity. All MAbs reacted with different strains of TGEV, but none of the MAbs was reactive with porcine enteropathogenic viruses such as rotavirus, epidemic diarrhea virus and enterovirus by fluorescence antibody(FA) test.

• Clinical and Experimental Pediatrics
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• v.55 no.3
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• pp.77-82
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• 2012

Human astrovirus (HAstV) is a major cause of acute diarrhea among children, resulting in outbreaks of diarrhea and occasionally hospitalization. Improved surveillance and application of sensitive molecular diagnostics have further defined the impact of HAstV infections in children. These studies have shown that HAstV infections are clinically milder (diarrhea, vomiting, fever) than infections with other enteric agents. Among the 8 serotypes of HAstV identified, serotype 1 is the predominant strain worldwide. In addition to serotype 1, the detection rate of HAstV types 2 to 8 has increased by using newly developed assays. HAstV is less common compared with other major gastroenteritis viruses, including norovirus and rotavirus; however, it is a potentially important viral etiological agent with a significant role in acute gastroenteritis. A better understanding of the molecular epidemiology and characteristics of HAstV strains may be valuable to develop specific prevention strategies.

• Pediatric Infection and Vaccine
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• v.7 no.1
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• pp.113-119
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• 2000

Purpose : Rotavirus is a most common etiologic agent of pediatric gastroenteritis. The standard method to diagnose rotavirus infection was the detection of viral particles in specimens through electron microscopy. But it was complex. Enzyme immunoassay and latex agglutinin are preferred because they are relatively handy, inexpensive and take a short time, in comparison with electron microscopy. However, several reports have shown that the use of ELISA to diagnose rotavirus infection in neonates can result in false positive reactions. The main purpose of this study is to compare ELISA and RT-PCR in the diagnosis of neonatal rotavirus infection. Methods : Data presented in this study were obtained form 123 newborn babies in the nursery of the Fatima Hospital, Masan, Korea, form Jury to December, 1997. We obtained two samples of stool from each of the newborn babies and then performed the Rotazyme test and the RT-PCR. In the Rotazyme test, the results were interpreted according to visual findings. The samples were used for the RT-PCR test after at stock $-30^{\circ}C$ to identify rotavirus group A. The result of the two tests were compared. Results : The informations are divided into 73 males and females. Out of the total informations 15 were transferred from other hospitals. Their average gestational age was $38.5{\pm}1.6$ weeks. The average birth weight was $3134.8{\pm}539gm$. In the Rotazyme test, 75 samples turned out to be positive. Out of them, 55 samples(75.3%) were positive and 18 samples(24.7%) were negative in the RT-PCR. On the other hand, in the Rotazyme test, 50 samples turned out be negative. Out of them, 27 samples(54%) were positive and 23 samples(46%) were negative in the RT-PCR. Conclusion : Rotavirus infection in uncommon in neonates. The diagnosis based on visual findings using Rotazyme test has a disadvantage in the sense that it can result in false positive reactions and false negative reactions in the diagnosis of neonatal rotavirus infection.

• Pediatric Infection and Vaccine
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• v.22 no.2
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• pp.81-90
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• 2015

Purpose: Group A rotavirus (RV) is most common etiologic agent of acute gastroenteritis (AGE) in children worldwide. Recently, vaccination has been introduced in several countries to reduce the disease burden caused by RV infections, but continuous surveillance of RV strains is necessary to detect the emergence of potential variants induced by vaccine-immune pressure. This study aimed to investigate the changing pattern of RV genotypes in children with AGE, following the introduction of vaccination in Korea. Methods: Genotyping of RVs by RT-PCR on the basis of VP7 and VP4 gene segment sequence was carried out on 201 rotavirus-positive stool samples, from children hospitalized with AGE between August 2009 and June 2013. We have directly sequenced PCR products and analyzed the phylogenetic tree. Results: The most prevalent G genotype was G9 (33.3%), followed by G1 (22.4%), G3 (15.9%), G2 (6.0%), G4 (3.0%), G10 (1.5%), and mixed G-type (15.4%), with some nontypeable cases (2.5%). The detected P genotypes were P[4] (45.3%), P[8] (43.8%), mixed P-type (10.4 %), and P[2] (0.5%). The G9P[4] genotype was predominantly observed in hospitalized cases in Seoul in 2010/2011, however G1P[8] has been re-emerged as the predominant genotype in the following season (P =0.004). Conclusions: It seems that the periodic fluctuation in predominance of the G1, G3, and G9 strains occurred in Korea during 2009-2013, following the introduction of RV vaccination.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.9 no.1
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• pp.1-13
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• 2006

Purpose: Acute gastroenteritis in children is one of the frequently encountered diseases with relatively high admission rate. The aim of this study is to determine the isolation trends of common and emerging pathogens in acute gastroenteritis in children over a 12-month period in a community hospital. Methods: The study group included the children who were hospitalized to Seoul National University Boramae Hospital from April, 2003 to March, 2004 or visited outpatient clinic from April, 2003 to July, 2003 with presenting features of acute gastroenteritis. Stool specimens were obtained within 2 days after the visit and examined for the following pathogens: rotavirus, adenovirus, Salmonella, Shigella, Vibrio, pathogenic Escherichia coli (E.coli), Campylobacter and Yersinia species. Viral study was done with commercial kits for antigen detection. Identification of the bacterial pathogens was done by culture using selective media. For pathogenic E.coli, polymerase chain reaction (PCR) was done with the target genes related to the pathogenecity of enterotoxigenic E.coli (ETEC), enteropathogenic E.coli (EPEC) and enterohemorrhagic E.coli (EHEC). Results: The 130 hospitalized children and 28 outpatients were included in this study. The majority of children (>93%) were less than 6 years. Pathogens were isolated in 47% of inpatients and 43% of outpatients, respectively. Rotavirus was the most frequently identified pathogen, accounting for 42.3% of inpatients and 29.6% of outpatients. Nontyphoidal salmonella is the most commonly isolated bacterial pathogen (3.9%) in hospitalized children. Pathogenic E.coli (EPEC, ETEC) was detected in 2.1% (2/97) of inpatients and 25% (3/12) of outpatients. EHEC, adenovirus, Campylobacter, Yersinia and Shigella species were not detected in this study. Conclusion: Rotavirus is the most common enteropathogen in children with acute gastroenteritis. Nontyphoidal salmonella and pathogenic E.coli are important bacterial pathogens. Campylobacter species may not be commonly detected organism in hospitalized children with acute diarrhea.

• Journal of Microbiology and Biotechnology
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• v.12 no.3
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• pp.463-469
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• 2002

Rotaviruses are the world-wide leading causative agents of severe dehydrating gastroenteritis in young children and animals. The outer capsid glycoprotein VP7 and inner capsid glycoprotein VP6 of rotaviruses are highly antigenic and immunogenic. An SFV-based expression system has recently emerged as a useful tool for heterologous protein production in mammalian cells, exhibiting a much more efficient performance compared to other gene expression systems. Accordingly, the current study adopted an SFV-based expression system to express the VP7 of a group A human rotavirus from a Korean isolate, and the VP6 of a group B bovine rotavirus from a Korean isolate, in mammalian cells. The genes of the VP6 and VP7 were inserted into the SFV expression vector pSFV-1. The RNA was transcribed in vitro from pSFV-VP6 and pSFV-VP7 using SP6 polymerase. Each RNA was then electroporated into BHK-21 cells along with pSFV-helper RNA containing the structural protein gene without the packaging signal. The expression of VP6 and VP7 in the cytoplasm was then detected by immunocytochemistry. The recombinant virus was harvested by ultracentrifugation and examined under electron microscopy. After infecting BHK-21 cells with the defective viruses, the expressed proteins were separated by SDS-PAGE and analyzed by a Western blot. The results indicate that an SFV-based expression system fur the VP6 and VP7 of rotaviruses is an efficient tool for developing a diagnostic kit and/or preventive vaccine.

• Journal of Microbiology and Biotechnology
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• v.8 no.4
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• pp.369-377
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• 1998

Rotavirus is a major cause of severe gastroenteritis in young children and animals throughout the world. The VP7 of rotavirus is thought to induce the synthesis of neutralizing antibodies and to be responsible for determining viral serotypes. The cDNA coding for the VP7 capsid protein of human rotavirus, obtained from Korean patients (HRV-Y14), was cloned and its nucleotide sequence was determined. Comparative analysis of the nucleotide sequences between VP7 of Y14 and that of other foreign isolates showed $92.7~95.2\%$ homology to G1 serotypes (RV-4, KU, K8, WA), $74.2\%$ homolgy to G2 serotype HU-5, $76.4\%$ homology to G3 serotype SA-11, and $77.6\%$ homology to G4 serotype A01321. These data suggest that HRV-Y14 can be classified as a G1 serotype. cDNA coding for VP7 of HRV-YI4 was subcloned into the baculovirus vector and the VP7 glycoprotein was expressed in insect cells. The expressed proteins in Sf9 cell extract and tissue culture fluid were separated on SDS-PAGE, and Western blot analysis with monoclonal antibody raised against the synthetic peptide containing 21 amino acids within the VP7 conserved region was performed. The molecular weight of recombinant VP7 was estimated to be 36 kDa which is about the same size as the native VP7. Addition of tunicamycin in the culture media caused a reduction of the molecular weight of the recombinant VP7 indicating that the expressed protein was glycosylated.

• Pediatric Infection and Vaccine
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• v.15 no.2
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• pp.121-128
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• 2008

Purpose : The seasonality of influenza virus and rotavirus are well recognized in winter and so viral surveillance and laboratory-based diagnostics are important to guide the timing of prophylaxis and other interventions. Yet the seasonality of these two viruses are changing in Korea. We evaluated the prevalence and clinical features of influenza virus and rotavirus. Methods : From September 2001 to August 2005, nasopharyngeal aspirates were cultured from the hospitalized patients with lower respiratory infections and the stools from hospitalized patients with gastroenteritis were tested for rotavirus. We retrospectively analysed the medical records. Results : During the study period, respiratory virus was isolated in 578 (18.5%) out of 3,121 patients. Influenza virus was isolated in 143 cases. The seasonal distribution of influenza infection was from December to June of the next year. The ratio of males to females was 1.3:1 and the median age was 17 months. The most common diagnosis of influenza infection was bronchiolitis. Fever and cough were present in 94.4% and 83.9% of the patients, respectively. During the same period, 3,850 patients were admitted for gastroenteritis and 1,047 (27%) patients were positive for rotavirus. Rotavirus was prevailed from December to June of the next year and it presented in year-round. The ratio of males to females was 1.1:1 and the median age was 16 months. Diarrhea and vomiting were the most common symptoms. Conclusion : The recent peak prevalence of influenza virus and rotavirus in Korea was in winter and the late spring, respectively. So we need to expand surveillance and carefully consider the correct period to vaccinate people.

• Korean Journal of Veterinary Service
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• v.43 no.4
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• pp.237-244
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• 2020

Porcine transmissible gastroenteritis (TGE) has been a significant cause of economic losses in pig farming industry since 1950s. Although transmissible gastroenteritis virus (TGEV) has declined in recent years, it should not be excluded because of its characteristics; the frequency of gene mutation, the mortality in piglets, and the possibility for sudden incidence. Therefore, the herd-level monitoring of the virus is important to prevent further circulation of TGE. The aim of this study is to develop a large-scale sandwich enzyme-linked immunosorbent assay (ELISA) with high specificity to rapidly detect TGEV in feces by using monoclonal antibodies (Mabs). The TGEV specific Mabs were produced in hybridoma cells. Among the Mabs belonged to the IgG class developed by this study, the final selected 8H6, 1B7, 4G3, and 1F8 were identified to have the neutralization ability against TGEV. The sandwich ELISA was established using 8H6 as a reporter antibody and 1B7 and the reported 5C8 as a capture antibody. The developed sandwich ELISA was able to distinguish TGEV from other pathogenic diarrheal agents (porcine rotavirus, porcine reovirus, porcine epidemic diarrhea virus (PEDV), E. coli, and C. perfringens) in tissue culture as well as fecal samples. And the detection rate of TGEV in feces was 80% compared with RT-PCR. The results suggested that the developed sandwich ELISA may be useful in the herd-level monitoring for effective preventive measures due to the early diagnosis of TGEV using a large amount of samples.

• Microbiology and Biotechnology Letters
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• v.47 no.2
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• pp.317-322
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• 2019

Gastroenteritis with diarrhea is one of the most infectious diseases in the world following respiratory infections. Notably, diarrhea-causing viruses (DVs) cause more than 70% of such cases. In this study, 3,065 stool specimens from patients with diarrhea (median age, 1.1 years; range, 0.0-91.1 years), who were admitted to the DanKook University Hospital, were examined using multiplex reverse transcription PCR (mRT-PCR). The target viruses were astrovirus (AstV), enteric adenovirus (EAdV), group A rotavirus (RotV), norovirus GI (NoV-GI), and norovirus GII (NoV-GII). The mRT-PCR results were analyzed based on various factors such as seasonality, age, presence of co-infection, and analyzed trends. The detection rate of the DVs during the study period was found to be 30.8% (n = 943/3,065). When the detection rate was analyzed monthly, the DV detection rate was found to be highest between December to January. Of the detected DVs, NoV-GII was the most common, accounting for 45.5% of the detected viruses (n = 446/980). Notably, 86.5% (n = 848/980) of the pathogens were detected in individuals who were less than 5 years of age. During the study period, NoV-GII and RotV showed alternating trends. In addition, both the number and rate of co-infections increased.