• Pediatric Infection and Vaccine
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• v.21 no.3
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• pp.207-213
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• 2014

Purpose: This study aimed to investigate the association between respiratory virus infection and pneumococcal colonization in children. Methods: From May 2009 to June 2010, nasopharyngeal (NP) aspirates were obtained from patients under 18 years old who visited Seoul National University Children's Hospital for respiratory symptoms. NP samples were used to detect respiratory viruses (influenza virus A and B, parainfluenza virus 1, 2 and 3, respiratory syncytial virus A and B, adenovirus, rhinovirus A/B, human metapneumovirus, human coronavirus 229E/NL63 and OC43/HKU1) by RT-PCR and pneumococcus by culture. Results: Median age of the patients was 27 months old. A total of 1,367 NP aspirates were tested for respiratory viruses and pneumococcus. Pneumococcus was isolated from 228 (16.7%) of samples and respiratory viruses were detected from 731 (53.5%). Common viruses were rhinovirus (18.4%), respiratory syncytial virus (RSV) A (10.6%), adenovirus (6.9%), influenza virus A (6.8%). Pneumococcal isolation rate was significantly higher in the cases of positive virus detection than negative detection [21.3% (156/731) vs. 11.3% (72/636), P <0.001]. For individual viruses, pneumococcal isolation rate was positively associated with detection of influenza virus A [24.7% (23/93) vs 16.1% (205/1274), P=0.001], RSV A [28.3% (41/145) vs 15.3% (187/1222), P=0.001], RSV B [31.3% (10/32) vs 16.3% (218/1335), P=0.042], rhinovirus A/B [22.6% (57/252) vs 15.3% (171/1115), P=0.010]. Conclusion: The study revealed that pneumococcal isolation from NP aspirates is related with respiratory virus detection. The result of this study could be used to investigate how respiratory viruses and pneumococcus cause clinical diseases.

• Korean Journal of Veterinary Service
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• v.45 no.1
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• pp.31-38
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• 2022

Swine influenza (SI) is an important respiratory disease in pigs and epidemic worldwide, which is caused by influenza A virus (IAV) belonging to the family of Orthomyxoviridae. As seen again in the 2009 swine-origin influenza A H1N1 pandemic, pigs are known to be susceptible to swine, avian, and human IAVs, and can serve as a 'mixing vessel' for the generation of novel IAV variants. To this end, the emergence of swine influenza viruses must be kept under close surveillance. Herein, we report the isolation and phylogenetic study of a swine IAV, A/swine/Korea/21810/2021 (sw21810, H3N2 subtype). BLASTN sequence analysis of 8 gene segments of the isolated virus revealed a high degree of nucleotide similarity (94.76 to 100%) to porcine strains circulating in Korea and the United States. Out of 8 genome segments, the HA gene was closely related to that of isolates from cluster I. Additionally, the NA gene of the isolate belonged to a Korean Swine H1N1 origin, and the PB2, PB1, NP and NS genes of the isolate were grouped into that of the Triple reassortant swine H3N2 origin virus. The PA and M genes of the isolate belonged to 2009 Pandemic H1N1 lineage. Human infection with mutants was most common through contact with infected pigs. Our results suggest the need for periodic close monitoring of this novel swine H3N2 influenza virus from a public health perspective.

• IMMUNE NETWORK
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• v.16 no.5
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• pp.311-315
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• 2016

A pandemic influenza A (H1N1) virus strain was isolated from a pig farm in Korea in December 2009. The strain was propagated in and isolated from both the Madin-Darby canine kidney cell line and embryonated eggs. The partial and complete sequences of the strain were identical to those of A/California/04/2009, with >99% sequence similarity in the HA, NA, M, NS, NP, PA, PB1, and PB2 genes. The isolated strain was inactivated and used to prepare a swine influenza vaccine. This trial vaccine, containing the new isolate that has high sequence similarity with the pandemic influenza A (H1N1) virus, resulted in seroconversion in Guinea pigs and piglets. This strain could therefore be a potential vaccine candidate for swine influenza control in commercial farms.

• Journal of Life Science
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• v.33 no.8
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• pp.605-611
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• 2023

Recently, sporadic cases of human infection by genetic reassortants of H7Nx influenza A viruses have been reported; such viruses have also been continuously isolated from avian species. In this study, A/wild bird/South Korea/sw-anu/2023, a novel reassortant of the H7N1 avian influenza virus, was analyzed using full-genome sequencing and molecular characterization. Phylogenetic analysis showed that A/wild bird/South Korea/sw-anu/2023 belonged to the Eurasian lineage of H7Nx viruses. The polymerase basic (PB)2, PB1, polymerase acidic (PA), and nucleoprotein (NP) genes of these viruses were found to be closely related to those of avian influenza viruses isolated from wild birds, while the hemagglutinin (HA), neuraminidase (NA), matrix (M), and nonstructural (NS) genes were similar to those of avian influenza viruses isolated from domestic ducks. In addition, A/wild bird/South Korea/sw-anu/2023 also had a high binding preference for avian-specific glycans in the solid-phase direct binding assay. These results suggest the presence of a new generation of H7N1 avian influenza viruses in wild birds and highlight the reassortment of avian influenza viruses found along the East Asian-Australasian flyway. Overall, H7Nx viruses circulate worldwide, and mutated H7N1 avian viruses may infect humans, which emphasizes the requirement for continued surveillance of the H7N1 avian influenza virus in wild birds and poultry.

• Bulletin of the Korean Chemical Society
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• v.35 no.4
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• pp.1082-1086
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• 2014

A multi-channel microchip electrophoresis (MCME) method with parallel laser-induced fluorescence (LIF) detection was developed for rapid screening of H1N1 virus. The hemagglutinin (HA) and nucleocapsid protein (NP) gene of H1N1 virus were amplified using polymerase chain reaction (PCR). The amplified PCR products of the H1N1 virus DNA (HA, 116 bp and NP, 195 bp) were simultaneously detected within 25 s in three parallel channels using an expanded laser beam and a charge-coupled device camera. The parallel separations were demonstrated using a sieving gel matrix of 0.3% poly(ethylene oxide) ($M_r$ = 8,000,000) in $1{\times}$ TBE buffer (pH 8.4) with a programmed step electric field strength (PSEFS). The method was ~20 times faster than conventional slab gel electrophoresis, without any loss of resolving power or reproducibility. The proposed MCME/PSEFS assay technique provides a simple and accurate method for fast high-throughput screening of infectious virus DNA molecules under 400 bp.

• Korean Journal of Poultry Science
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• v.46 no.3
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• pp.173-183
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• 2019

Based on their virulence, the avian influenza viruses (AIVs) are classified into two pathotypes: low pathogenic avian influenza (LPAI) virus and highly pathogenic avian influenza (HPAI) virus. Among the 16 HA subtypes of AIV, only the H5 and H7 subtypes are classified as HPAI. Some AIVs, including H5 and H7 viruses, can infect humans directly. Six H7 subtype isolates from wild birds of the H7N7 (n=4) and H7N1 (n=2) subtypes were characterized in this study. Phylogenetic analysis showed that eight viral genes (HA, NA, PB2, PB1, PA, NP, M, and NS) of the H7 isolates clustered in the Eurasian lineage, the genetic diversity of which is indicated by its division into several sublineages. The Korean H7 isolates had two motifs, PEIPKGR and PELPKGR, at the HA cleavage site, which have been associated with LPAI viruses. Six H7 isolates encoded glutamine (Q) and glycine (G) at positions 226 (H3 numbering) and 228 of HA, suggesting avian-type receptor-binding specificity. None of the Korean H7 isolates had the amino acid substitutions E627K in PB2 and I368V in PB1, which are critical for efficient replication in human cells. The Korean H7 isolates showed no deletions in the NA stalk region and in NS. These results suggest that the Korean H7 isolates from wild birds are different from the H7N9 influenza viruses isolated in China in 2013, which are capable of infecting humans.

• The Journal of Korean Society of Virology
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• v.30 no.1
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• pp.39-49
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• 2000

The genome of Hantaan virus, the prototype of the hantavirus genus, is composed of three segmented, single stranded negative sense RNA genome. The 5' and 3' termini of the Hantaan virus RNA genome contain noncoding regions (NCRs) that are highly conserved and complementary to form panhandle structures. There are some reports that these NCRs seems to control gene expression and viral replication in influenza virus and vesicular stomatitis virus. In this study, we examined whether NCRs in Hantaan virus playa role in expression of the viral nucleocapsid protein (Np) and foreign (luciferase) gene. The 5' and/or 3' NCR-deleted mutants were constructed and analysed. The Np expression of 5' NCR-deleted clone was similar to that of the clone containing full S genome. In the case of 3' NCR-deleted clone, it showed 40% reduction. To investigate the role of NCR in foreign gene expression, the clones which are replaced ORF of Hantaan viral Np gene with that of luciferase gene were constructed. The results were similar to those of the experiments using Np gene. These results suggest that 3' NCR is more important than 5' NCR in protein expression. To find out a critical region of 3' NCR in protein expression, several clones with a deleted part of 3' NCR were constructed and analyzed. The deletion of the conserved region in 3' NCR showed $20{\sim}30%$ decrease in Np expression. However there were no change in luciferase activities between clones with or without non-conserved region of 3' NCR. These results suggest that the 3' NCR of Hantaan virus S genome, especially conserved region in 3' NCR, plays an important role in the expression of Hantaan viral Np and foreign genes.

• Journal of Veterinary Science
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• v.21 no.2
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• pp.24.1-24.11
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• 2020

The pandemic of avian influenza viruses (AIVs) in Asia has caused enormous economic loss in poultry industry and human health threat, especially clade 2.3.4.4 H5 and H7 subtypes in recent years. The endemic chicken H6 virus in Taiwan has also brought about human and dog infections. Since wild waterfowls is the major AIV reservoir, it is important to monitor the diversified subtypes in wildfowl flocks in early stage to prevent viral reassortment and transmission. To develop a more efficient and sensitive approach is a key issue in epidemic control. In this study, we integrate multiplex reverse transcription recombinase polymerase amplification (RT-RPA) and capillary electrophoresis (CE) for high-throughput detection and differentiation of AIVs in wild waterfowls in Taiwan. Four viral genes were detected simultaneously, including nucleoprotein (NP) gene of all AIVs, hemagglutinin (HA) gene of clade 2.3.4.4 H5, H6 and H7 subtypes. The detection limit of the developed detection system could achieve as low as one copy number for each of the four viral gene targets. Sixty wild waterfowl field samples were tested and all of the four gene signals were unambiguously identified within 6 h, including the initial sample processing and the final CE data analysis. The results indicated that multiplex RT-RPA combined with CE was an excellent alternative for instant simultaneous AIV detection and subtype differentiation. The high efficiency and sensitivity of the proposed method could greatly assist in wild bird monitoring and epidemic control of poultry.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.273-273
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• 2013

Recently, Point-of-care (POC) testing microdevices enable to do the patient monitoring, drug screening, pathogen detection in the outside of hospital. Immunochromatographic strip (ICS) is one of the diagnostic technologies which are widely applied to POC detection. Relatively low cost, simplicity to use, easy interpretations of the diagnostic results and high stability under any circumstances are representative advantages of POC diagnosis. It would provide colorimetric results more conveniently, if the genetic analysis microsystem incorporates the ICS as a detector part. In this work, we develop a reverse transcriptase-polymerase chain reaction (RT-PCR) microfluidic device integrated with a ROSGENE strip for colorimetric influenza H1N1 virus detection. The integrated RT-PCR- ROSGENE device is consist of four functional units which are a pneumatic micropump for sample loading, 2 ${\mu}L$ volume RT-PCR chamber for target gene amplification, a resistance temperature detector (RTD) electrode for temperature control, and a ROSGENE strip for target gene detection. The device was fabricated by combining four layers: First wafer is for RTD microfabrication, the second wafer is for PCR chamber at the bottom and micropump channel on the top, the third is the monolithic PDMS, and the fourth is the manifold for micropump operation. The RT-PCR was performed with subtype specific forward and reverse primers which were labeled with Texas-red, serving as a fluorescent hapten. A biotin-dUTP was used to insert biotin moieties in the PCR amplicons, during the RT-PCR. The RT-PCR amplicons were loaded in the sample application area, and they were conjugated with Au NP-labeled hapten-antibody. The test band embedded with streptavidins captures the biotin labeled amplicons and we can see violet colorimetric signals if the target gene was amplified with the control line. The off-chip RT-PCR amplicons of the influenza H1N1 virus were analyzed with a ROSGENE strip in comparison with an agarose gel electrophoresis. The intensities of test line was proportional to the template quantity and the detection sensitivity of the strip was better than that of the agarose gel. The test band of the ROSGENE strip could be observed with only 10 copies of a RNA template by the naked eyes. For the on-chip RT-PCR-ROSGENE experiments, a RT-PCR cocktail was injected into the chamber from the inlet reservoir to the waste outlet by the micro-pump actuation. After filling without bubbles inside the chamber, a RT-PCR thermal cycling was executed for 2 hours with all the microvalves closed to isolate the PCR chamber. After thermal cycling, the RT-PCR product was delivered to the attached ROSGENE strip through the outlet reservoir. After dropping 40 ${\mu}L$ of an eluant buffer at the end of the strip, the violet test line was detected as a H1N1 virus indicator, while the negative experiment only revealed a control line and while the positive experiment a control and a test line was appeared.

• Korean Journal of Microbiology
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• v.45 no.3
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• pp.286-290
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• 2009

The transcription of mRNA of avian influenza virus is regulated temporally during infection. Therefore, the measurement of transcript level in host cells should be performed before viral release from host cells because errors can occur in the analysis of the transcript levels if the viruses released from the infected cells re-infect cells. In this study, the timing of viral release was determined by measuring the level of viral RNA from viruses released from H9N2-infected chicken fibroblast cell line UMNSAH/DF-1 by semi-quantitative RT-PCR. The viral genomic RNA was isolated together with mouse total RNA which was added to the collected medium as carrier to monitor the viral RNA recovery and to use its GAPDH as an internal control for normalizing reverse transcription reaction as well as PCR reaction. It was found that viral release of H9N2 in the chicken fibroblast cell line UMNSAH/DF-1 took between 16 and 20 h after infection. We measured all 8 viral mRNA levels. Of the 8 transcripts, 7 species of viral mRNAs (each encoding HA, NA, PB1, PB2, NP, M, NS, respectively) except PA mRNA showed robust amplification, indicating these mRNA can be used as targets for amplification to measure transcript levels. These results altogether suggest that the method in this study can be used for screening antiviral materials against viral RNA polymerase as a therapeutic target.