• Clinical and Experimental Pediatrics
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• v.61 no.6
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• pp.180-186
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• 2018

Purpose: Despite the availability of molecular methods, identification of the causative virus in children with acute respiratory infections (ARIs) has proven difficult as the same viruses are often detected in asymptomatic children. Methods: Multiplex reverse transcription polymerase chain reaction assays were performed to detect 15 common respiratory viruses in children under 15 years of age who were hospitalized with ARI between January 2013 and December 2015. Viral epidemiology and clinical profiles of single virus infections were evaluated. Results: Of 3,505 patients, viruses were identified in 2,424 (69.1%), with the assay revealing a single virus in 1,747 cases (49.8%). While major pathogens in single virus-positive cases differed according to age, human rhinovirus (hRV) was common in patients of all ages. Respiratory syncytial virus (RSV), influenza virus (IF), and human metapneumovirus (hMPV) were found to be seasonal pathogens, appearing from fall through winter and spring, whereas hRV and adenovirus (AdV) were detected in every season. Patients with ARIs caused by RSV and hRV were frequently afebrile and more commonly had wheezing compared with patients with other viral ARIs. Neutrophil-dominant inflammation was observed in ARIs caused by IF, AdV, and hRV, whereas lymphocyte-dominant inflammation was observed with RSV A, parainfluenza virus, and hMPV. Monocytosis was common with RSV and AdV, whereas eosinophilia was observed with hRV. Conclusion: In combination with viral identification, recognition of virus-specific clinical and laboratory patterns will expand our understanding of the epidemiology of viral ARIs and help us to establish more efficient therapeutic and preventive strategies.

• Neonatal Medicine
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• v.16 no.2
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• pp.182-189
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• 2009

Purpose: Recently, it is easy to find the causal virus of acute respiratory infections using multiplex RT-PCR. The aim of this study is to show the distribution of respiratory viruses and to define the characteristics of respiratory syncytial virus (RSV) infections compared to other respiratory viral infections. Methods: This was a prospective observational study conducted in the NICU. The infants with acute respiratory infections were performed multiplex RT-PCR using nasal swabs. The demographics, initial symptoms, course of illness, and laboratory and imaging findings were recorded. The infants were divided into RSV and No RSV groups. Results: Twenty-three infants (50%) were in the RSV group. Rhinovirus was the second most common virus. Coinfections with two viruses accounted for 6.5% of respiratory infections. The number of preterm infants, exposure to cigarette smoke and having siblings were not different between the two groups. Infections in the postnatal care center were more common in the RSV group than the No RSV group (60.9% vs. 21.7%, P=.007). Dyspnea (34.8% vs. 8.7%, P=.032) and pneumonia (73.9% vs. 43.5%, P=.036) were more common in the RSV group. The RSV group frequently needed oxygen (52.5% vs. 13.0%, P=.005) and received nothing by mouth (43.5% vs. 13.0%, P=.022). The incidence of right upper consolidation was higher in RSV group (56.5% vs. 8.7%, P=.001). Conclusion: This study showed that other viruses than RSV can induce respiratory infections in neonates and young infants born prematurely. RSV infections have a more severe course of illness than other respiratory viruses. We have to be careful of prevention even for healthy neonates especially in crowed situations, such as the postnatal care center.

• Journal of Microbiology and Biotechnology
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• v.23 no.2
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• pp.267-273
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• 2013

Multiplex RT-PCR was used to detect respiratory viruses in 5,318 clinical samples referred to the laboratory of a tertiary teaching hospital from December 2006 to November 2010. The acquired data were analyzed with respect to types, ratio, and co-infection trends of infected respiratory viruses. Trends in respiratory viral infection according to sex, age, and period of infection were also analyzed. Of the 5,318 submitted clinical samples, 3,350 (63.0%) specimens were positive for at least one respiratory virus. The infection rates were 15.8% for human rhinovirus, 14.4% for human respiratory syncytial virus A, 9.7% for human respiratory syncytial virus B, 10.1% for human adenovirus, 5.4% for influenza A virus, 1.7% for influenza B virus, 4.7% for human metapneumovirus, 2.3% for human coronavirus OC43, 1.9% for human coronavirus 229E/NL63, 3.7% for human parainfluenza virus (HPIV)-1, 1.1% for HPIV-2, and 5.3% for HPIV-3. The co-infection analysis showed 17.1% of double infections, 1.8% of triple infections. The median age of virus-positive patients was 1.3 years old, and the 91.5% of virus-positive patients were under 10 years old. Human respiratory syncytial virus was the most common virus in children < 5 years of age and the influenza A virus was most prevalent virus in children over 5 years of age. These results help in elucidating the tendency of respiratory viral infections.

• Proceedings of the Microbiological Society of Korea Conference
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• 2003.05a
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• pp.90-92
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• 2003

• Clinical and Experimental Pediatrics
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• v.52 no.11
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• pp.1241-1248
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• 2009

Purpose:The etiology of Kawasaki disease (KD) is still unknown. Recently, an association between human coronavirus NL63 (HCoV-NL63) and KD was implicated. Hence, we attempted to determine the association between KD and acute respiratory viral infections. Methods:Nasopharyngeal aspirate samples were obtained from 54 patients diagnosed with KD at the Seoul National University (SNU) Children's Hospital and SNU-Bundang Hospital between October 2003 and September 2006. Viral diagnoses of 11 respiratory viruses were made using multiplex reverse transcriptase-polymerase chain reaction (RT-PCR): respiratory syncytial virus (RSV), adenovirus, rhinovirus (RV), parainfluenza viruses (PIVs) 1 and 3, influenza viruses (IFVs) A and B, human metapneumovirus (HMPV), human bocavirus (HBoV), HCoV OC43/229E, and HCoV-NL63. Clinical data were reviewed retrospectively. Results:The median age was 32 months (6 months-10.4 years). Respiratory symptoms were observed in 37 patients (69%). The following respiratory viruses were identified in 12 patients (22%): RV (n=4), PIV-3 (n=2), HBoV (n=2), and adenovirus, RSV, PIV-1, IFV-A, and HCoV-NL63 (n=1). Co-infection with PIV-3 and RV was observed in one patient. Respiratory symptoms were observed in 7 (58.3%) and 30 (71.4%) patients of the virus-positive and virus-negative groups (P>0.05). Response rate to intravenous immunoglobulin administration was 67% (n=8) and 86% (n=36) in the virus- positive and virus-negative groups (P>0.05). Conclusion:Respiratory symptoms were commonly observed in KD patients but the association between respiratory viruses and KD were not found. Large multicenter-based investigations are required to confirm the association between acute respiratory viral infections and KD.

• Korean Journal of Veterinary Service
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• v.37 no.1
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• pp.1-9
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• 2014

Although it has been generally accepted that porcine reproductive and respiratory syndrome virus (PRRSV) induces weak and delayed protective immunity after infection, it is unclear that the same immunological features can be applicable to all PRRS viruses because huge genetic variation exists even among the same genotypes of PRRSV (Type 1 and 2). In the current study, two genetically distinct type 2 PRRSV strains (VR-2332 and JA142) which showed approximately 90% nucleotide homology based on ORF5 sequences were characterized by both in vitro and in vivo assessments to determine the immunological features of the viruses. For in vitro assessment, porcine alveolar macrophages (PAM) were infected with the viruses at $10^{-3}$ multiplicity of infection (MOI) and then supernatants and cells were collected separately at 36 hrs post infection to determine the relative expression levels of IL-$1{\alpha}$, IL-12, TNF-${\alpha}$ and INF-${\alpha}/{\beta}$ by quantitative RT-PCR. In addition, five PRRSV-free pigs were inoculated with either of JA142 or VR2332 for in vivo assessment. Serum samples were collected every week until 6 weeks post challenge. The serum samples were analyzed for the levels of viremia, PRRSV nucleocapsid-specific antibody and virus neutralizing antibody. Based on those assessments, the two viruses showed different patterns of cytokine expression in PAM and immune responses in pigs after infection. These results indicate that genetically distinct PRRSV strains have different immunological features, which might be criteria for virus classification and selection of candidate virus strains for vaccine development in the future.

• Biomedical Science Letters
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• v.29 no.4
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• pp.363-370
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• 2023

Human respiratory viral infections such as COVID-19 are highly contagious, so continuous management of airborne viruses is essential. In particular, indoor air monitoring is necessary because the risk of infection increases in poorly ventilated indoors. However, the current method of detecting airborne viruses requires a lot of time from sample collection to confirmation of results. In this study, we proposed a system that can monitor airborne viruses in real time to solve the deficiency of the present method. Air samples were collected in liquid form through a bio sampler, in which case the virus is present in low concentrations. To detect viruses from low-concentration samples, viral RNA was concentrated and extracted using silica-magnetic beads. RNA binds to silica under certain conditions, and by repeating this binding reaction, bulk samples collected from the air can be concentrated. After concentration and extraction, viral RNA is specifically detected through real-time qPCR (quantitative polymerase chain reaction). In addition, based on liquid handling technology, we have developed an automatic machine that automatically performs the entire testing process and can be easily used even by non-experts. To evaluate the system, we performed air sample collection and automated testing using bacteriophage MS2 as a model virus. As a result, the air-collected samples concentrated by 45 times then initial volume, and the detection sensitivity of PCR also confirmed a corresponding improvement.

• Journal of Life Science
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• v.30 no.9
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• pp.749-762
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• 2020

Influenza A viruses are circulating in a variety of hosts, including humans, pigs, and poultry. Swine influenza virus is a zoonotic pathogen that can be readily transmitted to humans. The influenza viruses of the 2009 H1N1 pandemic were derived from swine influenza viruses, and it has been suggested that the 1957 H2N2 pandemic and the 1968 H3N2 pandemic both originated in pigs. Pigs are regarded as a mixing vessel in the creation of novel influenza viruses since they are readily infected with human and avian influenza viruses. We isolated three novel H1N2 influenza viruses from pigs showing respiratory symptoms on a Korean farm in 2019. These viruses were reassortants, containing PA and NP genes from those of the 2009 H1N1 influenza virus in addition to PB2, PB1, HA, NA, M, and NS genes from those of triple-reassortant swine H3N2 and classical swine H1N2 influenza viruses circulating in Korean pigs. Mice infected with the isolated H1N2 influenza virus lost up to 17% body weight and exhibited interstitial pneumonia involving infiltration of many inflammatory cells. Results suggest that close surveillance to detect emerging influenza viruses in pigs is necessary for the health of both pigs and humans.

• Microbiology and Biotechnology Letters
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• v.49 no.2
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• pp.249-254
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• 2021

The study of the impact of weather on viral respiratory infections enables the assignment of causality to disease outbreaks caused by climatic factors. A better understanding of the seasonal distribution of viruses may facilitate the development of potential treatment approaches and effective preventive strategies for respiratory viral infections. We analyzed the incidence of human mastadenovirus infection using real-time reverse transcription polymerase chain reaction in 9,010 test samples obtained from Cheonan, South Korea, and simultaneously collected the weather data from January 1, 2012, to December 31, 2018. We used the data collected on the infection frequency to detect seasonal patterns of human mastadenovirus prevalence, which were directly compared with local weather data obtained over the same period. Descriptive statistical analysis, frequency analysis, t-test, and binomial logistic regression analysis were performed to examine the relationship between weather, particulate matter, and human mastadenovirus infections. Patients under 10 years of age showed the highest mastadenovirus infection rates (89.78%) at an average monthly temperature of 18.2℃. Moreover, we observed a negative correlation between human mastadenovirus infection and temperature, wind chill, and air pressure. The obtained results indicate that climatic factors affect the rate of human mastadenovirus infection. Therefore, it may be possible to predict the instance when preventive strategies would yield the most effective results.

• Particle and aerosol research
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• v.19 no.1
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• pp.1-11
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• 2023

Respiratory face masks are protective facepieces that are designed to filter inhaled air. They are easy-to-use devices that can protect the wearer against various hazardous particles in the air. Respiratory face masks also prevent the spread of viruses and bacteria-containing droplets that are released from the coughing or sneezing of the infected people. During the COVID-19 pandemic, various types of face masks have circulated on the market. Their ability to filter sub-micron particles, which are the sizes of harmful particulate matter and airborne viruses, needs to be investigated. Their breathability, the easiness of breath through the mask, also needs to be considered. In this study, wwe evaluated the performance of filters used for different types of face masks certified by different standards including Korean (KF94, KF80, KF-AD), USA (N95), and Chinese (KN95) standards. We also tested the filters of nanofiber masks and surgical masks for which there are no standards for filtration test. The N95 mask filters showed the highest quality factor for capturing virus-sized particles. The other types of mask filters have acceptable performance except for nanofiber mask filters whose performance is very low.