• Journal of Microbiology and Biotechnology
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• v.22 no.8
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• pp.1165-1169
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• 2012

In April 2009, the H1N1 pandemic influenza virus emerged as a novel influenza virus. The aim of this study was to compare the performances of several molecular assays, including conventional reverse transcription polymerase chain reaction (RT-PCR), two real-time reverse transcription (rRT)-PCRs, and two multiplex RTPCRs. A total of 381 clinical specimens were collected from patients (223 men and 158 women), and both the Seeplex RV7 assay and rRT-PCR were ordered on different specimens within one week after collection. The concordance rate for the two methods was 87% (332/381), and the discrepancy rate was 13% (49/381). The positive rates for the molecular assays studied included 93.1% for the multiplex Seeplex RV7 assay, 93.1% for conventional reverse transcription (cRT)-PCR, 89.7% for the multiplex Seeplex Flu ACE Subtyping assay, 82.8% for protocol B rRT-PCR, and 58.6% for protocol A rRT-PCR. Our results showed that the multiplex Seeplex assays and the cRT-PCR yielded higher detection rates than rRT-PCRs for detecting the influenza A (H1N1) virus. Although the multiplex Seeplex assays had the advantage of simultaneous detection of several viruses, they were time-consuming and troublesome. Our results show that, although rRT-PCR had the advantage, the detection rates of the molecular assays varied depending upon the source of the influenza A (H1N1)v virus. Our findings also suggest that rRT-PCR sometimes detected virus in extremely low abundance and thus required validation of analytical performance and clinical correlation.

• Biomedical Science Letters
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• v.27 no.4
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• pp.283-290
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• 2021

Severe acute respiratory syndrome coronavirus (SARS-CoV2) is a major coronavirus that infects humans with human Coronavirus (HuCoV)-229E, HCoV-OC43, HCoV-HKU1, HCoV-NL63, Severe acute respiratory syndrome coronavirus (SARS-CoV) and Middle east respiratory syndrome coronavirus (MERS-CoV). SARS-CoV2 is currently a global pandemic pathogen. In this study, we developed conventional RT-PCR based diagnostic system for the detection of SARS-CoV2 which is relatively inexpensive but has high stability and a wide range of users. Three conventional RT-PCR primer sets capable of forming specific band sizes by targeting the ORF1ab [232 nucleotide (nt)], E (200 nt) and N (288 nt) genes of SARS-CoV2 were developed, respectively, and it were confirmed to be about 10~100 times higher detection sensitivity than the previously reported methods. In addition, a standard positive control that can generate specific amplicons by reacting with the developed RT-PCR primers and verify the false-positiv from contamination of the laboratory was produced. Therefore, the diagnostic system that uses the RT-PCR method is expected to be used to detect SARS-CoV2.

• The Plant Pathology Journal
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• v.27 no.4
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• pp.385-389
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• 2011

A new reverse transcription loop-mediated isothermal amplification (RT-LAMP) method for the Potato leafroll virus (PLRV) was developed and compared with conventional reverse transcription polymerase chain reaction (RT-PCR) to address its advantages over RTPCR. RT-LAMP primers were designed from the open reading frame 3 (ORF3) sequence of PLRV. The RT-LAMP reactions were conducted without or with a set of loop primers. By real-time monitoring using Turbimeter, the RT-LAMP (with loop primers) detects PLRV in less than 30 min, compared to 120 min of RT-PCR. By adding fluorescent reagent during the reaction, final products of the RT-LAMP were fluorescently visualized under UV light or could be differentiated by naked-eye inspection under normal light. The RT-LAMP was extremely sensitive, about 2000-fold more sensitive than RT-PCR. This study presents great potential of the RT-LAMP for diagnosis and PLRV epidemiology because RT-LAMP method is speedy, sensitive, inexpensive, and convenient.

• Parasites, Hosts and Diseases
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• v.59 no.1
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• pp.77-82
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• 2021

As malaria remains a major health problem worldwide, various diagnostic tests have been developed, including microscopy-based and rapid diagnostic tests. LabChip real-time PCR (LRP) is a small and portable device used to diagnose malaria using lab-on-a-chip technology. This study aimed to evaluate the diagnostic performance of LRP for detecting malaria parasites. Two hundred thirteen patients and 150 healthy individuals were enrolled from May 2009 to October 2015. A diagnostic detectability of LRP for malaria parasites was compared to that of conventional RT-PCR. Sensitivity of LRP for Plasmodium vivax, P. falciparum, P. malariae, and P. ovale was 95.5%, 96.0%, 100%, and 100%, respectively. Specificity of LRP for P. vivax, P. falciparum, P. malariae, and P. ovale was 100%, 99.3%, 100%, and 100%, respectively. Cohen's Kappa coefficients between LRP and CFX96 for detecting P. vivax, P. falciparum, P. malariae, and P. ovale were 0.96, 0.98, 1.00, and 1.00, respectively. Significant difference was not observed between the results of LRP and conventional RT-PCR and microscopic examination. A time required to amplify DNAs using LRP and conventional RT-PCR was 27 min and 86 min, respectively. LRP amplified DNAs 2 times more fast than conventional RT-PCR due to the faster heat transfer. Therefore, LRP could be employed as a useful tool for detecting malaria parasites in clinical laboratories.

• Korean Journal of Veterinary Service
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• v.46 no.2
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• pp.123-135
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• 2023

Feline calicivirus (FCV) is considered the main viral pathogen of feline upper respiratory tract disease (URTD). The frequent mutations of field FCV strains result in the poor diagnostic sensitivity of previously developed molecular diagnostic assays. In this study, a more sensitive real-time reverse transcription-polymerase chain reaction (qRT-PCR) assay was developed for broad detection of currently circulating FCVs and comparatively evaluated the diagnostic performance with previously developed qRT-PCR assay using clinical samples collected from Korean cat populations. The developed qRT-PCR assay specifically amplified the FCV p30 gene with a detection limit of below 10 copies/reaction. The assay showed high repeatability and reproducibility, with coefficients of intra-assay and inter-assay variation of less than 2%. Based on the clinical evaluation using 94 clinical samples obtained from URTD-suspected cats, the detection rate of FCV by the developed qRT-PCR assay was 47.9%, which was higher than that of the previous qRT-PCR assay (43.6%). The prevalence of FCV determined by the new qRT-PCR assay in this study was much higher than those of previous Korean studies determined by conventional RT-PCR assays. Due to the high sensitivity, specificity, and accuracy, the new qRT-PCR assay developed in this study will serve as a promising tool for etiological and epidemiological studies of FCV circulating in Korea. Furthermore, the prevalence data obtained in this study will contribute to expanding knowledge about the epidemiology of FCV in Korea.

• Biomedical Science Letters
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• v.22 no.4
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• pp.215-219
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• 2016

The problems of tuberculosis and its drug resistance are very severe. Therefore, rapid and accurate drug susceptibility assay is required. Recently, there has been an increased understanding of the genetic mechanism of Mycobacterium tuberculosis (MTB) drug resistance as well as advancement of molecular technologies. While many gene mutations correlate well with drug resistance, many genes do not show a strong correlation with drug resistance. For this reason, the current study assessed the utility of rpoB mRNA as a target to detect live mycobacteria. In this study, RT-PCR targeting of rpoB mRNA in BCG treated with rifampin was performed. Conventional RT-PCR and real-time PCR targeting rpoB mRNA as well as 85B mRNA was performed to determine whether these two methods could distinguish between viable and non-viable MTB. The levels of rpoB and 85B mRNA detected by RT- PCR were compared in parallel with colony forming unit counts of BCG that were treated with rifampin for different periods of time. The data suggests that that even though both mRNA levels of rpoB and 85B decreased gradually when rifampin-treatment increased, the rpoB mRNA seemed to represent live bacteria better than 85B mRNA. This study clearly indicates that RT-PCR is a good method to monitor viable cell counts in the liquid culture treated with the anti-tuberculosis drug.

• Korean Journal of Environmental Agriculture
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• v.30 no.4
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• pp.367-376
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• 2011

BACKGROUND: In order to develop effective assessment method for Korean paddy soil microbial community structure, reliable genomic DNA extraction method from paddy soil and quantitative real-time PCR (qRT-PCR) method are needed to establish METHODS AND RESULTS: Out of six conventional soil genomic DNA extraction methods, anion exchange resin purification method was turn to be the most reliable. Various PCR primers for distinguishing five bacterial phylum (${\alpha}$-Proteobacteria, ${\beta}$-Proteobacteria, Actinobacteria, Bacteroidetes, Firmicutes), all bacteria, and all fungi were tested. Various qRT-PCR temperature conditions were also tested by repeating experiment. Finally, both genomic DNA extraction and qRT-PCR methods for paddy soil were well established. CONCLUSION: Quantitative real-time PCR (qRT-PCR) method to assess paddy soil microbial community was established.

• Journal of Microbiology and Biotechnology
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• v.21 no.1
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• pp.100-108
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• 2011

A method for the rapid detection and quantification of Newcastle disease virus (NDV) produced in an animal cell culture-based production system was developed to enhance the speed of the NDV vaccine manufacturing process. A SYBR Green I-based real-time RT-PCR was designed with a conventional, inexpensive RT-PCR kit targeting the F gene of the NDV LaSota strain. The method developed in this study was validated for specificity, accuracy, precision, linearity, limit of detection (LOD), limit of quantification (LOQ), and robustness. The validation results satisfied the predetermined acceptance criteria. The validated method was used to quantify virus samples produced in an animal cell culture-based production system. The method was able to quantify the NDV samples from mid- or late-production phases, but not effective on samples from the early-production phase. For comparison with other quantifiable methods, immunoblotting, plaque assay, and tissue culture infectious dose 50 ($TCID_{50}$) assay were also performed with the NDV samples. The results demonstrated that the real-time RT-PCR method is suitable for the rapid quantification of virus particles produced in an animal cell-culture-based production system irrespective of viral infectivity.

• Genomics & Informatics
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• v.18 no.4
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• pp.40.1-40.8
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• 2020

Avian influenza (AIV) outbreaks can induce fatal human pulmonary infections in addition to economic losses to the poultry industry. In this study, we aimed to develop a rapid and sensitive point-of-care AIV test using loop-mediated isothermal amplification (LAMP) technology. We designed three sets of reverse transcription LAMP (RT-LAMP) primers targeting the matrix (M) and hemagglutinin (HA) genes of the H5 and H9 subtypes. RT-LAMP targeting the universal M gene was designed to screen for the presence of AIV and RT-LAMP assays targeting H5-HA and H9-HA were designed to discriminate between the H5 and H9 subtypes. All three RT-LAMP assays showed specific amplification results without nonspecific reactions. In terms of sensitivity, the detection limits of our RT-LAMP assays were 100 to 1,000 RNA copies per reaction, which were 10 times more sensitive than the detection limits of the reference reverse-transcription polymerase chain reaction (RT-PCR) (1,000 to 10,000 RNA copies per reaction). The reaction time of our RT-LAMP assays was less than 30 min, which was approximately four times quicker than that of conventional RT-PCR. Altogether, these assays successfully detected the existence of AIV and discriminated between the H5 or H9 subtypes with higher sensitivity and less time than the conventional RT-PCR assay.

• The Plant Pathology Journal
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• v.38 no.6
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• pp.665-672
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• 2022

Cymbidium mosaic virus (CymMV) is one of economically important viruses that cause significant losses of orchids in the world. In the present study, a reverse transcription recombinase polymerase amplification (RT-RPA) assay combined with a lateral flow immunostrip (LFI) assay was developed for the detection of CymMV in orchid plants. A pair of primers containing fluorescent probes at each terminus that amplifies highly specifically a part of the coat protein gene of CymMV was determined for RT-RPA assay. The RT-RPA assay involved incubation at an isothermal temperature (39℃) and could be performed rapidly within 30 min. In addition, no cross-reactivity was observed to occur with odontoglossum ringspot virus and cymbidium chlorotic mosaic virus. The RT-RPA with LFI assay (RT-RPA-LFI) for CymMV showed 100 times more sensitivity than conventional reverse transcription polymerase chain reaction (RT-PCR). Furthermore, the RT-PCR-LFI assay demonstrated the simplicity and the rapidity of CymMV detection since the assay did not require any equipment, by comparing results with those of conventional RT-PCR. On-site application of the RT-RPA-LFI assay was validated for the detection of CymMV in field-collected orchids, indicating a simple, rapid, sensitive, and reliable method for detecting CymMV in orchids.