• Journal of Microbiology and Biotechnology
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• 제27권4호
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• pp.816-824
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• 2017

Human noroviruses are widespread and contagious viruses causing nonbacterial gastroenteritis. Real-time reverse transcription quantitative PCR (real-time RT-qPCR) is currently the gold standard for the sensitive and accurate detection of these pathogens and serves as a critical tool in outbreak prevention and control. Different surveillance teams, however, may use different assays, and variability in specimen conditions may lead to disagreement in results. Furthermore, the norovirus genome is highly variable and continuously evolving. These issues necessitate the re-examination of the real-time RT-qPCR's robustness in the context of accurate detection as well as the investigation of practical strategies to enhance assay performance. Four widely referenced real-time RT-qPCR assays (Assays A-D) were simultaneously performed to evaluate characteristics such as PCR efficiency, detection limit, and sensitivity and specificity with RT-PCR, and to assess the most accurate method for detecting norovirus genogroups I and II. Overall, Assay D was evaluated to be the most precise and accurate assay in this study. A ZEN internal quencher, which decreases nonspecific fluorescence during the PCR, was added to Assay D's probe, which further improved the assay performance. This study compared several detection assays for noroviruses, and an improvement strategy based on such comparisons provided useful characterizations of a highly optimized real-time RT-qPCR assay for norovirus detection.

• 대한임상검사과학회지
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• 제51권1호
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• pp.64-70
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• 2019

Dirofilaria immitis (D. immitis)는 개의 심폐사상충증을 일으키는 선형사상충이다. 이 기생충에 감염된 개는 감염 후기 단계에서 하나 이상의 증상과 혈관 주위의 염증을 동반한 심화된 심장 질환을 보인다. 감염 초기단계에 특이적이고 효율적으로 D. immitis를 검출하기 위해서, 선행연구에서 밝혀낸 D. immitis의 cytochrome c oxidase subunit I (COI)와 개의 glyceraldehyde-3-phosphate dehydrogenase (GAPDH)를 검출하는 특이적인 프라이머와 프로브를 이용하여 이중 TaqMan qPCR 방법을 개발했다. 양성 대조군인 플라스미드 유전자는 TA-cloning vector와 D. immitis의 COI나 개의 GAPDH로 구성되었다. 단일과 이중 TaqMan qPCR 방법은 특이적인 프라이머와 프로브, 그리고 게놈 유전자나 플라스미드 유전자로 수행했다. 프라이머의 농도를 최적한 후, 본 연구에서 개발한 이중 반응은 D. immitis의 COI와 개의 GAPDH를 동일 시료에서 동시에 검출했다. 검출 한계는 단일과 이중 방법 모두 25 copies였고, 두 방법 모두 좋은 선형성과 높은 민감도, 그리고 우수한 PCR 효율을 보여주었다. 병원체를 검출하기 위한 이중 방법은 단일 방법에 비해 비용과 노동력, 시간이 적게 든다. 따라서 이중 TaqMan qPCR 방법의 개발은 많은 수의 시료로부터 동시에 효율적으로 D. immitis 검출과 정량이 가능하게 할 것이다.

• 한국동물위생학회지
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• 제46권2호
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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.

• Parasites, Hosts and Diseases
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• 제51권5호
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• pp.573-577
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• 2013

A loop-mediated isothermal amplification (LAMP) assay allows rapid diagnosis of Toxoplasma gondii infection. In the present study, the LAMP assay was evaluated using blood from both naturally and experimentally infected pigs. The sensitivity of the LAMP assay was compared with that of Q-PCR. Both assays detected T. gondii in the blood of experimentally infected pigs, with 100% agreement. In infected blood samples, the parasite was detected as early as 2 days post-infection and reached a peak in 3-5 days. In 216 field serum samples, the detection rates of LAMP and Q-PCR assays were 6.9% and 7.8%, respectively. This result indicates that the sensitivity of the LAMP assay was slightly lower than that of the Q-PCR assay. However, the LAMP may be an attractive diagnostic method in conditions where sophisticated and expensive equipment is unavailable. This assay could be a powerful supplement to current diagnostic methods.

• Genomics & Informatics
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• 제21권2호
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• pp.24.1-24.7
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• 2023

Assays of clinical diagnosis and species identification using molecular markers are performed according to a quantitative method in consideration of sensitivity, cost, speed, convenience, and specificity. However, typical polymerase chain reaction (PCR) assay is difficult to quantify and have various limitations. In addition, to perform quantitative analysis with the quantitative real-time PCR (qRT-PCR) equipment, a standard curve or normalization using reference genes is essential. Within the last a decade, previous studies have reported that the digital PCR (dPCR) assay, a third-generation PCR, can be applied in various fields by overcoming the shortcomings of typical PCR and qRT-PCR assays. We selected Stilla Naica System (Stilla Technologies), Droplet Digital PCR Technology (Bio-Rad), and Lab on an Array Digital Real-Time PCR analyzer system (OPTOLANE) for comparative analysis among the various droplet digital PCR platforms currently in use commercially. Our previous study discovered a molecular marker that can distinguish Hanwoo species (Korean native cattle) using Hanwoo-specific genomic structural variation. Here, we report the pros and cons of the operation of each dPCR platform from various perspectives using this species identification marker. In conclusion, we hope that this study will help researchers to select suitable dPCR platforms according to their purpose and resources.

• 한국동물위생학회지
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• 제45권1호
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• pp.1-11
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• 2022

A novel porcine circovirus 4 (PCV4) was recently identified in Chinese and Korean pig herds. Although several conventional polymerase chain reaction (cPCR) and real-time PCR (qPCR) assays were used for PCV4 detection, more sensitive and reliable qPCR assay is needed that can simultaneously detect PCV4 and internal positive control (IPC) to avoid false-negative results. In the present study, a duplex qPCR (dqPCR) assay was developed using primers/probe sets targeting the PCV4 Cap gene and pig (glyceraldehyde-3-phosphate dehydrogenase) GAPDH gene as an IPC. The developed dqPCR assay was specifically detected PCV4 but not other PCVs and porcine pathogens, indicating that the newly designed primers/probe set is specific to the PCV4 Cap gene. Furthermore, GAPDH was stably amplified by the dqPCR in all tested viral and clinical samples containing pig cellular materials, indicating the high reliability of the dqPCR assay. The limit of detection of the assay 5 copies of the target PCV4 genes, but the sensitivity of the assay was higher than that of the previously described assays. The assay demonstrated high repeatability and reproducibility, with coefficients of intra-assay and inter-assay variation of less than 1.0%. Clinical evaluation using 102 diseased pig samples from 18 pig farms showed that PCV4 circulated in the Korean pig population. The detection rate of PCV4 obtained using the newly developed dqPCR was 26.5% (27/102), which was higher than that obtained using the previously described cPCR and TaqMan probe-based qPCR and similar to that obtained using the previously described SYBR Green-based qPCR. The dqPCR assay with IPC is highly specific, sensitive, and reliable for detecting PCV4 from clinical samples, and it will be useful for etiological diagnosis, epidemiological study, and control of the PCV4 infections.

• 한국환경농학회지
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• 제30권4호
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• pp.367-376
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• 2011

논 토양의 미생물 생태 다양성을 조사하기 위한 효과적인 방법으로 qRT-PCR을 적용하고자 본 연구를 수행하였다. 논 토양 미생물의 gDNA를 분리하기 위하여 Mo Bio kit를 사용한 효과적이고 안정적인 gDNA 분리 방법을 확립하였다. 논 토양 미생물 다양성을 qRT-PCR로 검출하기 위하여 bacteria를 세분한 ${\alpha}$-Proteobacteria, ${\beta}$-Proteobacteria, Actinobacteria, Bacteroidetes, Firmicutes 다섯 가지 문과 전체 bacteria, 전체 fungi를 구분할 수 있는 특이 primer set을 선정하여 다양한 조건의 시험을 통하여 최종 조건을 확립하였으며 재현성 실험을 통하여 방법의 유의성을 검증하였다.

• 대한의생명과학회지
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• 제22권3호
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• pp.83-97
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• 2016

The measurement of viral load in HIV-1 infected patients is essential for the establishment of a therapeutic strategy. Several commercial assays have shown shortcomings in quantifying rare genotypes of HIV-1 such as minor groups of N and O. In this study, the HIV-1 RT-qPCR assay was developed. The primers and probe of HIV-1 were designed to target the pol gene and to increase the detection efficiency of various subtypes including group N and O. The HIV-1 quantitative RT-qPCR assay was assessed for its analytical performance and clinical evaluation. The LoD was determined to 33.9 IU/ml. The LoD of several subtypes including A, C, D, CRF_01AE, F, CRF_02AG, G and H, were determined to less than 40 IU/ml. The HIV-1 quantitative RT-qPCR assay was evaluated using the China National Reference Panel of HIV-1 RNA to determine the analytical performance. The results were all within the acceptable range. The clinical evaluation was performed at Hunan CDC in China. The clinical evaluation results were compared with those of the China domestic commercial kit. A significant correlation (fresh samples; $R^2=0.84$, P<0.001, frozen samples; $R^2=0.76$, P<0.001) between the two systems was observed for 64 fresh samples and 76 frozen samples with viral loads, and the Bland-Altman plot showed good agreement (98.4%, 96.1%, respectively). In conclusion, the HIV-1 quantitative RT-qPCR assay had comparable analytical performance with several commercial kits. The study provides basic data for the research of HIV-1 diagnosis and the development of P < HIV-1 molecular diagnostic assay.

• 대한의생명과학회지
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• 제25권4호
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• pp.407-416
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• 2019

Recent years have seen an increase in the incidence of candidiasis caused by non-albicans Candida (NAC) species. In fact, C. glabrata is now second only to C. albicans as the most common cause of invasive candidiasis. Therefore, the rapid genotyping specifically for C. glabrata is required for early diagnosis and treatment of candidiasis. A number of genotyping assays have been developed to differentiate C. glabrata sequence types (STs), but they have several limitations. In the previous study, multi-locus sequence typing (MLST) has performed with a total of 101 C. glabrata clinical isolates to analyze the prevalent C. glabrata STs in Korea. A total of 11 different C. glabrata STs were identified and, among them, ST-138 was the most commonly classified. Thus, a novel probe-based quantitative PCR (qPCR) assay was developed and evaluated for rapid and accurate identification of the predominant C. glabrata ST-138 in Korea. Two primer pairs and hybridization probe sets were designed for the amplification of internal transcribed spacer 1 (ITS1) region and TRP1 gene. Analytical sensitivity of the probe-based qPCR assay was 100 ng to 10 pg and 100 ng to 100 pg (per 1 μL), which target ITS1 region and TRP1 gene, respectively. This assay did not react with any other Candida species and bacteria except C. glabrata. Of the 101 clinical isolates, 99 cases (98%) were concordant with MLST results. This novel probe-based qPCR assay proved to be rapid, sensitive, highly specific, reproducible, and cost-effective than other genotyping assay for C. glabrata ST-138 identification.

• 한국임상수의학회지
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• 제27권5호
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• pp.508-513
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• 2010

싸이토카인은 염증 및 면역 반응의 평가에 있어서 매우 중요한 요소이다. 따라서 이들의 mRNA 수준을 정량하고 평가하는 것은 염증 및 면역 반응을 평가하는데 있어서 그 민감도가 매우 높은 방법으로 알려져 있다. 본 연구의 목적은 SYBR green dye를 이용하여 개의 싸이토카인 mRNA를 정량적 실시간 역전사 중합효소연쇄반응(real-time reverse transcriptase PCR; qRT-PCR)으로 분석을 할 수 있도록 함에 있다고 할 수 있다. 제작된 시발체(primer)의 최적화된 붙임 온도(annealing temperature; $T_a$)는 인터루킨(interleukin; IL)-$1{\beta}$, IL-6, IL-10이 각각 $62^{\circ}C$, glyceraldehyde 3-phosphate dehydrogenase (GAPDH)와 tumor necrosis factor (TNF)-${\alpha}$가 $60^{\circ}C$ 그리고 high mobility group box 1 (HMGB1)이 $58^{\circ}C$였다. 표준 정량 곡선을 이용하여 측정한 시발체의 효율성은 97.1%에서 102.%로 매우 높았고, 2차 구조물(secondary structure)과 시발체-이합체 형성(primer-dimer formation)은 융해곡선(melt-curve)분석과 전기영동을 통해 확인하였다. 이렇게 정립된 qRT-PCR 분석법은 민감도와 특이도가 매우 높은 개 싸이토카인 유전자 정량법으로 활용될 수 있을 것이다.