• 한국동물위생학회지
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• 제45권2호
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• pp.87-99
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• 2022

A novel porcine circovirus 4 (PCV4) was recently emerged in Chinese and Korean pig herds, which provided epidemiological situation where three pathogenic PCVs, PCV2, PCV3, and newly emerged PCV4, could co-infect pig herds in these countries. In this study, a new triplex quantitative real-time polymerase chain reaction (tqPCR) method was developed for the rapid and differential detection of these viruses. The assay specifically amplified each viral capsid gene, whereas no other porcine pathogenic genes were detected. The detection limit of the assay was below 10 copies/µL and the assay showed high repeatability and reproducibility. In the clinical evaluation using 1476 clinical samples from 198 Korean pig farms, the detection rates of PCV2, PCV3 and PCV4 by the tqPCR assay were 13.8%, 25.4%, and 3.8%, respectively, which were 100% agreement with those of previously reported monoplex qPCR assays for PCV2, PCV3, and PCV4, with a κ value (95% CI) of 1 (1.00~1.00). The prevalence of PCV2, PCV3, and PCV4 at the farm levels were 46.5%, 63.6%, and 19.7%, respectively. The co-infection analysis for tested pig farms showed that single infection rates for PCV2, PCV3, and PCV4 were 28.8%, 44.4%, and 9.6%, respectively, the dual infection rates of PCV2 and PCV3, PCV2 and PCV4, and PCV3 and PCV4 were 12.6%, 3.5%, and 5.1%, respectively, and the triple infection rate for PCV2, PCV3, and PCV4 was 1.5%. These results demonstrate that three pathogenic PCVs are widely spread, and their co-infections are common in Korean pig herds, and the newly developed tqPCR assay will be useful for etiological and epidemiological studies of these pathogenic PCVs.

• 미생물학회지
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• 제43권3호
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• pp.179-185
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• 2007

본 연구는 polymerase chanin reaction(PCR)기법과 DNA enzyme-linked immunosorbent assay(DNA ELISA) 기법을 이용하여 토양내 식물병원균인 Ralstonia solanacearum를 검출하고자 하였다. 토양 시료로부터 분석에 사용될 R. solanacearum DNA를 추출하기 위하여 몇 가지 방법을 비교 평가한 결과 기존의 DNA 추출 방법에 비하여 Guanidin isothiocyanate와 Chelex-100 resin을 사용하는 방법 이 토양 내에 존재하는 다양한 중류의 반응 저해 물질과 R. solanacearum만의 고유한 PCR반응 저해물질들을 제거하는 데에 효과적이었다. R. solanacearum만을 특이적으로 검출하기 위해 fliC유전자 부위에 특이적인 몇 종의 primer들을 제작하였다. 이들 중 높은 민감도와 특이도를 나타내는 두 set의 primer RsolfliC(forward; 5-GAACGCCAACGGTGCGAACT-3 and reverse; 5-GGCGGCCTTCAGGGAGGTC-3, designed by J. $Sch\ddot{o}nfeld$ et al.)와 RS_247 (forward; 5-GGCGGTCTGTCGGCRG-3 and reverse; 5-CGGTCGCGTTGGCAAC-3, designed by this study)를 선정하여 nested PCR을 수행할 수 있도록 고안하였다. Nested PCR primer에 biotin을 표지하였고 nested PCR산물의 내부 서열과 특이적으로 교잡반응을 할 수 있는 probe를 제작하여 PCR 결과를 DNA-EIA반응으로 확인 분석할 수 있도록 하였다. Primary PCR과 nested PCR의 산물을 전기영동 상에서 확인한 결과, nested PCR이 약 $10^2$정도의 높은 민감도를 나타내었고 DNA-EIA의 경우 $10^2P{\sim}10^3$정도의 민감도를 상승시켜주는 것으로 확인되었다.

• Journal of Microbiology and Biotechnology
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• 제30권3호
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• pp.459-468
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• 2020

This study established a new polymerase spiral reaction (PSR) that combines with reverse transcription reactions for HCV detection targeting 5'UTR gene. To avoid cross-contamination of aerosols, an isothermal amplification tube (IAT), as a separate containment control, was used to judge the result. After optimizing the RT-PSR reaction system, its effectiveness and specificity were tested against 15 different virus strains which included 8 that were HCV positive and 7 as non-HCV controls. The results showed that the RT-PSR assay effectively detected all 8 HCV strains, and no false positives were found among the 7 non-HCV strains. The detection limit of our RT-PSR assay is comparable to the real-time RT-PCR, but is more sensitive than the RT-LAMP. The established RT-PSR assay was further evaluated for detection of HCV in clinical blood samples, and the resulting 80.25% detection rate demonstrated better or similar effectiveness compared to the RT-LAMP (79.63%) and real-time RT-PCR (80.25%). Overall, the results showed that the RT-PSR assay offers high specificity and sensitivity for HCV detection with great potential for screening HCV in clinical blood samples.

• Journal of Microbiology and Biotechnology
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• 제26권1호
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• pp.180-189
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• 2016

The widespread occurrence of drug-resistant Mycobacterium tuberculosis places importance on the detection of TB (tuberculosis) drug susceptibility. Conventional drug susceptibility testing (DST) is a lengthy process. We developed a rapid enzymatic color-reaction-based biochip assay. The process included asymmetric multiplex PCR/templex PCR, biochip hybridization, and an enzymatic color reaction, with specific software for data operating. Templex PCR (tem-PCR) was applied to avoid interference between different primers in conventional multiplex-PCR. We applied this assay to 276 clinical specimens (including 27 sputum, 4 alveolar lavage fluid, 2 pleural effusion, and 243 culture isolate specimens; 40 of the 276 were non-tuberculosis mycobacteria specimens and 236 were M. tuberculosis specimens). The testing process took 4.5 h. A sensitivity of 50 copies per PCR was achieved, while the sensitivity was 500 copies per PCR when tem-PCR was used. Allele sequences could be detected in mixed samples at a proportion of 10%. Detection results showed a concordance rate of 97.46% (230/236) in rifampicin resistance detection (sensitivity 95.40%, specificity 98.66%) and 96.19% (227/236) in isoniazid (sensitivity 93.59%, specificity 97.47%) detection with those of DST assay. Concordance rates of testing results for sputum, alveolar lavage fluid, and pleural effusion specimens were 100%. The assay provides a potential choice for TB diagnosis and treatment.

• Journal of Veterinary Science
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• 제23권4호
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• pp.51.1-51.10
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• 2022

Background: Due to the unavailability of an effective vaccine or antiviral drug against the African swine fever virus (ASFV), rapid diagnosis methods are needed to prevent highly contagious African swine fever. Objectives: The objective of this study was to establish the ladder-shape melting temperature isothermal amplification (LMTIA) assay for the detection of ASFV. Methods: LMTIA primers were designed with the p72 gene of ASFV as the target, and plasmid pUC57 was used to clone the gene. The LMTIA reaction system was optimized with the plasmid as the positive control, and the performance of the LMTIA assay was compared with that of the commercial real-time polymerase chain reaction (PCR) kit in terms of sensitivity and detection rate using 200 serum samples. Results: Our results showed that the LMTIA assay could detect the 10⁴ dilution of DNA extracted from the positive reference serum sample, which was the same as that of the commercial real-time PCR kit. The coincidence rate between the two assays was 100%. Conclusions: The LMTIA assay had high sensitivity, good detection, and simple operation. Thus, it is suitable for facilitating preliminary and cost-effective surveillance for the prevention and control of ASFV.

• 대한환경공학회지
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• 제29권8호
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• pp.904-908
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• 2007

병원성 원생동물인 지아디아 람블리아는 수인성 질병을 야기하는 주요 원인이 되고 있다. 본 연구는 PCR 및 RT-PCR 기법을 적용하여 한강본류 하천수 시료에서 사람감염성 종인 지아디아 람블리아를 동정하고, 활성 여부를 판별하여 현 표준시험방법을 보완하고자 하였다. PCR과 RT-PCR에는 지아디아의 복부 흡반 구성 유전자를 증폭하는 giardin primer를 사용하였으며, DNA/RNA 추출 및 PCR/RT-PCR 과정에서의 민감도 검사를 수행한 결과, 1포낭까지 검출가능한 것으로 나타났다. 또한 한강본류 및 유입지천 시료 48점에 적용하여 면역형광항체법과 PCR 및 RT-PCR 방법을 비교하였다. 면역형광항체법을 이용한 현미경관찰 결과 48개 시료의 지아디아 총포낭수의 평균 농도는 6.3 cysts/10 L이었고 양성율은 62.5%였으며, 속빈 포낭을 제외한 지아디아의 평균 농도는 4.5 cysts/10 L이었고 양성율은 52.1%였다. PCR 수행결과 48개 시료 중 24개(50%)의 시료에서 지아디아 람볼리아가 검출되었으며, RT-PCR 수행결과 10개(21%) 시료가 살아있는 G. lamblia를 포함한 것으로 나타났다. 본 연구를 통해 PCR/RT-PCR 기법이 지아디아 포낭을 저농도로 포함하고 있는 하천수 시료에 적용가능하며 원생동물 표준시험방법을 보완하여 종(species) 및 활성에 대한 정보를 제공할 수 있을 것으로 결과되었다.

• Journal of Microbiology and Biotechnology
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• 제15권3호
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• pp.595-602
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• 2005

A one-step real-time quantitative RT-PCR assay in combination with automated RNA extraction was evaluated for routine testing of HCV RNA in the laboratory. Specific primers and probes were developed to detect 302 bp on 5'-UTR of HCV RNA. The assay was able to quantitate a dynamic linear range of $10^7-10^1$ HCV RNA copies/reaction ($R^2=0.997$). The synthetic HCV RNA standard of $1.84{\pm}0.1\;(mean{\pm}SD)$ copies developed in this study corresponded to 1 international unit (IU) of WHO International Standard for HCV RNA (96/790 I). The detection limit of the assay was 3 RNA copies/reaction (81 IU/ml) in plasma samples. The assay was comparable to the Amplicor HCV Monitor (Monitor) assay with correlation coefficient r=0.985, but was more sensitive than the Monitor assay. The assay could be completed within 3 h from RNA extraction to detection and data analysis for up to 32 samples. It allowed rapid RNA extraction, detection, and quantitation of HCV RNA in plasma samples. The method provided sufficient sensitivity and reproducibility and proved to be fast and labor-saving, so that it was suitable for high throughput HCV RNA test.

• Journal of Microbiology and Biotechnology
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• 제24권6호
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• pp.862-868
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• 2014

Certain Escherichia coli (E. coli) strains have the ability to cause diarrheal disease. Five types of diarrheagenic E. coli have been identified, including EHEC, ETEC, EPEC, EAEC, and EIEC. To detect these five diarrheagenic types rapidly, we developed a one-step multiplex PCR (MP-PCR) assay using nine primer pairs to amplify nine virulence genes specific to the different virotypes, with each group being represented (i.e., stx1 and stx2 for EHEC, lt, sth, and stp for ETEC, eaeA and bfpA for EPEC, aggR for EAEC, and ipaH for EIEC). The PCR primers were constructed using MultAlin. The sensitivity and specificity of the constructed multiplex PCR primers were measured using DNA isolated from diarrheagenic E. coli strains representing each group. The limits of detection were as follows: $5{\times}10^1CFU/ml$ for EHEC, $5{\times}10^3CFU/ml$ for ETEC expressing lt and sth, $5{\times}10^4CFU/ml$ for ETEC expressing stp, $5{\times}10^2CFU/ml$ for EPEC, $5{\times}10^4CFU/ml$ for EAEC, and $5{\times}10^2CFU/ml$ for EIEC. To confirm the specificity, C. jejuni, C. perfringens, S. Typhimurium, V. parahaemolyticus, L. monocytogenes, Y. enterocolitica, B. cereus, and S. aureus were used as negative controls, and no amplification was obtained for these. Moreover, this kit was validated using 100 fecal samples from patients with diarrhea and 150 diarrheagenic E. coli strains isolated in Korea. In conclusion, the multiplex PCR assay developed in this study is very useful for the rapid and specific detection of five diarrheagenic E. coli types. This single-step assay will be useful as a rapid and economical method, as it reduces the cost and time required for the identification of diarrheagenic E. coli.

• 한국수산과학회지
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• 제48권5호
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• pp.731-738
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• 2015

Nematode infection in the epithelial tissue of cultured rockfish Sebastes schlegeli was first reported in 2012. Since then, nematode infections have caused serious economic losses in rockfish aquaculture on the west coast of Korea. Taxonomic and life cycle information for this parasite are currently unknown. In this study, 18S rRNA and cytochrome c oxidase subunit I (COI) genes were used for molecular identification and polymerase chain reaction (PCR) to detect the invisible stages of this parasite. Nucleotide sequences of the 18S rRNA of the rockfish nematode showed 98% identity with that of Philometra morii. Therefore, this rockfish nematode was classified to the Philometridae family. However, we could not identify it to genus level using 18S rRNA. Its COI nucleotide sequences shared 85% and 82% identities with those of Bursaphelenchus sinensis and Philometra overstreeti, respectively. In addition, two gene-specific primer sets were designed based on the 18S rRNA gene to detect the intermediate host and nematode larvae. These primers were specific to this rockfish nematode without cross-reacting to other pathogens. The detection limit of the PCR assay using these primers was 1,000 copies of nematoda plasmid DNA. Therefore, the PCR assay described here is suitable for the detection of nematode DNA within rockfish. In addition, this PCR assay could be used to detect nematode larvae and the intermediate host.

• 대한수의학회지
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• 제52권2호
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• pp.75-82
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• 2012

We have developed and optimized a multiplex polymerase chain reaction (mPCR) for simultaneous detection of Brucella, Salmonella and Leptospira with high sensitivity and specificity. Three pairs of oligonucleotide primers were designed to specifically amplify the targeted genes of Salmonella, Leptospira and Brucella species with sizes of 521, 408 and 223 bp, respectively. The mPCR did not produce any nonspecific amplification products when tested against 15 related species of bacteria. The sensitivity of the mPCR was 100 fg for Brucella and 1 pg for both Salmonella and Leptospira species. In the field application, kidney, liver and spleen were collected from wild rats and stray cats and examined by mPCR. The high specificity and sensitivity of this mPCR assay provide a valuable tool for diagnosis and for the simultaneous and rapid detection of three zoonotic bacteria that cause disease in both humans and animals. Therefore, this assay could be a useful alternative to the conventional method of culture and single PCR for the detection of each pathogen.