• Journal of Microbiology
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• v.44 no.1
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• pp.92-97
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• 2006

We developed an mPCR assay for the simultaneous detection, in one tube, of Escherichia coli O157:H7, Salmonella spp., Staphylococcus aureus and Listeria monocytogenes using species-specific primers. The mPCR employed the E. coli O157:H7 specific primer Stx2A, Salmonella spp. specific primer Its, S. aureus specific primer Cap8A-B and L. monocytogenes specific primer Hly. Amplification with these primers produced products of 553, 312, 405 and 210 bp, respectively. All PCR products were easily detected by agarose gel electrophoresis, and the sequences of the specific amplicons assessed. Potential pathogenic bacteria, in laboratory-prepared and four commercially available kimchi products, were using this mPCR assay, and the amplicons cloned and sequenced. The results correlated exactly with sequences derived for amplicons obtained during preliminry tests with known organisms. The sensitivity of the assay was determined for the purified pathogen DNAs from four strains. The mPCR detected pathogen DNA at concentrations ranging from approximately 0.45 to $0.05\;pM/{\mu}l$. Thus, this mPCR assay may allow for the rapid, reliable and cost-effective identification of four potentially pathogens present in the mixed bacterial communities of commercially available kimchi.

• Parasites, Hosts and Diseases
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• v.51 no.5
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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.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.47 no.6
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• pp.740-744
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• 2014

In this study, the ${\beta}$-lactamase (VPA0477) gene was used as a new target for the PCR-based detection of Vibrio parahaemolyticus. Primers specific for the ${\beta}$-lactamase (VPA0477) gene of V. parahaemolyticus, were designed and incorporated into a PCR-based assay. The assay was able to specifically detect all of the 191 V. parahaemolyticus strains tested, but did not result in amplification of 39 other Vibrio spp. and non-Vibrio spp. strains tested. The detection limit of the assay was 10 CFU of V. parahaemolyticus RIMD2210633 from pure culture broth. The ${\beta}$-lactamase (VPA0477) gene-based assay developed in this study was sensitive and specific, and has great potential for the accurate detection and identification of V. parahaemolyticus in seawater or seafood samples.

• Annals of Laboratory Medicine
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• v.39 no.1
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• pp.50-57
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• 2019

Background: The Automated Fluorescent Immunoassay System (AFIAS) rotavirus assay (Boditech Med Inc., Chuncheon, Korea) is a new rapid antigen test for rotavirus detection. We evaluated the performance of this assay for detecting rotaviruses and their specific genotypes in clinical stool samples. Methods: AFIAS rotavirus assay was performed in 103 rotavirus-positive and 103 rotavirus-negative stool samples (confirmed by both PCR and ELISA), and its results were compared with those of PCR, ELISA, and immunochromatographic assay (ICA). We evaluated diagnostic sensitivity/specificity, the detectability of rotavirus subtypes, lower limit of detection (LLOD), reproducibility, cross-reactivity, and interference of AFIAS rotavirus assay. Results: Based on PCR and ELISA results, diagnostic sensitivity and specificity of the AFIAS rotavirus assay were both 99.0%. LLOD results showed that the AFIAS assay had sensitivity similar to or greater than ICA and ELISA. High reproducibility was confirmed, and no cross-reactivity or interference was detected. This assay could detect genotypes G1P[8], G2P[4], G3P[8], G4P[6], G4P[8], G8P[4], G8P[8], G9P[4], and G9P[8]. Conclusions: The AFIAS rotavirus assay showed high reproducibility, sensitivity, and specificity as well as excellent agreement with ELISA, PCR, and ICA. It detected the most common as well as unusual genotypes of rotavirus prevalent in Korea. It could be a useful onsite assay for rapid, convenient, and cost-effective detection of rotavirus infection.

• Parasites, Hosts and Diseases
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• v.59 no.2
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• pp.167-171
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• 2021

Haemonchosis remains a significant problem in small ruminants. In this study, the assay of recombinase polymerase amplification (RPA) combined with the lateral flow strip (LFS-RPA) was established for the rapid detection of Haemonchus contortus in goat feces. The assay used primers and a probe targeting a specific sequence in the ITS-2 gene. We compared the performance of the LFS-RPA assay to a PCR assay. The LFS-RPA had a detection limit of 10 fg DNA, which was 10 times less compared to the lowest detection limit obtained by PCR. Out of 24 goat fecal samples, LFS-RPA assay detected H. contortus DNA with 95.8% sensitivity, compared to PCR, 79.1% sensitivity. LFS-RPA assay did not detect DNA from other related helminth species and demonstrated an adequate tolerance to inhibitors present in the goat feces. Taken together, our results suggest that LFS-RPA assay had a high diagnostic accuracy for the rapid detection of H. contortus and merits further evaluation.

• KSBB Journal
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• v.29 no.5
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• pp.361-371
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• 2014

Mycoplasma is well recognized as one of the most prevalent and serious microbial contaminants of biologic manufacturing processes. Conventional methods for mycoplasma testing, direct culture method and indirect indicator cell culture method, are lengthy, costly and less sensitive to noncultivable species. In this report, we describe a new TaqMan probe-based real-time PCR method for rapid and quantitative detection of mycoplasma contamination during manufacture of biologics. Universal mycoplasma primers were used for mycoplasma PCR and mycoplasma DNA was quantified by use of a specific TaqMan probe. Specificity, sensitivity, and robustness of the real-time PCR method was validated according to the European Pharmacopoeia. The validation results met required criteria to justify its use as a replacement for the culture method. The established real-time PCR assay was successfully applied to the detection of mycoplasma from human keratinocyte and mesenchymal stem cell as well as Vero cell lines artificially infected with mycoplasma. The overall results indicated that this rapid, specific, sensitive, and robust assay can be reliably used for quantitative detection of mycoplasma contamination during manufacture of biologics.

• Food Science and Biotechnology
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• v.17 no.2
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• pp.357-361
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• 2008

One of the major allergenic proteins in common buckwheat (Fagopyrum elculentum) was found to be a BW10KD. In this work, allergenic BW10KD genomic DNAs from the native common buckwheat 'Pyeongchang' and Tartarian buckwheat 'Clfa47' were cloned by polymerase chain reaction (PCR), and their nucleotide sequences were determined. In addition, a novel PCR assay targeting the allergenic BW10KD gene was developed to detect and differentiate both buckwheat species in food. The nucleotide sequences of the BW10KD genomic DNA from 'Pyeongchang' and 'Clfa47' were 94% identical. Base differences in the nucleotide sequences of the BW10KD genes are probably useful as a molecular marker for species-specific identification. The 'Pyeongchang'-specific primer set 154PF/400PR and the 'Clfa47'-specific primer set 154DF/253DR generated 247 and 100 bp fragments in singleplex PCR, respectively. A duplex PCR assay with 2 species-specific primer sets simultaneously differentiated the 'Pyeongchang' and 'Clfa47' in a single reaction. The PCR assay also successfully allowed for the rapid detection of buckwheat ingredients in foods.

• The Plant Pathology Journal
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• v.40 no.1
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• pp.40-47
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• 2024

Garlic can be infected by a variety of viruses, but mixed infections with leek yellow stripe virus, onion yellow dwarf virus, and allexiviruses are the most damaging, so an easy, inexpensive on-site method to simultaneously detect at least these three viruses with a certain degree of accuracy is needed to produce virus-free plants. The most common laboratory method for diagnosis is multiplex reverse transcription polymerase chain reaction (RT-PCR). However, allexiviruses are highly diverse even within the same species, making it difficult to design universal PCR primers for all garlic-growing regions in the world. To solve this problem, we developed an inexpensive on-site detection system for the three garlic viruses that uses a commercial mobile PCR device and a compact electrophoresis system with a blue light. In this system, virus-specific bands generated by electrophoresis can be identified by eye in real time because the PCR products are labeled with a fluorescent dye, FITC. Because the electrophoresis step might eventually be replaced with a lateral flow assay (LFA), we also demonstrated that a uniplex LFA can be used for virus detection; however, multiplexing and a significant cost reduction are needed before it can be used for on-site detection.

• Journal of Food Hygiene and Safety
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• v.33 no.1
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• pp.50-57
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• 2018

Salmonella continue to be a major cause of food poisoning worldwide. The rapid detection method of food-borne Salmonella is an important food safety tool. A real-time polymerase chain reaction (PCR) has been used as a rapid method for the detection of pathogens. It has been recently reported that NBS LabChip real-time PCR is a novel, ultrafast, and chip-type-convenient real-time PCR system. We developed the assay method based on NBS LabChip real-time PCR for the rapid detection of Salmonella, which its reaction time was within 20 minutes. Two target genes (invA and stn) were selected to design target specific primers and probes. The new method was validated by checking specificity and sensitivity (limit of detection). This study included forty-two target and twenty-one non-target strains to assess the specificity. This assay was able to identify the 42 Salmonella strains correctly. The limit of detection (LOD) was $10^1copies/{\mu}L$ in Salmonella genomes DNA, while LOD incubated for 4 hr in the inoculated sausage sample ranged from $10^1CFU/g$ to $10^2CFU/g$ as an inoculated cell count. The assay developed in this study could be applied for the investigation of food poisoning pathogens.

• Microbiology and Biotechnology Letters
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• v.33 no.2
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• pp.148-153
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• 2005

Malaria is a re-emerging infectious disease that is spreading to areas where it had been eradicated, such as Eastern Europe and Central Asia. To avoid the mortality from malaria, early detection of the parasite is a very important issue. The peripheral blood smear has been the gold standard method for the diagnosis of malaria infection. Recently, several other methods have been introduced for quantitative detection of malaria parasites. Real time PCR that employs fluorescent labels to enable the continuous monitoring of PCR product formation throughout the reaction has recently been used to detect several human malaria parasites. 18S rRNA sequences from malaria parasites have been amplified using Taqman real time PCR assay. Here, a SYBR Green-based real time quantitative PCR assay for the detection of malaria parasite-especially, Plasmodium vivax - was applied for the evaluation of 26 blood samples from Korean malaria patients. Even though SYBR Green-based real time PCR is easier and cheaper than Taqman-based assay, SYBR Green-based assay cannot be used because 18S rRNA cannot be specifically amplified using 1 primer set. Therefore, we used DBP gene sequences from Plasmodium vivax, which is specific for the SYBR Green based assays. We amplified the DBP gene from the 26 blood samples of malaria patients using SYBR Green based assay and obtained the copy numbers of DBP genes for each sample. Also, we selected optimal reference gene between ACTB and B2M using real time assay to get the stable genes regardless of Malaria titer. Using selected ACTB reference genes, we successfully converted the copy numbers from samples into titer, ${\sharp}$ of parasites per microliter. Using the resultant titer from DBP based SYBER Green assay with ACTB reference gene, we compared the results from our study with the titer from Taqman-based assay. We found that our results showed identical tendency with the results of 18S rRNA Taqman assay, especially in lower titer range. Thus, our DBP gene-utilized real time assay can detect Plasmodium vivax in Korean patient group semi-quantitatively and easily.