• Korean Journal of Clinical Laboratory Science
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• v.51 no.4
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• pp.414-419
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• 2019

JC polyomavirus (JCPyV) is a human pathogenic virus belonging to the family Polyomaviridae, a viral group containing dsDNA nucleic acid. A recent recommendation is to apply the presence of JCPyV as a fecal indicator for water contamination in environments like sewage, and techniques to monitor JCPyV in water are being proposed. To date, the conventional PCR system has been applied as a diagnostic method for detecting JCPyV. There is a need for a more rapid and sensitive JCPyV diagnostic detection method in clinical and environmental samples. In this study, we developed a loop-mediated isothermal amplification (LAMP) primer set for the detection of JCPyV. Our results indicate that the LAMP method using a specific primer set shows about 10-fold higher detection sensitivity than the conventional PCR system. The effectiveness of the LAMP method developed in this study has been validated by PCR product digestion using the HaeIII restriction enzyme. We, therefore, propose that the LAMP method using a specific primer set can be applied as a rapid and sensitive detection method for monitoring JCPyV in clinical and environmental samples.

• Journal of Microbiology and Biotechnology
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• v.33 no.8
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• pp.1101-1110
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• 2023

Streptococcus mutans is the primary causative agent of caries, which is one of the most common human diseases. Thus, rapid and early detection of cariogenic bacteria is critical for its prevention. This study investigated the combination of loop-mediated isothermal amplification (LAMP) and microfluid technology to quantitatively detect S. mutans. A low-cost, rapid microfluidic chip using LAMP technology was developed to amplify and detect bacteria at 2.2-2.2 × 10⁶ colony-forming units (CFU)/ml and its detection limits were compared to those of standard polymerase chain reaction. A visualization system was established to quantitatively determine the experimental results, and a functional relationship between the bacterial concentration and quantitative results was established. The detection limit of S. mutans using this microfluidic chip was 2.2 CFU/ml, which was lower than that of the standard approach. After quantification, the experimental results showed a good linear relationship with the concentration of S. mutans, thereby confirming the effectiveness and accuracy of the custom-made integrated LAMP microfluidic system for the detection of S. mutans. The microfluidic system described herein may represent a promising simple detection method for the specific and rapid testing of individuals at risk of caries.

• Animal Bioscience
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• v.36 no.4
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• pp.654-670
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• 2023

Objective: This study aimed to develop loop-mediated isothermal amplification (LAMP) combined with lateral flow dipstick (LFD) and compare it with LAMP-AGE, polymerase chain reaction (PCR), and standard Salmonella culture as reference methods for detecting Salmonella contamination in animal products and animal production environmental samples. Methods: The SalInvA01 primer, derived from the InvA gene and designed as a new probe for LFD detection, was used in developing this study. Adjusting for optimal conditions by temperature, time, and reagent concentration includes evaluating the specificity and limit of detection. The sampling of 120 animal product samples and 350 animal production environmental samples was determined by LAMP-LFD, comparing LAMP-AGE, PCR, and the culture method. Results: Salmonella was amplified using optimal conditions for the LAMP reaction and a DNA probe for LFD at 63℃ for 60 minutes. The specificity test revealed no cross-reactivity with other microorganisms. The limit of detection of LAMP-LFD in pure culture was 3×10² CFU/mL (6 CFU/reaction) and 9.01 pg/μL in genomic DNA. The limit of detection of the LAMP-LFD using artificially inoculated in minced chicken samples with 5 hours of pre-enrichment was 3.4×10⁴ CFU/mL (680 CFU/reaction). For 120 animal product samples, Salmonella was detected by the culture method, LAMP-LFD, LAMP-AGE, and PCR in 10/120 (8.3%). In three hundred fifty animal production environmental samples, Salmonella was detected in 91/350 (26%) by the culture method, equivalent to the detection rates of LAMP-LFD and LAMP-AGE, while PCR achieved 86/350 (24.6%). When comparing sensitivity, specificity, positive predictive value, and accuracy, LAMP-LFD showed the best results at 100%, 95.7%, 86.3%, and 96.6%, respectively. For Kappa index of LAMP-LFD, indicated nearly perfect agreement with culture method. Conclusion: The LAMP-LFD Salmonella detection, which used InvA gene, was highly specific, sensitive, and convenient for identifying Salmonella. Furthermore, this method could be used for Salmonella monitoring and primary screening in animal products and animal production environmental samples.

• The Plant Pathology Journal
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• v.36 no.1
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• pp.76-86
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• 2020

Cucumber mosaic virus (CMV) is damaging to the growth and quality of lettuce crops in Lanzhou, China. Recently, however, for the first time an isolate of lettuce necrotic yellows virus (LNYV) has been detected in lettuce crops in China, and there is concern that this virus may also pose a threat to lettuce production in China. Consequently, there is a need to develop a rapid and efficient detection method to accurately identify LNYV and CMV infections and help limit their spread. Reverse transcription loop-mediated isothermal amplification (RT-LAMP) assays were developed to detect the nucleoprotein (N) and coat protein (CP) genes of LNYV and CMV, respectively. RT-LAMP amplification products were visually assessed in reaction tubes separately using green fluorescence and gel electrophoresis. The assays successfully detected both viruses in infected plants without cross reactivity recorded from either CMV or LNYV or four other related plant viruses. Optimum LAMP reactions were conducted in betaine-free media with 6 mM Mg²⁺ at 65℃ for LNYV and 60℃ for 60 min for CMV, respectively. The detection limit was 3.5 pg/ml and 20 fg/ml using RT-LAMP for LNYV and CMV plasmids, respectively. Detection sensitivity for both RT-LAMP assays was greater by a factor of 100 compared to the conventional reverse transcription polymerase chain reaction assays. This rapid, specific, and sensitive technique should be more widely applied due to its low cost and minimal equipment requirements.

• 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.31 no.3
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• pp.219-225
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• 2015

The primary step for efficient control of viral diseases is the development of simple, rapid, and sensitive virus detection. Reverse transcription loop-mediated isothermal amplification (RT-LAMP) has been used to detect viral RNA molecules because of its simplicity and high sensitivity for a number of viruses. RT-LAMP for the detection of Potato virus X (PVX) was developed and compared with conventional reverse transcription polymerase chain reaction (RT-PCR) to demonstrate its advantages over RT-PCR. RT-LAMP reactions were conducted with or without a set of loop primers since one out of six primers showed PVX specificity. Based on real-time monitoring, RT-LAMP detected PVX around 30 min, compared to 120 min for RT-PCR. By adding a fluorescent reagent during the reaction, the extra step of visualization by gel electrophoresis was not necessary. RT-LAMP was conducted using simple inexpensive instruments and a regular incubator to evaluate whether RNA could be amplified at a constant temperature instead of using an expensive thermal cycler. This study shows the potential of RT-LAMP for the diagnosis of viral diseases and PVX epidemiology because of its simplicity and rapidness compared to RT-PCR.

• Journal of the Korean Chemical Society
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• v.52 no.3
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• pp.273-280
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• 2008

Mycobacterium tuberculosis (MTB) remains a major worldwide public health problem. In recent years, the incidence of MTB has been rising. Rapid and reliable diagnosis of Mycobacterium tuberculosis is essential to initiate correct treatment, avoid severe complications, and prevent transmission. LAMP was used to develop a rapid and sensitive laboratory diagnostic system for the MTB. In this research, the loop-mediated isothermal amplification method (LAMP) that amplifies DNA with high specificity and rapidity at an isothermal condition was evaluated for rapid detection of MTB. Undiluted DNA (2.10 × 106 copy/mL), 10-1, 10-2, 10-3, 10-4, 10-5 and 10-6 (copy/mL) of MTB DNA were amplified by PCR and LAMP to determine the sensitivity of the assay. At results, the LAMP assay reported here has the advantages of rapid amplification, high sensitivity, and high specificity and will be useful for rapid and reliable clinical diagnosis of MTB in hospital clinical laboratory.

• Journal of Food Hygiene and Safety
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• v.34 no.2
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• pp.135-139
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• 2019

The objective of this research was to compare loop-mediated isothermal amplification (LAMP) with real-time polymerase chain reaction (PCR) for the rapid detection of pathogens in foods. In this study, the limits of detection (LODs) for Salmonella Typhimurium, Listeria monocytogenes, and Cronobacter sakazakii were evaluated in various foods. Among 11 samples tested for S. Typhimurium, LAMP and real-time PCR had the same LODs in beef and duck meat whereas real-time PCR was more sensitive than the LAMP in 8 samples. However, S. Typhimurium in chocolate samples was not detected by real-time PCR. The sensitivity of real-time PCR was high in all samples inoculated with L. monocytogenes and C. sakazakii whereas LAMP was more sensitive than real-time PCR in oil-rich foods. Therefore, LAMP can be shown as an easrer, more convenient method, as well as effective analytical method for testing difficult samples when employed in PCR.

• Parasites, Hosts and Diseases
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• v.54 no.3
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• pp.329-334
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• 2016

Trichomoniasis caused by Trichomonas vaginalis is a common sexually transmitted disease. Its association with several health problems, including preterm birth, pelvic inflammatory disease, cervical cancer, and transmission of human immunodeficiency virus, emphasizes the importance of improved access to early and accurate detection of T. vaginalis. In this study, a rapid and efficient loop-mediated isothermal amplification-based method for the detection of T. vaginalis was developed and validated, using vaginal swab specimens from subjects suspected to have trichomoniasis. The LAMP assay targeting the actin gene was highly sensitive with detection limits of 1 trichomonad and 1 pg of T. vaginalis DNA per reaction, and specifically amplified the target gene only from T. vaginalis. Validation of this assay showed that it had the highest sensitivity and better agreement with PCR (used as the gold standard) compared to microscopy and multiplex PCR. This study showed that the LAMP assay, targeting the actin gene, could be used to diagnose early infections of T. vaginalis. Thus, we have provided an alternative molecular diagnostic tool and a point-of-care test that may help to prevent trichomoniasis transmission and associated complications.

• Research in Plant Disease
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• v.22 no.3
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• pp.178-183
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• 2016

Soybean yellow mottle mosaic virus (SYMMV) is a new emerging plant virus detected in soybean (Glycine max) in Korea. Reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay for rapid detection of SYMMV has been developed. In this study, we have designed primers (SYMM-F3/B3/FIP/BIP) specific to sequences from the coat protein gene of SYMMV genome. Sensitivity analysis showed that RT-LAMP was 10 to 100 times more sensitive than reverse transcription polymerase chain reaction (RT-PCR). The optimal reaction condition of RT-LAMP was determined at $65^{\circ}C$ for 50 minutes. The result indicates that RT-LAMP assay does not require special equipment and long time for SYMMV detection. Therefore, it can be an alternative detection method of RT-PCR in laboratory.