• Journal of Microbiology
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• 제44권4호
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• pp.403-408
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• 2006

The purpose of this study was to determine the efficacy of a nucleic acid sequence-based amplification (NASBA) method of detecting noroviruses in artificially and naturally contaminated shellfish. We used 58 fecal samples that tested positive for noroviruses with electron microscopy (EM) to develop an NASBA assay for these viruses. Oligonucleotide primers targeting the polymerase coding region were used to amplify the viral RNA in an isothermal process that resulted in the accumulation of RNA amplicons. These amplicons were detected by hybridization with digoxigenin-labeled oligonucleotide probes that were highly specific for genogroup I (GI) and genogroup II (GII) of noroviruses. The expected band of 327bp appeared in denaturing agarose gel without any nonspecific band. The specific signal for each amplicon was obtained through Northern blotting in many repeats. All fecal samples of which 46(79.3%) belonged to GII and 12(20.6%) belonged to GI were positive for noroviruses by EM and by NASBA. Target RNA concentrations as low as 5pg/ml were detected in fecal specimens using NASBA. When the assay was applied to artificially contaminated shellfish, the sensitivity to nucleic acid was 100pg/1.5g shellfish tissue. The potential use of this assay was also confirmed in naturally contaminated shellfish collected from different ponds in Guangzhou city of China, of which 24 (18.76%) out of 128 samples were positive for noroviruses; of these, 19 (79.6%) belonged to GII and 5 (20.4%) belonged to GI. The NASBA assay provided a more rapid and efficient way of detecting noroviruses in fecal samples and demonstrated its potential for detecting noroviruses in food and environmental samples with high specificity and sensitivity.

• 한국균학회지
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• 제20권4호
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• pp.315-323
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• 1992

재현성 있는 RAED marker들의 증폭을 위해서 PCR에 영향을 주는 조건들에 대해 조사를 하였다. 그 결과 약 15 ng의 DNA가 효과적인 PCR에 적합한 양이었으며 PCR에 사용되는 성분(reaction component)들의 농도가 PCR 결과에 있어서 상호의존관계에 있었고 DNA 용액에 포함되어 있는 RNA가 DNA 증폭을 방해하는 작용을 하였다. $25\;{\mu}l$의 PCR 반응용액에 30ng의 10-mer primer, $200\;{\mu}M$ dNTP, 0.001% gelatin, 1.5 mM $MgCl_2$, 10 mM Tris-Cl(pH 8.8), 50 mM KCl, 0.1%, Triton X-100, 2units의 Taq DNA polymerase, 그리고 RNA를 제거한 15 ng의 DNA를 사용한 결과 가장 재현성있는 RAPD marker들이 증폭되었다.

• Journal of Microbiology and Biotechnology
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• 제22권7호
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• pp.1021-1028
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• 2012

In this study, a reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay was developed for the rapid, sensitive, and inexpensive detection of nervous necrosis virus (NNV) in olive flounder, Paralichthys olivaceus, in Korea. A set of six specific primers was designed to target the RNA 2 gene encoding the coat protein of Korean NNV strains. The RT-LAMP reaction successfully detected NNV after 30 min at $65^{\circ}C$. When the sensitivities among RT-LAMP, RT-PCR, and nested RTPCR were compared, the RT-LAMP was shown to be able to detect the RNA template at $2.58{\times}10^{-2}\;TCID_{50}/ml$, whereas the RT-PCR and nested RT-PCR were only able to detect the RNA template at $2.58{\times}10^2\;TCID_{50}/ml$ and $2.58TCID_{50}/ml$, respectively. Thus, the sensitivity of the RT-LAMP assay was higher than those of the RT-PCR assays. In the specificity test of the RT-LAMP, 2 genotypes of NNVs (SJNNV and RGNNV) were positive; however, no other fish viruses were positive with the primers, indicating that the RT-LAMP assay is only specific to NNV. A total of 102 olive flounder were collected from hatcheries between 2009 and 2011. The occurrence of NNV in olive flounder was determined to be 53.9% (55/102) by the RT-LAMP. On the other hand, the prevalence based on the nested RT-PCR and RT-PCR results was 33.8% (34/102) and 20.6% (21/102), respectively. This result indicates that the RT-LAMP assay developed in this study is suitable for early field diagnosis of NNV with high sensitivity.

• 대한의생명과학회지
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• 제25권1호
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• pp.75-82
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• 2019

We developed the multiplex LAMP assay using 16S rRNA, femA and mecA genes for direct detection of the methicillin resistance in Staphylococci from positive blood culture. To simultaneously recognize Staphylococci genus, S. aureus and methicillin resistance, three sets of six primers for 16S rRNA, femA and mecA were designed, respectively. The performance of LAMP assay was affirmed using VITEK system for the phenotypic methods of identification and for oxacillin and cefoxitin antimicrobial susceptibility. The optimal condition for LAMP assay was obtained under $64^{\circ}C$ for 50 min. The detection limit was determined to be of 20 copies and CFU/reaction ($10^4CFU/mL$). For clinical application of comparison with phenotypic methods, the sensitivity and specificity of the LAMP with femA gene for detecting S. aureus was 95.31% and 100%, respectively. The sensitivity and specificity of the LAMP with mecA gene for detecting methicillin resistance was 98.46% and 100%, respectively. The multiplex LAMP assay with femA and mecA gene successfully detected all of MRSA (38 isolates) isolates from 103 Staphylococci in blood cultures. The LAMP assay developed in this study is sensitive, specific, and of excellent agreement with the phenotypic methods.

• 미생물학회지
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• 제45권3호
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• pp.286-290
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• 2009

조류인플루엔자 바이러스 mRNA의 전사는 감염 동안에 시간적으로 조절되어진다. 감염 후 세포 내에서 증식된 바이러스가 방출되어 세포를 다시 감염하게 되면 전사 수준 분석에 오차가 발생할 수 있으므로 바이러스가 방출 되기 이전에 전사 수준의 측정이 이루어져야 한다. 본 연구에서는 조류인플루엔자 H9N2를 감염시킨 닭의 섬유아세포주 UMNSAH/DF-1에서 바이러스 감염 후 증식된 바이러스의 방출까지의 시간을 측정하기 위하여 배양액 중에 방출되는 바이러스 RNA 게놈 수준을 semi-quantitative RT-PCR에 의해 측정하였다. 배양액 중의 바이러스 RNA 게놈의 분리 과정에서 발생할 수 있는 RNA 회수율의 오차를 보정하기 위해 mouse의 전체 RNA를 배양액 시료에 넣어서 바이러스 RNA 분리에 carrier로 사용하고 그 속에 포함된 mouse의 GAPDH를 RNA를 역전사 반응 및 PCR의 내부 대조 RNA로 사용하였다. 그 결과 감염 후 방출까지 16~20시간이 소요됨을 알 수 있었다. 따라서 감염 후 12시간 후에 세포 내에서 합성된 8종의 전사체의 수준을 측정하였다. 8종의 mRNA 중 PA를 제외한 7종의 mRNA (HA, NA, PB1, PB2, NP, M, NS를 암호화하는 mRNA)는 뚜렷한 증폭 band를 보였으며, 이것은 이들이 전사활성 측정에 사용될 수 있는 것으로 나타났다. 이상과 같은 전사수준의 측정 방법은 조류인플루엔자 바이러스의 RNA polymerase를 표적으로 한 항바이러스제의 검색에 사용할 수 있을 것으로 보인다.

• Journal of Microbiology and Biotechnology
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• 제25권3호
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• pp.321-327
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• 2015

Nocardia salmonicida is one of the main pathogens of fish nocardiosis. The purpose of this study was to build a loop-mediated isothermal amplification (LAMP) method for the rapid and sensitive detection of N. salmonicida. A set of four primers were designed from the 16S-23S rRNA intergenic spacer region of N. salmonicida, and conditions for LAMP were optimized as incubating all the reagents for 60 min at 64℃. LAMP products were judged with agar gel electrophoresis as well as with the naked eye after the addition of SYBR Green I. Results showed the sensitivity of the LAMP assay was 1.68 × 10³ CFU/ml (16.8 CFU per reaction) and 10-fold higher than that of PCR. The LAMP method was also effectively applied to detect N. salmonicida in diseased fish samples, and it may potentially facilitate the surveillance and early diagnosis of fish nocardiosis.

• 농업과학연구
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• 제47권1호
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• pp.173-182
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• 2020

Human Astrovirus (HuAstV), known as a waterborne virus, is a group IV positive-sense single-stranded RNA that belongs to Astroviridae. The first outbreak of HuAstV was reported in England in 1975. HuAstV can exist not only among clinical patients but also in various water environments, such as water for agriculture and vegetables. For diagnosis of HuAstV from water samples, a polymerase chain reaction (PCR) system has been developed. However, the PCR-based diagnostic method has problems in field application, such as reaction time, sensitivity and specificity. For this reason, in this study we developed the loop-mediated isothermal amplification assay (LAMP) system, aimed specifically at HuAstV. Three prepared LAMP primer sets were tested by specificity, non-specificity and sensitivity; one LAMP primer set was selected with optimum reaction temperature. The developed LAMP primer set reaction conditions were confirmed at 62℃, and detection sensitivity was 1 fg/μL. In addition, restriction enzyme HaeIII (GG/CC) was introduced to confirm that the LAMP reaction was positive. As a result, selected LAMP primer set was 100 - 1000 times more specific, rapid, and sensitive than conventional-nested PCR methods. For verification of the developed LAMP assay, twenty samples of cDNA from groundwater samples were tested. We expect that the developed LAMP assay will be used to diagnose HuAstV from various samples.

• 한국동물위생학회지
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• 제34권4호
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• pp.333-339
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• 2011

Loop-mediated isothermal amplification (LAMP) was developed to detect Mycobacterium tuberculosis complex (MTC) and non-tuberculous mycobacterium (NTM) genomic DNA in blood samples of Korea native cattle. A set of four primers, two outer and two inner, were designed from M. bovis and M. avium genomic DNA targeting the IS6110 and 16S rRNA gene, respectively. Based on 85 Intradermal Tuberculin Test (ITT) positive blood sample and using conventional PCR and LAMP, the agreement quotient (kappa), which measures agreement beyond chance were 0.93 (conventional PCR) and 0.97 (LAMP), respectively. The detection limit of the LAMP method was $2.0{\times}10^2$ copy/ml M. bovis and M. avium cells, compared to $2.0{\times}10^3$ copy/ml M. bovis and M. avium cells for conventional PCR. These results suggest that the LAMP is a powerful tool for rapid, sensitive, and practical detection of MTC and NTM in blood samples of Korea native cattle.

• 식물병연구
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• 제28권2호
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• pp.92-97
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• 2022

Apple stem grooving virus (ASGV) is a high-risk viral pathogen that infects many types of fruit trees, especially pear and apple, and causes serious economic losses across the globe. Thus, rapid and reliable detection assay is needed to identify ASGV infection and prevent its spread. A reliable reverse transcription loop-mediated isothermal amplification (RT-LAMP) was developed, optimize, and evaluated for the coding region of coat protein of ASGV in pear leaf. The developed RT-LAMP facilitated the simple screening of ASGV using visible fluorescence and electrophoresis. The optimized reaction conditions for the RT-LAMP were 63℃ for 50 min, and the results showed high specificity and 100-fold greater sensitivity than the reverse transcription polymerase chain reaction. In addition, the reliability of the RT-LAMP was validated using field-collected pear leaves. Furthermore, the potential application of paper-based RNA isolation, combined with RT-LAMP, was also evaluated for detecting ASGV from field-collected samples. These assays could be widely applied to ASGV detection in field conditions and to virus-free certification programs.

• 대한의생명과학회지
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• 제17권3호
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• pp.191-196
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• 2011

Noroviruses (noroV) are the major cause of nonbacterial gastroenteritis in humans worldwide. Since noroV cannot yet be cultured in vitro and their diagnosis by electron microscopy requires at least $10^6$ viral particles/g of stool a variety of molecular detection techniques represent an important step towards the detection of noroV. In the present study, we have applied real-time nucleic acid sequence-based amplification (real-time NASBA) for simultaneous detection of NoroV genogroup I (GI) and genogroup II (GII) using standard viral RNA. For real-time NASBA assay which can detected noroV GI and GII, a selective region of the genes encoding the capsid protein was used to design primers and genotype-specific molecular beacon probes. The specificity of the real-time NASBA using newly designed primers and probes were confirmed using standard viral RNA of noroV GI and GII. To determine the sensitivity of this assay, serial 10-fold dilutions of standard viral RNA of noroV GI and GII were used for reverse transcription polymerase chain reaction (RT-PCR) and real-time NASBA. The results showed that while agarose gel electrophoresis could detect RT-PCR products with 10 pg of standard viral RNA, the real-time NASBA assay could detect 100 fg of standard viral RNA. These results suggested that the real-time NASBA assay has much higher sensitivity than conventional RT-PCR assay. This assay was expected that might detect the viral RNA in the specimens which could have been false negative by RT-PCR. There were needed to perform real-time NASBA with clinical specimens for evaluating accurate sensitivity and specificity of this assay.