Dataset Information

Development of loop-mediated isothermal amplification (LAMP) assays for rapid detection of Ehrlichia ruminantium.

ABSTRACT: BACKGROUND: The rickettsial bacterium Ehrlichia ruminantium is the causative agent of heartwater, a potential zoonotic disease of ruminants transmitted by ticks of the genus Amblyomma. The disease is distributed in nearly all of sub-Saharan Africa and some islands of the Caribbean, from where it threatens the American mainland. This report describes the development of two different loop-mediated isothermal amplification (LAMP) assays for sensitive and specific detection of E. ruminantium. RESULTS: Two sets of LAMP primers were designed from the pCS20 and sodB genes. The detection limits for each assay were 10 copies for pCS20 and 5 copies for sodB, which is at least 10 times higher than that of the conventional pCS20 PCR assay. DNA amplification was completed within 60 min. The assays detected 16 different isolates of E. ruminantium from geographically distinct countries as well as two attenuated vaccine isolates. No cross-reaction was observed with genetically related Rickettsiales, including zoonotic Ehrlichia species from the USA. LAMP detected more positive samples than conventional PCR but less than real-time PCR, when tested with field samples collected in sub-Saharan countries. CONCLUSIONS: Due to its simplicity and specificity, LAMP has the potential for use in resource-poor settings and also for active screening of E. ruminantium in both heartwater-endemic areas and regions that are at risk of contracting the disease.

SUBMITTER: Nakao R

PROVIDER: S-EPMC3000401 | biostudies-literature | 2010

REPOSITORIES: biostudies-literature

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Development of loop-mediated isothermal amplification (LAMP) assays for rapid detection of Ehrlichia ruminantium.

Nakao Ryo R Stromdahl Ellen Y EY Magona Joseph W JW Faburay Bonto B Namangala Boniface B Malele Imna I Inoue Noboru N Geysen Dirk D Kajino Kiichi K Jongejan Frans F Sugimoto Chihiro C

BMC microbiology 20101119

<h4>Background</h4>The rickettsial bacterium Ehrlichia ruminantium is the causative agent of heartwater, a potential zoonotic disease of ruminants transmitted by ticks of the genus Amblyomma. The disease is distributed in nearly all of sub-Saharan Africa and some islands of the Caribbean, from where it threatens the American mainland. This report describes the development of two different loop-mediated isothermal amplification (LAMP) assays for sensitive and specific detection of E. ruminantium. ...[more]

PMID: 21087521

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Project description:Recently, a novel coronavirus (SARS-CoV-2; coronavirus disease 2019, COVID-19) has emerged, rapidly spreading and severely straining the capacity of the global health community. Many nations are employing combinations of containment and mitigation strategies, where early diagnosis of COVID-19 is vital in controlling illness progression and limiting viral spread within the population. Thus, rapid and accurate methods of early detection are vital to contain COVID-19 and prevent further spread and predicted subsequent infectious waves of viral recurrence in future. Immediately after its initial characterization, Chinese and American Centers for Disease Control and Prevention (CDCs) rapidly employed molecular assays for detection of COVID-19, mostly employing real-time polymerase chain reaction (RT-PCR) methods. However, such methods require specific expensive items of equipment and highly trained analysts, requiring upwards of 4-8 h to process. These requirements coupled with associated financial pressures may prevent effective deployment of such diagnostic tests. Loop mediated isothermal amplification(LAMP) is method of nucleic acid amplification which exhibits increased sensitivity and specificity are significantly rapid, and do not require expensive reagents or instruments, which aids in cost reduction for coronavirus detection. Studies have shown the successful application of LAMP assays in various forms to detect coronavirus RNA in patient samples, demonstrating that 1-10 copies of viral RNA template per reaction are sufficient for successful detection, ~100-fold more sensitive than conventional RT-PCR methods. Importantly, studies have also now demonstrated the effectiveness of LAMP methodology in the detection of SARS-CoV-2 RNA at significantly low levels, particularly following numerous improvements to LAMP assay protocols. We hypothesise that recent advancements in enhanced LAMP protocols assay perhaps represent the best chance for a rapid and robust assay for field diagnosis of COVID-19, without the requirement of specialized equipment and highly trained professionals to interpret results. Herein, we present our arguments with a view to disseminate such findings, to assist the combat of this virus that is proving so devastating. We hope that this strategy could be applied rapidly, and confirmed for viability with clinical samples, before being rolled out for mass-diagnostic testing in these current times.

Project description:The COVID-19 pandemic caused by SARS-CoV-2 has infected millions worldwide, therefore there is an urgent need to increase our diagnostic capacity to identify infected cases. Although RT-qPCR remains the gold standard for SARS-CoV-2 detection, this method requires specialised equipment in a diagnostic laboratory and has a long turn-around time to process the samples. To address this, several groups have recently reported the development of loop-mediated isothermal amplification (LAMP) as a simple, low cost and rapid method for SARS-CoV-2 detection. Herein we present a comparative analysis of three LAMP-based assays that target different regions of the SARS-CoV-2: ORF1ab RdRP, ORF1ab nsp3 and Gene N. We perform a detailed assessment of their sensitivity, kinetics and false positive rates for SARS-CoV-2 diagnostics in LAMP or RT-LAMP reactions, using colorimetric or fluorescent detection. Our results independently validate that all three assays can detect SARS-CoV-2 in 30 min, with robust accuracy at detecting as little as 1000 RNA copies and the results can be visualised simply by color changes. Incorporation of RT-LAMP with fluorescent detection further increases the detection sensitivity to as little as 100 RNA copies. We also note the shortcomings of some LAMP-based assays, including variable results with shorter reaction time or lower load of SARS-CoV-2, and false positive results in some experimental conditions and clinical saliva samples. Overall for RT-LAMP detection, the ORF1ab RdRP and ORF1ab nsp3 assays have faster kinetics for detection but varying degrees of false positives detection, whereas the Gene N assay exhibits no false positives in 30 min reaction time, which highlights the importance of optimal primer design to minimise false-positives in RT-LAMP. This study provides validation of the performance of LAMP-based assays as a rapid, highly sensitive detection method for SARS-CoV-2, which have important implications in development of point-of-care diagnostics for SARS-CoV-2.

Dataset Information

Development of loop-mediated isothermal amplification (LAMP) assays for rapid detection of Ehrlichia ruminantium.

Publications

Development of loop-mediated isothermal amplification (LAMP) assays for rapid detection of Ehrlichia ruminantium.

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