Loop mediated isothermal amplification (LAMP) assays as a rapid diagnostic for COVID-19

Abstract

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.

Keywords: COVID-19; Coronavirus; Diagnostic; Loop mediated isothermal amplification (LAMP); Polymerase chain reaction (PCR).

Conflict of interest statement

Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Copyright © 2020 Elsevier Ltd. All rights reserved.

Figures

Fig. 1

The impact of rapid detection of infectious diseases in controlling and preventing an outbreak. Figure adapted from Nguyen et al 2020 .

Fig. 2

Demonstrating the outcome of the LAMP assay using a colorimetric change to detect presence of COVID-19 viral DNA in A) simulated patient samples employed by El-Tholoth et al., 2020 (darker colour represents a positive assay, while lighter colour represents negative assay result), and B) actual patient samples (n = 7) from Wuhan province in China, analysed by Zhang et al., 2020 (yellow colour represents positive assays, while pink tubes represent negative assay results. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)

Fig. 3

Schematic representation of the experimental procedure of the Penn-RAMP procedure in the same tube. While the reactions could be performed in separate tubes and combined later, this envisaged procedure ensures rapid and simple flow-through and prevents potential for contamination. Figure adapted from El-Tholoth et al., (2020).