Loop-Mediated Isothermal Amplification in Schistosomiasis

Abstract

Human schistosomiasis is one of the most important parasitic diseases, causing around 250 million cases (mostly in Africa) and 280,000–500,000 deaths every year. Due to the limited resources and the far-removed nature of many endemic areas, the implementation of new, sensitive and specific diagnostic tools has had little success. This is particularly true for PCR-based molecular methods that require expensive equipment and trained personnel to be executed. Loop-mediated isothermal amplification (LAMP) along with other isothermal techniques appeared in the early 21st century as an alternative to those methods, overcoming some of the aforementioned limitations and achieving a more inexpensive diagnostic. However, to this date, neither LAMP nor any other isothermal technique have signified a meaningful change in the way schistosomiasis diagnosis is routinely performed. Here, we present the recent developments in LAMP-based schistosomiasis diagnosis. We expose the main advantages and disadvantages of LAMP technology over PCR and other classical diagnostic methods focusing in various research approaches on intermediate hosts, animal models and patients. We also examine its potential clinical application in post-therapy monitoring, as well as its usefulness as a point-of-care test.

Molecular Techniques as Alternatives of Diagnostic Tools in China as Schistosomiasis Moving towards Elimination

“…The LAMP technique, which uses isothermal conditions to amplify DNA, is relatively simple, cost-effective, rapid, and more field-friendly compared with commonly used PCR-based methods [ 51 , 112 ]. Isothermal amplification does not require specific equipment, such as a thermocycler, electrophoresis apparatus, UV transilluminator, etc., while only a heating block or hot water bath is required for the reaction to progress [ 83 , 113 , 114 ]. The amplification results can be judged by precipitation turbidity of magnesium pyrophosphate or color reaction with the naked eye [ 115 ].…”

“…Hence, it is more suitable in resource-poor settings and grass-roots units. In addition, the four specific primers designed for six regions of target genes make the assay highly specific [ 113 , 114 ]. Of course, the LAMP technique has some shortcomings that need to be improved.…”

“…Although DNA amplification-based molecular diagnostic techniques for schistosomiasis japonica truly have made gratifying progress in recent 20 years, continuous efforts are still needed to establish accurate, field-deployable diagnostics, meeting the demands of national control programs and adapting to resource-limited and low prevalence endemic settings. It should also be noted that the current variable temperature and isothermal DNA amplification techniques present several important disadvantages in real application, including complicated DNA extraction, inseparable cryogenic storage, instability, carry-over contamination, and the unfriendliness of large-scale screening [ 51 , 113 , 116 , 117 ]. Nucleic acid extraction is a pivotal procedure, and it may be a bottleneck in DNA detection assays since the yield and quality of DNA directly affect the outcome of the amplification procedure.…”

Context-Specific Procedures for the Diagnosis of Human Schistosomiasis – A Mini Review

“…NAATs have also demonstrated to be very useful for detection and strain typing of hybrid schistosome infections (3). To overcome the need for expensive laboratory equipment and highly trained personnel, more field-friendly alternatives have been developed, such as for example loopmediated isothermal amplification (LAMP) (64,65) and recombinase polymerase amplification (RPA) (6,66), although both need further validation.…”

Diagnostic performance of a urine-based ELISA assay for the screening of human schistosomiasis japonica: A comparative study

“…Improved coprological tests, such as the saline gradient method ( Coelho et al, 2009 ), formalin-ethyl acetate sedimentation-digestion (FEA-SD) ( Xu et al, 2012 ), and the Helmintex method (a procedure that isolates eggs from fecal samples with the use of paramagnetic particles in a magnetic field) ( Lindholz et al, 2018 ), showed increased diagnostic sensitivity compared with the traditional techniques; on the down side, these procedures are usually labor-intensive, and have a lengthy processing time. Molecular methods based on polymerase chain reaction (PCR) technology, including real-time quantitative (q)PCR ( Cnops et al, 2013 ; Gordon et al, 2015 ; Magalhaes et al, 2020 ; Mu et al, 2020 ; Halili et al, 2021 ), loop-mediated isothermal amplification (LAMP) ( Gandasegui et al, 2015 , 2018 ; Garcia-Bernalt Diego et al, 2021 ), and droplet digital (dd) PCR-based tests ( Weerakoon et al, 2016 , 2017a , b ), are alternatives for schistosomiasis surveillance due to their exceptional diagnostic performance; however, these tests are expensive (e.g., the high price of DNA extraction, qPCR assay reagents, and equipment), and require experienced human resources, making their implementation in resource-limited areas challenging.…”