Biompha-LAMP: A New Rapid Loop-Mediated Isothermal Amplification Assay for Detecting Schistosoma mansoni in Biomphalaria glabrata Snail Host

Abstract

BackgroundSchistosomiasis remains one of the most common endemic parasitic diseases affecting over 230 million people worlwide. Schistosoma mansoni is the main species causing intestinal and hepatic schistosomiasis and the fresh water pulmonate snails of the genus Biomphalaria are best known for their role as intermediate hosts of the parasite. The development of new molecular monitoring assays for large-scale screening of snails from transmission sites to detect the presence of schistosomes is an important point to consider for snail control interventions related to schistosomiasis elimination. Our work was focussed on developing and evaluating a new LAMP assay combined with a simple DNA extraction method to detect S. mansoni in experimentally infected snails as a diagnostic tool for field conditions.Methodology/Principal findingsA LAMP assay using a set of six primers targeting a sequence of S. mansoni ribosomal intergenic spacer 28S-18S rRNA was designed. The detection limit of the LAMP assay was 0.1 fg of S. mansoni DNA at 63°C for 50 minutes. LAMP was evaluated by examining S. mansoni DNA in B. glabrata snails experimentally exposed to miracidia at different times post-exposure: early prepatent period (before cercarial shedding), light infections (snails exposed to a low number of miracidia) and detection of infected snails in pooled samples (within a group of uninfected snails). DNA for LAMP assays was obtained by using a commercial DNA extraction kit or a simple heat NaOH extraction method. We detected S. mansoni DNA in all groups of snails by using no complicated requirement procedure for DNA obtaining.Conclusions/SignificanceOur LAMP assay, named Biompha-LAMP, is specific, sensitive, rapid and potentially adaptable as a cost-effective method for screening of intermediate hosts infected with S. mansoni in both individual snails and pooled samples. The assay could be suitable for large-scale field surveys for schistosomes control campaigns in endemic areas.

Field and laboratory comparative evaluation of a LAMP assay for the diagnosis of urogenital schistosomiasis in Cubal, Central Angola

“…At present, LAMP technology has all the characteristics required of a high-efficiency diagnostic assay along with simple operation for potential use in the clinical diagnosis of infectious diseases, including point-of-care testing under field conditions in developing countries [21,22]. Additionally, several LAMP assays have already been successfully used for detecting DNA from several schistosomes species, including Schistosoma japonicum, Schistosoma mansoni and S. haematobium [23][24][25][26][27][28][29][30][31][32][33].…”

Molecular detection of prepatent Schistosoma mansoni infection in Biomphalaria glabrata snail vectors

“…Subsequently, the same group reported the molecular identification of the parasite, targeting a mitochondrial DNA repeat in S. mansoni that allowed its detection in infected B. glabrata, with absence of non-specific (spurious) bands. This result points to the selectivity and specificity of this marker in the previous identification of infected snail hosts 4,7 . Since then, other studies aimed at performing the molecular diagnosis of infection in intermediate hosts have been developed and employed the loop-mediated isothermal amplification 4,5,8 .…”

“…In Brazil, one of the main intermediate hosts of this parasite is the Biomphalaria glabrata snail [1][2][3] . The early detection of larval stages in intermediate hosts is an important challenge to public health, but it has the potential to detect positive snail hosts before the emergence of cercariae, thus becoming a new alternative to detect intramollusc forms 4,5 , revealing reliable parasite prevalence rates. The objective of this study is to evaluate the prepatent detection of S. mansoni DNA in B. glabrata snails using the polymerase chain reaction (PCR) 14 days after snails exposed to miracidia.…”

Diagnóstico da infecção de Biomphalaria glabrata por Schistosoma mansoni em área de baixa endemicidade no Estado de São Paulo, utilizando técnicas de biologia molecular

“…A região cefalopodal foi eleita como a melhor para esse trabalho, pois, é onde ocorre o primeiro contato parasitário com início da multiplicação das células germinativas e diferenciação em esporocisto primário Lenzi, 2008;Neves, 2002;Guaraldo et al, 1981). Gandasegui et al, 2016Gandasegui et al, , 2018Jannotti-Passos et al, 2006;Hamburger et al, 2017).…”

“…Assim, representa uma inovação, uma vez que, a nested PCR e outras técnicas moleculares anteriormente analisadas tem como desvantagens um aumento da possibilidade de contaminação, ou a falta de um controle interno da reação (Janotti-Passos et al, 1997;Gandasegui et al, 2016;Santos Carvalho, 2017 (Guaraldo et al, 1981;Ohlweiler e Kawano, 2002;Simões et al, 2017;Pinaud et al, 2019).…”