Baseline miRNA profiling and targeted expression analysis following Schistosoma mansoni challenge across Biomphalaria strains with distinct compatibility profiles

Schistosomiasis is a neglected tropical disease caused by Schistosoma spp., whose transmission depends on successful development within freshwater snails of the genus Biomphalaria . Host–parasite compatibility is a genetically determined and multifactorial phenotype that plays a central role in parasite transmission and is primarily mediated by the snail's internal defense system. Increasing evidence suggests that microRNAs (miRNAs) regulate immune responses and developmental pathways involved in host–parasite interactions; however, their contribution to compatibility between Biomphalaria spp. and Schistosoma mansoni remains poorly understood. In this study, we identified the miRNA repertoire of Biomphalaria species and lineages exhibiting distinct compatibility profiles with S. mansoni and investigated constitutive and infection-induced miRNA expression patterns to identify regulatory signatures associated with compatible and incompatible host–parasite interactions. Biomphalaria glabrata, Biomphalaria tenagophila, Biomphalaria straminea lineages exhibiting distinct compatibility profiles with the LE strain of Schistosoma mansoni were maintained under laboratory conditions. Hemolymph samples and Bge cells were subjected to small RNA sequencing to characterize the miRNA repertoire and identify differentially expressed miRNAs among snail populations using bioinformatic analyses. In addition, snails were experimentally exposed to S. mansoni miracidia, and hemolymph and cephalopodal mass samples were collected from exposed and non-exposed snails. The expression of five selected miRNAs (miR-8-3p, miR-184-3p, miR-750-3p, miR-1984-5p, and miR-1985-5p) was quantified by RT-qPCR to evaluate constitutive and infection-induced expression patterns. Small RNA sequencing revealed a conserved core repertoire of miRNAs shared among Biomphalaria together with species- and lineage-specific miRNA signatures. Comparative analyses identified distinct miRNA profiles between B. glabrata and B. tenagophila lineages exhibiting different compatibility phenotypes with S. mansoni , including specific expression patterns associated with higly compatible, partially compatible, partially resistant, and incompatible lineages. RT-qPCR analyses of selected miRNAs (miR-8-3p, miR-184-3p, miR-750-3p, miR-1984-5p, and miR-1985-5p) demonstrated tissue-dependent and parasite-responsive expression patterns across different Biomphalaria lineages. Integrated expression analyses showed that tissue origin had a greater influence on miRNA profiles than parasite exposure or compatibility status, with distinct miRNA signatures between hemolymph and cephalopodal mass. Furthermore, comparison between B. glabrata hemolymph and Bge cells revealed partially overlapping miRNA repertoires but distinct expression profiles, indicating that the cell line does not fully reproduce the in vivo miRNA landscape of the snail host. The Biomphalaria–Schistosoma mansoni compatibility is not determined by a single miRNA or miRNA-regulatory pathway, but rather by a complex network. Here, we identified conserved miRNAs, species-specific, tissue-specific, and infection-responsive expression patterns in three intermediate host species and different lineages. Among the identified candidates, miR-8, miR-184, miR-750, and miR-1985 emerged as potential regulators associated with host–parasite interactions. These findings provide the first comparative characterization of miRNA expression across the three major intermediate host species of S. mansoni in the Americas and highlight the importance of post-transcriptional regulation in shaping snail susceptibility and resistance. Future functional studies integrating miRNA targets, transcriptomic data, and experimental validation will be essential to elucidate the molecular mechanisms underlying compatibility and resistance in Biomphalaria spp.