Reanalysis links two snail gene regions to schistosome resistance

A reanalysis of an older genome-wide association study identified two previously unreported genomic regions associated with resistance to Schistosoma mansoni infection in the freshwater snail Biomphalaria glabrata. The regions, named LG5R and LG11L, contain candidate genes encoding membrane-bound receptors and secreted lectins, respectively, adding to the genetic map of a host–parasite system involved in the transmission of schistosomiasis. Schistosomiasis is a major neglected tropical disease caused by trematodes in the genus Schistosoma.

Humans are infected through contact with freshwater in which schistosomes are shed from their intermediate hosts, freshwater snails. Snail control can reduce transmission, but it can be expensive and ecologically problematic. This motivates research into the genetic mechanisms behind variation in snail resistance, with the broader goal of identifying information that could support transmission reduction at the snail stage.

The present study does not itself demonstrate disease prevention or clinical benefit in humans. The researchers reanalyzed an older genome-wide association study dataset from B. glabrata snails experimentally challenged with S. mansoni. The analysis identified association signals at LG5R and LG11L.

LG11L contains a cluster of genes for a diverse set of secreted lectins, which the authors suggest could be involved in some form of recognition. LG5R contains a cluster of genes that appear to encode membrane-bound receptors. LG5R has a notable parallel with a recent genome-wide association study of the African snail Biomphalaria sudanica challenged by the same parasite species.

Genes in an adjacent genomic region in that study are very similar to the receptor-like genes identified at LG5R. The authors also compared LG5R with two previously described B. glabrata resistance-associated regions, PTC1/GRC and PTC2. Both contain clusters of genes for single-pass transmembrane proteins.

Together, the findings indicate that resistance-associated regions identified across these Biomphalaria–Schistosoma systems repeatedly include genes for secreted or membrane-associated molecules. The researchers hypothesize that proteins encoded by these clusters may participate in a matching-polymorphism mechanism, in which compatibility between snail and parasite populations depends on particular combinations of host and parasite variants. This proposed explanation remains a hypothesis rather than a demonstrated mechanism.

The work provides candidate loci for further study and places the new associations in the context of genome-wide mapping in Biomphalaria species, but determining which loci could best support transmission reduction in natural snail populations remains an open question that the present evidence does not resolve.

Subject of Research: Genome-wide mapping of snail loci associated with resistance to Schistosoma mansoni infection

Article Title: The growing repertoire of putative pathogen interaction genes in the Biomphalaria glabrata vs Schistosoma mansoni system

Article References: Calvelo, J., Bollmann, S. R., Tennessen, J. A., & Blouin, M. S. (2026). The growing repertoire of putative pathogen interaction genes in the Biomphalaria glabrata vs Schistosoma mansoni system. PLOS Neglected Tropical Diseases, 20(10), e0014803. https://doi.org/10.1371/journal.pntd.0014803

Image Credits: AI Generated

DOI: 10.1371/journal.pntd.0014803

Keywords: schistosomiasis, Biomphalaria glabrata, Schistosoma mansoni, snail resistance, genome-wide association study, secreted lectins, membrane receptors, matching polymorphism, host–parasite genetics, transmission, growing, repertoire