Immune targets for schistosomiasis control identified by a genome-wide association study of African snail vectors

Schistosomiasis, a neglected tropical disease, is transmitted by freshwater snails. Interruption of transmission will require novel vector-focused interventions. We performed a genome-wide association study of African snails, Biomphalaria sudanica, exposed to Schistosoma mansoni in an endemic area of high transmission in Kenya. Two snail genomic regions, SudRes1 and SudRes2, were significantly associated with snail immunity to schistosomes. SudRes1 includes receptor-like protein tyrosine phosphatases while SudRes2 includes a class of leucine-rich repeat-containing G-protein coupled receptors, both comprising diverse extracellular binding domains suggestive of host-pathogen interaction. Resistant and susceptible haplotypes show numerous coding differences including presence/absence of entire genes. No loci previously tied to schistosome resistance in neotropical snail species showed any association with compatibility suggesting that loci involved in the resistance of African vectors are distinct. Snail ancestry was also strongly correlated with parasite compatibility. These results will inform future efforts to predict and manipulate immunity of a major schistosome vector.