An isoenzyme marker possibly associated with the susceptibility of Biomphalaria glabrata populations to Schistosoma mansoni.

Nine laboratory populations and one field population of the snail host Biomphalaria glabrata were compared with respect to their electrophoretic patterns for acid phosphatase (AcP) and with their susceptibility to Schistosoma mansoni infection. A strong correlation (r = 0.98) was noted between the frequency of the isoenzymes AcP2-S and Acp2-F observed in the populations and the level of snail susceptibility as determined by bioassay. The isoenzyme AcP2-S was associated with susceptibility, AcP2-F with the refractory state. Breeding experiments between refractory and susceptible snails demonstrated that the refractory state was dominant and all F1 snails exhibited the AcP2-F isoenzyme and proved refractory to infection.