Differential display analysis of hemocytes from schistosome-resistant and schistosome-susceptible intermediate hosts

Hemocytes from schistosome-resistant and schistosome-susceptible Biomphalaria glabrata differ fundamentally in their behavior towards an invading parasite. When the schistosome infects a resistant snail host it is quickly surrounded by hemocytes, encapsulated and destroyed. Hemocytes from susceptible hosts fail to kill the parasite. To detect the differences between these two host phenotypes, we used differential-display reverse-transcription PCR (DDRT-PCR), based on RNA extracted from isolated hemocytes. A number of differentially expressed fragments from resistant and susceptible snails were detected by DDRT-PCR and confirmed using single-strand conformation polymorphism. These methods proved to be sensitive enough to allow comparison and verification of differential gene expression in our system, where only small numbers of cells are available. The most interesting phenotype-specific fragments detected so far show sequence homologies to an adhesion molecule, defensin, serine/ threonine kinases, peroxidases and glycosidases.