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

Hemocytes from schistosome-resistant and schistosome-susceptible Biomphalar ia glabrata differ fundamentally in their behavior towards an invading para site. When the schistosome infects a resistant snail host it is quickly sur rounded by hemocytes, encapsulated and destroyed. Hemocytes from susceptibl e 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 di fferentially expressed fragments from resistant and susceptible snails were detected by DDRT-PCR and confirmed using single-strand conformation polymo rphism. These methods proved to be sensitive enough to allow comparison and verification of differential gene expression in our system, where only sma ll 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.