Suppression-Subtractive Hybridization (SSH) was used to identify differentially expressed Ruditapes decussatus genes against the protozoan Perkinsus olseni infection. A total of 305 differentially expressed sequences were obtained, 221 of them in haemocytes and 84 in gills of infected clams. The pattern of expression of the immune selected genes was studied by quantitative PCR with samples of naturally Perkinsus infected clams and compared with samples from an in vitro infection of clam haemocytes with Perkinsus zoospores. The maximum expression was found 1h post infection. The complete open reading frames of selected sequences (Rd adiponectin-C1q and Rd DAD-1) were determined. Our results provide new insights into the molecular basis of host-pathogen interactions in R. decussatus.
