Final Activity Report Summary - PIMAQUABI (Pathogens and immune response of aquacultured bivalve molluscs) Bivalve culture is strikingly growing in importance in the aquaculture of many European Union Member States. Confinement and high density of cultured bivalve molluscs improve the development of pathogenic organisms. The protozoan parasite Perkinsus atlanticus, as well as bacteria of the genus Vibrio, are considered one of the most devastating pathogens in the culture of one of the most important species in Spanish aquaculture, the carpet-shell clam Ruditapes decussatus, producing important looses in condition and even high mortalities.The main goal of this project is the characterisation of pathology produced by the most important pathogens identified in aquacultured bivalve molluscs, the host-parasite relationships and the molecular basis of molluscs immune response developed against the infection, as well as the identification and characterisation of genes involved on the immune response of the bivalve mollusc carpet-shell clam.Ultrastructural analysis showed the important pathology produced by the parasite at tissue level. The study of hemolymph cellular and humoral parameters showed the active role of hemocytes in the immune response associated to the host defense against the pathogen infection. The search for genes implicated in the immune response of bivalves, carried out by the use of the Suppression subtractive hybridisation (SSH) technique, allowed the identification of differentially expressed genes in stimulated and non stimulated hemocytes and tissues.The identification of genes potentially involved in defence mechanisms such as new types of antimicrobial peptides, complement factor, genes with high similarity to C1q-TNF and also some specific C-type lectins are described and characterised in infected clams. The known and study of these genes with relevant role in immune defence, can lead to found useful response strategies and identify marker genes that could later be used in the selection for resistance to the diseases of bivalve populations.
