A proteomic approach envisaged to analyse the bases of oyster tolerance/resistance to bonamiosis

The European flat oyster Ostrea edulis is highly susceptible to infection by the protozoan Bonamia ostreae, an intracellular parasite able to survive and proliferate within the oyster haemocytes. On the contrary, the Pacific cupped oyster Crassotrea gigas is resistant. Two-dimensional electrophoresis was adapted to analyse the proteins of the oyster haemolymph. Comparisons of the haemolymph protein profiles between the two oyster species and between O. edulis stocks with different susceptibility to bonamiosis were performed. Differences in the number of proteins detected from each oyster species/stock were recorded; the highest number corresponded to the species resistant to bonamiosis, whereas the lowest number corresponded to the most susceptible O. edulis stock. Protein spots exclusive to each species and stock were detected; identification of those proteins could help to understand the key of tolerance/resistance to bonamiosis. Comparison between “healthy” and B. ostreae infected oysters was also performed. A substantial reduction of the number of proteins in the oyster haemolymph associated with B. ostreae infection was recorded. Protein spots exclusive to healthy and infected groups were detected; identification of haemolymph proteins whose synthesis is induced, repressed, up regulated or down regulated should help to understand the inability of O. edulis to neutralise or overcome B. ostreae infection. The results support a promising utility of 2-D electrophoresis, applied to the analysis of haemolymph proteins, to understand the oyster–B. ostreae interaction and to find the bases of tolerance/resistance to bonamiosis.