In vitro binding of parasites (Bonamia ostreae) and latex particles by hemocytes of susceptible and insusceptible oysters.

Bonamia ostreae is a protozoan parasite that has caused severe losses in the flat oyster (Ostrea edulis) industry in Europe. The cupped oyster (Crassostrea gigas), recently introduced and cultured in Europe, is not infected by the disease. In vitro tests were conducted to determine whether there was a difference in the ability of hemocytes from each species to recognize and bind inert foreign particles (fluorescent latex beads) and purified, infective B. ostreae. The results indicated no difference in their ability to bind latex beads, but C. gigas were able to bind more B. ostreae than were O. edulis. The relative inability of the O. edulis hemocytes to recognize the parasite is discussed as a possible factor in flat oyster susceptibility.