Susceptibility and immune response of Catarina scallop (Argopecten ventricosus) against Vibrio parahaemolyticus, the causative agent of AHPND in shrimp

Susceptibility and immune response of Argopecten ventricosus challenged with Vibrio parahaemolyticus were determined. Mortality and median lethal concentration of V. parahaemolyticus were assessed in scallop seeds and adults challenged by immersion. Histopathological analysis was done in adults challenged by immersion. The immune response was analyzed in adults by injecting heat-inactivated bacteria in the adductor muscle. Hemolymph samples were taken at 0, 8, 24, 48, and 72 h. Time zero corresponded to samples of scallop hemolymph before challenging with vibrio. In bioassays, scallops were fed with microalgae concentrate Shellfish Diet 1800®. Seeds and adults of A. ventricosus were susceptible to V. parahaemolyticus showing a LC₅₀ of 623 CFU mL^{− 1} and 62,853 CFU mL^{− 1}, respectively. V. parahaemolyticus toxins caused lesions in digestive glands of adults analyzed. Significant variations were observed in hemocyte number, phenoloxidase activity, and lysosomal hydrolytic enzymes, mainly at 8 and 24 h, post infection. Results confirm that seeds and adults of A. ventricosus are susceptible to V. parahaemolyticus infection, but seeds are more susceptible than adults. In adults, the immune response of A. ventricosus was modulated by V. parahaemolyticus.