Evaluation of immune response and resistance to diseases in tiger shrimp, Penaeus monodon fed with biofilm of Vibrio alginolyticus

Immune response in juvenile tiger shrimp, Penaeus monodon fed with biofilm (BF) and free cells (FC) of Vibrio alginolyticus was studied by evaluating the hemocyte count, phenoloxidase activity and antibacterial activity. The above immune responses were higher in BF fed shrimp than that in FC fed or control shrimp. Among the different doses of BF of V. alginolyticus tested, 109 cfu g−1 shrimp day−1 for two weeks could evoke higher immune response. BF fed shrimp were more resistant to injection challenge with V. alginolyticus and whitespot syndrome virus (WSSV) with significantly higher RPS compared to that with FC fed and control shrimp. Better resistance was also reflected by rapid clearance of V. alginolyticus and WSSV from the hemolymph as confirmed by immunodot and histopathology.