Effect of Formalin-Killed Vibrio anguillarum Administration on Immunity and Resistance to Vibrio harveyi in Pond-Reared Banana Shrimp Fenneropenaeus merguiensis

Abstract

The present study reports the effects of oral administration of formalin-killed Vibrio anguillarum on immune response parameters and resistance to Vibrio harveyi in banana shrimp, Fenneropenaeus merguiensis. The Vibrio bacterin was administered as a feed top-dressing at 108 cfu/kg feed, twice a week, for 120 days. Shrimp seed, produced at the institute’s hatchery, were stocked in 1500-m2 earthen ponds at the Navsari Agricultural University experimental station in Gujarat and adult shrimp (12±2.53 g) were collected at the end of the experimental period to determine immune response and protection against challenge with virulent V. harveyi. Total hemocyte counts, granulocyte counts, bacterial clearance tests, and phagocytic assays were used to evaluate in vivo and in vitro immune responses. Animals fed the bacterin had significantly (p<0.05) higher hemocyte and granulocyte counts and in vivo and in vitro immune responses than those fed the control feed. Bacterin-fed animals had significantly higher (p<0.05) relative survival (43-50%) than the control shrimp. Results suggest that oral administration of V. anguillarum bacterin can induce humoral and cellular immune responses and protect against V. harveyi infection in shrimp cultured in earthen ponds.