Anti-PirA-like toxin immunoglobulin (IgY) in feeds passively immunizes shrimp against acute hepatopancreatic necrosis disease.

Abstract

Acute hepatopancreatic necrosis disease (AHPND), caused by a toxin-producing Vibrio parahaemolyticus strain, has become a serious threat to shrimp aquaculture. The need to regulate antibiotic use prompted the development of alternative ways to treat infections in aquaculture including the use of chicken egg yolk immunoglobulin (IgY) for passive immunization. This study evaluated the protective effect of IgY against AHPND infection in Litopenaeus vannamei (Boone). IgY was isolated from eggs laid by hens immunized with recombinant PirA-like (rPirA) and PirB-like (rPirB) toxins. Whole-egg powders having IgY specific to rPirA (anti-PirA-IgY) and rPirB (anti-PirB-IgY) and IgY from non-immunized hen (control-IgY) were mixed with basal diets at 20% concentrations and used to prefeed shrimp 3days before the bacterial challenge test. Survival rates of the challenged shrimp fed the anti-PirA-IgY, anti-PirB-IgY and control-IgY diets were 86%, 14% and 0%, respectively. Only the feed containing anti-PirA-IgY protected shrimp against AHPND. Increasing the concentration of rPirA antigen to immunize hens and lowering the amount of egg powder in feeds to 10% consistently showed higher survival rates in shrimp fed with anti-PirA-IgY (87%) compared with the control (12%). These results confirm that addition of anti-PirA-IgY in feeds could be an effective prophylactic method against AHPND infection in shrimp.