Small abalone (Haliotis diversicolor supertexta) is a high value-added shellfish. It however has been suffering Vibrio alginolyticus
infections, which cause mass death of small abalone and thus great economic losses, particularly in artificial aquaculture. In this study, we attempted to treat small abalone with anti-Vibrio
IgY to elicit a passive immunity directly against V. alginolyticus
infections. Anti-Vibrio
IgY was
alginate encapsulated in egg powders as feed, which may avoid antibody inactivation in the gastrointestinal tract of small abalone. The feed was tested for the stability of anti-Vibrio
IgY in a gastrointestinal mimic environment. The result showed anti-Vibrio
IgY retained activity as high as 90% after 4 h exposure to pancreatic
enzymes. Addition of 0, 5 or 10% anti-Vibrio
IgY-encapsulated egg powders into a basal diet to form abalone diet formulae. Small abalones fed with the anti-Vibrio
IgY formulae showed a relatively high respiratory burst activity than those without anti-Vibrio
IgY treatments. The survival rates of small abalones fed with 5 or 10% anti-Vibrio
IgY egg powders were in the range of 65-70% 14 days post-V. alginolyticus challenge (1 x 10⁶ c.f.u.), which was significantly higher than 0% of those fed without anti-Vibrio
IgY. The anti-Vibrio
IgY-encapsulated formulae were thus concluded to be an effective means to prevent small abalone from V. alginolyticus
infection, and may be practical in use in abalone aquaculture.