Effect of oral immunization with Aeromonas hydrophila ghosts on protection against experimental fish infection.

Abstract

AIMS: To investigate whether oral immunization with Aeromonas hydrophila ghosts (AHG) vaccine can elicit mucosal and systemic immune responses of Carp (Carassius auratus gibelio) compared to conventional formalin-killed bacteria (FKC). METHODS AND RESULTS: Fish were fed diets coated with AHG, FKC or phosphate buffered saline (PBS) alone, after immunization, more antigen-specific antibody was significantly detected in serum and intestinal mucus in AHG group than FKC group and PBS group. In addition, after challenged with the parent strain J-1, the survival of bacterial ghost-vaccinated fish was higher than PBS group and FKC group, the relative per cent survival (RPS) being 76.8%, 58.9%, respectively. CONCLUSIONS: Oral immunization with A. hydrophila ghosts can elicit systemic and mucosal adaptive immune responses and has higher potential to induce protective adaptive immunity than normal vaccine. SIGNIFICANCE AND IMPACT OF THE STUDY: Oral immunization with bacterial ghosts is a promising new solution with potential application to prevent diseases in fish.