Oral immunization of common carp with a liposome vaccine containing Aeromonas hydrophila antigen

Abstract

We developed a liposome vaccine in which Aeromonas hydrophila antigens were entrapped within the liposomal membrane compartment. Oral administration of the vaccine was found to immunize common carp Cyprinus carpio (mean body weight, 30 g) against A. hydrophila. Two fish groups received the liposome vaccine (protein concentration, 33 μg/mL) at doses of 10 and 30 μL/fish/day for a period of 3 days. The levels of antibodies in the serum rose at 2 and 3 wk post vaccination (p.v.) and then declined at 4 wk p.v.. When fish groups orally immunized with a total of 30 μL/fish for 3 days were challenged by an intra-subcutaneous injection with live A. hydrophila at a dose of 3.0 × 105 or 1.0 × 106 CFU/fish at 22 days p.v., the fish were protected against the bacterial infection with RPS of 63.6 or 55.0%, respectively. © 2006 The Japanese Society of Fish Pathology.