Parenteral immunization of fish, Labeo rohita with Poly d, l-lactide-co-glycolic acid (PLGA) encapsulated antigen microparticles promotes innate and adaptive immune responses

Immunogenicity of different antigen preparations of outer membrane proteins (OMP) of Aeromonas hydrophila such as Poly d, l-lactide-co-glycolic acid (PLGA) microparticles, oil emulsion, neat OMP and bacterial whole cells were compared through intra-peritoneal injection in fish, Labeo rohita. Among these preparations, PLGA encapsulated antigen stimulated both innate and adaptive immune parameters and the immunogenicity exhibited by PLGA microparticles was significantly higher (p < 0.05) at both 21 and 42 days post-immunization suggesting that the above delivery system would be a novel antigen carrier for parenteral immunization in fish, Labeo rohita