Efficacy of chitosan-based nanoparticle vaccine administered to broiler birds challenged with Salmonella.

Two experiments were conducted to evaluate the immune response of broilers vaccinated with Salmonella chitosan-nanoparticle (CNP) vaccine and challenged with Salmonella. The Salmonella CNP vaccine was synthesized with Salmonella enterica outer membrane proteins (OMPs) and flagellin proteins. In Experiment I, birds were orally gavaged with PBS or 500, 1000, or 2000μg of CNP vaccine 1 and 7d-of-age. At 14d-of-age, birds were orally challenged with 1 X 105 CFU/bird of live S. Enteritidis (SE). Macrophage-nitrite production 11d-post-challenge was higher (P<0.05) in the 500μg group when compared to the control. At d14 (8h-post-challenge), broilers vaccinated with 1000μg CNP had higher (P<0.05) serum anti-OMPs IgG and IgA and cloacal anti-OMP IgA amounts. At 11d-post-challenge, birds vaccinated with 1000μg CNP vaccine had greater (P<0.05) bile anti-OMP and anti-flagellin IgA amounts. At 11d-post-challenge, birds administered 1000μg CNP vaccine has increased (P<0.05) IL-1β and IL-10 mRNA in cecal tonsils. In Experiment II, birds were orally gavaged with PBS or 1000μg CNP or a live commercial vaccine at 1 and 7d-of-age. At 14d-of-age, birds were orally challenged with 1 X 105 CFU/bird of live SE or S. Heidelberg (SH). Birds vaccinated with CNP showed higher (P<0.05) serum anti-OMPs IgG amounts at 8h-post-challenge. At 4d-post-SH challenge, birds vaccinated with CNP had higher (P<0.05) bile anti-flagellin IgA amounts. CNP decreased (P<0.05) anti-OMPs IgG levels in serum at 2d-post-SE challenge and 4d-post-SH or SE challenge. Salmonella Enteritidis loads in cecal content at 2d-post-challenge was decreased (P<0.05) by 65.9% in birds vaccinated with CNP, when compared to the control. Chitosan-nanovaccine had no adverse effects on bird's production performance. In conclusion, 1000μg CNP vaccine can induce a specific immune response against Salmonella and has the potential to mitigate SE cecal colonization in broiler birds.