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Abstract
There are currently no licensed vaccines against C. perfringens, which causes necrotic enteritis in poultry. In aim 1, chitosan nanoparticles were formulated with native (CN) or toxoids (CT) extracellular proteins (ECP) from C. perfringens, both surface-tagged with Salmonella flagellar proteins. CN and CT were stable at pH 2 to 8, and when incubated at 100 μg/ml PBS with chicken red blood cells (cRBCs) released 1% and 0% hemoglobin, respectively. At 7.2 pH, CN had an average size of 389.7 nm and a zeta potential of -66.9 mV while CT had an average size of 352.5 nm and zeta potential of -63.6 mV. In aim 2, broilers were randomized to treatments;
sham-vaccinated (Control), CN-vaccinated (CN), and CT-vaccinated (CT). Each bird was orally sham-vaccinated or vaccinated with 50μg CN or CT on d 0, 3, 7 and 14 post-hatch. On d 17 post-hatch, the CN group had higher anti-flagellar IgG than control (P < 0.05). On d 21 posthatch, the CN group had higher anti-ECP IgA than control (P < 0.05) while the CN and CT group had higher anti-ECP IgA than control (P < 0.05). Splenic T-cells from the CN and CT groups ex-vivo stimulated with ECP had higher proliferation than control (P < 0.05). In aim 3, broiler chicks were randomized to treatments: non-vaccinated non-challenged (NVNC), vaccinated challenge (VC), and non-vaccinated challenge (NVC). On d 0, 7, and 14 post-hatch, VC birds were orally vaccinated with CN while NVC birds were sham-vaccinated. VC and NVC birds were challenged with E. maxima at d 14 post-hatch, and C. perfringens on d 19, 20, and 21
post-hatch. On d 18 post-hatch splenic T cells from VC birds had higher CD4/CD8 ratio than control and NVC (p < 0.05). On d 28 post-hatch, lesion scores and mortality were numerically lower in VC than NVC birds. FCR was significantly higher in VC than NVC birds (p < 0.05). In conclusion, the nanoparticle vaccine was safe immunogenic and partially protective in boilers. Further studies are needed to improve the efficacy of the vaccine and understand the mechanism underlying protection in vaccinated birds.
sham-vaccinated (Control), CN-vaccinated (CN), and CT-vaccinated (CT). Each bird was orally sham-vaccinated or vaccinated with 50μg CN or CT on d 0, 3, 7 and 14 post-hatch. On d 17 post-hatch, the CN group had higher anti-flagellar IgG than control (P < 0.05). On d 21 posthatch, the CN group had higher anti-ECP IgA than control (P < 0.05) while the CN and CT group had higher anti-ECP IgA than control (P < 0.05). Splenic T-cells from the CN and CT groups ex-vivo stimulated with ECP had higher proliferation than control (P < 0.05). In aim 3, broiler chicks were randomized to treatments: non-vaccinated non-challenged (NVNC), vaccinated challenge (VC), and non-vaccinated challenge (NVC). On d 0, 7, and 14 post-hatch, VC birds were orally vaccinated with CN while NVC birds were sham-vaccinated. VC and NVC birds were challenged with E. maxima at d 14 post-hatch, and C. perfringens on d 19, 20, and 21
post-hatch. On d 18 post-hatch splenic T cells from VC birds had higher CD4/CD8 ratio than control and NVC (p < 0.05). On d 28 post-hatch, lesion scores and mortality were numerically lower in VC than NVC birds. FCR was significantly higher in VC than NVC birds (p < 0.05). In conclusion, the nanoparticle vaccine was safe immunogenic and partially protective in boilers. Further studies are needed to improve the efficacy of the vaccine and understand the mechanism underlying protection in vaccinated birds.