This work discusses the present-day limitations of current commercial Salmonella vaccines for broilers and layers and explores a novel approach towards poultry vaccination using biodegradable nanoparticle vaccines against Salmonella. With the increasing global population and poultry production and consumption, Salmonella is a potential health risk for humans. The oral administration of killed or inactivated vaccines would provide a better alternative to the currently commercially available Salmonella vaccines for poultry. However, there are currently no commercial oral killed-vaccines against Salmonella for use in broilers or layers. There is a need for novel and effective interventions in the poultry industry. Polymeric nanoparticles could give way to an effective mass-administered mucosal vaccination method for Salmonella. The scope of this work is limited to polymeric nanoparticles against Salmonella for use in broilers and layers. This review is based on the information available at the time of the investigation.

There is a critical need for an oral-killed Salmonella vaccine for broilers. Chitosan nanoparticle (CNP) vaccines can be used to deliver Salmonella antigens orally. We investigated the efficacy of a killed Salmonella CNP vaccine on broilers. CNP vaccine was synthesized using Salmonella enterica serovar Enteritidis (S. Enteritidis) outer membrane and flagella proteins. CNP was stable at acidic conditions by releasing 14% of proteins at pH 5.5. At 17 h post-incubation, the cumulative protein release for CNP was 75% at pH 7.4. Two hundred microliters of PBS with chicken red blood cells incubated with 20 μg/ml CNP released 0% hemoglobin. Three hundred chicks were allocated into 1) Control, 2) Challenge, 3) Vaccine + Challenge. At d1 of age, chicks were spray-vaccinated with PBS or 40 mg CNP. At d7 of age, chicks were orally-vaccinated with PBS or 20 μg CNP/bird. At d14 of age, birds were orally-challenged with PBS or 1 × 10⁷ CFU/bird of S. Enteritidis. The CNP-vaccinated birds had higher antigen-specific IgY/IgA and lymphocyte-proliferation against flagellin (p < 0.05). At 14 days post-infection, CNP-vaccinated birds reversed the loss in gut permeability by 13% (p < 0.05). At 21 days post-infection, the CNP-vaccinated birds decreased S. Enteritidis in the ceca and spleen by 2 Log₁₀ CFU/g, and in the small intestine by 0.6 Log₁₀ CFU/g (p < 0.05). We conclude that the CNP vaccine is a viable alternative to conventional Salmonella poultry vaccines.

The objective of this study was to identify the effects of experimental necrotic enteritis (NE) infection on the production performance, gut microbiome, and cecal tonsil transcriptome in broiler birds. A total of 192 chicks were not-induced (control) or induced with NE. NE was induced by inoculating Eimeria maxima at 14 d of age and Clostridium perfringens at 19, 20, and 21 d of age. NE challenge increased (p < 0.01) NE lesion score at 7 days post-E.maxima infection (dpi), decreased (p < 0.01) average weight gain and increased (p < 0.01) mortality at 7 and 14 dpi. NE challenge increased (p < 0.05) gut permeability at 5, 6, and 7 dpi and increased ileal C. perfringens load at 5 dpi. NE challenge increased (p < 0.01) Eimeria oocyst shedding at 5, 6, 7, 8 and 14 dpi. NE challenge decreased (p < 0.05) the relative abundance of Lactobacillaceae and increased (p < 0.05) the relative abundance of Campylobacteriaceae, Comamonadaceae, and Ruminococcaceae at 6 dpi. NE challenge upregulated (p < 0.05) genes related to immune response and downregulated (p < 0.05) genes related to lipid metabolism at 6 dpi. It can be concluded that NE infection decreased beneficial bacteria and increased gut permeability.