Mannose-Modified Chitosan-Nanoparticle-Based Salmonella Subunit OralVaccine-Induced Immune Response and Efficacy in a Challenge Trial in Broilers

Abstract

Controlling Salmonella enterica serovar Enteritidis (SE) infection in broilers is a huge challenge. In this study, our objective was to improve the efficacy of a chitosan nanoparticle (CS)-based Salmonella subunit vaccine for SE, containing immunogenic outer membrane proteins (OMP) and flagellin (FLA), called the CS(OMP+FLA) vaccine, by surface conjugating it with mannose to target dendritic cells, and comparing the immune responses and efficacy with a commercial live Salmonella vaccine in broilers. The CS(OMP+FLA)-based vaccines were administered orally at age 3 days and as a booster dose after three weeks, and the broilers were challenged with SE at 5 weeks of age. Birds were sacrificed 10 days post-challenge and it was observed that CS(OMP+FLA) vaccine surface conjugated with both mannose and FLA produced the greatest SE reduction, by over 1 log10 colony forming unit per gram of the cecal content, which was comparable to a commercial live vaccine. Immunologically, specific mucosal antibody responses were enhanced by FLA-surface-coated CS(OMP+FLA) vaccine, and mannose-bound CS(OMP+FLA) improved the cellular immune response. In addition, increased mRNA expression of Toll-like receptors and cytokine was observed in CS(OMP+FLA)-based-vaccinated birds. The commercial live vaccine failed to induce any such substantial immune response, except that they had a slightly improved T helper cell frequency. Our data suggest that FLA-coated and mannose-modified CS(OMP+FLA) vaccine induced robust innate and adaptive cell-mediated immune responses and substantially reduced the Salmonella load in the intestines of broilers.

A Novel Approach against Salmonella: A Review of Polymeric Nanoparticle Vaccines for Broilers and Layers

“…However, there are currently no killed vaccines that are delivered through the oral route to provide dual systemic and mucosal protection for poultry flocks. Recent research has adapted the use of modern nanotechnology to improve the poultry industry [ 78 , 80 , 102 , 103 , 104 , 105 , 106 , 107 , 108 , 109 ]. The use of a biodegradable nanoparticle that protects the vaccines antigens from the harsh pH of the GIT and that can be “programmed” to deliver the antigens to the intestinal PPs is a new step towards innovative vaccines.…”

“…Few studies have assessed the effects of Salmonella chitosan nanoparticle vaccines in chickens. Recent studies designed and demonstrated the immune response of broilers and layers to an oral chitosan nanoparticle (CNP)-based vaccine against Salmonella [ 78 , 102 , 103 , 104 , 105 , 106 , 107 ]. For these studies, the Salmonella subunit CNP vaccine was synthesized to contain S. enteritidis immunogenic outer membrane proteins (OMPs) and flagellin protein combined with a flagellin surface coating.…”

“…Multiple studies with broilers and layers identify that the loaded CNP can induce significantly higher antigen-specific mucosal IgA production at different time points postvaccination and postchallenge [ 78 , 102 , 103 , 104 , 105 , 106 , 107 ]. The OMPs- and flagellin-specific IgA antibody response in serum, cloacal swabs, bile, small intestine, and tracheal wash samples are significantly increased at different time-points across studies, demonstrating that the vaccine under study can provide an antigen-specific mucosal immune response that is essential against enteric pathogens.…”

Chitosan Nanoparticle Based Mucosal Vaccines Delivered Against Infectious Diseases of Poultry and Pigs

“…Whereas, lower dose (10 µg antigen), vaccination at young age (3rd day), and two or three doses of nanovaccine administration heightened the systemic and mucosal antibody, cell mediated immune response, TLRs gene expression, resulting in reduced S. Enteritidis load in the cecum (Han et al, 2020a). Mannose receptor is expressed on dendritic cells and macrophages, targeting them using mannose ligand conjugated nanovaccine elicited enhanced cell mediated immune response, and in without mannose conjugated nanovaccine received birds observed increased mucosal antibody response, while both the nanovaccines formualtions reduced the challenge Salmonella load in the intestines comparable to a commercial live vaccine (Han et al, 2020b). Altogether, our broiler experiments revealed that the selection of antigen, vaccine dose, age of birds vaccinated and the type of modifications on CS NPs are important to achieve robust immune response and protective efficacy against Salmonella.…”

Chemical Conjugation Strategies for the Development of Protein-Based Subunit Nanovaccines

“…Negatively charged nanovaccines with a size smaller than 100 nm may have potentially more specific immunomodulatory capacity, as they do not interact with positively charged non-immune cells [45]. The capacity for antigen-associated NPs to elicit immune responses can be strengthened by incorporating targeting moieties on the NP surface to improve their recognition by APCs [46][47][48][49][50]. Various targeting moieties, such as mannose and antibodies, have been used for this purpose for different subsets of APCs [48,49,51,52].…”