Protection Conferred by Drinking Water Administration of a Nanoparticle-Based Vaccine against Salmonella Enteritidis in Hens

Abstract

Salmonellosis remains a major medical and an unmet socioeconomic challenge. Worldwide, more than three million deaths per year are associated with Salmonella enterica serovar Enteritidis infections. Although commercially available vaccines for use in poultry exist, their efficacy is limited. We previously described a method for isolating a heat extract (HE) fraction of the cell surface of S. Enteritidis that contained major antigenic complexes immunogenic in hens naturally infected with the bacterium. One single dose of S. Enteritidis’ HE induced protection against lethal salmonellosis in mice. Furthermore, HE encapsulation in nanoparticles of the copolymer of methyl vinyl ether and maleic anhydride (PVM/MA), Gantrez AN, improved and prolonged the protection against the disease in mice. We formulated new preparations of Gantrez AN nanoparticles with HE S. Enteritidis and assessed their stability in drinking water and their efficacy in hens after experimental infection. The oral treatment of six-week-old hens with two doses of HE nanoparticles significantly reduced the Salmonella excretion in hens. Due to the effectiveness of the treatment in reducing bacterial excretion, we conclude that HE nanoencapsulation obtained from S. Enteritidis is a viable novel vaccination approach against salmonellosis in farms.

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.…”

“…As with chitosan, there are limited studies on polyanhydride-based Salmonella vaccines. Two major studies conducted in 2018 and 2021 with layers are highlighted [ 80 , 108 ]. Both studies utilized PVM/MA loaded with Salmonella antigens and administered to layer birds through oral gavage [ 80 ] and drinking water [ 108 ].…”

“…In the 2021 study [ 108 ], PVM/MA nanoparticles were loaded with a heat extract (HE) fraction of the cell surface of S. enteritidis strain 449 (NP-HE). The loaded NP-HE had an average size of 430 nm, which is optimal for DCs uptake.…”

“…The loaded NP-HE nanoparticle also demonstrated the capability to circumvent the current oral-antigen delivery problems. Results demonstrated that the nanoparticle sustained a high stability in tap water (pH 6.9) and acidic and basic pH for up to two hours [ 108 ]. The vaccine displays two very critical traits for the efficient delivery of vaccine’s antigens to the GIT; however, this study did not evaluate the mucoadhesion mechanism of the NP-HE nanoparticle vaccine upon oral administration to chickens.…”

“…For the same 2021 study, hens were immunized by oral gavage with two doses of NP-HE at 6 and 9 weeks of age and orally challenged with S. enteritidis strains [ 108 ]. Bacteriological analysis of cloacal swabs, cecum, liver, and spleen were done to assess the percentage of Salmonella -positive samples in immunized hens.…”