vector induces protective immunity againstandin murine model using prokaryotic expression system.

Abstract

BACKGROUND: is the causative agent of proliferative enteropathy and is associated with several outbreaks, causing substantial economic loss to the porcine industry. OBJECTIVES: In this study, we focused on demonstrating the protective effect in the mouse model through the immunological bases of two vaccine strains against porcine proliferative enteritis. METHODS: We used live-attenuatedTyphimurium (ST) secreting two selected immunogenic LI antigens (autotransporter A epitopes and flagellin [FliC]-peptidoglycan-associated lipoprotein-FliC) as the vaccine carrier. The constructs were cloned into aexpression vector (pJHL65) and transformed into the ST strain (JOL912). The expression of immunogenic proteins withinwas evaluated via immunoblotting. RESULTS: Immunizing BALB/c mice orally and subcutaneously induced high levels of LI-specific systemic immunoglobulin G and mucosal secretory immunoglobulin A. In immunized mice, there was significant upregulation of interferon-γ and interleukin-4 cytokine mRNA and an increase in the subpopulations of cluster of differentiation (CD) 4and CD 8T lymphocytes upon splenocytes re-stimulation with LI antigens. We observed significant protection in C57BL/6 mice against challenge with 10times the median tissue culture infectious dose of LI or 2 × 10colony-forming units of the virulent ST strain. Immunizing mice with either individual vaccine strains or co-mixture inhibited bacterial proliferation, with a marked reduction in the percentage of mice sheddingin their feces. CONCLUSIONS: -mediated LI gene delivery induces robust humoral and cellular immune reactions, leading to significant protection against LI and salmonellosis.