The mcpC mutant of Salmonella enteritidis exhibits attenuation and confers both immunogenicity and protective efficacy in mice Article Swipe
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· 2025
· Open Access
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· DOI: https://doi.org/10.3389/fmicb.2025.1548920
· OA: W4407343726
Background Salmonella enteritidis ( SE ) is a Gram-negative, facultative anaerobic intracellular pathogen that not only causes disease and mortality in livestock and poultry but also contaminates animal-derived products, leading to foodborne illnesses in humans. This presents a significant threat to public health. To eliminate this pathogen, the development of novel vaccines targeting SE is imperative. Attenuated live vaccines are capable of eliciting robust immune protection against SE . Methods In this study, an mcpC gene deletion strain (Δ mcpC ) was constructed by the wild strain C50336, to evaluate its potential as a genetically engineered attenuated live vaccine. The virulence of Δ mcpC was assessed by examining its resistance to environmental stresses, biofilm formation capacity, motility, adhesion, invasion ability, intracellular survival, LD 50 , expression levels of virulence genes, and in vivo colonization ability. Furthermore, the immunogenicity of Δ mcpC was analyzed in mice by measuring specific IgG and SIgA antibody levels, lymphocyte proliferation, cytokine expression, and the protective efficacy of Δ mcpC vaccination. Results Compared to the wild-type strain, Δ mcpC exhibited no significant changes in biofilm formation or adhesion to Caco-2 cells. However, Δ mcpC showed significantly reduced survival under acidic, alkaline, thermal, and oxidative stress conditions; markedly diminished motility; weakened invasion of Caco-2 cells; and reduced intracellular survival in RAW264.7 macrophages. The LD 50 of Δ mcpC increased by 30-fold, and the expression levels of certain virulence genes were significantly downregulated. Additionally, Δ mcpC demonstrated significantly decreased colonization in the liver, spleen, and cecum of mice, indicating attenuated virulence. Immunization with Δ mcpC induced the production of specific IgG and SIgA antibodies, enhanced lymphocyte proliferation, upregulated cytokine expression, and achieved a 100% survival rate in immunized mice. These findings indicate that Δ mcpC provides effective immune protection in mice. Conclusion This study demonstrates that deletion of the mcpC gene attenuates the virulence of SE . The Δ mcpC offers strong immune protection in mice, providing a solid foundation for the development of genetically engineered attenuated live vaccines against SE .
