{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,15]],"date-time":"2026-07-15T14:42:59Z","timestamp":1784126579018,"version":"3.55.0"},"reference-count":49,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2025,2,10]],"date-time":"2025-02-10T00:00:00Z","timestamp":1739145600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Microbiol."],"abstract":"<jats:sec><jats:title>Background<\/jats:title><jats:p><jats:italic>Salmonella enteritidis<\/jats:italic> (<jats:italic>SE<\/jats:italic>) 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 <jats:italic>SE<\/jats:italic> is imperative. Attenuated live vaccines are capable of eliciting robust immune protection against <jats:italic>SE<\/jats:italic>.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods<\/jats:title><jats:p>In this study, an <jats:italic>mcpC<\/jats:italic> gene deletion strain (\u0394<jats:italic>mcpC<\/jats:italic>) was constructed by the wild strain C50336, to evaluate its potential as a genetically engineered attenuated live vaccine. The virulence of \u0394<jats:italic>mcpC<\/jats:italic> was assessed by examining its resistance to environmental stresses, biofilm formation capacity, motility, adhesion, invasion ability, intracellular survival, LD<jats:sub>50<\/jats:sub>, expression levels of virulence genes, and <jats:italic>in vivo<\/jats:italic> colonization ability. Furthermore, the immunogenicity of \u0394<jats:italic>mcpC<\/jats:italic> was analyzed in mice by measuring specific IgG and SIgA antibody levels, lymphocyte proliferation, cytokine expression, and the protective efficacy of \u0394<jats:italic>mcpC<\/jats:italic> vaccination.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>Compared to the wild-type strain, \u0394<jats:italic>mcpC<\/jats:italic> exhibited no significant changes in biofilm formation or adhesion to Caco-2 cells. However, \u0394<jats:italic>mcpC<\/jats:italic> 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<jats:sub>50<\/jats:sub> of \u0394<jats:italic>mcpC<\/jats:italic> increased by 30-fold, and the expression levels of certain virulence genes were significantly downregulated. Additionally, \u0394<jats:italic>mcpC<\/jats:italic> demonstrated significantly decreased colonization in the liver, spleen, and cecum of mice, indicating attenuated virulence. Immunization with \u0394<jats:italic>mcpC<\/jats:italic> 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 \u0394<jats:italic>mcpC<\/jats:italic> provides effective immune protection in mice.<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusion<\/jats:title><jats:p>This study demonstrates that deletion of the <jats:italic>mcpC<\/jats:italic> gene attenuates the virulence of <jats:italic>SE<\/jats:italic>. The \u0394<jats:italic>mcpC<\/jats:italic> offers strong immune protection in mice, providing a solid foundation for the development of genetically engineered attenuated live vaccines against <jats:italic>SE<\/jats:italic>.<\/jats:p><\/jats:sec>","DOI":"10.3389\/fmicb.2025.1548920","type":"journal-article","created":{"date-parts":[[2025,2,10]],"date-time":"2025-02-10T06:50:22Z","timestamp":1739170222000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":2,"title":["The mcpC mutant of Salmonella enteritidis exhibits attenuation and confers both immunogenicity and protective efficacy in mice"],"prefix":"10.3389","volume":"16","author":[{"given":"Lu","family":"Zhang","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Li","family":"Chen","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xuqiang","family":"Zhang","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yang","family":"Li","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Qingfeng","family":"Zheng","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yun","family":"Li","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ning","family":"Li","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Qiumei","family":"Shi","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yanying","family":"Zhang","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Tonglei","family":"Wu","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2025,2,10]]},"reference":[{"key":"ref1","doi-asserted-by":"publisher","first-page":"e00237","DOI":"10.1128\/JB.00237-20","article-title":"Role of OB-fold protein YdeI in stress response and virulence of Salmonella enterica serovar Enteritidis","volume":"203","author":"Arunima","year":"2020","journal-title":"J. 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