Decoding the Functionality of pESA3 in Cronobacter sakazakii: A Balancing Act between Survival and Pathogenicity

Purpose Cronobacter sakazakii is a foodborne pathogen notable for both virulence and desiccation tolerance. This study investigates the functional roles of the pESA3 plasmid in mediating these two traits and explores the potential trade-off between them. Methods Proteomic profiling identified pESA3 -encoded proteins, followed by construction of targeted deletion mutants ( hcp , ESA_pESA3p05542 ) and a plasmid-cured strain. Phenotypic assays evaluated growth, desiccation survival, surface hydrophilicity, and virulence in a neonatal rat model. Results Deletion of ESA_pESA3p05542 impaired desiccation tolerance and reduced surface hydrophilicity, while hcp deletion attenuated virulence but enhanced desiccation survival. Notably, complete loss of pESA3 abolished virulence without affecting desiccation resistance, suggesting functional antagonism between plasmid-encoded virulence and stress-response genes. Conclusions pESA3 enables C. sakazakii to balance host pathogenicity and environmental persistence. Its gene modules promote either virulence or desiccation resistance, but not both, reflecting an evolutionary trade-off that supports survival across diverse niches.