Recent data from our group indicate that null mutants of Salmonella enterica in genes encoding for Naps (nucleoid-associated proteins) are attenuated for virulence and capable of inducing protection, in different degrees in a murine model of infection. These results suggest an important role of the Naps proteins on bacterial virulence. Based on this, the aim of this project is improve the studies on the biological role of the Naps IhfA and IhfB on S. Typhimurium and Enteritidis and to assess the potential of these strains as live vaccine strains for use in the commercial poultry industry, concerning the superiority of live attenuated vaccines in face of bacterins. This propose will be achieved through various experiments to confirm the attenuation of these strains in chickens and subsequent evaluation of the prevention of mortality and reduction of systemic infection and fecal excretion of S. Enteritidis and S. Typhimurium in groups of chickens vaccinated with the attenuated mutant strains and challenged experimentally. Once the vaccine potential of attenuated strains is confirmed, experiments to ensure the safety of the mutant strains about the reversal virulence potential and security to overdose administration will be carried out. In a last step, in order to better understand and evaluate the role of Naps in the virulence of S. enterica, a transcriptome using the RNA-seq approach will be performed with the vaccine strains in comparison to wild-type strains into the chickens macrophage cell line HD11.
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