Infection capacity of Salmonella Typhimurium mutants in phagocytic cells

MARIELA A. TORRES; MARIA CECILIA LECCESE TERRAF; MARÍA DE LAS MERCEDES PESCARETTI; CARLOS J MINHAK; MÓNICA A. DELGADO

Buenos Aires

Congreso; Reunión Conjunta de Sociedades de Biociencias 2017. LIII Reunión Anual Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB); 2017

Salmonella is among the main causative agent of foodborne diseases in Argentina. During the infection process, the virulence genes are regulated in response to different signals by several regulation systems in specific time and space. One of the most important regulatory mechanisms is the Salmonella RcsCDB system, which regulates the colanic acid and flagellum biosynthesis, and virulence genes, among others. The rcsC11 mutant used in this work has a point mutation that affects the ATPasa domain of the RcsC preventing the dephosphorlation of RcsB regulator. Therefore, the RcsCDB system is constitutively active, producing a mucoid phenotype and the attenuation of virulence. Previously, the rcsC11 mutant was subjected to stress conditions in order to study the stability of this mutation, and we found colonies with a different phenotype (smaller size). In this study we performed an infection assay with the aim to determinate the invasiveness and replication capacity of these strains. For this propose, we infected Raw 264.7 macrophage with the Salmonella wild-type strain, the rcsC11 mutant and the mutants with different phenotype previously found. The results showed that the rcsC11 mutant has an invasion capacity deficiency with respect to wild-type strain. In addition, we observed that rcsC11 and the mutants with different phenotype have a lower replication capacity within macrophages, where the rcsC11 mutant presents the lower levels. These properties allow us to propose this strain as a good candidate for the development of attenuated vaccines against enteropathogens.