Identification ofGenes Preferentially Expressed after Phagocytosis byand Involvement of Methionine Sulfoxide Reductases.

Abstract

Free-living protozoa affect the survival and virulence evolution of pathogens in the environment. In this study, we explored the fate ofwhen co-cultured with the bacteriovorous ciliateand investigated bacterial gene expression associated with the co-culture. Virulentstrains were found to have ability to evade digestion in the vacuoles of this protozoan. In, a total of 116 genes were identified as up-regulated following co-culture withby selective capture of transcribed sequences (SCOTS) and comparative dot-blot analysis. A large proportion of these genes (42/116) play a role in metabolism, and some of the genes have previously been characterized as required for bacterial survival and replication within macrophages. Then, we inactivated the genes encoding methionine sulfoxide reductases,, and, in. Compared to the wild-type, the mutants Δand Δdisplayed significantly reduced resistance to predation by, and 50% lethal dose (LD) determinations in zebrafish demonstrated that both mutants were highly attenuated. This study forms a solid foundation for the study of mechanisms and implications of bacterial defenses.