Design, Development, and Interrogation of Salmonella Typimurium Minimal Effector Networks During Infection

Abstract

Pages 136-174 are misnumbered as pages 137-175.Salmonella enterica serovar Typhimurium utilize a Type Three Section System (T3SS) to deliver virulent "effector" proteins directly into the host cell cytoplasm. Some of these effectors have been biochemically characterized, but many of them can be deleted individually with little reduction in bacterial pathogenicity. Thus, determining the interrelationship between effector gene networks, host substrates, and pathogen virulence has been challenging. Using targeted mutagenesis and phenotypically informed genome reassembly, we engineered a minimal SPI-2 T3SS effector gene network that supports Salmonella enterica serovar Typhimurium (STm) intracellular replication in vitro and disease pathogenesis in a murine model of Typhoid-fever. Genetic analysis of the host immune response to this minimal effector gene network reveals a sophisticated interplay between host immunity and bacterial disease progression. Further analysis reveals the specific immune responses during infection at a dynamically novel resolution. The interplay between SPI-2 effector proteins and immune cell targets reveals an advanced complexity of host-pathogen interactions, illustrating the cooperation necessary to drive tissue tropism during bacterial pathogenesis and a powerful tool for interrogating effector functions in vivo which has further implications for Salmonella pathogenesis in the host