Abstract: Compositions, methods and kits are provided for identifying at least one virulence factor of a Gram-negative bacterial strain, and for preparing attenuated bacterial strain vaccines or a modulator that selectively binds to or inhibits expression of the virulence factor. The Gram-negative bacterial strain is a short facultatively aerobic or micro-aerobic rod or an enteric strain including at least one pathogen selected from the group of: Salmonella, Escherichia, Yersinia, Klebsiella, Shigella, Enterobacter, Serratia, Pseudomonas, and Citrobacter. Novel genes encoding virulence factors are identified, so that non-virulent mutant strains are available for vaccine development.

Abstract: The disclosure relates to compounds and methods of inhibiting type three secretion system effector molecules, to methods of detecting compounds that inhibit Yops translocation, and to methods of treating or preventing infections by administering compounds described herein to a subject in need thereof.

Abstract: Attenuated strains of Gram negative bacteria carrying a mutation in one or more ysc genes or homologs are provided, as are methods of use for immunization against infection with a pathogenic strain and for delivery of a therapeutic agent.

Abstract: Attenuated strains of Gram negative bacteria carrying a mutation in one or more ysc genes or homologs are provided, as are methods of use for immunization against infection with a pathogenic strain and for delivery of a therapeutic agent.