Inducible prophages contribute to Salmonella virulence in mice

Mol Microbiol. 1999 Jul;33(1):167-76. doi: 10.1046/j.1365-2958.1999.01461.x.


We show that Salmonella typhimurium harbours two fully functional prophages, Gifsy-1 and Gifsy-2, that can be induced by standard treatments or, more effectively, by exposing bacteria to hydrogen peroxide. Curing bacteria for the Gifsy-2 prophage significantly reduces Salmonella's ability to establish a systemic infection in mice. Cured strains recover their virulence properties upon relysogenization. Phage Gifsy-2 carries the sodC gene for a periplasmic [Cu,Zn]-superoxide dismutase previously implicated in the bacterial defences against killing by macrophages. The contribution of the Gifsy-1 prophage to virulence - undetectable in the presence of Gifsy-2 as prophage - becomes significant in cells that lack Gifsy-2 but carry the sodC gene integrated in the chromosome. This confirms the involvement of Gifsy-2-encoded SodC protein in Salmonella pathogenicity and suggests that the Gifsy-1 prophage carries one or more additional virulence genes that have a functional equivalent on the Gifsy-2 genome.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Base Sequence
  • Chromosomes, Bacterial / genetics
  • Escherichia coli Proteins*
  • Hydrogen Peroxide / pharmacology
  • Lysogeny
  • Mice
  • Mitomycin / pharmacology
  • Molecular Sequence Data
  • Nalidixic Acid / pharmacology
  • Salmonella Infections, Animal / microbiology*
  • Salmonella Phages / drug effects
  • Salmonella Phages / genetics
  • Salmonella Phages / growth & development
  • Salmonella Phages / physiology*
  • Salmonella typhimurium / drug effects
  • Salmonella typhimurium / genetics
  • Salmonella typhimurium / pathogenicity
  • Salmonella typhimurium / virology*
  • Superoxide Dismutase / genetics
  • Virulence / genetics
  • Virus Activation / drug effects


  • Escherichia coli Proteins
  • Nalidixic Acid
  • Mitomycin
  • Hydrogen Peroxide
  • Superoxide Dismutase
  • sodC protein, E coli

Associated data

  • GENBANK/AF147699