Salmonella typhimurium mutants lacking flagella or motility remain virulent in BALB/c mice

H. A. Lockman, R. Curtiss

Research output: Contribution to journalArticlepeer-review

102 Scopus citations


Nonmotile flagellated (mot) and nonflagellated (fla) mutants of Salmonella typhimurium LT-2 were isolated from a collection of mutants with random Tn10-insertion mutations. Both classes of mutants were resistant to infection by the flagellotropic bacteriophage χ. The nonflagellated (fla::Tn10) mutants did not react with H antigen-specific antisera and did not possess flagella when examined by electron microscopy, and sheared-cell extracts were devoid of flagellin. The nonmotile (mot::Tn10) mutants reacted with H-specific antisera and expressed paralyzed flagella that were indistinguishable from wild-type flagella. The tn10 insertions in strain LT-2 were mapped to loci in regions II (flh and mot) and III (fli) of the flagellar genes, and the mutations were transduced into the mouse-virulent S. typhimurium strains SR-11 and SL1344. Lack of motility reduced the ability of S. typhimurium to invade Henle cells in vitro, yet the virulence in mice of the nonmotile mutants of SR-11 and SL1344 was unaffected by the inactivity or loss of flagella. Wild-type SR-11 had a 50% lethal dose (LD50) in BALB/c mice following oral (p.o.) challenge of 2.4 x 104 CFU. The p.o. LD50 of the SR-11 fli-8007::Tn10 mutant was 4.5 x 104 CFU. The mot-8008::Tn10 mutation in SR-11 conferred paralyzed flagella and increased the p.o. LD50 in mice to 22 x 105 CFU, but this was not statistically significant. A similar increase in the p.o. LD50 was observed when the SL1344 mot-8008::Tn10 mutant was tested in mice. Wild-type SR-11 and the isogenic nonflagellated and nonmotile mutants were equally virulent in mice challenged via intraperitoneal injection.

Original languageEnglish (US)
Pages (from-to)137-143
Number of pages7
JournalInfection and immunity
Issue number1
StatePublished - 1990

ASJC Scopus subject areas

  • Parasitology
  • Microbiology
  • Immunology
  • Infectious Diseases


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