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Constitutively Expressed phoP Inhibits Mouse‐Virulence of Salmonella typhimurium in an Spv‐Dependent Manner
Author(s) -
Matsui Hidenori,
Kawakami Takatoshi,
Ishikawa Satoshi,
Danbara Hirofumi,
Gulig Paul A.
Publication year - 2000
Publication title -
microbiology and immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.664
H-Index - 70
eISSN - 1348-0421
pISSN - 0385-5600
DOI - 10.1111/j.1348-0421.2000.tb02519.x
Subject(s) - virulence , biology , plasmid , microbiology and biotechnology , mutant , gene , salmonella , enterobacteriaceae , escherichia coli , bacteria , genetics
In Salmonella typhimurium , the transcription of several virulence genes including spvB is regulated by the PhoP/PhoQ regulatory system. To further examine the relationship between the PhoP/PhoQ and Spv systems for virulence in mice, we examined a non‐polar phoP mutation combined with different virulence plasmid genotypes for effects on virulence of S. typhimurium in the mouse model. PhoP – /Spv + PhoP – / Spv – mutants were not detectably recovered from the spleens of subcutaneously or orally inoculated mice. The phoP gene constitutively expressed from the lacZ promoter of a low copy number vector ( phoP C ) only partially complemented the non‐polar phoP mutation for mouse‐virulence in both the Spv + Spv – backgrounds; both PhoP C strains exhibited virulence equal only to a PhoP + /Spv – strain. Interestingly, in a PhoP + background, the phoP C gene reduced splenic infection of the Spv + but not Spv – salmonellae after subcutaneous or oral inoculation compared with the PhoP + parents. Additionally, the phoP C gene in an Spv + background reduced the net growth of salmonellae in macrophages in vitro; phoP C in an Spv – background was without effect. These data suggest that the constitutive expression of the phoP gene attenuates the virulence of S. typhimurium in mice in an Spv‐dependent manner.