SALMONELLA-TYPHI RPOS MUTANT IS LESS CYTOTOXIC THAN THE PARENT STRAINBUT SURVIVES INSIDE RESTING THP-1 MACROPHAGES

Transcription of the stationary-phase sigma factor RpoS of Salmonella typhi increased in the macrophage. A single rpoS mutant of S. typhi wa s constructed to analyze the role of RpoS in intracellular multiplicat ion of the bacterium and host cell killing. This mutant was sensitive to starvation, low pH and hydrogen peroxide; however, it could still m ultiply inside resting macrophages and was less cytotoxic than the wil d-type strain. Therefore, S. typhi might produce RpoS-dependent factor s which could contribute to host cell death. (C) 1998 Federation of Eu ropean Microbiological Societies. Published by Elsevier Science B.V.