Prolonged inhibition of bacterial protein synthesis abolishes Salmonella invasion.

We have found that prolonged inhibition of bacterial protein synthesis abolishes the ability of Salmonella typhimurium to enter HEp-2 cells. Our results suggest that an essential invasion factor has a functional half-life that is seen as a gradual loss of invasiveness in the absence of protein synthesis. Therefore, Salmonella invasiveness appears to be a transient phenotype that is lost unless protein synthesis is maintained. This finding may explain why salmonellae grown to stationary phase lose their ability to enter cultured cells. In addition, a short-lived capacity to enter cells may be important during infection so that bacterial invasiveness is limited to certain times and host sites during pathogenesis.