Inhibition of Salmonella intracellular proliferation by non-phagocytic eucaryotic cells.

Salmonella typhimurium is an intracellular pathogen capable of proliferating within vacuolar compartments of non-phagocytic eucaryotic cells. This process has been shown to be essential for virulence in the mouse typhoid model (Leung and Finlay, Proc. Natl. Acad. Sci. USA, 88, 11470-11474, 1990). Here we present evidence that certain non-phagocytic eucaryotic cell lines, such as 3T3 (mouse fibroblasts) and NRK (rat fibroblasts) cells, are not permissive for S. typhimurium intracellular proliferation. Moreover, viability of intracellular bacteria residing within both cell types notably decreases at late postinfection times (72 h). These results clearly demonstrate that non-phagocytic eucaryotic cells are capable of destroying intracellular S. typhimurium. Experimentation with 3T3 and NRK cell lines might provide an appropriate in vitro model for identifying new bacterial and/or eucaryotic factors regulating Salmonella intracellular proliferation within vacuoles of the host eucaryotic cell.