SALMONELLA INVASION OF NONPHAGOCYTIC CELLS INDUCES FORMATION OF MACROPINOSOMES IN THE HOST-CELL

Salmonella typhimurium induced massive uptake of extracellular fluid i n epithelial cells in the form of macropinosomes. The appearance of ma cropinosomes in the infected cell was related to the induction of memb rane ruffling during bacterial invasion, A noninvasive S. typhimurium invA mutant did not trigger such effects in the host cell. Similarly, S. typhimurium invA mutants that invaded via the invasin protein from Yersinia pseudotuberculosis or adhered to the host cell ria the afimbr ial AFA-I adhesin from Escherichia coli did not trigger formation of m acropinosomes. In contrast to the formation of macropinosomes in macro phages, the appearance of macropinosomes in S. typhimurium-infected ep ithelial cells did not require microtubules. These data suggest that m assive uptake of extracellular fluid in S. typhimurium-infected epithe lial cells is an event related to the invasion mechanisms used by this pathogen.