CONJUGATIVE TRANSFER BY THE VIRULENCE SYSTEM OF LEGIONELLA-PNEUMOPHILA

Legionella pneumophila, the causative agent of Legionnaires' pneumonia , replicates within alveolar macrophages by preventing phagosome-lysos ome fusion. Here, a large number of mutants called dof (defective for organelle trafficking) that were unable to replicate intracellularly b ecause of an inability of the bacteria to alter the endocytic pathway of macrophages were isolated. The dot virulence genes encoded a large putative membrane complex that functioned as a secretion system that w as able to transfer plasmid DNA from one cell to another.