Altering the balance between pathogen containing vacuoles and lysosomes: a lesson from Salmonella.

Intracellular pathogens like Salmonella, Mycobacteria and Listeria has several survival mechanisms to combat the host assault. One of the very interesting strategies observed in case of these intracellular bacteria is their ability to survive and replicate in specialized vacuole inside the infected cells. Salmonella, in its turn, resides in a low pH and nutritionally depleted compartment termed as Salmonella containing vacuole (SCV) which never fuses with the lysosomes. Using macrophage cells we have recently demonstrated a unique characteristic of the SCV. Our data indicates that during Salmonella cell division, the SCV also divides and always a single SCV contains only one bacterium. This actually increases the total SCV number in the Salmonella infected cells. Further, Salmonella infection reduces the lysosome numbers and gives the pathogen an upper hand in the infected cells. Here we will summarize and expand upon our previous findings.