Phagolysosomal escape by intracellular pathogens.

It has often been suggested that intracellular parasites invade cells in order to evade the host's immune response. Whether or not this view is correct, have successfully avoided excessive scrutiny by biomedical investigators. Published descriptions of the intracellular compartments occupied by parasites often contradict each other, reflecting the fact that the early events following host cell invasion remained, until recently, poorly understood. In this review, Norma Andrews and Paul Webster focus on what is now known about a dramatic transition that some parasites undergo after invading cells: escape from a membrane-bound vacuole into the cytosol. They discuss the information available on strategies for phagolysosomal escape of pathogens ranging from bacteria to protozoa, with emphasis on the cases in which the molecular mechanisms controlling this event have been investigated.