Figure 9.

Escape from the phagosome. Several pathogens escape from the phagosome to persist in the less harsh environment of the cytoplasm. (a) The intracellular pathogen Listeria monocytogenes uses its virulent factor listeriolysin O (LLO) (264) and phospholipases (PLC and PLD) (265) to escape the phagosome. Once in the cytosol, the bacterium is propelled by the formation of actin “comet tails” that push it across the cell, allowing it to transfer between cells (266–268). (b) Staphylococcus aureus can escape from neutrophil phagosomes (269) by producing phenol soluble modulins (PSM), which are peptides with lytic activity toward many mammalian cells (270). (c) The fungus Cryptococcus neoformans escapes the cell by vomocytosis (257, 258). Here, the phagosome fuses with the cell membrane with assistance of the secreted phospholipase B1 (PLB₁) (260), leaving the pathogen free and the phagocytic cell alive.