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Monday, 7 July 2014

Survival inside the Phagocyte.

http://en.wikipedia.org/wiki/Phagocyte

Bacteria have developed ways to survive inside phagocytes, where they continue to evade the immune system.To get safely inside the phagocyte they express proteins called "invasins". When inside the cell they remain in the cytoplasm and avoid toxic chemicals contained in the phagolysosomes.Some bacteria prevent the fusion of a phagosome and lysosome, to form the phagolysosome.Other pathogens, such as Leishmania, create a highly modified vacuole inside the phagocyte, which helps them persist and replicate.Legionella pneumophila produces secretions that cause the phagosome to fuse with vesicles other than the ones that contain toxic substances.Other bacteria are capable of living inside of the phagolysosome. Staphylococcus aureus, for example, produces the enzymes catalase and superoxide dismutase, which break down chemicals—such as hydrogen peroxide—produced by phagocytes to kill bacteria.Bacteria may escape from the phagosome before the formation of the phagolysosome: Listeria monocytogenes can make a hole in the phagosome wall using enzymes called listeriolysin O and phospholipase C.

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