Mechanism of intracellular bacterial parasitism

Algorithm of intracellular bacterial parasitism does not depend on if bacterium is obligate or facultative intracellular parasite. Depending on replicative niche’s localization intracellular bacterial parasites are divided onto cellular and vacuolated. Rickettsia spp., Shigella spp., Chlamydia spp. and Listeria monocytogenes use cell’s machinery of actin polymerization during process of their intracellular parasitism. These bacteria possess some of effector’s proteins which contain domains identical to effector proteins from the host cell. Shigella spp. T3SS and autotransporter protein IscA provide this process together with spreading bacteria intra colonic epithelium. In contrast other intracellular bacterial parasites, Listeria monocytogenes switches from dissemination in cytosol to persist in vacuole. In case of Brucella spp. the leading role in the creation of a replicative niche and in the modulation of the innate immune response is played by effector proteins of fourth type secretory system (T4SS).