is an obligatory intracellular and cholesterol-dependent bacterium that has evolved special proteins and functions to proliferate inside leukocytes and cause disease. has a multigene family of major outer membrane proteins with porin activity and induces infectious entry using its entry-triggering protein to bind the human cell surface protein DNase X. During intracellular replication, three functional pairs of two-component systems are sequentially expressed to regulate metabolism, aggregation, and the development of stress-resistance traits for transmission. A type IV secretion effector of blocks mitochondrion-mediated host cell apoptosis. Several type I secretion proteins are secreted at the –host interface. strains induce strikingly variable inflammation in mice. The central role of MyD88, but not Toll-like receptors, suggests that species have unique inflammatory molecules. A recent report about transient targeted mutagenesis and random transposon mutagenesis suggests that stable targeted knockouts may become feasible in .


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