Chlamydia species are obligate intracellular pathogens with a unique biphasic lifecycle initiated by the attachment of the metabolically quiescent elementary body to the host cell and subsequent invasion into a plasma-membrane derived vacuole termed an inclusion body. Inside the inclusion, EB transform into metabolically active reticulate bodies that remain associated with the inclusion membrane. Chlamydia RB are thought to interact with the host cell cytoplasm across the inclusion membrane using the type III secretion injectisome. Chlamydiae are capable of commandeering host cell pathways to acquire lipids, cholesterol, and other nutrients crucial for growth and replication and some of these functions may be mediated by T3S. RB continue to replicate until an unknown GI 254023X signal triggers differentiation into EB, which temporally coincides with detachment of the RB and the T3S injectisome from the inclusion membrane. Chlamydiae then exit the cell through either lysis or a packaged release mechanism termed extrusion. The complete replication cycle takes approximately 48�C72 hours depending on the species. T3S is a virulence mechanism used by several Gram-negative bacteria, including Yersinia, E. coli, and Salmonella to inject effector proteins from the bacterial cytoplasm directly into the host cell. The T3SS consists of 20 to 25 components, all of which form a functional T3S injectisome. The needle filament protein extends from the bacterial outer membrane into the extracellular matrix, and houses a distal needle-tip complex. This needle-tip complex contains the needletip protein and the translocators, which are CBIQ involved in sensing the host cell and initiating secretion. Upon host cell contact, a signal is transmitted to the inner membrane effector recognition complex, which consists of several membrane proteins including an ATPase. The ATPase binds effector-chaperone complexes, dissociating the effector from their cognate chaperone followed by unfolding to facilitate their passage through the injectisome. The translocators present at the tip of the complex initiate pore formation in the host cell in preparation for effector secretion.