FIG 6.

A simplified schematic representation of the B. pseudomallei intra- and intercellular life cycles. Initial nonphagocyte host cell attachment occurs via flagella, type 4 pili, and adhesins BoaA and BoaB. Cellular invasion is facilitated by the T3SS, which injects effector proteins, including BopA, BopE, BipB, BipC, and BipD. During internalization the bacterium is enveloped by the host cell in an endocytic vesicle or endosome. Survival within the endosome occurs via multiple processes, including production of a protease inhibitor, ecotin. Escape from the endosome is mediated by the T3SS and subsequent upregulation of biosynthesis pathways, including purine, histidine, fatty acid, and amino acid, aid in replication within the cytosol. Bacilli may localize to nuclei or form a BimA-dependent actin tail used for motility and intercellular spread. The T6SS forms a bridge between host cells and transfers effector proteins which aid the formation of MNGC.