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Figure 3: APC crypts, exosomes/microvesicles (MVs), filopodia, and tunneling nanotubes (TNTs) are associated with HIV-1 trans infection of T cells. HIV-1 infected APCs enhance trans infection of T cells by transferring (a) infectious virus within crypts (extracellular invaginations), (b) release of infected exosomes that express CD1b and tetraspanins, and transporting virus harbored within endosomal MVs expressing CD1b and tetraspanins; (c) viral Nef and cellular dia2 and cdc42 proteins rearrange actin filaments in the infected APC membrane to form filopodia; virus buds from the tips to form the virus synapse with the T cells, which involves ICAM/LFA-1 adhesion molecules and CD4/CCR5 (CXCR4) viral receptors. (d) Virus is transported through within TNT conduits and on the outside (“surfing”) of TNTs directly into T cells.