Figure 1.

Schematic representation of the entry of HIV and its viral proteins into the brain. HIV enters the perivascular space (the main site for viral replication) by migration across the BBB via infected macrophages or blood lymphocytes or as free virions (viral particles) where it infects and activates macrophages, astrocytes, and microglia. The activation of these cells plays a key role in the release of proinflammatory cytokines and can amplify the alteration and permeability of the BBB. HIV-1 envelopes glycoprotein; attaches the virion to macrophages, astrocytes, and microglia; and induces the fusion of viral and cell membranes to initiate infection. It interacts with the chemokine receptor CCR5 or CXCR4 to allow viral entry by triggering large structural rearrangements and unleashing the fusogenic potential of gp41 to induce membrane fusion.