HIV also infects some susceptible cells

HIV also infects some susceptible cells in the central nervous system. The exact mechanism of HIV entry into the brain is unknown. Possible modes of entry across the blood-brain barrier include HIV entry as a single cell-free viral particle (virion), entry via infected monocyte or lymphocyte, and infection of endothelial cells (cells forming brain border). Regardless of the mechanism, evidence suggests that the cerebral spinal fluid is seeded with HIV very early in the infection process.

Although not all patients will follow them precisely, the course of AIDS generally progresses through the three stages (acute retroviral syndrome, latency period, and late-stage AIDS) that follow.