Fig. 1.

Schematic diagram of the salient systemic and central nervous system (CNS) disease components of human immunodeficiency virus (HIV) infection. CNS HIV infection and immune responses originate as extensions across the blood–brain and blood–cerebrospinal fluid barriers (horizontal dashed line) of their systemic counterparts, though with variable selection and local evolution depending on the stages of disease, and likely individual host factors. Within the nervous system, both the virus and immune responses may alter the integrity and function of the CNS in the depicted triangle of pathogenetic components.