HIV-1 and the Blood-Brain Barrier
Central nervous system (CNS) dysfunction represents a common and serious manifestation of HIV-1 infection. Approximately one-third of adults and one-half of children with AIDS have neurological complications, which are directly attributable to infection of the CNS by HIV-1 (1,2). Neurological manifestations of primary HIV-1 infection are associated with an accelerated progression of disease (3), and the presence of progressive encephalopathy has been correlated with poor outcome (4). The exact timing of HIV-1 infection of the CNS is unknown. Several studies have shown entry of HIV-1 into the CNS early after infection (5-13); however, how HIV-1 enters the CNS is unclear. HIV-1-associated neurological dysfunction occurs in the absence of opportunistic infections, implying the limited role of coinfection in the pathogenesis of HIV-1 encephalopathy. In addition, neurological impairment has been shown to be the first signs of HIV-1-related diseases in some cases (6,9).