HIV mediates a productive infection of the brain

Background: Approximately one quarter of patients with AIDS develop severe cognitive deficits called HIV-associated dementia complex. There is some co ntroversy regarding the importance of viral load and distribution in mediat ing this neurologic disease. Objective: Brain HIV proviral and RNA loads were compared to define the mol ecular nature of HIV infection of the brain. Method: Neuropathologic examination was performed on brains from 10 autopsi es of patients with AIDS that had short post-mortem intervals and no eviden ce of opportunistic infection. Viral DNA and RNA were extracted and quantif ied from multiple brain regions. These findings were compared with triple-l abel immunofluorescence for viral and cell markers. Results: Brains with histopathologic evidence of HIV encephalitis contained abundant HIV RNA and DNA. Regions without productive HIV infection showed minimal proviral load. By immunocytochemistry, only brain macrophages/micro glia double labeled for viral proteins. Conclusions: HIV mediates a productive infection of brain macrophages/micro glia. There was no evidence supporting the hypothesis of substantial neuron al or macroglial infection, or evidence of substantial proviral burden prio r to the development of productive infection. (C) 1999 Lippincott Williams & Wilkins.