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 controversy regarding the importance of viral load and distribution in mediating this neurologic disease.

OBJECTIVE

Brain HIV proviral and RNA loads were compared to define the molecular nature of HIV infection of the brain.

METHOD: Neuropathologic examination was performed on brains from 10 autopsies of patients with AIDS that had short post-mortem intervals and no evidence of opportunistic infection. Viral DNA and RNA were extracted and quantified from multiple brain regions. These findings were compared with triple-label 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/microglia double labeled for viral proteins.

CONCLUSIONS

HIV mediates a productive infection of brain macrophages/microglia. There was no evidence supporting the hypothesis of substantial neuronal or macroglial infection, or evidence of substantial proviral burden prior to the development of productive infection.