Early SIV encephalopathy.

SIV encephalopathy was studied in rhesus macaques early after intracerebral (IC) or intravenous (IV) inoculation. Although SIV was detected in the brain of all IC-inoculated animals, the CNS showed moderate neuropathological changes. IV-inoculated animals presented a spectrum of brain changes ranging from perivascular infiltrates to multinucleated giant cells. CNS infection was detected as early as seven days post-IV-inoculation, mostly in a perivascular localization. Using combined immunohistochemistry and in situ hybridization, infected cells were shown to express macrophage markers.