Cortical astrocytosis in juvenile rhesus monkeys infected with simian immunodeficiency virus.

The pattern of expression of GFAP immunoreactivity in astrocytes of the juvenile rhesus monkey cortex was examined following infection with simian immunodeficiency virus (SIV). Blocks of cerebral cortex plus subjacent white matter from saline- and formalin-perfused brain were examined by peroxidase-linked immunochemical and immunofluorescence staining of deparaffinized sections. Strong GFAP immunoreactivity was found in astrocytic cells in both uninfected and SIV-infected juvenile macaque in the subpial cerebral cortex and in subcortical white matter, where GFAP-positive cells were abundant. GFAP staining of cortical layers 2-6 on the other hand was weak or absent in three uninfected controls and one infected animal without cognitive impairment, but moderate to strong in animals productively infected with SIV that demonstrated cognitive and/or motor impairment. These data demonstrate a cortical locus of astrocytic activation in rhesus monkeys infected with primate immunodeficiency virus isolate SIVB670 which, like HIV-1 in man, causes motor/cognitive impairment as well as immunodeficiency disease.