LOW SUSCEPTIBILITY OF RESIDENT MICROGLIA TO SIMIAN IMMUNODEFICIENCY VIRUS-REPLICATION DURING THE EARLY STAGES OF INFECTION

To assess the susceptibility of resident microglia to simian immunodef iciency virus (SIV) infection, we analysed the brains of rhesus macaqu es after intracerebral (i.c.) inoculation of the virus into the centra l region at 7 days, 1, 2 and 3 months post-inoculation (p.i.). The bra ins of animals showed the same moderate neuropathological changes in c entral, frontal and parietal regions of the brain, characterized by gl iosis, microglial nodules, perivascular infiltrates and occasional whi te matter pallor and similar low numbers of infected cells detected by in situ hybridization. These results, showing that i.c. inoculation d id not lead to preferential infection of brain tissue. even near the i noculation point at 7 days p.i., provide evidence for the low suscepti bility of resident microglia to SIV replication during the early stage s of infection.