FIG. 1.

Multinucleated giant cell formation in uninfected microglial cells (A) and in microglial cultures infected with HIV-1_KJ-br (B), HIV-1_DS-br (C), or HIV-1_RC-br (D). Microglial cultures were infected as described in Materials and Methods, and syncytium formation was monitored 12 days after infection. Syncytium formation was also quantified by counting the number of nuclei and the number of cells and was consistent with these photomicrographs, which are representative of seven experiments with each of the illustrated isolates.