FIG. 6.

Detection of infectivity in transduced cells by a syncytium formation assay with Vero cells. Ninety percent confluent Vero cells were overlaid with piNT2 cells transduced for 12 days and nontransduced and incubated at 37°C to allow cell fusion. At 72 h, large syncytia were formed with nontransduced piNT2-HcRed cells (A), whereas smaller syncytia were formed with HcRed-positive cells and no syncytia were formed with EGFP-positive cells in overlays with shN1 (B)-, shP6 (C)-, and shL4 (D)-transduced cells. Enlargements as indicated show red syncytia and green single cells present in the cultures.