FIG. 7.

Expression of CD21 in Raji cells and different epithelial cell lines. (A) FACS analysis of Raji cells, HeLa cells, 293 cells, and 293-TB cells for human CD21 surface expression. Cells (3 × 10⁵ for each cell line) were incubated with two anti-CD21 monoclonal antibodies (HB5 and FE8) and subsequently incubated with a Cy3-conjugated goat anti-mouse IgG antibody. As negative controls, each cell sample was incubated with the second antibody only. The results shown are representative of two independent experiments. (B) RT-PCR analysis. cDNA (100 ng) was used to amplify CD21-specific mRNA transcripts in Raji cells, HeLa cells, 293 cells, and 293-TB cells. (C) Infection inhibition experiment using the monoclonal antibody FE8. Cells (10⁵) were incubated with increasing amounts of the antibody for 20 min at 37°C. As indicated, 0.5 ml of supernatant containing either complemented mutant EBV (designated ‘wt EBV’) or BLLF1-negative EBV was added and incubated for 24 h. Afterwards, supernatant and antibody were removed, and fresh medium was added to the cells. After an additional 24 h, cells were evaluated for GFP expression. As controls, Raji cells were incubated with increasing amounts of the HB5 antibody, as described for FE8, prior to infection with BLLF1-KO EBV or complemented BLLF1 mutant virus (data not shown).