Engagement of the EBV membrane-fusion complex is required for inhibition of DC development.

(A) Culture of monocytes in the presence of recombinant gp350/220 did not inhibit the development of DCs. Purified monocytes were cultured for 7 days in medium containing GM-CSF, IL-4, and the indicated concentration of purified recombinant gp350. Results are from 1 of 4 representative experiments. (B) CD14⁺ monocytes were infected with B95.8 virus or virus preincubated for 30 minutes at room temperature with 100 μg/mL mAb, as indicated. The inhibitory activity of the virus was blocked by mAb F-2-1, which interferes with the interaction of gp42 with HLA class II, and by E1D1, which prevents gp85–gp25-mediated membrane fusion and inhibits binding to epithelial cells in the absence of gp42. The 72A1 antibody to gp350 and OKT3 antibody to CD3 had no effect. Results from 1 of 2 experiments giving comparable results are shown. (C) Recombinant EBV lacking gp42 or gp85 showed a significantly impaired inhibitory activity compared to wild-type viruses derived from Akata or B95.8. Mean ± SD of 3 experiments.