FIG 4.

ApoA1-mediated lipid raft depletion from ABCA1-expressing cells inhibits DENV2 attachment to the cell membrane. (A) RAW 264.7 cells were treated with 0.3 mM 8-Br-cAMP for 16 h. Total cell lysate was analyzed by Western blotting with anti-ABCA1. (B) Lipid rafts were quantified by flow cytometry of cells labeled with CTB-FITC. Control cells were treated with PBS (pH 7.4) or depleted with 3 mM MβCD for 2 h. ABCA1-expressing cells were treated with 100 μg/ml ApoA1 for 2 h. MFI was calculated relative to control cells. (C) After induced lipid raft depletion, RAW 264.7 cells were challenged with DENV2 for 1 h at 4°C for viral attachment. Unbound virus was washed out with PBS, and total RNA was extracted. vRNA was quantified by qRT-PCR. (D) ABCA1-expressing cells were incubated with ApoA1 for 2 h in the presence of different concentrations of NS1. Lipid rafts were quantified by flow cytometry of CTB-FITC. Each bar represents the SD of at least three biological replicates. Asterisks represent significant differences, compared to control. *, P < 0.01; **, P < 0.01; ***, P < 0.001.