Variable inhibition of pSTAT1 by DENV clinical isolates.

(A) Clinical isolates from each DENV (1–4) serotype or (B) from all DENV-2 genotypes (American, Southeast Asian, Asian/American, and cosmopolitan) were tested for their ability to inhibit IFN-α/β signaling. A549 cells were infected with DENV strains at an MOI = 2 for 24 hours and stimulated with IFN-β for 30 minutes. Cells were processed and stained with fluorescently labeled anti-DENV and anti-pSTAT1 antibodies. The percent of pSTAT1 was calculated from cells in cells infected with DENV. Experiments were performed in triplicate. Results shown are representative of four independent experiments. Data are expressed as means ± standard deviation. Statistical evaluation was carried out by one-way analysis of variance (ANOVA) followed by Dunnett's t-test for multiple comparisons. * = P < 0.05.