CHIKV interferes equally with the nuclear translocation of phospho-STAT1 in both HS 633T and HT-1080 cells . (A) Double immunostaining was performed for pSTAT1 (red) and CHIKV envelope E1 (green) using HS633T cells either mock-infected (a, b, c); IFN-α-stimulated (d, e, f); CHIKV-infected (g, h, i); and finally CHIKV-infected and IFN-α-stimulated (j, k, l), view X600. Nuclei were stained in blue with DAPI. All experiments were done in triplicate. (B) Percentage of HS 633T or HT-1080 cells with nuclear pSTAT1 from experiments performed in A. Cells were counted in three random fields and the results are expressed as mean ± standard error (**: p < 0.01).