Figure 2. Endogenous IFI16 is IFN-inducible and restricts HIV-1.

(A) Expression of IFI16 in primary macrophages (MDM) and CD4+ T cells. Cells were either left untreated or stimulated for 3 days with IL-2 [10 ng/ml] alone or together with IFNα2 [500 U/ml], IFNγ [200 U/ml], anti-CD3/CD28 beads or TNFα [20 ng/ml] and analyzed by Western blot. The left panel shows examples of primary data from two donors and the right panel shows mean IFI16 levels of five donors ± SEM. IFI16 expression levels were normalized to the corresponding GAPDH control. * p<0.05, ** p<0.01.

(B) IFI16 restricts infectious HIV-1 production in macrophages. Monocyte-derived macrophages were treated with IFI16-specific or control siRNA and transduced with VSV-G pseudotyped NL4-3 or infected with HIV-1 AD8. Infectious virus production was determined by infection of TZM-b1 cells. Each point represents data obtained from one donor.

(C) LTR-driven eGFP expression in macrophages transduced with VSV-G pseudotyped HIV-1 NL4-3 IRES-eGFP constructs after treatment with control or IFI16-specific siRNA. Shown are mean eGFP fluorescence intensities obtained by flow cytometry at 3 days post-transduction from four donors (±SEM).

(D) PMA-differentiated parental, IFI16 or STING KO THP-1 cells were transduced with the indicated VSV-G pseudotyped viruses. Three days later, supernatants were harvested and infectious virus yield was determined by infection of TZM-b1 cells. Mean values of three independent experiments ± SEM are shown. See also Figure S2.