(A-C) HEK293T cells were cotransfected with increasing
doses of expression constructs for IFI16 (0.004, 0.02, 0.1, 0.5 and 2.5
μg) and constant quantities (2.5 μg) of the proviral HIV-1 NL4-3
construct. Cells and supernatants were harvested 40 hours post-transfection.
Data show mean percentages (±SEM) relative to those detected in the
absence of IFI16 (100%) and were derived from three experiments each performed
in triplicate. * p < 0.05, ** p < 0.01, *** p < 0.001.
(A) Infectious virus yield and p24 antigen levels in the
HEK293T cell supernatants determined by TZM-b1 cell infection assay and p24
antigen ELISA, respectively. (B) Levels of different viral
transcripts determined by qRT-PCR in multiplex reactions with GAPDH as control.
(C) Expression of HIV-1 proteins, IFI16 and GAPDH in viral
particles or cellular extracts was determined by Western blot.
(D) IFI16 does not induce IFN in HEK293T cells lacking
STING expression. HEK293T cells were transfected with the indicated constructs
(1 μg) or infected with Sendai virus (SeV). 40 hours later, cells and
supernatants were harvested. Cells were used for Western blot analysis and
supernatants were used to stimulate HL116 IFN-reporter cells in triplicates. An
IFNα standard curve was used for comparison. After 8 hours, luciferase
expression in the HL116 cells was determined. Shown are mean values from
triplicates ± SD. See also Figure S1.