VLPs rescue HIV-1 infectivity from pretreatment of MDDC with pattern recognition receptor (PRR) agonists. (A) MDDCs were incubated for 24 h with recombinant type I interferon (10 ng⁄mL IFN-α, 10 ng⁄mL IFN-β), or PRR agonists as indicated: 100 ng⁄mL LPS, 25 μg⁄mL poly(I:C) with no lipid carrier, or 2 μg⁄mL poly(dA-dT). Then, cells were treated for 3 h with media or VSV-G-pseudotyped SIVMAC-251 VLPs, followed by challenge with a VSV G-pseudotyped HIV-1NL4-3 GFP reporter virus (A) or with a CCR5-tropic, HIV-1NL4-3 GFP reporter virus (B). The percent GFP-positive cells was determined by flow cytometry 72 h after addition of the reporter virus. Error bars represent ± SD (n = 3). In each case, one representative example of at least three independent experiments is shown.