Cells were transfected with either pcCIITA or empty pcDNA vector 4.5 hours prior to Lopinavir (NIH AIDS Research and Reference Reagent Program) or DMSO (vehicle-only) treatment at indicated concentrations. Virus and cell supernatants were collected approximately 17 hours post-treatment. For determina-tion of p160Gag-Pol to p55Gag ratios, producer cells were transfected with CIITA constructs (pcCITIA, GTP2, GTP3, L1035P) or vector only control (pcDNA) and then transfected with pNL4-3 16 hours later, prior to being treated with 80 nM Lopinavir. Cell lysates were used to monitor the levels of Pr55Gag to Pr160Pol via western blotting with HIV-1 a CA p24 (183-H12-5C) after 17 hours.