Preparation of HIV Stocks

HEK293T17 cells (obtained from ATCC – cells were not tested for mycoplasma) were transfected with 89.6 or JR-CSF proviral plasmids (NIH AIDS Reagent Program) using 25kDa polyethylenimine (PEI; Polysciences). 40-48 hours post-transfection, culture supernatants were collected, centrifuged at 3000 xg for 10 minutes to remove cell debris, filtered through a 0.45 μm membrane to remove smaller aggregates and concentrated with PEG-it Virus Precipitation Solution (System Biosciences) as per manufacturer’s instructions and frozen at −80°C. Viral stocks were titered via p24 ELISA (Frederick National Laboratory for Cancer Research).