Viral DNA load from peripheral blood mononuclear cells (PBMC) in the upper culture well of the Transwell co-culture system at 7 and 14 days post ex vivo culture with PBMC from cat 165 (A) and 187 (B). Cells were cultured in media alone (NoTx), media containing 1 uM SAHA (S), SAHA and allogenic SPF PBMC (S+P), or SAHA, allogeneic PBMC, and a mitogen (5 ug/mL concanavalin A) (S+P+M). FIV gag transcripts were normalized to cellular GAPDH; the average and standard deviation of triplicate measurements are displayed (BLD – below the limit of detection). A schematic of the concept behind the Transwell co-culture system is shown in (C), where naïve SPF PBMC are co-cultured with FIV-infected PBMC separated by a 400 nm permeable membrane. Putative antilatency therapy (ALT) is used to reactivate latent virus in the lower well.