All conditions were tested in triplicate. Cells were incubated at 37°C and 5% CO2. The efficiency of transduction was confirmed by fluorescence microscopy. A luciferase reporter assay was used as described previously [24, 32] to confirm the ability of the recombinant Tax2 proteins to regulate viral transcription. Cell-free supernatants from Tax-treated PBMCs were harvested at various time-points and assayed for MIP-1α,

MIP-1β and RANTES expression by quantitative enzyme-linked immunosorbent assay (ELISA) (R&D Systems), as described previously [24]. Absorbance values at 490 nm were used to quantify the chemokine levels in

the culture EPZ6438 supernatants from the standard concentration curve and CC-chemokine protein levels were expressed in picograms per millilitre (pg/ml). To determine the activation of the canonical NF-κB pathway, immunofluorescence studies were performed using Tax-treated-PBMCs for an incubation period of 1 and 2 h. Cells were harvested, washed with phosphate-buffered saline (PBS), fixed and cytocentrifuged onto clean glass slides, then permeabilized with 0·3% Triton X-100 (Sigma) and blocked with 5% normal goat serum (Sigma) for 1 h at room temperature. Phosphorylated p65/RelA was detected with phospho-p65/RelA Tamoxifen monoclonal antibodies (mAbs) (diluted at 1:100) followed by FITC-labelled goat anti-rabbit IgG (H + L), F(ab′)2 mAbs (diluted at 1:200) and incubated at dark-room temperature for 1 h. 4′,6-Diamidino-2-phenylindole (DAPI; Sigma) was use to stain the nucleus. Slides were mounted using anti-fade fluorescent mounting very media. Jurkat and MoT cells were used as negative and positive controls. Images were acquired with an Olympus BX51 epifluorescence microscope equipped with an Olympus DP-70 controller digital

camera system and applicable computer capture software (Tokyo, Japan). ImageJ software was used to determine the intensity of cell fluorescence and the non-specific background was subtracted to obtain the corrected total cell fluorescence (CTCF) as integrated density – (area of selected cell × mean fluorescence of background readings) [33]. PBMCs (1 × 106/ml) were stimulated with 100 pM of recombinant Tax proteins and cells were harvested at 1 or 2 h. Nuclear extracts were obtained and tested for activation of p65/RelA and p50 subunits using the TransAM NF-κB DNA-binding ELISA kit (Active Motif, Carlsbad, CA, USA). Briefly, 10 μg of each nuclear extract were incubated in 96-well plates containing a consensus (5′-GGGACTTTCC-3′) binding site for NF-κB.