Spleens from DENV-2-infected mice were surgically removed at different time-points and single cell suspensions were prepared. Approximately 0·5 × 106 to 1 × 106 spleen cells were incubated with either 10 μg/ml of the indicated peptide, RPMI-1640 medium (Gibco) or PMA (0·1 μg/ml) + ionomycin (1 μg/ml). Golgi plug (BD Biosciences, San Jose, CA) was added to each of the selleck compound above samples and incubated at 37° for 6 hr. Cells
were washed with FACS buffer, blocked with Fc block (2.4G2) for 10 min and then surface stained with peridinin chlorophyll protein-Cy5.5-hCD45 (clone 2D1), phycoerythrin-Cy7-mCD45 (clone 30-F11), FITC-hCD3 (clone UCHT1), phycoerythrin-hCD8 (clone H1T8a) and Pacific Blue-hCD4 (clone RPAT4) antibodies for 20 min at room temperature. Cells were washed with FACS buffer, then permeabilized using Cytofix/Cytoperm buffer (BD Biosciences) and stained with allophycocyanin-hIFN-γ (clone B27) and Alexa700-TNF-α for 20 min at room temperature. AUY-922 In all experiments the viability marker LIVE/DEAD® Aqua (Molecular Probes, Eugene, OR) was added to exclude dead cells. All cell preparations were fixed with Cytofix (BD Biosciences). Cytokine levels were also assessed by ELISA; 0·5 × 106 to 1 × 106 spleen cells from DENV-2-infected mice
were incubated with either 10 μg/ml of the indicated peptide, RPMI-1640 medium (Gibco) or PMA (0·1 μg/ml) + ionomycin (1 μg/ml) and incubated at 37° for 96 hr. Culture supernatants were collected and IFN-γ level was determined by IFN-γ ELISA (R&D Systems, Minneapolis, MN). Levels of DENV-2 envelope (E) protein-specific antibody in the serum of DENV-infected
engrafted, uninfected engrafted and non-engrafted mice were determined using a standard ELISA. Ninety-six-well microplates were coated overnight with 100 ng/well of DENV-2 E protein (Hawaii Biotech, Aiea, HI) or 1 : 40 dilution of DENV-2-infected Vero cell lysate. The plates were blocked with 1% bovine serum albumin for 90 min and a 1 : 20 dilution of sera diluted with PBS was added to the wells for 1 hr. Plates were washed with PBS containing 0·1% Tween-20. Horseradish peroxidase-labelled goat anti-human IgM or IgG (Bethyl Laboratories Inc., Montgomery, Sucrase TX) was added as the secondary antibody. TMB Solution (Sigma-Aldrich Inc., St Louis, MO) was used as the substrate. The enzyme reaction was stopped by addition of 1 m HCl and the plates were read at 450 nm. Positive controls included sera from a known DENV-positive human. Sera from uninfected engrafted and non-engrafted mice were used as negative controls. All assays were carried out in duplicate or triplicate. Splenocytes from DENV-2 S16803-infected or naive mice were stimulated in vitro with CpG (2·5 μg/ml) + interleukin-2 (1 μg/ml) and Epstein–Barr virus (50 μl/ml). Supernatants of stimulated splenocytes collected 14 days after in vitro stimulation were tested for DENV-specific IgM antibodies and for DENV neutralization activity.