Fig. 2

Analysis of ADE infection of U937 cells with high and low passage DENVs. DENV 4 LAB, DENV 4 DF or DENV 4 DHF were incubated with a 1:200 dilution of monoclonal antibody HB114 (+HB 114) or with an isotype matched anti-alphavirus antibody (+alpha) control as appropriate, or with an equivalent volume of medium before incubation with U937 cells for 2 h after which cells were a washed with PBS and incubated with normal growth media (RPMI supplemented with 10 % FBS) with daily addition of normal medium to the cells, or b incubated with normal growth media with daily addition of normal medium to the cells or d incubated with normal growth media with daily addition of normal growth medium containing a 1:1000 dilution of HB 114 antibodies. Percentage infection was determined by flow cytometry and all experiments were undertaken independently in triplicate. Error bars show SEM M mock infection, DH (DENV 4 DHF) DF (DENV 4 DF), DL (DENV 4 LAB). c Plaque assay of supernatants from (b) assayed on days “0” (immediately after infection) 1, 2, 3 and 5 post infection. Input virus titer (−2 h) is also displayed. Plaque assays were undertaken independently in triplicate with duplicate assay of titer