Figure 1

Enhancement of CHIKV infection in purified primary human cells. Primary human (a,c) monocytes and (b,d) B cells (2 × 10⁶ cells per infection) were infected with CHIKV (moi 10) in the presence (enhanced) or absence (non-enhanced) of diluted CHIKV-specific patient plasma containing total IgG at a concentration of 3.6 ± 2.9 μg/ml. (a,b) Detection of CHIKV antigen and (c,d) viral RNA load were determined at 0 and 6 hpi. Level of CHIKV antigen detected is expressed as fold enhancement relative to the non-enhanced infection controls. Data shown are mean ± SD from 3 independent experiments by parametric unpaired t test (**P = 0.0015 for 0 hpi monocytes; *P = 0.0458 for 0 hpi B cells and **P = 0.0053 for 6 hpi B cells). Expression of FcγRs in (e) monocytes and (f) B cells. Primary human (g) monocytes and (h) B cells (2 × 10⁶ cells per infection) were treated with 10 μg of FcγRs blocking agent prior to CHIKV infection (moi 10) under enhancing conditions (as above). Percentage of infection is expressed as level of CHIKV antigen detected relative to the non-treated infection controls at 0 hpi. Data are presented as mean ± SD from 4 independent experiments by Mann-Whitney U test (*P = 0.0286 for monocytes and *P = 0.0143 for B cells).