Figure 1.

Antibody-dependent enhancement of Zika virus (ZIKV) infection by dengue virus (DENV)–specific antibodies and levels of interleukin 6 (IL-6). FcγRII-expressing K562 cells were infected with ZIKV PE/243 in the absence of antibodies or in the presence of a panel of serum samples from pregnant women with different dengue immune status, as determined by plaque reduction neutralization test: monotypic (DENV-3) (n = 10) and multitypic (DENV-3 and DENV-4) (n = 10). Cell culture supernatants were collected 48 hours postinfection, and levels of IL-6 were determined by Citometric bead array (BD CBA Human Th1/Th2/Th17 Cytokine Kit) following the manufacturer’s instructions. Mann-Whitney test was used to determine statistical significance. Statistical analysis was performed using Graph Pad Prism software, version 7.0a.