Antibody-dependent enhancement describes the mechanism by which virus complexed with Abs at sub-neutralizing concentration enters the cell via Fc gamma-receptor (FcγR)-mediated endocytosis, resulting in more efficient infection compared to endocytosis of virus alone.17,18 This route of immune-complex-mediated infection has been widely documented in vitro and is clinically most relevant in babies born to dengue-immune mothers, whose IgG Abs cross the placenta. This evidence concerns the gene FCGR2A and infection.