Abstract
Dengue virus (DENV) causes disease ranging from dengue fever (DF), a self-limited febrile illness, to the potentially lethal dengue hemorrhagic fever and dengue shock syndrome (DHF/DSS). DHF/DSS usually occurs in patients who have acquired DENV-reactive antibodies prior to infection, either from a previous infection with a heterologous DENV serotype or from an immune mother. Hence, it has been hypothesized that subneutralizing levels of antibodies exacerbate disease, a phenomenon termed antibody-dependent enhancement (ADE). However, given the lack of suitable animal models for DENV infection, the mechanism of ADE and its contribution to pathology remain elusive. Here we demonstrate in mice that DENV-specific antibodies can sufficiently increase severity of disease so that a mostly nonlethal illness becomes a fatal disease resembling human DHF/DSS. Antibodies promote massive infection of liver sinusoidal endothelial cells (LSECs), resulting in increased systemic levels of virus. Thus, a subprotective humoral response may, under some circumstances, have pathological consequences.