Enterovirus 71 infection of human dendritic cells.

Enterovirus 71 (EV71) causes death and long-term neurologic sequelae in hundreds of thousands of young children, but its pathogenesis remains elusive. Dendritic cells (DCs) play a crucial role in antiviral immunity by functioning as professional antigen-presenting cells to prime T cells and by secreting cytokines to modulate immune responses. Here, we show that EV71 productively infected human immature DCs and expressed viral antigen in DCs. EV71 entry into DCs was partially mediated by DC-SIGN. Further analyses revealed that EV71 increased the viability, activation, release of cytokines, interleukin-6, interleukin-12, and tumor necrosis factor-alpha in DCs. Moreover, EV71 enabled DCs to stimulate T-cell proliferation. Collectively, these findings suggest that EV71 infection of human DCs in vivo is very likely to elicit protective immunity, because in infected mice, both T cells and IL-6 function to reduce mortality.