DC-SIGN molecule mediates viral surface binding and transfer. (A) Knocking-down of DC-SIGN expression in MDDCs. Expression of DC-SIGN was interfered with by specific siRNAs, and detected by flow cytometry, the positive expression percentage is shown; (B, C) Interference of DC-SIGN expression impaired EV71 binding as quantified by detecting viral mRNA (B) and by measuring with flow cytometry (C). (D) DC-SIGN Knocking-down impaired MDDC-mediated EV71 trans-infection of RD cells. Data are mean ± SD. ***P <0.001, **P <0.01, were considered significant differences in paired t test. (E, F, G) Raji/DC-SIGN cells mediate EV71 binding and transmission. Parental Raji cells and DC-SIGN-expressing derivative were tested for expression of DC-SIGN and PSGL-1 with flow cytometry (E). EV71 was added to cells (MOI 0.3) for viral binding at 4°C, and bound viruses were quantified by flow cytometry (F), and in (G) Raji and Raji/DC-SIGN cells were incubated with different amounts of EV71 for 1 h at 37°C, after washing, cells were cocultured with RD cells for 1 day, and viral replication was detected as above. One representative from three repeats is shown.