Dengue virus inhibits TLR-induced activation of mDC.

<p>A: Left panel, 48 hours after the first TLR stimulation, mDC were activated in the groups receiving TLRs but not in the group receiving only the virus. Coincident with the peak of viremia at day 4, an inhibitory effect of DENV on the mDC subset was evidenced by the frequency of activated cells in the DENV group, which was significantly lower compared to the DENV/TLR and TLR groups. Right panel, 10 days after the infection (72 hours after second TLR stimulation) the mDC subset was still significantly activated in both groups that received TLRs when compared to the Control group. However, the inhibitory effect of DENV was absent as there were no significant differences between the DENV and DENV/TLR groups, supporting the role of DENV replication in the inhibitory effect on mDC activation on day 4. B: Ten days after infection and 72 hours after the secondary TLR stimulation the frequency of activated pDC was significantly higher in the DENV/TLR and TLR groups compared to the DENV and Control groups. However, an inhibitory effect of DENV on this subset of DC was not observed. Asterisks denote significant differences, (*) p <0.05, (**) p <0.01, and (***) p<0.00.