Taiwanese DENV-2 strain PL046 used in this study was isolated from patient with DF, and this virus has been used in the studies of viral pathogenesis and host responses mechanism in vitro and in vivo [7, 12, 51, 52, 53] . Other groups have reported that DENV-2 strains MON601 (a laboratory strain of NGC) and 16681 downregulate the activation of NF-kB and production of type I IFN and TNFa in human DC, macrophage, and Huh7 cells [14, 54] . A recent report by Chase A. J. et al. [55] also revealed that human DCs infected with several endemic DENV-2 strains failed to polarize the naïve CD4 + T cells to effectors, suggesting a defect on T cell priming for DENV-infected DCs [55] . However, one of the strain ARA6894 did not show such kind of inhibition effect, as ARA6894-infected DCs triggered CD4 + Th1 polarization with high expression of IFNc and TNFa. Interestingly, the polyprotein sequences of strain ARA6894 contain nonsynonymous amino acids that are not present in other DENV-2 strains such as PL046, 16681 and NGC [55] , suggesting that different impacts on DC's function between these DENV-2 strains might be due to viral genome diversity.