TLR4 and infection: While DENV-2 infection-induced up-regulation of TLR2 and TLR7 mRNA during the early stages of infection (1.5 and 3 h.p.i), the mRNA expression of TLR2, TLR3, TLR4, TLR7, and TLR8 reaches its maximum peak of expression at 24 h.p.i (Figs 2A, S1A).