TLR3 and infection: Upon infection or stimulation, TLR4 forms a complex with its specific coreceptor, i.e., myeloid differentiation factor 2 (MD2), to induce the activation of the myeloid differentiation (MyD) 88-dependent (signaling for all the TLRs with the exception of TLR3) and the MyD88-independent (signaling only for TLR3 and TLR4) pathway [16].