After viral infection or vaccination, the signaling pathway of high mobility group B1 (HMGB1)/Toll-like receptor 4 (TLR4)/Nf-κB is activated (19, 20) and can further induce specific immune responses, promote T-cell differentiation, and induce the activation and release of cytokines such as IL-6 and IL-1 (21, 22). Here, TLR4 is linked to viral infectious disease.