TLR9 and viral infectious disease: The study confirmed that the expression of cytokines (IL-4, IL-8, IL-12p70, IFN-γ, and TNF-α) in BMDCs treated with recombination virus was significantly up-regulated and was positively correlated with the expression of MHC-II, co-stimulatory molecules CD80/86, and TLRs on the surface of BMDCs, which suggested that the secretion of TNF-α and IL-12p70 induced by the recombinant virus may be mediated by TLRs, and the potential mechanism may be related to the expression of TLR3, TLR7, and TLR9 caused by viral infection.