RSV prolifically entered and infected N2a neuronal cells, leading to the modulated expression of Toll-like receptor 4 (TLR4) and C23, as well as of TLR3, TLR7, and their downstream inflammatory factors, suggesting a direct induction of RSV-associated encephalopathy in infants by the infection of neuronal cells (Yuan et al., 2018; Hu et al., 2019). This evidence concerns the gene TLR4 and infection.