As major immune cells of the host’s first line of defense, monocytes and macrophages can be exposed to translocated bacterial flagellin during viral–bacterial co-infection, which can promote HIV-1 infection through the TLR5 and NF-κB signaling pathways, resulting in the induction of various inflammatory cytokines [6,10]. The gene discussed is TLR5; the disease is HIV-1 infection.