Interferon (IFN), which was first discovered by British scientist Isaacs in 1957 when he used the chick embryo chorionic villi allantoic membrane to study the phenomenon of influenza virus interference, is a cytokine with various effects such as inhibiting cell division, regulating immunity, antiviral and antitumor. Its essence is protein, and the types can be divided into α, β, γ, ω, etc. IFN can induce cellular resistance to viral infection, and it prevents or limits viral infection by interfering with viral gene transcription or translation of viral protein components, and is currently the most important antiviral infection and antitumor biologic. So, what is the role of interferon? 1, antiviral effect Its antiviral activity is not to kill but to inhibit the virus, it is generally a broad-spectrum virus inhibitor, both RNA and DNA viruses have inhibitory effects. When the recovery period of viral infection can be seen in the presence of interferon, on the other hand, with exogenous interferon can also relieve the infection. 2, antibacterial effect The antibacterial effect of interferon is mainly reflected in IFN-γ. IFN-γ can reduce bacterial iron supply by down-regulating transferrin receptor or directly inhibit intracellular bacteria by inducing endogenous NO production, and also increase the phagocytic vesicles of mononuclear macrophages – lysosomal lysis of bacteria, through the above pathways together The effect of eliminating bacteria can be achieved through the above pathways. 3.Anti-parasitic effect The anti-parasitic effect of interferon is mainly manifested in IFN-γ. Interferon can activate macrophages, and the activated macrophages can express high level of inducible nitric oxide synthase catalyzing L-arginine to produce nitric oxide, which has inhibitory and killing effects on inoculated pathogens. 4.Immunomodulatory effects Interferon has immunomodulatory effects on humoral immunity and cellular immunity, and also has certain immune enhancing effects on macrophages and NK cells. It plays an important role in anti-tumor and virus.