Interferon-stimulated gene
An interferon-stimulated gene is a gene whose expression is stimulated by interferon. Interferon activates the JAK-STAT signaling pathway to induce transcription of ISGs. ISGs can be divided based on what class of interferon they are activated by: type I, type II, or type III interferon. The protein products of ISGs control pathogen infections.
Specifically, type I and type III interferons are antiviral cytokines, triggering ISGs that combat viral infections. Type I interferons are also involved in bacterial infections; however, they can have both beneficial and harmful effects. The type II interferon class only has one cytokine, which has some antiviral activity, but is more important in establishing cellular immunity through activating macrophages and promoting major histocompatibility complex class II.
