The protein produced from the IRF5 gene, called interferon regulatory factor 5 (IRF5), acts as a transcription factor, which means that it attaches (binds) to specific regions of DNA and helps control the activity of certain genes. When a virus is recognized in the cell, the IRF5 gene is turned on (activated), which leads to the production of IRF5 protein. The protein binds to specific regions of DNA that regulate the activity of genes that produce interferons and other cytokines. Cytokines are proteins that help fight infection by promoting inflammation and regulating the activity of immune system cells. In particular, interferons control the activity of genes that help block the replication of viruses, and they stimulate the activity of certain immune system cells known as natural killer cells.