A group of immune system proteins, produced and released by cells infected by a virus, which inhibit viral multiplication and modify the body’s immune response. One of the interferons, interferon beta-1b (Betaseron®) was approved by the Food and Drug Administration in 1993 for treatment of relapsing-remitting MS. It was found in a clinical trial to reduce the frequency and severity of exacerbations by approximately 30 percent. A second interferon, interferon beta-1a (Avonex®) has also been shown to reduce the frequency and severity of MS exacerbations in people with relapsing-remitting disease. Avonex® was approved for use in MS in 1996.
