Question

Interferons are regarded as "the first line of defense against viral infection". Summarise their primary effects.

Answer 1

Interferons (IFNs ) are a group of signaling proteins made and released by host cells in response to the presence of several viruses. In a typical scenario, a virus-infected cell will release interferons causing nearby cells to heighten their anti-viral defenses.

• Interferon medication is used to treat various cancers (e.g., leukemia, melanoma, AIDS-related Kaposi's sarcoma). It is also used to treat virus infections (e.g., chronic hepatitis B, chronic hepatitis C, condylomata acuminata).
• IFNs belong to the large class of proteins known as cytokines, molecules used for communication between cells to trigger the protective defenses of the immune system that help to eradicate pathogens. Interferons are named for their ability to "interfere" with viral replication by protecting cells from virus infections.
• IFNs also have various other functions: they activate immune cells, such as natural killer cells and macrophages; they increase host defenses by up-regulating antigen presentation .
• Certain symptoms of infections, such as fever, muscle pain and "flu-like symptoms", are also caused by the production of IFNs and other cytokines.
• Types of Interferon
• Interferon Type 1 : Are produced when the body recognizes a virus that has invaded it. They are produced by fibroblasts and monocytes. All type I IFNs bind to a specific cell surface receptor complex known as the IFN-alpha/ beta receptor ( IFNAR ) .IFN alpha is used to treat hepatitis B and C infections, while IFN-beta can be used to treat multiple sclerosis.
• Interferon type II (IFN-γ in humans): This is also known as immune interferon and is activated by Interleukin-12.
• Interferon type III: Discovered more recently than type I and type II IFNs, recent information demonstrates the importance of Type III IFNs in some types of virus or fungal infections.
• Interferon beta-1a and interferon beta-1b are used to treat and control multiple sclerosis, an autoimmune disorder. This treatment may help in reducing attacks in relapsing-remitting multiple sclerosis and slowing disease progression and activity in secondary progressive multiple sclerosis.
• Interferon therapy is used (in combination with chemotherapy and radiation) as a treatment for some cancers. This treatment can be used in hematological malignancy, such as in leukemia and lymphomas including hairy cell leukemia, chronic myeloid leukemia, nodular lymphoma, and cutaneous T-cell lymphoma.
• Patients with recurrent melanomas receive recombinant IFN-alpha 2b. Both hepatitis B and hepatitis C are treated with IFN-alpha, often in combination with other antiviral drugs. Some of those treated with interferon have a sustained virological response and can eliminate hepatitis virus. Hepatitis C genotype I virus can be treated with a 60-80% success rate.
• Biopsies of patients given the treatment show reductions in liver damage and cirrhosis. Some evidence shows giving interferon immediately following infection can prevent chronic hepatitis C, although diagnosis early in infection is difficult since physical symptoms are sparse in early hepatitis C infection. Control of chronic hepatitis C by IFN is associated with reduced hepatocellular carcinoma.
• Interferon eye drops may be an effective treatment for people who have herpes simplex virus epithelial keratitis, a type of eye infection.