(INF: Definition, Antiviral Properties, Classification and Clinical Significance)
Interferons are Glycoproteins with Antiviral Properties
Interferons or INFs are low molecular weight glyco-proteins produced by certain eukaryotic cells in response to viral infections. They are cytokines with indirect or non-specific antiviral activities. Interferons stimulate the production of antiviral proteins in the cells which inhibit the synthesis of viral RNA and proteins.
Interferons cannot directly inhibit the viral entry into the host cell. However, they can inhibit the replication of viral gene and the assembly of viral particles and thereby they limit the viral infection.
Interferons also regulate the growth, differentiation and functions of different types of immune cells in animals. Several classes of interferons are recognized in eukaryotes such as INFα, INFβ and INFγ. INFα and INFβ are produced by virus infected fibroblasts. Virus infected leukocytes, antigen stimulated T cells and natural killer cells can produce INFγ.
Interferon Production is Triggered by Viral Infection
The synthesis and release of interferons form a cell is induced by the viral particles. The intact viral particles and even the presence of double stranded viral RNA (dsRNA) in the cell can evoke the production of interferons. Specific interferons are recognized by receptors present on the plasma membrane. Once a cell receives the stimuli, the interferon proteins are synthesized and they are released out of the cell. Since they are secreted to the exterior of the cells, they can bind to its plasma membrane receptors. The secreted interferon molecules then bound to the ganglioside receptors on the plasma membrane of another cell (nearby or located far away from the secretion).