Interferons. By: Katy Nassif. Discovery of Interferons. 1957 Isaacs and Lindenmann Did an experiment using chicken cell cultures Found a substance that interfered with viral replication and was therefore named interferon
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By: Katy Nassif
Interferons are small proteins released by macrophages, lymphocytes, and tissue cells infected with a virus. When a tissue cell is infected by a virus, it releases interferon. Interferon will diffuse to the surrounding cells. When it binds to receptors on the surface of those adjacent cells, they begin the production of a protein that prevents the synthesis of viral proteins. This prevents the spread of the virus throughout the body.
Receptors are encoded by separate genes (IFNGR1 and IFNGR2, respectively) that are located on different chromosomes.
As the ligand-binding (or a) chains interact with IFN-g they dimerise and become associated with two signal-transducing chains.
Receptor assembly leads to activation of the Janus kinases JAK1 and JAK2 and phosphorylation of a tyrosine residue on the intracellular domain of IFN-gR1.
This leads to the recruitment and phosphorylation of STAT1, which forms homodimers and translocates to the nucleus to activate a range of IFN-g-responsive genes.
After this, the ligand-binding chains are internalised and dissociate.
The chains are then recycled to the cell surface.
Pegasys is recombinant interferon alpha-2a that is covalently conjugated with bis-monomethoxy polyethylene glycol (PEG)