a protective protein manufactured by cells in mammals and birds and by cell cultures in response to their infection by viruses, suppressing the reproduction (replication) of the viruses in the cells.
Interferon was discovered in 1957 in the cells of infected chickens by the English scientists A. Isaacs and J. Lindenman. It was later discovered that the formation of interferon is also induced by bacteria, rickettsia, toxins, nucleic acids, and synthetic polynucleotides. Interferon is not an individual substance but a group of proteins of low molecular weight (25,000110,000). They are stable within a wide pH range, resistant to nucleases, and destroyed by proteolytic enzymes. The formation of interferon in the cells is due to the development of a virus in them—that is, it is a reaction of the cells to the penetration of foreign nucleic acid. Interferon is not found after the disappearance of the infecting virus from the cells or in normal cells. The mechanism of interferon’s action is different in principle from that of antibodies: it is not specific in relation to viral infections (it is active against a variety of viruses), and it does not neutralize the infectiousness of the virus, but suppresses the reproduction of the virus in the body by inhibiting the synthesis of the viral nucleic acids. Interferon is ineffective when it enters cells after a viral infection has already developed in them. Moreover, interferon is, as a rule, specific for the cells that form it; for example, the interferon of chicken cells is active in those cells only and does not inhibit the reproduction of a virus in rabbit or human cells. It has been suggested that it is not interferon itself that acts on the viruses, but rather another protein that is produced under its influence. Encouraging results have been obtained in testing interferon for the prevention and treatment of viral diseases (herpes infection of the eyes, influenza, cytomegaly). However, broad clinical use of interferon is limited by the difficulty of obtaining the preparation, the necessity for multiple injections, and its species specificity.
KH. KH. PLANEL’ES