Interferon at a glance

Definition:  Interferon’s are host coded glycoproteins of cytokine family that inhibit viral replication by inhibiting early and late translation.

Properties:

1. Non-specific in its action.

2. Produced by infected cells.

3. Smaller in comparison to virus.

4. Glycoprotein in nature.

5. More heat stable and resist inactivation by acid or very alkaline pH.

6. Antiviral antibodies cannot inactive interferon.

7. Species specific.

8. Can be purified by chromatography and electrophoresis.

9. It is one of the cytokines.

10. Alpha and beta interferons are induced by virus; where as gamma (T cell immune) interferon is induced by antigens and is one of the effectors of cell-mediated immunity.

11. Interferon’s inhibit the intracellular replication of a wide variety of DNA and RNA virus.

12. Interferon has no effect on extracellular virus particles.

13. Interferon use three cell proteins for their action

       a) 2, 5-oligo a sythetase synthesizes an adenine trinucleotide (2, 5-oligo A).

       b) Ribonuclease degrades viral and cellular mRNAs.

       c) A protein kinase phosphorylase an initiation factor (elF-2) for protein synthesis.

             14. Interferon’s are produced within a few hours of the initiation of viral replication.

Type: (On the basis of sources)

• 1.       Leukocyte interferon-produced by leucocytes (Alpha interferon).
• 2.       Fibroblast interferon-produced by fibroblast (Beta interferon).
• 3.       Immune interferon-produced by T-lymphocytes (Gamma interferon).

Mechanism of action:

1.       It acts by interfering with virus replication within the cell.

2.       It causes virus infected cell to produce a protein which is called ‘Translation Inhibiting Protein’ which interferes with viral mRNA in the cell to synthesize viral proteins.

Uses:

1.       Antiviral activity as a prophylactic and therapeutic agent.

(Alpha interferon has been approved for use in patients with condyloma acuminatum and chronic active hepatitis caused by hepatitis B and C viruses.

Beta interferon is used in the treatment of multiple sclerosis.

Gamma interferon reduces recurrent infections in patients with chronic granulomatous disease. Interferon’s are also used clinically in patients with cancers such as Kaposi’s sarcoma and hairy cell leukemia.)

2.       In cancer therapy.

3.       As immunomodulator.

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