Control on viral infections

Control on viral infections:
Dr. Jawad K. AL-Khafaji
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Control on viral infections and diseases by the following main methods:
1. Host defenses.
2. Viral vaccines.
3. Antiviral chemotherapy.
4. Public hygiene (include personal and community).

1-Host defenses:
Host defenses against viruses fall into two major categories:
1. Non specific defenses , of which the most important are anatomic barriers, interferon (IFN) and natural killer(NK)cells.
2. Specific defenses, including both humoral and cellular immunity .

A-Non specific host defenses:

1. Anatomic barriers :
Anatomic barriers are located at body surface (skin and mucosa) or within the body (endothelial cell). They are partly effective in preventing viral infection.

2. Interferon :
Interferon is glycoprotein produced by any type of cell (all vertebrate species) after viral infection .
Interferons are produced from infected cell with virus to protect other cells from viral infection. Interferon does not protect the virus-infected cell that is produce it.
Interferons are divided into three types based on the cell of origin:
1. IFN-alpha is produced by leukocytes.
2. IFN-beta is produced by fibroblasts.
3. IFN-gamma is produced by lymphocytes .
•IFN-alpha and beta are induced by viruses , whereas IFN-gamma is not produced in response to most viruses but is induced by mitogen stimulation. The induction of IFN is not specific to any virus.
•Action of IFN: IFN inhibits replication of widely viruses range. IFN don’t interact directly with virus but move to other cells , and bind to receptor on cell surface which induces the cells to activate specific signals for synthesis of antiviral proteins (AVP)that are usually result in an inhibit viral replication. IFN inhibit the growth of virus by blocking the translation of viral mRNA into proteins without affecting the translation of cellular mRNA.