| Abstract: |
Background: Viruses are the smallest infectious agents containing only one kind of nucleic acid (RNA or DNA) as their genome, the nucleic acid is encased in a protein shell, which may be surrounded by a lipid-contianing membrane. The entire infectious unit is termed a virion. Viruses form a diverse group of infectious agents that share a distinctive composition and a unique mode of replication. They are not cellular organisms as, although certain viruses encode a small number of enzymes, they do not possess functional ribosomes or other cellular organelles and therefore lack much of the machinery required for their own multiplication, so that they multiply only inside cells, where they make use of the cellular synthetic apparatus to produce the components of the virus. It is because of their dependence on the cell for their replication that viruses are often referred to as obligate intracellular parasite. To produce disease, viruses must enter a host, come in contact with susceptible cells, replicate, and produce cell injury. Steps of viral replicative cycle are adsorption (attachment), penetration, uncoating, biosynthesis, assembly, and release. The difficulty encountered in finding an agent which specifically inhibits the virus is to find one which is much less toxic to the host cell than to the virus. This is frequently difficult. The topic of antiviral agents for dermatologic disease is an area that is rapidly changing and expanding as our knowledge of human herpes viruses, HIV, and human papilloma viruses continues to expand. Therapies used in management of viral skin diseases are: antiviral drugs, topical immunomodulators, interferons, vaccines and immunoglobulin therapy. Following topical application onto the skin, interleukin-6, interleukin-8, and interferon-α synthesis by keratinocytes has also been shown. Interferon-α’s anitivral activity is mediated in part by a number of proteins including the 2`,5`-oligoadenylatsynthetase and the MxA protein. Imiquimod and resiquimod have also been shown to enhance antigen presentation and maturation of Langerhans cells via tumor necrosis factor-α and interferon-γ as well as their migration to regional lymph nodes. This therapy treats anogenital warts, intra-anal warts, filiform, plane facial warts, plantar warts, common warts and mollusca.Their side effects were mainly erythema, erosions, and pruritus as has been reported for the treatment of condyloma accuminate. The alpha and beta interferons are cytokines which are secreted by virus infected cells. They bind to specific receptors on adjacent non-infected cells and protect them from infection by viruses.Objectives: After the era of AIDS and the wide use of immunotherapy after organ transplantation, the treatment of viral diseases showed major importance.The aim of the work is to review the available different antiviral drugs and to stress on the recent drugs in order to have a better understanding of antiviral therapy. The work will also discuss the different clinical applications of the antiviral therapy and the future of antiviral vaccines.
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