EFFECTS ON HOST CELLS - and tissues Phagocytosis is...

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EFFECTS ON HOST CELLS Viruses can have one of several different effects on their cellular hosts. Abortive infections may result when a virus mistakenly infects a cell that does not permit viral replication. At the other extreme, cytolytic infections lead to cell lysis and release of large numbers of virus. Persistent infections may be productive, latent or transforming. The table to the right outlines some of these effects. Type of Effect Virus Production Fate of Cell Abortive No No Effect Cytolytic Yes Death Persistent •Produ ctive Yes Senescence •LatentNo No Effect •Trans formin g •DNA No Immortalization •RNA Yes Immortalization HOST DEFENSES AGAINST VIRAL INFECTION A number of host defenses contribute to the prevention and/or elimination of viral infections. Nonspecific defenses include (prior to infection) anatomical barriers, viral inhibitors in fluids
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Unformatted text preview: and tissues. Phagocytosis is somewhat variable. After infection, factors such as fever (viral replication is strongly influenced by temperature) and inflammatory processes including edema, leukocyte accumulation, local hyperthermia, reduced oxygen tension and altered cell metabolism can all act to reduce viral replication. Another important anti-viral factor is interferon. This substance is produced by an infected cell. It then reacts with other cells to i) activate an RNA endonuclease causing mRNA degradation or ii) cause phosphorylation of eIF2, essentially turning off cellular protein synthesis. Specific host defenses include antiviral antibody, which may prevent adsorption to target cells and cytotoxic T-lymphocytes, which recognize virally-infected cells and destroy them, reducing viral production....
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EFFECTS ON HOST CELLS - and tissues Phagocytosis is...

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