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netLibrary - eBook Summary Structure-based Drug Design by ...

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Figure 2<br />

A simplified schematic of the replication cycle of an influenza virion in the host<br />

respiratory epithelia. Details of viral transport through mucin and pathways of<br />

viral spread on budding from the epithelial cell membrane during replication is<br />

not understood. Neuraminidase activity is important for release of budding<br />

progeny virions, desialyation of viral glycoproteins, and probably facilitates<br />

transport through sialic-acidrich mucin.<br />

Page 461<br />

Release of virions occur 8 hours post infection and the onset of infection is sudden, resulting in pyroxia,<br />

muscular and joint pain, and a dry cough [6]. Virus shedding continues for up to a week, when a rise in<br />

virus-specific antibody clears the virus from the host. The vulnerability of the host succumbing to<br />

viremea during this week of rising viral titer is mediated <strong>by</strong> interferon induction [7] 48 hours post<br />

infection, which attenuates viral replication until the cell-mediated immune response begins to clear the<br />

virus. The severity of the illness is thought to depend on the level of cross protection arising from<br />

antibodies raised from previous influenza infections [19]. The course of the illness can be debilitating,<br />

and no effective treatment is available at present to halt the progression of the disease. Death can result<br />

for susceptible populations (neonate and elderly) primarily as a result of secondary infections [8]. This<br />

chapter shall examine a structural basis for the continual emergence of new influenza strains, and the<br />

reasons current vaccines against influenza fail to protect against all<br />

http://legacy.netlibrary.com/nlreader/nlReader.dll?bookid=12640&filename=Page_461.html (1 of 2) [4/9/2004 12:13:07 AM]

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