https://wikimd.org/index.php?action=history&feed=atom&title=CapsidCapsid - Revision history2026-05-13T07:38:22ZRevision history for this page on the wikiMediaWiki 1.44.2https://wikimd.org/index.php?title=Capsid&diff=5417368&oldid=prevPrab at 20:58, 20 March 20242024-03-20T20:58:23Z<p></p>
<p><b>New page</b></p><div>A capsid is comprised of protein subunits known as [[Capsomere|capsomeres]], which assemble into a protective shell around the virus's nucleic acid, either [[DNA]] or [[RNA]]. This assembly can adopt various structural patterns, resulting in different capsid morphologies such as icosahedral, helical, or complex formations.<br />
[[File:Norwalk Caspid.jpg|Norwalk Caspid (X-ray crystallographic structure)|thumb]]<br />
[[File:15194 lores.jpg|Capsid - ultrastructural morphology exhibited by numbers of rotavirus icosahedral protein capsid particles|thumb]] [[File:Flu und legende color c.jpg|Structure of swine influenza virus showing different type of antigens present on and inside the capsid|thumb]]<br />
=='''Types of Capsid Structures'''==<br />
* '''[[Icosahedral Capsid|Icosahedral Capsids]]''': Characterized by their spherical symmetry, these capsids consist of equilateral triangles that form a shell, optimizing both capacity and stability with a minimal number of capsomere types.<br />
* '''[[Helical Capsid|Helical Capsids]]''': These structures are cylindrical, with capsomeres arranged in a spiral around the nucleic acid. This arrangement allows for variability in the capsid's length, adapting to the size of the genome.<br />
* '''[[Complex Capsid|Complex Capsids]]''': Some viruses exhibit capsids that do not conform to the icosahedral or helical categories, incorporating additional components like tails or enveloping layers.<br />
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==Function and Role==<br />
The capsid fulfills several critical functions in a virus's lifecycle:<br />
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* '''Protection''': It safeguards the viral genetic material against enzymatic degradation and environmental stressors.<br />
* '''Attachment and Entry''': Capsid proteins can bind to specific receptors on the host cell, facilitating viral entry through mechanisms such as [[Endocytosis|endocytosis]] or membrane fusion.<br />
* '''Packaging and Release''': During viral assembly, the capsid plays a role in packaging the genetic material and aids in the release of newly formed virions from the host cell.<br />
* '''Immunogenicity''': The capsid proteins are primary targets for the host's immune response, with their antigenic properties stimulating the production of [[Antibody|antibodies]].<br />
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==Clarification on Viroids==<br />
It's essential to address that [[Viroid|viroids]] do not possess capsids. Viroids are small, circular RNA molecules that infect plants, lacking any protein coating. This absence of a capsid is a distinctive feature, separating viroids from viruses and underscoring the diversity among pathogenic entities at the molecular level.<br />
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==Significance in Medical Research and Therapeutics==<br />
The study of capsid structures and functions is integral to devising antiviral strategies:<br />
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* '''[[Vaccine]] Development''': Many vaccines target capsid proteins to elicit an immune response without causing disease, exploiting their immunogenic properties.<br />
* '''Antiviral Drugs''': Investigating the mechanisms of capsid assembly and disassembly provides targets for drugs aimed at interrupting these processes.<br />
* '''Viral Vector Engineering''': For gene therapy, capsids can be engineered to deliver therapeutic genes, with modifications made to target specific tissues or evade immune detection.<br />
{{Virus topics}}<br />
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[[Category:Virology]]<br />
[[Category:Protein complexes]]</div>Prab