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Capsid
protein coat that surrounds the infective nucleic acid in some virus particles / From Wikipedia, the free encyclopedia
A capsid is the protein shell of a virus. It is made of several protein subunits. The observable 3-dimensional subunits are called 'capsomeres'. The capsid encloses the nucleic acid of the virus.
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Capsids are broadly classified according to their structure.[1][2] Some viruses, such as bacteriophages, have developed more complicated structures.[3] The icosahedral shape, which has 20 equilateral triangular faces, approximates a sphere, while the helical shape is cylindrical.[4] The capsid faces may consist of one or more proteins. For example, the foot-and-mouth disease virus capsid has faces consisting of three proteins called VP1–3.[5]