Capsid

A capsid or capsid (from Latin capsula: small capsule) is a complex, regular protein structure in viruses that serves to package the virus genome. A capsid is composed of a fixed number of protein subunits, the capsomers. In non-enveloped viruses, the capsid forms the outermost structure of the virus and is thus responsible for its attachment and penetration into the host cell; in enveloped viruses, the capsid interacts with the outer viral envelope and often gives it the necessary stability. The arrangement of the proteins of a capsid is based on different symmetries and is very diverse. These different structures and symmetries of capsids in turn affect biological properties such as pathogenicity, replication and environmental stability. The structure of the capsid also serves as a criterion for the classification of viruses within viruses.

https://de.wikipedia.org/wiki/Kapsid

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