Editing Capsid (section)

==Functions==
The functions of the capsid are to:
* protect the genome, 
* deliver the genome, and 
* interact with the host.  
The virus must assemble a stable, protective protein shell to protect the genome from lethal chemical and physical agents. These include extremes of [[pH]] or temperature and proteolytic and nucleolytic [[enzyme]]s.  For non-enveloped viruses, the capsid itself may be involved in interaction with receptors on the host cell, leading to penetration of the host cell membrane and internalization of the capsid. Delivery of the genome occurs by subsequent uncoating or disassembly of the capsid and release of the genome into the cytoplasm, or by ejection of the genome through a specialized portal structure directly into the host cell nucleus.