What is the Difference Between Capsid and Nucleocapsid?

The capsid and nucleocapsid are two distinct components of a virus particle that serve different purposes.

A capsid is the protein shell surrounding the nucleic acid genome of a virus particle, providing protection and structure. The capsid consists of several oligomeric structural subunits made of protein called protomers, and the observable 3-dimensional morphological subunits are called capsomeres. Capsid proteins or viral coat proteins (VCP) are the proteins that make up the capsid.

A nucleocapsid, on the other hand, refers to the combination of the capsid and the nucleic acid core within the virus particle. The nucleic acid core contains either RNA or DNA, but not both, and can be single-stranded or double-stranded. The nucleocapsid is a discrete substructure within the virus particle and plays a crucial role in viral survival and infectivity.

In summary, the key differences between capsid and nucleocapsid are:

• Capsid is the protein coat that surrounds the nucleic acid of the virus particle, while the nucleocapsid is the combination of the capsid and the nucleic acid core.
• The capsid does not include the viral genome, whereas the nucleocapsid includes the viral genome.

Comparative Table: Capsid vs Nucleocapsid

Here is a table comparing the differences between capsid and nucleocapsid:

In summary, the capsid is the protein shell that surrounds the viral genome, while the nucleocapsid is the combination of the capsid and the nucleic acid core containing either RNA or DNA. Both structures play crucial roles in viral survival, infectivity, and protection of the viral genome.