Nucleocapsid

Nucleocapsid is a complex formed by nucleic acids and capsid proteins in a virus. It is the core structure of a virus, which protects the viral genome and aids in its transfer between host cells.

Structure

The nucleocapsid is composed of the viral genome and the capsid, a protein shell that encloses the genome. The capsid is made up of multiple copies of one or more types of capsid proteins, which can self-assemble to form the shell. The structure of the nucleocapsid can vary greatly between different types of viruses. In some viruses, the nucleocapsid is surrounded by an additional layer called the viral envelope, which is derived from the host cell membrane.

Function

The primary function of the nucleocapsid is to protect the viral genome from degradation by nucleases and to aid in its transfer between host cells. The capsid proteins can interact with host cell structures to facilitate viral entry and exit. In some viruses, the capsid proteins also have roles in the replication of the viral genome and in the assembly of new virus particles.

Types of Nucleocapsids

There are two main types of nucleocapsids: helical and icosahedral. Helical nucleocapsids are cylindrical in shape, with the viral genome arranged in a helix along the length of the cylinder. Icosahedral nucleocapsids are spherical and have a highly symmetrical structure, with the viral genome packaged inside.

See also

• Virus
• Viral replication
• Viral envelope
• Capsid