Viral replication

Viral particles:

A fully formed viral particle is called a virion, the basic structural components of a virion are:

• Genome:

The genome may be RNA or DNA, single or double stranded and linear or circular. The genome is generally very fragile, particularly RNA genomes

• Capsid

The capsid is a protein coat which surrounds and protects the genome from UV light and potential defences of a host organism. The capsid is formed of proteins called capsomers and plays an important role in recognising host cells and docking with these cells. Once inside a host cell the capsid must break down to release the genome. 

The capsid gives a virus its shape, viruses are very simple particles and self-assemble into repetitive structures; there are several different shapes that a virus can take, these are by no means unique to each type of virus:

Enveloped

Complex 

Helical

Icosahedral

Prolate 

• Enveloped

A virion may or may not have an extra envelope, this is usually made up of bits of cell membrane from the host cell. It can aid docking to other host cells and evading the hosts immune system

• Peplomers

If a virus is enveloped it may have peplomers on the surface of that envelope, which are small protrusions. Peplomers are thought to aid recognition…