Question

How are viruses classified based on capsid architecture?

Answer 1

Viruses:

Based on the capsid architecture, viruses can be classified as follows – Helical viruses, Prolate, Icosahedral, Complex viruses & Enveloped viruses.

1. Helical viruses – Consist of a single kind of capsomer organized around a central axis forming a helical structure, that may or may not have a central cavity, for instance – TMV.
2. Prolate – These are icosahedrons elongated along one axis and are common arrangements of heads of bacteriophages.
3. Icosahedral – the majority of the animal viruses are near-spherical or icosahedral with icosahedral symmetry, for instance, adenovirus.
4. Complex viruses – have a capsid that is neither purely icosahedral nor helical. It can have surplus structures such as the outer wall or protein tails, for instance, bacteriophages.
5. Enveloped viruses – a few viruses wrap themselves in an altered outer lipid bilayer – viral envelope, for instance, HIV.