The animation starts by brief explanation of the virus replication cycle. It is covered under three main headings 1) Initiation of infection 2) Replication and the expression of the virus genome 3) Release of the mature virions from the infected cells.
There are eight stages of virus replication these are 1) Attachment 2) Penetration 3) Uncoating 4) Gene expression 5) Genome Replication 6) Assembly 7) Maturation 8) Release
Attachment : This is the crucial stage for the initiation of virus life cycle within a living cell. As a virion comes across a specific host cell, it first binds to the host cell.
Viruses have specific proteins on their surface to attach to a host cellular surface molecule. The cellular molecules that allow the virus to attach on the cell surface are called virus receptors and the virion proteins that mediate the attachment are called as attachment proteins.
The attachment proteins and their positioning vary for different type of viruses. This protein is needed by the virus to attach to its target (host) cell before it can enter that cell.
The attachment proteins of the virus are of the same shape as that of a particular messenger molecule, thus allowing the viruses to easily contact the cell via cellular receptors. However, A virus can only infect the cells, which have the correct receptor. This specificity provides the basis for a virus's host range. In addition, this binding specificity limits viruses to only infecting certain cell types within their host.
Also covered are:
- List of some viruses and their receptors
- Specific nature of binding
- Attachment of HIV, influenza, polio virus to human cells, Bacteriophages attachment.