There are 6 basic stages such as attachment, penetration, uncoating, replication, assembly and lastly released that a virus have to experience in its life cycle.
· Attachment
Attachment is a specific binding of viral capsid protein and its specific receptor on the host cellular surface. It is specific so as to determine the host range for a certain virus.
For example, HIV only infect human’s T cells as its GP120 protein coat only interact with CD4 on the receptor surface of T cell.
· Penetration
Penetration is when the viruses that sucessfully attaches onto the cell surface enter the host through endocytosis or membrane fusion known as viral entry. However this only happen in human being, in plants the cell wall have to be broken down in order for virus to be able to enter.
· Uncoating
Uncoating is the process where viral capsid is degraded by viral enzyme or even host’s enzyme and hence releasing the viral genomic nucleic acid from the virus.
· Replication
Replication is the process of synthesizing messenger RNA for virus. For RNA viruses , replication happens in the cytoplasm while for DNA viruses, replication takes place in the nucleus.
· Assembly
The assembly of newly synthesized viral component into complete virions to be released out.
· Released
Viruses are release out of a cells through lysis while enveloped viruses ar e released out of the cells through budding. This departure of new virion from host cells will in turn cause death of the host cells.
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