Viral Replication Flashcards
8 steps
Attachment
Penetration
Uncaring
Replication
Gene expression
Assembly
Maturation
Release
Attachment
Virus attachment protein binds to host receptor molecule
Virus attachment proteins
Typically envelope glycoproteins
Host receptors
Typically transmembrane proteins but can also be carbohydrates on glycoproteins or glycolipids
How do naked viruses attach
Canyon pit where capsid monomers act as the virus attachment protein
Tropism
Type of host cell the viruses can replicate in
Cellular
Tissue
Host
Attachment exceptions
Fungal viruses spread through fungal cell division
Plant viruses use mechanical damage to enter cell
3 options for penetration
Translocation - naked
Endocytosis - naked and enveloped
Membrane fusion - enveloped
Translocation
Entire naked virion crosses cell membrane
Rare and not well understood
Endocytosis
Names and enveloped virions are taken up by intracellular vacuoles
Random or can be triggered by virus attachment protein - receptor mediation
Virus must escape vesicle to enter cell
High risk high reward
Why is Endocytosis high risk high reward
Endocytosis ends in lysosomal degradation
Viruses evolves to trigger membrane fusion as pH lowers so they’re closer to the nucleus
Membrane fusion
Enveloped viruses use a fusion peptide to facilitate fusion at the cell surface or the endosomal membrane
Nucleocapsid released into the cell
Uncoating
Removal of capsid from genome
Can occur simultaneously with penetration
Genome replication and gene expression
Depends on genome class
Assembly
Site depends on virus type
