Flashcards in Viruses Deck (6)
What are obligate intracellular parasites
Need cell machinery of host cell to replicate
How do envelopes affect the virus
enveloped - sensitive
naked - resistant and more easily transmitted
Helical or icosahedral (closest shape to a sphere so can fit a lot in)
How are capsids formed
Self assemble, each subunit has identical bonding contacts with neighbouring proteins.
Symmetrical assemblies of oligomers which are linked by non-covalent bonds (fast assembly, disassembly)
What is the capsid for?
Protection for nucleic acid, specific attachment to receptors
Describe the FIVE stages of a viral life cycle
1) Attachment - binds to specific receptors (cell tropism)
2) Penetration - found in lipid rafts rich in cholesterol and sphingolipids providing more rigid regions more suitable for attachment
3) Uncoating - if enveloped, fusion with host cells plasma membrane then capsid disassembly releasing into cytosol. If naked, taken in by endocytosis, pH drops then proton pump causes release of virus
4) Replication - needs to replicate nucleic acid, ECLIPSE PHASE. need to be assembled into new visions
5) Maturation - may still be non-infectious, proteolytic cleavage by viral or cellular proteases.
6) Budding - are assembled viruses released, can be through lysis