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33 Cards in this Set

  • Front
  • Back
What are viruses made of?
Protein, nucleic acids, lipids, sugars
3 types of virus coatings
complex, enveloped (with lipid coat), naked viruses
General size of virus
50-100 nm
Pathogenic viruses in respiratory tract
rhinovirus, influenze A/B/C, RSV, PIV, Measles Mumps, Coronaviruses (SARS), Adenoviruses, Epstein-Barr, cytomegalovirus, HSV
Impact of structure on Respiratory tract viruses
Doesn;t necessarily matter
Viral genome functions
Genome replication, assembly and packaging, regulation of replication, modulation of host defences (no protein synthesis machinery, energy, membrane biosynthesis)
Purpose of secondary structure in HIV gene
Regulation of gene expression
4 classic viruses to consider structure
Rabies (raptovirus), HSV1, HIV, AdV
How does the rabies virus protect its genome?
Protein encrusted to prevent degradation, lends itself to helical shape
Surrounding structure of AdV
HSV surrounding layers
Lipid envelope and protein capsid
HIV surrounding layers
Protein capsid, secondary capsid, lipid membrane
Shape of lipid enveloped viruses
pleomorphic (many) (depends on from which cell it came)
What is the same for virus architecture?
Structure and assembly
Basic unit of viral structure
Capsid protein
Function of capsid protein?
Protect vNA, interact specifically with vNA for packaging, Interact w/ host receptors, Allow for release of vNA, Assist viral/host gene regulation
Ways to study viral structure
electron microscopy, cryo-EM, x-ray diffraction
Best resolution for viral study
X-ray crystallography
two protein coat types
icosahedral (spherical, 20 sided, limited NA)
helical (rod shaped, no limit to NA)
Principles of virus architecture
Viral genome insufficient to code for more than a few diff proteins, identical subunits, packed to provide each with identical environment
Where are enveloped viruses derived from?
Host cell membranes (composition varies)
What else do virus envelopes contain in addiiton to membranes?
Virally encoded proteins=glycoproteins (for structure)
Sometimes host cell proteins
What do the envelope glycoproteins form?
Spikes on surface of virion
Ex of viruses that have glycoproteins
Semliki Forest virus, Dengue virus
Goal of virus attachment
Bring close to cell surface (3D->2D)
How does IFV and PIV attach?
Use Hemaggluttinin glycoprotein to attach to sialic acid (lots in respiratory tract)
-Good affinity resulting in strong avidity bc of numbers
How does RSV attach?
Has glycoprotein that doesn't bind, but is highly glycosylated. These bring "fusogenic protein" of virus closer to PM, looks like normal cell surface on airway.
How do viruses enter into cells? (2)
-Membrane fusion, genome dump
-Receptor mediated endocytosis
How do Viruses address endosome changes in clathrin-coated pits?
Don't activate until pH drops. Must delay so not to rupture before replication
How do influenze viruses enter cells?
Receptor-mediated endocytosis (requires pH change)
How do parainfluenza viruses enter cells?
Surface fusion
How do adenoviruses enter the cell?
Receptor mediated endocytosis with fiber R and integrin
2 options of viral load destination
cytoplasm or nucleus