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11 Cards in this Set
- Front
- Back
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Virion of flaviviridae.
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-Spherical
-Enveloped -No projections -Diameter: 50nm -Linear (+) ss RNA -10-12.3 kb |
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What is a key difference of flavivirus genome (that all the flaviviridae have in common)?
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-Doesn't have a 3' Poly (A) Tail
(has a 5' cap, but no tail) |
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Which members of Flaviviridae don't hav a 5' Cap?
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-HCV and Pestiviruses
-Have IRES instead of the 5' cap |
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Where are the capping enzymes located in the viral genome?
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In the NS5 (polymerase) ptn
-Next to NS5 is the capping enz, a methyl transferase |
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What are the 3 genera of flaviviridae and who do they infect?
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Flavivirus: infects humans, bats, monkeys, birds...
Pestivirus:infects [pigs, cattle, ruminants (don't affect humans). most common virus here is BVDV (diarrhea) Hepacivirus: Hep C in humans only (chronic virus, doesn't shut down ptn synthesis or kill our liver cells) |
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What are the ptns involved in these viruses?
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All genes translatd as a single polyptn which is later cleaved
-1 capsid ptn (C): makes shell that holds the RNA -2 Envelope ptns ( M and E) - 7 NS ptns |
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How ar flaviviruses transmitted (not Hep C)?
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Throught ticks/mosquitoes
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What kind of human diseases are caused by Flaviviruses?
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-Yellow fever: transmitted by mosquitoes, vaccine available
-Dengue:has 4 types of viruses, causes fever, arthlagia, rash, ... Transmitted by mosquitoes, no vaccine -Japanses Encephalitis: Encephalitis (brain problem) in birds, pigs and monkeys -West Nile Virus: Cuases fever, arthalgia and rash. Infects birds and humans -Tick-borne encepalitis: causes encephalitis and affects birds, rodents and humans |
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How do flaviviruses enter the cell?
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pH-dependent fusion
-Bind specific receptors, get endocytosed and are then found in vesicles that have a very low pH. -Low pH helps them fuse with the mb and release their content (RNA) into the cytosol |
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What are the structural proteins of flaviviriviruses? Nonstructural?
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Structural: Capsid ptn C, envelope glycoptns M and E
Non-structural: NS5 (RNA-dep-RNA-polymerase + capping enx) and NS3 (protease activity at N-terminal) -NS2B partof NS3 protease activity |
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Viral exit/release.
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Before intracellular virion can be released, it expresses prM and E ptns
-E ptn has a small peptide on it= fusion peptide (imp for fusion with the plasma mb) -fusion peptide hidden by prM ptn (in this state, virion can't bin with the PM .: is a non-infectious particle and can't leave the cell) -When the virion gets close to the PM, Furin (a host protease) cleaves prM to M -E ptn can be rearranged so its parallel to the PM -2 E ptns dimerize -Fusion peptide becomes exposed, making the virus infectious |
