Fluck Exam 3 - Virology Exam 3: FLUCK Poliovirus, Picorna...

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Virology Exam 3: FLUCK Poliovirus, Picorna and other + strand Viruses Some naked/some enveloped Three subclasses: o 1mRNA (vRNA=mRNA) polio naked icosahedron o 2mRNAs (vRNA=mRNA, partially translated and 1 subgenomic mRNA) enveloped o Many mRNAs (vRNA=mRNA, many subgenomic mRNAs) Enveloped Picornavirus: o Rhinovirus: common cold o Aphthovirus: foot and mouth o Enterovirus: Polio, coxackie Picorna related: o Calicivorus: Norwalk Virus o Potyvirus: Plumpox + RNA enveloped, most are flea/tick borne o Flavovirus: 1mRNA West nile/yellow fever o Hepatitis C virus: not arthropod borne o Togavirus: 2mRNA Not Mosquito borne Rubella o Alphavirus Sindbusm, fever, rashes, etc
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Replication Strategy of + strand viruses o All produce a “polyprotein” Cleaved by a virally encoded protease o Proteins produced: Minimum: 4-5 Polymerase, coat=capsid, protease o All encode an RNA-dependent RNA pol In viron??? Check** o All undergo: + - + etc Picornavirus: o Positive sense single-strand RNA o Covalently attached protein at 5’end (vPg) o PolyA tail o Viron Structure: 4 viral proteins (VP1-4) make up capsid icosahedral capsids: o Cell receptor: Immunoglobulin Superfamily (pvr-polio, Icam-Rhino) o Virus attachment: Rhinovirus: neutralizing antibody, binds to Icam-1 o Rhinovirus entry: No envelope no membrane fusion Virus binds receptor induces change in VP1 conformation exposes N-ter hydrophobic peptide of VP1 peptide inserts into membrane and forms a pore viral genome released thru pore Steps after uncoating Translation NO CAP Cap independent translation Role for secondary structure at 5’ end No role for VPg in translation VPg is NOT a polymerase o Polio genome:
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No cap therefore no cap binding eIF4G is cleaved by polio protease IRES can bind to cleaved eIF4G IRES- 5’ end structure (internal ribosome entry site) Modifies Host translation machinery Recap: Contains a canyon where receptor (or neutralizing Ab) binds; and a pore that plays a role in attachment Attachment to “Pvr” member of the Ig family Entry: no fusion, role of hydrophobic peptide from capsid VP1 1 st step after genome release: translation is cap independent unusual RNA structure (IRES) at the 5’ end recuits host initation factor eIF4(G) produces polyprotein cleaves by virally encoded proteases (+
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Fluck Exam 3 - Virology Exam 3: FLUCK Poliovirus, Picorna...

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