FLEXGeneralStructureofViruses. Complex viruses: atypical viruses- Poxviruses lack a typical capsid and are covered by adense layer of lipoproteins- Some bacteriophages have a polyhedral nucleocapsidalong with a helical tail and attachment fibersCopy right @ The McGraw-Hill Conies.Inc.Permisrreproduction or display240300nmNucleic acidCoreCapsidheacmembraneCollar200nmNucleicacidSheathOuterenvelopeSolubleTailproteinLateralbodyfibersantigens(a)TailBaseplatepins(c)11@ Bin Ni, Chisholm Lab, MIT(b)
11 General Structure of Viruses • Complex viruses: atypical viruses – Poxviruses lack a typical capsid and are covered by a dense layer of lipoproteins – Some bacteriophages have a polyhedral nucleocapsid along with a helical tail and attachment fibers 240 – 300 nm Nucleic acid 200 nm Core membrane Outer envelope Soluble protein antigens Lateral body (a) (b) (c) Tail fibers Tail pins Base plate Sheath Collar Nucleic acid Capsid head © Bin Ni, Chisholm Lab, MIT Copy right © The McGraw-Hill Companies, Inc. Permission required f or reproduction or display
FEXTypes ofVirusesCopyrightTheMcGraw-Hill Companies.nc.Permission requiredfor reproductionordisplayA.ComplexVirusesB.Enveloped VirusesHelicalIcosahedral(1)(3)(5)(2)(6)(4)A. Complexviruses:C.NonenvelopedNakedViruses(1)poxvirus,alarge DNA virusHelical(2)flexible-tailedbacteriophageIcos ahedralB.Envelopedviruses:Withahelicalnucleocapsid:(3) mumps virus(4) rhabdovirusWithanicosahedralnucleocapsid:(5) herpesvirus(8)(6) HV (AIDS)C. Naked viruses:Helical capsid:(7) plum poxvirusIcosahedralcapsid:12(8) poliovirus(9)(7)(9) papillomavirus
12 Types of Viruses A. Complex Viruses A. Complex viruses: (1) poxvirus, a large DNA virus (2) flexible-tailed bacteriophage B. Enveloped viruses: With a helical nucleocapsid: (3) mumps virus (4) rhabdovirus With an icosahedral nucleocapsid: (5) herpesvirus (6) HIV (AIDS) C. Naked viruses: Helical capsid: (7) plum poxvirus Icosahedral capsid: (8) poliovirus (9) papillomavirus B. Enveloped Viruses C. Nonenveloped Naked Viruses Helical Icosahedral Helical Icosahedral (1) (2) (3) (4) (5) (6) (8) (7) (9) Copyright © The McGraw -Hill Companies, Inc. Permission required for reproduction or display
TheMcGraw-Hill CompaniesConcept Check:CopyrightTheMcGraw-Hill Companies,Irc.Permission required forfeproduction of disptayHowwould you describe this virus?A.IcosahedralandNakedB.Helical and NakedC.Complex and NakedD.lcosahedralandEnvelopedE.Helical and EnvelopedF.ComplexandEnvelopedDeryisKunkel/CNRi/Phototak
Concept Check: How would you describe this virus? A. Icosahedral and Naked B. Helical and Naked C. Complex and Naked D. Icosahedral and Enveloped E. Helical and Enveloped F. Complex and Enveloped © Dennis Kunkel/CNRI/Phototake Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display
NucleicAcidsViral genome-either DNA or RNA but neverboth Carries genes necessary to invade host cell andredirect cell's activity to make new viruses Number of genes varies for each type of virus -few to hundreds14
14 Nucleic Acids • Viral genome – either DNA or RNA but never both • Carries genes necessary to invade host cell and redirect cell’s activity to make new viruses • Number of genes varies for each type of virus – few to hundreds
NucleicAcids· DNA viruses- Usually double stranded (ds) but may be singlestranded (ss)- Circular or linear·RNAviruses- Usually single stranded, may be double stranded, maybe segmented into separate RNApieces-ssRNAgenomes readyforimmediatetranslation arepositive-sense RNA- ssRNA genomes that must be converted into properform are negative-sense RNA15
15 Nucleic Acids • DNA viruses – Usually double stranded (ds) but may be single stranded (ss) – Circular or linear • RNA viruses – Usually single stranded, may be double stranded, may be segmented into separate RNA pieces – ssRNA genomes ready for immediate translation are positive-sense RNA – ssRNA genomes that must be converted into proper form are negative-sense RNA