Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings PowerPoint ® Lecture Slide Presentation prepared by Christine L. Case M I C R O B I O L O G Y a n i n t r o d u c t i o n ninth edition TORTORA  FUNKE  CASE Part A 13 Viruses, Viroids, and Prions

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 Contain DNA or RNA –sDNA, dDNA, sRNA, dRNA  Contain a protein coat  Some are enclosed by an envelope  Some viruses have spikes  Most viruses infect only specific types of cells in one host  Host range is determined by specific host attachment sites and cellular factors Viruses

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Viruses Figure 13.1

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Viruses Figure 13.1

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Virion Size Figure 13.1

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Helical Viruses Figure 13.4a–b

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Helical Viruses Figure 13.4a–b

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Polyhedral Viruses Figure 13.2a–b

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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Viral Taxonomy  Family names end in -viridae.  Genus names end in -virus.  Viral species: A group of viruses sharing the same genetic information and ecological niche (host). Common names are used for species.  Subspecies are designated by a number.

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Viral Taxonomy  Herpesviridae  Herpesvirus  Human herpes virus HHV-1, HHV-2, HHV-3  Retroviridae  Lentivirus  Human immunodeficiency virus HIV-1, HIV-2

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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Viruses Figure 13.1

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Growing Viruses  Viruses must be grown in living cells.  Bacteriophages form plaques on a lawn of bacteria. Figure 13.6

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Growing Viruses  Animal viruses may be grown in living animals or in embryonated eggs. Figure 13.7

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Growing Viruses  Animal and plants viruses may be grown in cell culture.  Continuous cell lines may be maintained indefinitely. Figure 13.8

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Virus Identification  Cytopathic effects  Serological tests  Detect antibodies against viruses in a patient.  Use antibodies to identify viruses in neutralization tests, viral hemagglutination, and Western blot.  Nucleic acids  RFLPs  PCR

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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Multiplication of Bacteriophages (Lytic Cycle)  Attachment: Phage attaches by tail fibers to host cell.  Penetration: Phage lysozyme opens cell wall, tail sheath contracts to force tail core and DNA into cell.  Biosynthesis: Production of phage DNA and proteins.  Maturation: Assembly of phage particles.  Release: Phage lysozyme breaks cell wall.

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 13.11, steps 1–3, 6–7

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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings  Lytic cycle: Phage causes lysis and death of host cell.  Lysogenic cycle: Prophage DNA incorporated in host DNA.

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings The Lysogenic Cycle Figure 13.12

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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Multiplication of Animal viruses  Attachment: Viruses attach to cell membrane.  Penetration by endocytosis or fusion.  Uncoating by viral or host enzymes.  Biosynthesis: Production of nucleic acid and proteins.  Maturation: Nucleic acid and capsid proteins assemble.  Release by budding (enveloped viruses) or rupture.

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Multiplication of Animal viruses

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Multiplication of Animal viruses

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Multiplication of Animal viruses

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Multiplication of Animal viruses

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings PERSISTANCE VS. LATENT INFECTIONSs

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings PERSISTANCE VS. LATENT INFECTIONSs

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings PRIONS  Infectious Proteins

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings VIROIDS  Infectionus RNA  Plant diseases so far