Viruses, Viroids, and Prions

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Basics microbiology, that have as learning objective: Differentiate a virus from a bacterium. Characteristics about viruses. (Des Moines Area Community College´s PPT File)

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Viruses, Viroids, and Prions

  1. 1. Chapter 13 Viruses, Viroids, and PrionsCopyright © 2010 Pearson Education, Inc. Lectures prepared by Christine L. Case
  2. 2. Q&A  Researchers converted skin cells into embryonic stem cells. They first inserted RNA complementary for four embryonic genes into a virus; the resulting provirus inserted the genes into the skin cells’ DNA. What virus can do this?Copyright © 2010 Pearson Education, Inc.
  3. 3. General Characteristics of VirusesLearning Objective13-1 Differentiate a virus from a bacterium.Copyright © 2010 Pearson Education, Inc.
  4. 4. General Characteristics of Viruses Obligatory intracellular parasites Contain DNA or RNA 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 factorsCopyright © 2010 Pearson Education, Inc.
  5. 5. Virus SizesCopyright © 2010 Pearson Education, Inc. Figure 13.1
  6. 6. Check Your Understanding How could the small size of viruses have helped researchers detect viruses before the invention of the electron microscope? 13-1Copyright © 2010 Pearson Education, Inc.
  7. 7. Viral StructureLearning Objective13-2 Describe the chemical and physical structure of both an enveloped and a nonenveloped virus.Copyright © 2010 Pearson Education, Inc.
  8. 8. Virion Structure Nucleic acid  DNA or RNA Capsid  Capsomeres Envelope SpikesCopyright © 2010 Pearson Education, Inc. Figure 13.2a
  9. 9. Morphology of a Polyhedral VirusCopyright © 2010 Pearson Education, Inc. Figure 13.2
  10. 10. Polyhedral VirusesCopyright © 2010 Pearson Education, Inc. Figure 13.16a
  11. 11. Morphology of an Enveloped VirusCopyright © 2010 Pearson Education, Inc. Figure 13.3
  12. 12. Enveloped VirusesCopyright © 2010 Pearson Education, Inc. Figure 13.16b
  13. 13. Morphology of a Helical VirusCopyright © 2010 Pearson Education, Inc. Figure 13.4
  14. 14. Morphology of a Complex VirusCopyright © 2010 Pearson Education, Inc. Figure 13.5
  15. 15. Check Your Understanding Diagram a nonenveloped polyhedral virus that has spikes. 13-2Copyright © 2010 Pearson Education, Inc.
  16. 16. Taxonomy of VirusesLearning Objectives13-3 Define viral species.13-4 Give an example of a family, genus, and common name for a virus.Copyright © 2010 Pearson Education, Inc.
  17. 17. Taxonomy of Viruses 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 © 2010 Pearson Education, Inc.
  18. 18. Taxonomy of Viruses Herpesviridae  Retroviridae Herpesvirus  Lentivirus Human herpes virus  Human HHV-1, HHV-2, HHV-3 immunodeficiency virus HIV-1, HIV-2Copyright © 2010 Pearson Education, Inc.
  19. 19. Check Your Understanding How does a virus species differ from a bacterial species? 13-3 Attach the proper endings to Papilloma- to show the family and genus that includes HPV, the cause of cervical cancer. 13-4Copyright © 2010 Pearson Education, Inc.
  20. 20. Isolation, Cultivation, and IdentificationLearning Objectives13-5 Describe how bacteriophages are cultured.13-6 Describe how animal viruses are cultured.13-7 List three techniques used to identify viruses.Copyright © 2010 Pearson Education, Inc.
  21. 21. Growing Viruses Viruses must be grown in living cells  Bacteriophages form plaques on a lawn of bacteriaCopyright © 2010 Pearson Education, Inc. Figure 13.6
  22. 22. Growing Viruses Animal viruses may be grown in living animals or in embryonated eggsCopyright © 2010 Pearson Education, Inc. Figure 13.7
  23. 23. Growing Viruses Animal and plant viruses may be grown in cell culture  Continuous cell lines may be maintained indefinitelyCopyright © 2010 Pearson Education, Inc. Figure 13.8
  24. 24. 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  PCRCopyright © 2010 Pearson Education, Inc.
  25. 25. Virus IdentificationCopyright © 2010 Pearson Education, Inc. Figure 13.9
  26. 26. Check Your Understanding What is the plaque method? 13-5 Why are continuous cell lines of more practical use than primary cell lines for culturing viruses? 13-6 What tests could you use to identify influenza virus in a patient? 13-7Copyright © 2010 Pearson Education, Inc.
  27. 27. Viral MultiplicationLearning Objectives13-8 Describe the lytic cycle of T-even bacteriophages.13-9 Describe the lysogenic cycle of bacteriophage lambda.Copyright © 2010 Pearson Education, Inc.
  28. 28. The 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 wallCopyright © 2010 Pearson Education, Inc.
  29. 29. A Viral One-Step Growth CurveCopyright © 2010 Pearson Education, Inc. Figure 13.10
  30. 30. Lytic Cycle of a T-Even Bacteriophage 1 2 3Copyright © 2010 Pearson Education, Inc. Figure 13.11
  31. 31. Lytic Cycle of a T-Even Bacteriophage 4Copyright © 2010 Pearson Education, Inc. Figure 13.11
  32. 32. Results of Multiplication ofBacteriophages Lytic cycle  Phage causes lysis and death of host cell Lysogenic cycle  Prophage DNA incorporated in host DNA  Phage conversion  Specialized transduction ANIMATION Viral Replication: Virulent Bacteriophages ANIMATION Viral Replication: Temperate BacteriophagesCopyright © 2010 Pearson Education, Inc.
  33. 33. The Lysogenic CycleCopyright © 2010 Pearson Education, Inc. Figure 13.12
  34. 34. Generalized Transduction 2 3 4 5 6Copyright © 2010 Pearson Education, Inc. Figure 8.28
  35. 35. Specialized TransductionCopyright © 2010 Pearson Education, Inc. Figure 13.13
  36. 36. Specialized Transduction 2 3 4 5 ANIMATION Transduction: Generalized Transduction 6 ANIMATION Transduction: Specialized TransductionCopyright © 2010 Pearson Education, Inc.
  37. 37. Check Your Understanding How do bacteriophages get nucleotides and amino acids if they don’t have any metabolic enzymes? 13-8 Vibrio cholerae produces toxin and is capable of causing cholera only when it is lysogenic. What does this mean? 13-9Copyright © 2010 Pearson Education, Inc.
  38. 38. Viral MultiplicationLearning Objective13-10 Compare and contrast the multiplication cycle of DNA- and RNA-containing animal viruses.Copyright © 2010 Pearson Education, Inc.
  39. 39. 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 ruptureCopyright © 2010 Pearson Education, Inc.
  40. 40. Attachment, Penetration, Uncoating By pinocytosisCopyright © 2010 Pearson Education, Inc. Figure 13.14a
  41. 41. Attachment, Penetration, Uncoating By fusionCopyright © 2010 Pearson Education, Inc. Figure 13.14b
  42. 42. Budding of an Enveloped VirusCopyright © 2010 Pearson Education, Inc. Figure 13.20
  43. 43. Budding of an Enveloped VirusCopyright © 2010 Pearson Education, Inc. Figure 13.20
  44. 44. Multiplication of DNA VirusCopyright © 2010 Pearson Education, Inc. Figure 13.15
  45. 45. Sense Strand (+ Strand) RNA VirusCopyright © 2010 Pearson Education, Inc. Figure 13.17a
  46. 46. Antisense Strand (– Strand) RNA VirusCopyright © 2010 Pearson Education, Inc. Figure 13.17b
  47. 47. Double-Stranded RNA VirusCopyright © 2010 Pearson Education, Inc. Figure 13.17c
  48. 48. Multiplication of RNA-ContainingVirusesCopyright © 2010 Pearson Education, Inc. Figure 13.17
  49. 49. Multiplication of a RetrovirusCopyright © 2010 Pearson Education, Inc. Figure 13.19
  50. 50. ANIMATION Viral Replication: Overview ANIMATION Viral Replication: Animal VirusesCopyright © 2010 Pearson Education, Inc.
  51. 51. Check Your Understanding Describe the principal events of attachment, entry, uncoating, biosynthesis, maturation, and release of an enveloped DNA-containing virus. 13-10Copyright © 2010 Pearson Education, Inc.
  52. 52. Viruses and CancerLearning Objectives13-11 Define oncogene and transformed cell.13-12 Discuss the relationship between DNA- and RNA-containing viruses and cancer.Copyright © 2010 Pearson Education, Inc.
  53. 53. Cancer Activated oncogenes transform normal cells into cancerous cells Transformed cells have increased growth, loss of contact inhibition, tumor-specific transplant antigens, and T antigens The genetic material of oncogenic viruses becomes integrated into the host cells DNACopyright © 2010 Pearson Education, Inc.
  54. 54. Oncogenic Viruses Oncogenic DNA  Oncogenic RNA viruses viruses  Adenoviridae  Retroviridae  Herpesviridae  Viral RNA is  Poxviridae transcribed to DNA,  Papovaviridae which can integrate into host DNA  Hepadnaviridae  HTLV-1  HTLV-2Copyright © 2010 Pearson Education, Inc.
  55. 55. Check Your Understanding What is a provirus? 13-11 How can an RNA virus cause cancer if it doesn’t have DNA to insert into a cell’s genome? 13-12Copyright © 2010 Pearson Education, Inc.
  56. 56. Latent and Persistent Viral InfectionsLearning Objectives13-13 Provide an example of a latent viral infection.13-14 Differentiate persistent viral infections from latent viral infections.Copyright © 2010 Pearson Education, Inc.
  57. 57. Latent and Persistent Viral InfectionsCopyright © 2010 Pearson Education, Inc. Figure 13.21
  58. 58. Latent Viral Infections Virus remains in asymptomatic host cell for long periods  Cold sores, shinglesCopyright © 2010 Pearson Education, Inc. Figure 13.21
  59. 59. Persistent Viral Infections Disease processes occurs over a long period; generally is fatal  Subacute sclerosing panencephalitis (measles virus)Copyright © 2010 Pearson Education, Inc. Figure 13.21
  60. 60. Check Your Understanding Is shingles a persistent or latent infection? 13-13, 13-14Copyright © 2010 Pearson Education, Inc.
  61. 61. Prions, Viroids, and Plant VirusesLearning Objectives13-15 Discuss how a protein can be infectious.13-16 Differentiate virus, viroid, and prion.13-17 Describe the lytic cycle for a plant virus.Copyright © 2010 Pearson Education, Inc.
  62. 62. Prions Proteinaceous Infectious particle Inherited and transmissible by ingestion, transplant, and surgical instruments  Spongiform encephalopathies: Sheep scrapie, Creutzfeldt- Jakob disease, Gerstmann-Sträussler-Scheinker syndrome, fatal familial insomnia, mad cow diseaseCopyright © 2010 Pearson Education, Inc.
  63. 63. Prions PrPC: Normal cellular prion protein, on cell surface PrPSc: Scrapie protein; accumulates in brain cells, forming plaques ANIMATION Prion: Overview ANIMATION Prion: Characteristics ANIMATION Prion: DiseasesCopyright © 2010 Pearson Education, Inc.
  64. 64. How a Protein Can Be InfectiousCopyright © 2010 Pearson Education, Inc. Figure 13.22
  65. 65. Plant Viruses and Viroids Plant viruses: Enter through wounds or via insects Viroids: Infectious RNA; e.g., potato spindle tuber diseaseCopyright © 2010 Pearson Education, Inc. Figure 13.23
  66. 66. Copyright © 2010 Pearson Education, Inc.
  67. 67. Check Your Understanding Contrast viroids and prions, and for each name a disease it causes. 13-15, 13-16 How do plant viruses enter host cells? 13-17Copyright © 2010 Pearson Education, Inc.
  68. 68. Virus Families That Affect HumansLearning Objective13-10 Compare and contrast the multiplication cycle of DNA and RNA containing animal viruses.Copyright © 2010 Pearson Education, Inc.
  69. 69. Parvoviridae Single-stranded DNA, nonenveloped viruses  Fifth disease  Anemia in immunocompromised patientsCopyright © 2010 Pearson Education, Inc. Table 13.2
  70. 70. Adenoviridae Double-stranded DNA, nonenveloped viruses  Respiratory infections in humans  Tumors in animalsCopyright © 2010 Pearson Education, Inc. Figure 13.16a
  71. 71. Papovaviridae Double-stranded DNA, nonenveloped viruses  Papillomavirus − Human wart virus  Polyomavirus − Cause tumors; some cause cancerCopyright © 2010 Pearson Education, Inc. Table 13.2
  72. 72. Poxviridae Double-stranded DNA, enveloped viruses  Orthopoxvirus (vaccinia and smallpox viruses)  Molluscipoxvirus  Smallpox  Molluscum contagiosum  CowpoxCopyright © 2010 Pearson Education, Inc. Figure 13.5b
  73. 73. Herpesviridae Double-stranded DNA, enveloped viruses  Simplexvirus (HHV-1 and HHV-2)  Varicellovirus (HHV-3)  Lymphocryptovirus (HHV-4)  Cytomegalovirus (HHV-5)  Roseolovirus (HHV-6)  HHV-7  Kaposis sarcoma (HHV-8) Some herpesviruses can remain latent in host cellsCopyright © 2010 Pearson Education, Inc. Figure 13.16b
  74. 74. Hepadnaviridae Double-stranded DNA, enveloped viruses  Hepatitis B virus  Use reverse transcriptaseCopyright © 2010 Pearson Education, Inc. Figure 25.15
  75. 75. Picornaviridae Single-stranded RNA, + strand, nonenveloped  Enterovirus − Poliovirus and coxsackievirus  Rhinovirus  Hepatitis A virusCopyright © 2010 Pearson Education, Inc. Table 13.2
  76. 76. Caliciviridae Single-stranded RNA, + strand, nonenveloped  Hepatitis E virus  Norovirus causes gastroenteritisCopyright © 2010 Pearson Education, Inc. Table 13.2
  77. 77. Togaviridae Single-stranded RNA, + strand, enveloped  Alphavirus − Transmitted by arthropods; includes EEE and WEE  Rubivirus (rubella virus)Copyright © 2010 Pearson Education, Inc. Table 13.2
  78. 78. Flaviviridae Single-stranded RNA, + strand, enveloped  Arboviruses can replicate in arthropods; include yellow fever, dengue, SLE, and West Nile viruses  Hepatitis C virusCopyright © 2010 Pearson Education, Inc. Clinical Focus, p. 223
  79. 79. Coronaviridae Single-stranded RNA, + strand, enveloped  Upper respiratory infections  Coronavirus  SARSCopyright © 2010 Pearson Education, Inc. Table 13.2
  80. 80. Rhabdoviridae Single-stranded RNA, – strand, one RNA strand  Vesiculovirus  Lyssavirus (rabies virus)  Cause numerous animal diseasesCopyright © 2010 Pearson Education, Inc. Figure 13.18a
  81. 81. Filoviridae Single-stranded RNA, – strand, one RNA strand  Filovirus  Enveloped, helical viruses  Ebola and Marburg virusesCopyright © 2010 Pearson Education, Inc. Figure 23.21
  82. 82. Paramyxoviridae Single-stranded RNA, – strand, one RNA strand  Paramyxovirus  Morbillivirus  Parainfluenza  Mumps  Newcastle disease (chickens)Copyright © 2010 Pearson Education, Inc. Table 13.2
  83. 83. Deltaviridae Single-stranded RNA, – strand, one RNA strand  Hepatitis D virus  Depends on coinfection with hepadnavirusCopyright © 2010 Pearson Education, Inc. Table 13.2
  84. 84. Orthomyxoviridae Single-stranded RNA, – strand, multiple RNA strands  Envelope spikes can agglutinate RBCs  Influenzavirus (influenza viruses A and B)  Influenza C virusCopyright © 2010 Pearson Education, Inc. Table 13.2
  85. 85. Avian InfluenzaCopyright © 2010 Pearson Education, Inc. Clinical Focus, p. 371
  86. 86. Bunyaviridae Single-stranded RNA, – strand, multiple RNA strands  Bunyavirus (CE virus)  HantavirusCopyright © 2010 Pearson Education, Inc. Table 13.2
  87. 87. Arenaviridae Single-stranded RNA, – strand, multiple RNA strands  Helical capsids contain RNA-containing granules  Lymphocytic choriomeningitis  VEE and Lassa feverCopyright © 2010 Pearson Education, Inc. Table 13.2
  88. 88. Retroviridae Single-stranded RNA, 2 RNA strands, produce DNA  Use reverse transcriptase to produce DNA from viral genome  Lentivirus (HIV)  Oncogenic viruses − Includes all RNA tumor virusesCopyright © 2010 Pearson Education, Inc. Figure 19.13
  89. 89. Reoviridae Double-stranded RNA, nonenveloped  Reovirus (respiratory enteric orphan)  Rotavirus (mild respiratory infections and gastroenteritis)  Colorado tick feverCopyright © 2010 Pearson Education, Inc. Table 13.2
  90. 90. Q&A  Researchers converted skin cells into embryonic stem cells. They first inserted RNA complementary for four embryonic genes into a virus; the resulting provirus inserted the genes into the skin cells’ DNA. What virus can do this?Copyright © 2010 Pearson Education, Inc.

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