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Virus structure, classification and replication

Virus structure, classification and replication. Viruses defined. Obligate intracellular parasites. Under attack!. (From Medical Microbiology, 4 th ed., Murray, Rosenthal, Kobayashi & Pfaller, Mosby Inc., 2002, Fig. 65-1.). Structures compared.

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Virus structure, classification and replication

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  1. Virus structure, classification and replication

  2. Viruses defined Obligate intracellular parasites

  3. Under attack! (From Medical Microbiology, 4th ed., Murray, Rosenthal, Kobayashi & Pfaller, Mosby Inc., 2002, Fig. 65-1.)

  4. Structures compared From Medical Microbiology, 5th ed., Murray, Rosenthal & Pfaller, Mosby Inc., 2005, Fig. 6-4.

  5. DNA or RNA Basic virus structure Capsid protein Naked capsid virus Nucleocapsid + = Lipid membrane, glycoproteins Nucleocapsid Enveloped virus +

  6. Matrix Lipid Glycoprotein Capsid symmetry Icosahedral Helical Naked capsid Enveloped

  7. Adenovirus Electron micrograph Foot and mouth disease virus Crystallographic model Icosahedral naked capsid viruses http://virology.wisc.edu/virusworld/ICTV8/fmd-foot-and-mouth-ictv8.jpg http://www.ncbi.nlm.nih.gov/ICTVdb/Images/Ackerman/Animalvi/Adenovir/799-16.htm

  8. Helical naked capsid viruses RNA Protein http://www.ncbi.nlm.nih.gov/ICTVdb/ICTVdB/em_tmv.gif Caspar and Klug, Adv Virus Res. 1960;7:225-325 Tobacco mosaic virus Electron micrograph Tobacco mosaic virus Model

  9. Icosahedral enveloped viruses http://web.uct.ac.za/depts/mmi/stannard/emimages.html http://virology.wisc.edu/virusworld/images/herpescapsid.GIF Herpes simplex virus Electron micrograph Herpes simplex virus Nucleocapsid cryoEM model

  10. Helical enveloped viruses http://web.uct.ac.za/depts/mmi/stannard/fluvirus.html http://web.uct.ac.za/depts/mmi/stannard/paramyx.html Influneza A virus Electron micrograph Paramyxovirus Electron micrograph

  11. Taxonomy of the Order Mononegavirales a V, vertebrate; I, insect; P, plant. Fields Vriology (2007) 5th edition, Knipe, DM & Howley, PM, eds, Wolters Kluwer/Lippincott Williams & Wilkins, Philadelphia Table 2.2

  12. Classification of Human Viruses Fields Vriology (2007) 5th edition, Knipe, DM & Howley, PM, eds, Wolters Kluwer/Lippincott Williams & Wilkins, Philadelphia Table 2.1

  13. Major diseases caused by human viruses

  14. Virus replication: general

  15. Virus replication:variations on the theme • dsDNA • ssDNA • (+)ssRNA • (-)ssRNA • dsRNA • RNA retro • DNA retro

  16. dsDNA virus replication (+)mRNA dsDNA dsDNA

  17. (+)mRNA (+) ssDNA dsDNA ssDNA virus replication

  18. (+)RNA (+)RNA (-)RNA (+)ssRNA virus replication

  19. (+)mRNA (+)RNA (-)RNA (-)RNA (-)ssRNA virus replication

  20. (+)mRNA dsRNA dsRNA dsRNA virus replication

  21. (+)mRNA (+)mRNA ssDNA (+)RNA (+)RNA dsDNA (+)ssRNA retrovirus replication

  22. (+)mRNA (+)mRNA ssDNA (+)RNA dsDNA dsDNA dsDNA retrovirus replication

  23. Virus growth 1,000 – 100,000 viruses/cell, 5 – 24 hours From Schaechter’s Mechanisms of Microbial Disease; 4th ed.; Engleberg, DiRita & Dermody; Lippincott, Williams & Wilkins; 2007; Fig. 31-8

  24. Summary: structure,classification & replication • Structure • Nucleic acid in a protein shell, +/- lipid envelope • Structure impacts on biological properties • Classification • Many virus families, organized by structure and biology • Replication • Generic scheme • Varying strategies depending on nucleic acid

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