Chapter 19 <ul><li>Genetics of viruses </li></ul><ul><ul><li>Structure of viruses </li></ul></ul><ul><ul><li>Viruses are p...
Outline of this chapter <ul><li>Phages and viruses </li></ul><ul><ul><li>Structure </li></ul></ul><ul><ul><li>Replication ...
Size comparison <ul><li>Eukaryotic cell </li></ul><ul><ul><li>10 µm </li></ul></ul><ul><li>Bacteria </li></ul><ul><ul><li>...
Virus or phage eukaryotic or prokaryotic host <ul><li>My definition: A virus infects eukaryotes, a phage bacteria </li></u...
3  Types of viruses or phages
4  Simplified reproduction cycle <ul><li>Host machinery </li></ul><ul><ul><li>DNA polymerase </li></ul></ul><ul><ul><li>Ri...
5  Lytic cycle of phage T4
5  Lytic cycle of phage T4
If phages destroy bacteria: why are there still bacteria? <ul><li>Restriction enzymes </li></ul><ul><ul><li>Protect bacter...
6   Lysogenic cycle of phage lambda  λ
6   Lysogenic cycle of phage lambda  λ
Table 19.1  Classes of animal viruses <ul><li>Envelope </li></ul><ul><ul><li>lipid bilayer </li></ul></ul><ul><ul><li>vira...
Table 19.1  Classes of animal viruses Examples Envelop Class HIV, HLTV Yes ssRNA, retrovirus Filovirus, Rhabdovirus,  Orth...
Influenza in 1918
7  Reproduction of enveloped RNA virus (example Influenza virus) <ul><li>Flu-genome is minus strand ssRNA,  </li></ul><ul>...
8  HIV structure <ul><li>HIV: human immunodeficiency virus </li></ul><ul><ul><li>Cause of the disease AIDS </li></ul></ul>...
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Hoofdstuk 19 2008 deel 1

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Hoofdstuk 19 2008 deel 1

  1. 1. Chapter 19 <ul><li>Genetics of viruses </li></ul><ul><ul><li>Structure of viruses </li></ul></ul><ul><ul><li>Viruses are parasites: they only reproduce in host cells </li></ul></ul><ul><ul><li>Viruses, viroids, and prions as pathogens </li></ul></ul><ul><ul><ul><li>In plants and animals </li></ul></ul></ul>Measles
  2. 2. Outline of this chapter <ul><li>Phages and viruses </li></ul><ul><ul><li>Structure </li></ul></ul><ul><ul><li>Replication </li></ul></ul><ul><ul><ul><li>Lytic: lyses cells </li></ul></ul></ul><ul><ul><ul><li>Lysogenic </li></ul></ul></ul><ul><li>Viroids-prions </li></ul>Herpes virus E coli attacked by T4
  3. 3. Size comparison <ul><li>Eukaryotic cell </li></ul><ul><ul><li>10 µm </li></ul></ul><ul><li>Bacteria </li></ul><ul><ul><li>1 µm= 1000 nm </li></ul></ul><ul><li>Viruses </li></ul><ul><ul><li>20-500 nm </li></ul></ul><ul><li>Prions </li></ul><ul><ul><li>Proteins: 0.1 nm </li></ul></ul><ul><li>Viroids </li></ul><ul><ul><li>Naked RNA: 0.1 nm </li></ul></ul>
  4. 4. Virus or phage eukaryotic or prokaryotic host <ul><li>My definition: A virus infects eukaryotes, a phage bacteria </li></ul><ul><li>Protein coat: ‘capsid’ </li></ul><ul><ul><li>Repetitive units </li></ul></ul><ul><ul><ul><li>capsomeres </li></ul></ul></ul><ul><li>Sometimes envelop </li></ul><ul><ul><li>Lipids from host </li></ul></ul><ul><li>Genome </li></ul><ul><ul><li>RNA or DNA </li></ul></ul><ul><li>Replicate only in host </li></ul><ul><ul><li>‘ Host range’ or ‘tropism’ </li></ul></ul><ul><ul><li>Host-specific </li></ul></ul><ul><ul><ul><li>Common cold </li></ul></ul></ul><ul><li>Life cycle </li></ul><ul><ul><li>30 min for phage </li></ul></ul><ul><ul><li>Virus 3 h up to 24 h </li></ul></ul>
  5. 5. 3 Types of viruses or phages
  6. 6. 4 Simplified reproduction cycle <ul><li>Host machinery </li></ul><ul><ul><li>DNA polymerase </li></ul></ul><ul><ul><li>Ribosomes </li></ul></ul><ul><ul><li>Energy </li></ul></ul><ul><li>Virus-specific enzymes </li></ul><ul><ul><li>RNA-polymerase </li></ul></ul><ul><li>‘ Burst’: 100-1000 viruses/cell </li></ul>
  7. 7. 5 Lytic cycle of phage T4
  8. 8. 5 Lytic cycle of phage T4
  9. 9. If phages destroy bacteria: why are there still bacteria? <ul><li>Restriction enzymes </li></ul><ul><ul><li>Protect bacteria against foreign DNA attack </li></ul></ul><ul><li>Methylation </li></ul><ul><ul><li>Self-defense of bacteria </li></ul></ul><ul><li>Evolution </li></ul><ul><ul><li>Of both bacteria as well as phages </li></ul></ul><ul><li>Lysogenic or temperate phages </li></ul><ul><ul><li>Or transforming animal viruses </li></ul></ul>
  10. 10. 6 Lysogenic cycle of phage lambda λ
  11. 11. 6 Lysogenic cycle of phage lambda λ
  12. 12. Table 19.1 Classes of animal viruses <ul><li>Envelope </li></ul><ul><ul><li>lipid bilayer </li></ul></ul><ul><ul><li>viral and host (glyco)proteins </li></ul></ul><ul><li>Genome </li></ul><ul><ul><li>RNA </li></ul></ul><ul><ul><ul><li>Plus - stranded </li></ul></ul></ul><ul><ul><ul><li>Minus - stranded </li></ul></ul></ul><ul><ul><ul><li>RNA  DNA  RNA </li></ul></ul></ul><ul><ul><ul><ul><li>Retrovirus: HIV </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Reverse transcriptase </li></ul></ul></ul></ul><ul><ul><li>DNA </li></ul></ul><ul><ul><ul><li>ss </li></ul></ul></ul><ul><ul><ul><li>ds </li></ul></ul></ul>
  13. 13. Table 19.1 Classes of animal viruses Examples Envelop Class HIV, HLTV Yes ssRNA, retrovirus Filovirus, Rhabdovirus, Orthomyxovirus (Flu) Yes - ssRNA Picorna, Corona, Flavi, Toga +/- + ssRNA Reo No dsRNA Parvo No ssDNA Adeno, Papova, Herpes, Pox +/- dsDNA
  14. 14. Influenza in 1918
  15. 15. 7 Reproduction of enveloped RNA virus (example Influenza virus) <ul><li>Flu-genome is minus strand ssRNA, </li></ul><ul><ul><li>Viral polymerase makes plus-stranded RNA </li></ul></ul><ul><li>Envelope can be from nucleus </li></ul><ul><ul><li>Herpes (dsDNA) </li></ul></ul><ul><ul><ul><li>Integration in host genome: provirus </li></ul></ul></ul>Clearly indicate + or – strand!!!
  16. 16. 8 HIV structure <ul><li>HIV: human immunodeficiency virus </li></ul><ul><ul><li>Cause of the disease AIDS </li></ul></ul><ul><ul><ul><li>Acquired immunodeficiency syndrome </li></ul></ul></ul>

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