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The Nature of Viruses

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  1. The Nature of Viruses Chapter 27

  2. Structure of Viruses

  3. Types of Viruses • DNA • RNA • Retroviruses

  4. Main Shapes • Helical • Icosahedral

  5. Sizes of Viruses

  6. How Viruses Replicate • 1. Attach to and Enter Host Cell • 2. Take over Protein synthesis machinery inside of cell- Lysogenic Cycle • 3. Lytic Cycle- Lyse out of cell to go make more Virus Babies

  7. Retroviruses • Use Reverse Transcriptase to make Viral RNA into DNA – HIV is a Retrovirus

  8. Who can get a virus? • Just about every kind of organism • Obligate intracellular parasites • Host Range and Tissue Tropism • Hep- liver • Rabies-neurons • Chickenpox…..can you ever really get rid of it?

  9. HIV • AIDS first reported in the US in 1981 • Originated in Africa in the 1950’s based on the rate of mutation • Closely related to a chimpanzee virus

  10. Some people are resistant to HIVHow? • Recent research suggests that people who were immuned to smallpox may also be immuned to AIDS • Due to a mutation in CCR5 receptor • Makes virus unable to bind to cells and enter.

  11. How the HIV Infection Works

  12. Treatments • Combination Drug Therapy • AZT and Protease inhibitors • Vaccine Therapy • Chemokines and CAF • Blocking CCR5

  13. Other Viruses • Flu • Recombination vs mutation • Emerging viruses • Ebola • Sars • Hantavirus • Viruses can cause cancer

  14. Prions and Viroids • Prions- misfolded protein • TSE’s are caused by prions • Why is this controvericial? • Viroids- infections RNA with no protein coat.