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The Nature of Viruses. Chapter 27. Structure of Viruses. Types of Viruses. DNA RNA Retroviruses. Main Shapes. Helical Icosahedral. Sizes of Viruses. How Viruses Replicate. 1. Attach to and Enter Host Cell 2. Take over Protein synthesis machinery inside of cell- Lysogenic Cycle
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The Nature of Viruses Chapter 27
Types of Viruses • DNA • RNA • Retroviruses
Main Shapes • Helical • Icosahedral
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
Retroviruses • Use Reverse Transcriptase to make Viral RNA into DNA – HIV is a Retrovirus
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?
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
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.
Treatments • Combination Drug Therapy • AZT and Protease inhibitors • Vaccine Therapy • Chemokines and CAF • Blocking CCR5
Other Viruses • Flu • Recombination vs mutation • Emerging viruses • Ebola • Sars • Hantavirus • Viruses can cause cancer
Prions and Viroids • Prions- misfolded protein • TSE’s are caused by prions • Why is this controvericial? • Viroids- infections RNA with no protein coat.