Part 3 Viruses

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Part 3 Viruses
West Nile
Common Cold
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What are Viruses?

• 1. strand of hereditary material surrounded by
  protein coating.
• 2. dont have nucleus, cell membrane, or other
  organelles.
• 3. cant be cured, treated, but some can be
  prevented.

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How do Viruses Multiply

• 1. since its not a living organism it must be
  inside a host organism to reproduce.
• 2. Once inside it either becomes
• A. active (you become sick)
• B. latent (becomes part of the cell and then
  becomes active)

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Active Viruses

• A. causes the host cell to make new viruses and
  destroys host
• B. Reproduction Steps
• Attach (attaches to surface of the cell)
• Invade (nucleic acid attacks cell)
• Copy (viral acid controls cell and makes copies)
• Release (cell bursts when full and virus
  infects other cells)
• C. Examples- cold, chicken pox, flu

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Chicken Pox Virus
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Flu Virus
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Latent Viruses

• A. virus enters the cell and becomes part of the
  DNA without destroying the cell or reproducing.
• B. can stay hidden for years and then become
  active. It runs its course, but never leaves the
  body.
• C. Examples- cold sores, warts, AIDS

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Cold Sore Virus
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Wart virus
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How do Viruses Affect Organisms

• 1. affect all 6 kingdoms
• 2. some affect only one type of organism or part
  of an organism (ex-potato leaf roll virus).
  Others like rabies affect only mammals

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Fighting Viruses

• 1. Vaccine- weakened or dead strain of the virus
  which allow the host to fight off some diseases.
• 2. Famous First Vaccines
• Edward Jenner in 1796 for small pox
• Jonas Salk in 1952 for polio

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Small Pox
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Polio
Receiving polio vaccine
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Treating and Preventing Viral Disease

• A. antibiotics are only useful with bacteria
• B. interferon- bodies natural defense against
  viruses.
• C. antiviral drugs- help fight or shorten the
  length of virus.

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Treating Viruses, cont.

• D. public health measures
• Vaccines
• Improving sanitary conditions
• Quarantining patients
• Controlling animals that spread disease

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Gene Therapy

• Placing of normal hereditary material enclosed in
  a virus inside of an infected cell. The virus
  infects the cell and takes over- infecting the
  body with normal material