Viruses The word virus means “poison” in Latin.
Introduction <ul><li>Influenza pandemic of 1918 </li></ul><ul><li>Smallpox in the 18 th  and 19 th  century. </li></ul><ul...
Viral Diseases <ul><li>Common Cold </li></ul><ul><li>Flu (influenza) </li></ul><ul><li>Mumps  </li></ul><ul><li>Measles </...
More Viral Diseases… <ul><li>Cold Sores </li></ul><ul><li>Polio </li></ul><ul><li>AIDS </li></ul><ul><li>Bronchitis </li><...
How are viral illnesses treated? <ul><li>Some have a vaccine to protect you. </li></ul><ul><li>Rest, plenty of fluids and ...
Germs are everywhere. How can you avoid being infected?  <ul><li>Wash your hands !!! </li></ul><ul><li>The 3 most common p...
History of Vaccines <ul><li>1796 – Edward Jenner  (England) </li></ul><ul><ul><li>Took infected matter from a sore on the ...
6 weeks later: <ul><li>Jenner took some infected matter from a victim of  smallpox  and rubbed it into incisions made in P...
 
Louis Pasteur - 1884 <ul><li>Produced a weakened infective material from rabid dogs that was used as a  rabies vaccine . <...
Rabies symptoms <ul><li>After a symptom-free incubation period that ranges from 10 days to a year or longer (the average i...
 
Jonas Salk - 1953 <ul><li>Created a polio vaccine . </li></ul><ul><li>He actually  killed  the active form of the virus an...
 
Albert Sabin - 1960 <ul><li>Treated the polio virus to  weaken  it.  </li></ul><ul><li>Produced a longer lasting immunity ...
Vaccinations :  artificial immunity <ul><li>1. Inject a dead or weakened form of the virus (called an  antigen .) </li></u...
 
macrophage engulfs antigen by phagocytosis.
Definitions: <ul><li>Antigen  – A substance that stimulates the production of antibodies. </li></ul><ul><li>Antibodies  – ...
Definitions cont….. <ul><li>Vaccines  – a commercially produced antigen of a particular disease. </li></ul><ul><li>It is n...
More definitions… <ul><li>Pathogen  – an agent that causes disease. </li></ul>
Discovery of a Virus - 1933 <ul><li>Read pages 455-456 in textbook. </li></ul>
Size of a virus <ul><li>Much smaller than any cell. </li></ul><ul><ul><li>Smallest is 17 nm (.000000017 meter) or 17 billi...
Composition of a Virus <ul><li>A strand of  nucleic acid  (DNA or RNA) surrounded by a  protein coat  known as a capsid. <...
Is a virus a living organism? <ul><li>Living things   vs.  Virus </li></ul><ul><li>Made of cells   Not a cell </li></ul><u...
Bacteriophage -  “bacteria eater” <ul><li>See page 457 in textbook. </li></ul>
Lytic Cycle – 5 steps <ul><li>Step 1 –  Attachment  – Virus attaches to a specific receptor site on a cell. </li></ul><ul>...
Lysogenic Cycle <ul><li>Same as the lytic cycle but the  viral DNA becomes incorporated into the host cell’s DNA.  </li></...
Viral Subunit Reassortment <ul><li>Two strains of a virus infect a cell at the same time. </li></ul><ul><li>The nucleic ac...
Gene Therapy –  A useful purpose of a virus <ul><li>The harmful DNA is removed from a virus. </li></ul><ul><li>A “helpful”...
Problems with gene therapy: <ul><li>Locating the correct cells. </li></ul><ul><li>Genes accidentally spliced in the wrong ...
Current Research with gene therapy: <ul><li>What diseases could be treated with gene therapy? ( From AMA website.) </li></...
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Notes - Viruses

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Notes - Viruses

  1. 1. Viruses The word virus means “poison” in Latin.
  2. 2. Introduction <ul><li>Influenza pandemic of 1918 </li></ul><ul><li>Smallpox in the 18 th and 19 th century. </li></ul><ul><li>AIDS statistics… </li></ul>
  3. 3. Viral Diseases <ul><li>Common Cold </li></ul><ul><li>Flu (influenza) </li></ul><ul><li>Mumps </li></ul><ul><li>Measles </li></ul><ul><li>Smallpox </li></ul><ul><li>Chicken Pox </li></ul><ul><li>Hepatitis </li></ul><ul><li>Warts </li></ul>
  4. 4. More Viral Diseases… <ul><li>Cold Sores </li></ul><ul><li>Polio </li></ul><ul><li>AIDS </li></ul><ul><li>Bronchitis </li></ul><ul><li>Viral Pneumonia </li></ul><ul><li>Mononucleosis </li></ul><ul><li>West Nile Virus </li></ul><ul><li>Rabies </li></ul>
  5. 5. How are viral illnesses treated? <ul><li>Some have a vaccine to protect you. </li></ul><ul><li>Rest, plenty of fluids and time… </li></ul><ul><li>Sometimes an antibiotic is given to prevent a secondary infection. </li></ul>
  6. 6. Germs are everywhere. How can you avoid being infected? <ul><li>Wash your hands !!! </li></ul><ul><li>The 3 most common places to get germs: </li></ul><ul><ul><li>#3 Door knob </li></ul></ul><ul><ul><li>#2 Computer mouse </li></ul></ul><ul><ul><li>#1 Shopping cart handles </li></ul></ul><ul><ul><li>http://www.youtube.com/watch?v=MWQ86R-aT-I </li></ul></ul><ul><ul><li>http://www.youtube.com/watch?v=RHqNk8_rOHk&feature=related </li></ul></ul>
  7. 7. History of Vaccines <ul><li>1796 – Edward Jenner (England) </li></ul><ul><ul><li>Took infected matter from a sore on the hand of local milkmaid who had cowpox . </li></ul></ul><ul><ul><li>He rubbed it into small incisions on the arm of an 8 year old boy named Edward Phipps. </li></ul></ul><ul><ul><li>The boy developed a cowpox sore on his arm. </li></ul></ul>
  8. 8. 6 weeks later: <ul><li>Jenner took some infected matter from a victim of smallpox and rubbed it into incisions made in Phipp’s arm again. </li></ul><ul><li>The boy remained healthy! </li></ul><ul><ul><li>Jenner produced a vaccine for smallpox . </li></ul></ul>
  9. 10. Louis Pasteur - 1884 <ul><li>Produced a weakened infective material from rabid dogs that was used as a rabies vaccine . </li></ul><ul><li>First used on a young boy who had been bitten by a rabid dog. </li></ul>
  10. 11. Rabies symptoms <ul><li>After a symptom-free incubation period that ranges from 10 days to a year or longer (the average is 30 to 50 days), the patient complains of malaise, loss of appetite, fatigue , headache , and fever . Over half of all patients have pain (sometimes itching) or numbness at the site of exposure. They may complain of insomnia or depression . </li></ul><ul><li>Two to 10 days later, signs of nervous system damage appear, hyperactivity and hypersensitivity, disorientation , hallucinations, seizures, and paralysis . Death may be sudden, due to cardiac or respiratory arrest, or follow a period of coma that can last for months with the aid of life-support measures . </li></ul>
  11. 13. Jonas Salk - 1953 <ul><li>Created a polio vaccine . </li></ul><ul><li>He actually killed the active form of the virus and used it as a vaccine. </li></ul><ul><ul><li>1952 – 57,000 cases of polio. </li></ul></ul><ul><ul><li>1957 – virtually no cases. </li></ul></ul>
  12. 15. Albert Sabin - 1960 <ul><li>Treated the polio virus to weaken it. </li></ul><ul><li>Produced a longer lasting immunity to polio than the Salk vaccine . </li></ul>
  13. 16. Vaccinations : artificial immunity <ul><li>1. Inject a dead or weakened form of the virus (called an antigen .) </li></ul><ul><li>2. Your body produces antibodies . </li></ul><ul><li>3. The antibodies recognize the protein coat of the virus and hold it as it enters the body. </li></ul><ul><li>4. Macrophage (a type of white blood cell) surround and digest the virus. </li></ul><ul><li>5. You are now immune to this virus. </li></ul>
  14. 18. macrophage engulfs antigen by phagocytosis.
  15. 19. Definitions: <ul><li>Antigen – A substance that stimulates the production of antibodies. </li></ul><ul><li>Antibodies – A substance produced by plasma cells (in the blood) in response to specific antigens. They “hold” the antigen until white blood cells (phagocytes) surround and destroy it. </li></ul>
  16. 20. Definitions cont….. <ul><li>Vaccines – a commercially produced antigen of a particular disease. </li></ul><ul><li>It is not as “strong” as the actual disease itself. </li></ul><ul><li>Passive immunity – Babies receive antibodies from their mother. </li></ul><ul><li>It is temporary: it usually lasts for only 6-12 months. </li></ul>
  17. 21. More definitions… <ul><li>Pathogen – an agent that causes disease. </li></ul>
  18. 22. Discovery of a Virus - 1933 <ul><li>Read pages 455-456 in textbook. </li></ul>
  19. 23. Size of a virus <ul><li>Much smaller than any cell. </li></ul><ul><ul><li>Smallest is 17 nm (.000000017 meter) or 17 billionth of a meter! (nm = 10 -9 meter) </li></ul></ul><ul><ul><li>The largest is 100 nm (.0000001 nm) or 1 ten millionth of a meter. </li></ul></ul><ul><ul><li>Barely visible in an electron microscope. </li></ul></ul><ul><ul><li>http://www.cellsalive.com/howbig.htm </li></ul></ul>
  20. 24. Composition of a Virus <ul><li>A strand of nucleic acid (DNA or RNA) surrounded by a protein coat known as a capsid. </li></ul><ul><li>It may also have an outer “envelope” that it has taken from a host cell. </li></ul><ul><li>It is the shape of the capsid or outer envelope that our immune system recognizes. </li></ul>
  21. 25. Is a virus a living organism? <ul><li>Living things vs. Virus </li></ul><ul><li>Made of cells Not a cell </li></ul><ul><li>Metabolism No metabolism </li></ul><ul><li>Use energy No cell respiration </li></ul><ul><li>Grow/develop No growth or development </li></ul><ul><li>Definite life span Life span? </li></ul><ul><li>Reproduce Need host cell to reproduce </li></ul><ul><li>Respond to stimuli “Inert” (inactive) </li></ul>
  22. 26. Bacteriophage - “bacteria eater” <ul><li>See page 457 in textbook. </li></ul>
  23. 27. Lytic Cycle – 5 steps <ul><li>Step 1 – Attachment – Virus attaches to a specific receptor site on a cell. </li></ul><ul><li>Step 2 – Penetration – Virus enters the host cell </li></ul><ul><li>Step 3 – Replication – Viral DNA and protein is copied. </li></ul><ul><li>Step 4 – Assembly - DNA and protein is assembled into a virus. </li></ul><ul><li>Step 5 – Release – Viruses rupture the cell membrane and are released to infect other cells. </li></ul><ul><li>http://biology.about.com/gi/dynamic/offsite.htm?site=http://faculty.ccbcmd.edu/courses/bio141/lecguide/unit3/viruses/adlyt.html </li></ul>
  24. 28. Lysogenic Cycle <ul><li>Same as the lytic cycle but the viral DNA becomes incorporated into the host cell’s DNA. </li></ul><ul><li>It lies “dormant” until a later date. </li></ul><ul><li>http://student.ccbcmd.edu/courses/bio141/lecguide/unit3/viruses/lysolc.html#si </li></ul>
  25. 29. Viral Subunit Reassortment <ul><li>Two strains of a virus infect a cell at the same time. </li></ul><ul><li>The nucleic acid (DNA or RNA) mix to create new combinations . </li></ul><ul><li>New viruses are produced. </li></ul><ul><li>*It is believed this happens with cold and flu viruses commonly. </li></ul><ul><li>http://www.hhmi.org/biointeractive/animations/subunit/sub_middle_frames.htm </li></ul>
  26. 30. Gene Therapy – A useful purpose of a virus <ul><li>The harmful DNA is removed from a virus. </li></ul><ul><li>A “helpful” strand of DNA is inserted in its place. </li></ul><ul><li>Allow virus to deliver the genes to their target cells. </li></ul><ul><li>http://www.edu365.cat/aulanet/comsoc/Lab_bio/simulacions/GeneTherapy/GeneTherapy.htm </li></ul>
  27. 31. Problems with gene therapy: <ul><li>Locating the correct cells. </li></ul><ul><li>Genes accidentally spliced in the wrong place. </li></ul><ul><li>May trigger a nearby oncogene (cancer causing gene.) </li></ul><ul><li>May cause too much of something to be produced. </li></ul><ul><li>May cause a severe immune response. </li></ul>
  28. 32. Current Research with gene therapy: <ul><li>What diseases could be treated with gene therapy? ( From AMA website.) </li></ul><ul><li>About 4,000 diseases have been traced to gene disorders. Current and possible candidates for gene therapy include cancer , AIDS , cystic fibrosis , Parkinson’s and Alzheimer’s diseases , amyotrophic lateral sclerosis ( Lou Gehrig's disease ), cardiovascular disease and arthritis . </li></ul>

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