Curious?

Ebola – nurse http://www.bbc.com/news/world-

europe-29547432Bubonic Plague -

http://science.howstuffworks.com/life/cellular-microscopic/plague3.htm

TED – The Jungle Search for Viruses• http://

www.ted.com/talks/nathan_wolfe_hunts_for_the_next_aids

Vaccines & Human Health

Vaccines• a weakened,

diluted or dead form of a virus that is injected (because saliva & stomach enzymes would destroy it) into the body to produce immunity.

Vaccines (cont’d)– The body reacts to the shape of the virus and

produces antibodies – so immune system can fight off the disease (produce immunity).

Vaccines (cont’d)– can prevent outbreaks, infection and death. – Yet, can also weaken your immune system – you

cannot fight off other diseases because your immune system is busy.

Effects of viruses on human healthHarmful Beneficial

•Causes disease, cancer •Vector for gene splicing (to “replace” bad gene)

•Causes brain damage (ex. Measles)

•Biological control (control or eliminate other organisms)

•Destroys organs ex. Hepatitis – liver, heart

•Make vaccines

•Can be fatal

Avoiding Viruses

• Vaccinations• Good hygiene – wash hands, bedding,

clothing…• Abstinence• Boil water where cleanliness is in question• Eat healthy

Case StudyVaccines: The Needle of Hope

Nelson (Orca text) p. 206

a) Dairy maids often had cowpox sores on their hands. Suggest a possible source of the virus.

Source of the cowpox sores was probably the cows milked by the dairy maids.

b) Assuming that the virus is contagious, would you expect to find that cowpox would infect people other and diary maids? Give your reasons.

The virus would likely infect anyone who worked with the cows or with people with cowpox

c) What dangers did Jenner’s untried procedure hold for young James Phipps?•After the injection of smallpox he could have developed smallpox or even diedd) Why do you think using humans as a first test subject is no longer accepted?

There are laws against using humans as subjects for experimentation without their permission. Usually tried on other animals first. Is this acceptable?

e) What makes the cowpox virus less virulent than smallpox? Cowpox is less virulent than smallpox because smallpox reproduces faster than cowpox and therefore the immune system cant make antibodies quick enough.f) Explain why cowpox antibodies stop the spread of smallpox in the human body? The cowpox antibodies are similar in shape to the smallpox antibodies therefore they bind to smallpox antigens and stop them from invading cells (cowpox most likely led to smallpox)

Part II:g) Explain why the reproduction of the virus (rabies) inside the host cell makes it especially dangerous. Because the virus reproduces inside the cell, the immune system of host can’t “find” it and therefore, can’t produce the antibodies against it.h) Why do the symptoms of rabies not show up immediately after the virus enters the first cell? Symptoms of rabies don’t show up until the virus has reproduce inside cells.

i) Why did Pasteur want to weaken the rabies virus before injecting it into a person? Pasteur wanted to weaken the virus so the immune system could make antibodies before the virus could reproduce enough to cause the disease in host.j) Draw a diagram showing how the virus is defeated when it emerges from the body cells after it incubation period. Diagram with the correct shape antibodies should be available to bind with the antigens when the virus emerges from the cell.

Part III:k) Propose an explanation for why an antibody would work well against one type of polio but not against another. Different types of viruses means that they will have a different protein coat and therefore different shaped antigens. Antibodies shape is specific to antigen shape.