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Making Vaccines
Attenuated vaccine: measles virus

measles step 1 Step 1
Use the tissue culture to grow new viruses.

  You are about to create a live-attenuated vaccine, which means that you need to alter a pathogen—in this case a measles virus—so that it will still invade cells in the body and use those cells to make many copies of itself, just as would any other live virus. The altered virus must be similar enough to the original measles virus to stimulate an immune response, but not so similar that it brings on the disease itself.

To create a new strain of the virus, you'll need to let it grow in a tissue culture.

Measles step 2 Step 2
Fill the syringe with a strain of the virus that has desirable characteristics.

  The tissue culture is an artificial growth medium for the virus. You will intentionally make the environment of the culture different than that of the natural human environment. For this vaccine, you'll keep the culture at a lower temperature.

Over time, the virus will evolve into strains that grow better in the lower temperature. Strains that grow especially well in this cooler environment are selected and allowed to evolve into new strains. These strains are more likely to have a difficult time growing in the warmer environment of the human body. After many generations, a strain is selected that grows slow enough in humans to allow the immune system to eliminate it before it spreads.

Measles done Done
The measles vaccine is complete.

Select another pathogen.

  Congratulations. You have just produced a live-attenuated measles vaccine.

Like the smallpox vaccine, the virus within the vaccine will invade body cells, multiply within the cells, then spread to other body cells. The virus used in the measles vaccine today took almost ten years to create. The starting stock for the virus originated from a virus living in a child in 1954.

Live-attenuated vaccines are also used to protect the body against mumps, rubella, polio, and yellow fever.

Smallpox icon
Similar-pathogen vaccine:
smallpox virus
  Measles icon
Attenuated vaccine:
measles virus
  Polio icon
Killed vaccine:
polio virus
Tetanus icon
Toxoid vaccine:
  Hepatitis icon
Subunit vaccine:
hepatitis B
  HIV icon
Naked-DNA vaccine:

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