Vaccines allow the immune system to identify the bacteria or virus. These are called antigens. The body builds up a defense mechanism made of antibodies. Antibodies recognize invaders and allow the body to attack. Antibodies remember the antigen so that the next time it is seen in the body, it can send a defense to attack.
This storage of information is why a person does not often get a disease such as chicken pox twice. The first time a person get it, or gets the vaccine, the body builds up antibodies against the disease. The second time the body sees this invader, it knows exactly what to fight against.
The first vaccine was created by Edward Jenner. Jenner created a vaccine for small pox. He found that people who had cow pox didn't get small pox. Cow pox is similar to small pox except it is much weaker, lasts a lot shorter, and usually only forms blisters on the hands. To test this theory, he injected cow pox into a boy who then got the disease. A short time later, the boy recovered, perfectly fine. Weeks later, Jenner injected small pox into the boy. This boy did not get the disease and thus created the very first vaccine.
It is important to know that vaccines only include just enough antigens for the body to recognize and complete the immune process. This means that the body is able to get rid of the antigen so it isn't harmful.
There are six different types of vaccines:
Similar pathogen vaccine:
*an example is small pox
This vaccine uses a pathogen from a similar to the virus that you want to protect against but different enough so that it doesn't cause the disease when it enters your body.
The fluid containing the virus is separated so just the virus is left. This is what is used for the vaccine.
Attenuated vaccine:
*examples: measles, mumps, rubella, yellow fever
For this vaccine, a live form of the virus is grown in a tissue culture. The virus is different enough from the original virus so that it doesn't cause the disease but similar enough so your body can recognize it.
These are a very weakened version of the virus but still alive.
Killed vaccine:
*examples: polio, typhus, influenza, rabies
The purpose of this vaccine is to keep the shape and characteristics to generate an immune response but disable the ability to replicate.
In other words, the vaccine is harmless but still contains antigens.
Attenuated vs Killed
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Live but very weak
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Inactivated/killed
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Long lasting & few boosters
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Boosters are required
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Smaller dose b/c it replicates
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Larger dose b/c it doesn’t replicate
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Toxoid vaccine:
*tetanus, pertussis, diphtheria
This vaccine conditions the immune system to fight the toxin produced by an invader and isolates its toxins.
The toxins are separated from the virus and then the toxins are neutralized. An adjuvant is added to the neutralized toxins to help it cause an immune response.
The vaccine still requires boosters to help it be completely effective.
Subunit vaccine:
*hepatitis B, anthrax
This vaccine contains a piece of protein that surrounds either the DNA or RNA.
To create the vaccine, the DNA is separated from the virus. The DNA is then combined with the DNA of a yeast culture. The desired antigen, created by the yeast cells, is isolated and then used for the vaccine.
The isolated vaccine does not contain any of the viral DNA, so it is not possible to catch the disease after the vaccine.
Naked DNA vaccine: (Genetic vaccines)
*HIV/AIDS, herpes, influenza, malaria
A gene is used from the pathogen to produce a response.
A single gene is copied using PCR. Vectors are then combined with the virus's gene. Vectors are agents that can cause a cell to make proteins based on the vector's DNA. Bacteria is used to help the altered vectors replicate. Once the altered vectors are separated, this is what it used for the vaccine.
