Vaccines can protect individuals and populations a
- While B cells divide to build up numbers in order to deal with the pathogen(eg. Primary response) you suffer from the disease.
- Vaccination can help avoid this.
- Vaccinations contain antigens --> make you body produce memory cells against the pathogen ( with out causing disease)
- This means you become immune with out getting any symptoms
- They can reduce the occurrence of a disease. Even not vaccinated people will be less likely to catch the disease due to less people to catch it from. ( HERD IMMUNITY)
- Vaccinations always contain pathogens- free, or attached to dead/ attenuated( weakend) pathogen.
- Vaccinations can be taken via injection or orally. But if they are taken orally a disadvantage would be enzymes in the gut could break it down OR molecules may be too large to be absorbed in to the blood.
- Booster vaccines can be give later on to make sure memory cells are produced.
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Antigenic Variation helps some pathogens evade the
- Antigens on pathogens surface activate primary response
- When infected a second time by the same pathogen you get a secondary response..
- BUT some pathogens can change their surface anitigens ( antigenic variation)
- Different antigens are formed due to changes in the genes of a pathogen
- SO when you are infected for the second time, the memory cells from 1st infection wont recognise the different antigens.
- The immune system will have to start from scratch and carry out primary response again
- You suffer symptoms again and feel ill as the primary response takes time to get rid of new infection
- Antigenic variation makes it difficult to develop vaccines against some pathogens for the same reason
- FOR EXAMPLE - HIV, S.pneumonia and influenza
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Antigenic Variation and the Influenza Virus
- Causes Flu
- Protiens ( neuraminidase and haemagglutinin) on the surface of the influenza virus act as antigens --> triggering an immune response.
- These antigens change frequently forming new strains of the virus.
- Memory cells produced from the infection with one strain, will not recognise other strains with the other antigens,
- So your immune system produces a primary response every time you are infected with a new strain
- SO, you suffer from the flu more than once ( each time with a new strain)
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Monoclonal Antibodies can be used to target specif
- Monoclonal antibodies= produces from a single group of genetically identical b cells
EXAMPLE ONE - CANCER
- Cancer cells have tumour markers- not found on normal body cells
- Monoclonal antibodies can be made to bind to these markers when they come into contact
- you can attatch anti cancer drugs to the antibodies
- So the drug will only accumilate where there are cancer cells- reduces side effects of drugs
EXAMPLE TWO - PREGNANCY TESTS ( they detect human chorionic gonadotropin (hCG) )
- Antibodies for hCG are attatched to a blue bead
- When urine is applied to application area any hCG will bind to antibody - antigen-antibody complex
- urine moves up the stick to test strip carrying the beads with it
- strip contains hCG that are stuck in place ( immobilsed)
- If there is hCG present test strip turns blue, if not it will pass through test area and not turn blue.
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Ethical Issues surrounding vaccines and antibodies
- All vaccines are tested on animals first
- Animal based substances may be used to produce a vaccine
- Testing on humans - volunteers put them selves at unnecassary risk ( eg contracting the disease)
- Some people dont want to take the vaccine due to risks of side effects, but are still protected due to herd immunity - unfair
- If there was an epidermic of a new disease, there would be a rush to receive it. Difficult decisions would have to be made about who would be 1st to receive it
Monoclonal Antibody therapy
- Animals are used to produce the cells from with they are produced.
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