Immunity and vaccines
- Created by: jessicawarren
- Created on: 18-04-16 12:14
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- Immunity and Vaccines
- Protection
- 1) Vaccines contain antigens that initiate production of memory cells without pathogen causing the disease. Become immune without symptoms
- 2) Vaccines reduce occurrence of disease- those not vaccinated less likely to catch disease. Herd immunity
- 3) Contain dead/weakened antigens
- 4) May be injected/taken orally. Oral vaccines can be broken down by enzymes/may be too big to be absorbed into blood.
- 5) Booster vaccines given to make sure memory cells produced
- Antigenic variation
- 1) Antigens on surface of pathogen activate primary response
- 2) Second infection of same pathogen activate secondary response- don't get ill
- 3: Some pathogens change surface antigens
- 4) Memory cells produced from first infection will not recognise different antigens on second infection. Primary response carried out again
- 5) Person gets ill again, primary response slow
- 6) Difficult to develop vaccines against some pathogens e.g. HIV/ influenza
- Flu
- 1) Flu vaccine changes every year as antigens on flu virus change regularly and form new strains on virus.
- 2) Memory cells produced from one strain will not recognise other strains with different antigens- immunologically distinct
- 3) Every year different strains of influenza circulate population, different vaccine has to be made
- 4) New vaccines are developed every year, most effective against recent strain chosen
- 5) Government implements programme of vaccination using most suitable vaccine
- Active Immunity
- Immune system makes own antibodies
- Natural: become immune after catching disease
- Artificial: become immune after vaccination
- Requires exposure to antigen, takes a while for protection to develop, memory cells produced, long term protection due to memory cells
- Passive
- Given antibodies made by different organism
- Natural: mother provides antibodies to baby through placenta/milk
- Artificial: Become immune after injection of antibodies from someone else
- Doesn't require exposure to antigen, immediate protection, no memory cells produced, short term protection
- Protection
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