Vaccines and Antibodies in Medicine

• 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.

• 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

• 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)

• 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 ***** carrying the beads with it
• ***** contains hCG that are stuck in place ( immobilsed)
• If there is hCG present test ***** turns blue, if not it will pass through test area and not turn blue.

Vaccines:

• 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.