What is vaccination?
-Vaccination provides immunity to specific diseases.
-A person who has been vaccinated has artifical active immunity.This is created by deliberate exposure to antigenic materials that the immune system treats as a real pathogen and as a result manufatures antibodies and memory cells to provide long term immunity.
-Antigenic materials can be in the form of:
-whole, live micro-organisms that arent as harmful as the real disease but have similar antigens that stimulate antibodies which will be effective on the real disease.
-Harmless version of the pathogenic organism
-A dead pathogen
-Preparations of antigens from a pathogen or harmless toxins.
How does vaccination control disease?
-By providing immunity to all those at risk.
Herd Vaccination: using a vaccine to provide immunity to all or almost all of the population at risk. Once enough people are immune, the diease can no longer spread. In order to be effective it is essential to vaccinate almost all of the population. Eg. smallpox.
Ring Vaccination: is used when a new case of disease is reported. Ring vaccination involves immunising all the people in the immediate vicinity of the new cases.
Influenza: Many pathogenic organisms can form a new strain by mutation. This may mean the exisiting vaccine is ineffective. Influenza is a disease caused by a virus which affects the respiratory system. People over 65 or with respiratory tract conditions are msot at risk.
-To avoid pandemic people at risk may be immunised. In the UK there is a vaccination programme to immunise all those over 65 and those at risk for any other reason. The strains of flu used change each year and research is taken to determine which is most likely to spread that year.
Active and Passive immunity
Active Immunity: is achieved by the activation of the immune system. Lymphocytes in the body manufacture antibodies and release them into the blood. This form of immuity is long lasting.
Passive Immunity: is provided by antibodies that have not been manufactured by stimulating the immune system. Antibodies may have been provided over the placenta or through breast milk or by injection.
Natural and Artifical Immunity
-natural immunity: is gained in the normal course of living processes. It may be gained as a result of an infection that stimulates and immune response. It can be active or passive, for example naturally and passively antibodies can be given through the placenta or breast milk btu naturally actively by infection.
-Artifical immunity: is gained by the deliberate exposure to antibodies or antigens. It can be passive or active, for example injecting antibodies is passive artifical but antibodies provided by vaccination is active artifical.
Finding New Drugs.
-Need for new drugs: new diseases are still emerging, there are still many diseases for which there are no effective treatments, some antibiotic treatments are becoming less effective as the bacteria continue to evolve due to the drugs putting seletion pressure on them.
-New drugs are discovered by accident (penicillin), use of traditional medicine, anaethetics, observation of wildlife and modern research.
-Natural medicines: discovery of natural drugs has concentrated on tropical plants. Due to their diversity there may be many new drugs to discover and this is why we need to maintain biodiversity.
-Further research: Antibiotic have been developed from micro-organisms and biologists hope to learn how bacteria produce antibiotics by finding out what their genes do.
-HIV virus CD4 receptor can be isolated and sequenced. Once the amino acid sequence is determined molecular modelling can be used to determine the shape of the receptor. A drug that blocks that receptor then needs to be found.
-Genomics and DNA comparison.