Transcript preventing-disease6

Protection against
Disease
Vaccination
Learning Objectives
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Explain how vaccination helps to
make you immune to diseases
Starter Activity
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Crossword
Vaccination
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Vaccination aims to make you immune to a disease without
having to be ill
A vaccine contains antigens derived from pathogenic
organisms
When injected into an individual the antigen stimulates a
primary response that leaves memory cells to generate the
secondary response (which is rapid and produces massive
quantities of antibody) if the individual is subsequently
infected by the relevant pathogen
Adults have immunity to most common diseases (except
colds and flu)
This immunity is acquired through contact with the pathogen
of vaccination
This is called acquired active immunity and is the most
effective and can last a long time
Foetal Immunity
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During development of a human some antibodies may
leak across the placenta from the mother to the foetus.
Also during the first few days of breast feeding the
breasts produce a high protein , low fat liquid called
COLOSTRUM which contains many antibodies and
provides young infant with immunity against a number of
diseases until its own immune system is fully functional
Antibodies are also present in later milk
This is naturally induced passive immunity but no primary
response occurs in baby because it is simply receiving
antibodies
This is PASSIVE IMMUNITY – SHORT LIVED
IMMUNITY
Artificial Immunity
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Artificially induced passive immunity arises
when someone receives an injection
containing an antibody- the recipient is
supplied with ready made antibodies from an
outside source e.g. tetanus, diphtheriaproduced/cultured in horses
Natural of artificial, passive immunity only
lasts a few months – the body does not
produce its own antibody or memory cells
since both these processes require the
presence of an antigen. The antibody
molecules themselves are proteins and
continually being broken down and replaced
Vaccines
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Children must receive vaccinations as they
grow up to prevent large outbreaks of disease
Immunisation – artificially creating immunityfirst developed by 18th century physician
Edward Jenner
Sometimes the original vaccine is not enough
and boosters are needed
In 94-95 the possibility of a measles epidemic
was so high there was a big publicity
campaign to ensure all school age children
were immunisation
Measles
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Measles can be very dangerous to school
age children
Symptoms – high temp, rash, cough , sore
eyes. It can also lead to blindness,
deafness and brain damage
Side effects of the vaccine include a mild
rash or fever for about a week and small
risk of brain damage
Dangers of measles far outweigh the
dangers of the vaccine
Types of Vaccines
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2.
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5.
Killed pathogens
Isolated pathogens
Attenuated strains
Toxoids
Genetically engineered antigens
Killed Pathogens
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E.g. whooping cough vaccine is made up of
killed virulent pathogens
Because the cells are dead they cannot
cause the disease but when they are
injected the body reacts to the antigens
present in the cell membranes and a
primary response is induced
This sort of vaccine is used against
whooping cough
This vaccine is injected into muscle tissue
and lasts for many years
Isolated Pathogens
Some vaccines are made from
antigen that has been isolated from
the organism that produced it. The
isolated antigen cannot cause the
disease
 Some flu vaccines are of this type
 This vaccine is injected into muscle
tissue and last for 1-3 years
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Attenuated strains
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Sometimes a less virulent strain of the
pathogen is used
This is usually a mutated form which does not
cause the disease
Such a non virulent form is called an
attenuated strain. This is used to combat
rubella
Attenuation may be achieved by culturing the
organism at a higher temp or adding specific
chemicals to the culture medium
This is injected subcutaneously and is
permanent
Toxoids
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With many diseases the illness is caused by
the toxin that was produced by the
pathogen. The toxin is often the antigen that
induces the immune response
Some vaccines eg for diphtheria are made
of altered or modified toxin molecules that
cannot cause the disease but do evoke an
immune response. These are called
TOXOIDS
This vaccine is injected into muscle tissue
and lasts for 10 years
Genetically Engineered
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GE bacteria and yeasts are used to produce vaccines for
the viral disease hep B
The gene coding for the viral antigen (the virus coat protein)
is cloned and inserted into bacterial or yeast cells
This enable large scale production of the antigenic protein
which is then purified for use as a vaccine is generated for
many years
When the antigen is injected into muscle tissue it stimulates
the immune response and long lasting immunity is
generated for many years
Sometimes a person may be in a very high risk situation, for
example a baby born to a mother with hep b
In such case temporary immunity against hep b can be
created by injecting antibody and long term immunity
produce by injecting antigen at the same time
Tetanus
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Caused by clostridium tetanus producing a
deadly toxin
Spores of the bacterium are found
everywhere esp in soil and dust
The effect of tetanus jab lasts about 10
years and a new booster is needed after
Few people keep up to data so whenever a
person has an accident it is vital to check up
on the patient immunity
Tasks