Principles of Immunisation Flashcards
what does passive immunity mean?
the body NOT making its own antibodies but need to be GIVEN to the body instead
what is natural passive immunity?
passed through mammal milk (IgA) or placenta (IgG)
what is artificial passive immunity?
passed through antibody (immunoglobulin) injection by antibodies against a specific organism ( post-exposure injection e.g. rabies)
what are 2 types of artificial passive immunity?
- human natural immunoglobulin; contains ALL antibodies, proteins excreted from pooled blood donations
- Human specific immunoglobulin; SELECTED blood donors with high antibodies for a specific organism (post-exposure injection)
Human normal immunoglobulin for post-exposure prophylaxis (preventive measure) is given for what 4 conditions usually?
- hepA
- measles
- polio
- rubella
Specific immunoglobulin for post-exposure prophylaxis (preventive measure) is given for what 4 conditions usually?
- hepB
- rabies
- tetanus
- varicella-zoster virus
what are main advantages of passive immunity? (2)
- immediate protection
2. works well in emergency situations when disease enters the body
what are main disadvantages of passive immunity? (3)
- short term effect ( no immunological memory)
- serum sickness (new antibody recognised as foreign and can lead to anaphylaxis)
- incoming immune cells reject the recipient
what is meant by active immunity?
the body makes ITS OWN antibodies (antigen stimulates an immune response)
what is natural active immunity?
exposure to infection (from the outside environment)
what is artificial active immunity?
vaccination ( the body makes its own antibodies when antigen from vaccine enters the body)
what are main advantages of active immunity? (2)
- long term immunity (may be life long)
- has immunological memory (adaptive)
what is the main disadvantage of active immunity?
- no immediate effect, takes time to develop (but next response will be much faster if encounters the antigen again)
what are 3 main diseases we vaccinate against from early childhood?
measles, mumps and rubella
what happens at primary response?
Immune response is relatively slow at first antigen exposure but creates memory cells.
-IgM remains slightly higher than IgG (both relatively low)
what happens at secondary response?
Immune response is much quicker and effective at second antigen response.
- IgM remains the same but IgG production increases significantly
what are 2 types of vaccines?
- temporary (febrile/fever illness, pregnant women can’t be given live attenuated vaccines)
- permanent (allergy)
how do vaccines work?
- disease causing organism contains antigens
- antigens stimulate production of antibodies in the body
- antibodies bind to organism and lead to its destruction
- memory B cells are made
why can’t live and virulent organisms be used?
they would cause the disease, they’re too dangerous
what is a live attenuated vaccine?
- attenuated/inactivated pathogenic organism by repeated passage in cell culture or non-human host
- attenuation happens by aging or changing growth conditions
- excellent “teachers’ of immune system
- elicit strong cellular and antibody response (lifelong immunity)
what group of people cannot be given a live vaccine?
- immunocompromised patients
-pregnant women
(in case pathogen mutates back to original form)
what vaccines use live attenuated vaccines?
- MMR
- BCG
- polio
- varicella zoster virus
- yellow fever
disadvantages of live attenuated vaccine?
- possibility pathogen could mutate back to original and virulent form
advantages of live attenuated vaccine?
- lifelong immunity without requiring booster shots
- multiply quickly
- most successful
- cause a large immune response
what is an inactivated vaccine?
- produced by KILLING the disease causing microbe with a chemical (formaldehyde), heat or radiation
what vaccines use inactivated vaccines?
- bubonic plague
- typhoid
- HepA
- rabies
what are advantages of an inactivated vaccine?
- don’t require refrigeration and can be easily stored
- more safe and stable than life vaccine
- accessible to people in developing countries
what are disadvantages to inactivated vaccines?
- stimulate a weaker immune response (less effective)
- often require an adjuvant (booster)
- no longlasting immunity
- booster shots required to maintain long immunity
what are 3 types of inactivated vaccine?
- killed organism (pertussis vaccine)
- inactivated microbial exotoxin (tetanus toxoid)
- purified fractions of microorganism (pneumococcus vaccine)
what are acellular vaccines?
uses only the antigenic part of the disease causing organism (capsule, flagella or part of the protein cell wall)
what vaccines use acellular vaccines?
haemophilus influenza B (HIB)
what are advantages of an acellular vaccine?
- cannot cause the disease
- safe for immunocompromised patients (like killed vaccines)
what are disadvantages of acellular vaccine?
- don’t induce a strong immune response
- may require a booster to ensure long lasting immunity
what are toxoid vaccines?
Used when bacterial toxin is the cause of disease. Vaccines are made from toxins; toxins are inactivated by treating them with formalin (detoxified toxins)
- when immune system receives a harmless toxoid, it learns how to fight off the natural toxin
when are toxins changed to toxoids?
when toxins are treated with aluminium or adsorbed onto aluminium salts to decrease its harmful effects
what vaccines use toxoid vaccines?
- tetanus
- diphtheria
- pertussis
what are disadvantages to toxoid vaccines?
- induce weak immune response
- require adjuvant/booster
what is a vaccine using related organism?
- organism which is similar to virulent organism is used which doesn’t cause the serious disease.
(eg. when Jenner used cowpox to make smallpox vaccine)
what vaccines use vaccine using related organism?
BCG (protects against TB)
what is the disadvantage to vaccines using related organism?
requires booster every 3-4 years
what are subunit vaccines?
- includes only the antigens which best stimulate the immune response.
- genes are isolated which code for appropriate subunits from the genome of the infectious agent.
- genetic bacterium is placed into bacteria/yeast host cells which produce large quantities of subunit molecules by transcribing or translating inserted foreign DNA
- subunit molecules are encoded by genetic material from the INFECTIOUS agent not from host cell’s genetic material
- foreign molecules are isolated, purified and used in vaccine
- epitopes (part of antigen that t cell recognise) isolated
what is the main advantage of subunit vaccines?
- chances of adverse reactions are low
- strong immune response stimulated
- safe to use in immunocompromised patients
- cannot cause the disease
what vaccines are made using the subunit vaccine?
HepB vaccine
what are conjugate vaccines?
links antigens and toxoids from the microbe that an infant’s immune system can recognise to the polysaccharides coatings on bacteria’s cell wall
- this is because polysaccharide coatings disguise bacterial antigens so that the immature immune systems of infants cannot recognise and respond to them
- allows body to defend itself against disease causing bacterium
what vaccines use the conjugate vaccines?
HepB, Petussis and HPV
what are DNA vaccines?
- still at experimental stages
- uses only genetic material
- cells will take up DNA from microbe’s antigens and make antigen molecules
what are main advantages of DNA vaccines?
- stimulates strong immune response to free-floating antigen secreted by cells
- cannot cause the disease
- easy and inexpensive design
what are adjuvants?
substance which enhances the body’s immune response to an antigen
what is a common adjuvant?
aluminium salts (cause mild inflammatory reaction, are safe and generate memory)
what is the aim of herd immunity?
reduced the risk of unvaccinated individuals being exposed to infection. Individuals who cannot be vaccinated will benefit from herd immunity and route vaccination programmes
what are important vaccinations for travellers?
- hepA
- typhoid
- meningitis
- cholera and yellow fever
- Japanese encephalitis
- rabies
- tick-borne encephalitis
