Principles of Immunisation Flashcards
What are 2 examples of natural passive immunity?
- placental transfer of IgG
- colostral transfer of IgA
What are 2 examples of artificial passive immunity?
- treatment with immunoglobulin
- immune cells
What is human normal immunoglobulin?
contains all antibodies- protein extracted from pooled blood donations
What is human specific immunoglobulin?
selected blood donor with high antibody titres against a specific organism
When is HNIG used for post-exposure prophylaxis?
- hep A
- measles
- polio
- rubella
When are specific immunoglobulins used for post-exposure prophylaxis?
- hep B
- rabies
- tetanus
- Varicella-Zoster virus
What is an advantage of passive immunity?
gives immediate protection
What are the disadvantages of passive immunity?
- short term: no immunological memory
- serum sickness
- graft versus host disease
What is an example of natural active immunity?
exposure/infection
What is an example of artificial active immunity?
vaccination
What are the advantages of active immunisation?
- antigen stimulated immune response
- long term immunity
- immunological memory
- faster and better response on second encounter
Vaccination
the administration of antigenic material to stimulate and individual’s immune system to develop adaptive immunity to a pathogen
Why might someone not receive a vaccination?
- febrile illness
- pregnant woman cannot receive live attenuated vaccines
- allergy
- immunocompromised cannot be given live attenuated viruses
How does an immune response occur?
- disease causing organism contains antigens
- antigens stimulate the production of antibodies
- antibodies bind to the organism and lead to its destruction and memory B cells are formed
How are live attenuated vaccines made?
attenuation of a pathogenic organism by repeated passage in cell culture or a non-human host
Advantage of live attenuated vaccines
they elicit strong cellular and antibody responses and often confer lifelong immunity with only one or two doses
Disadvantages of live attenuated vaccines
- remote possibility exists that an attenuated microbe could revert to a virulent form and cause disease
- require refrigeration
How are inactivated vaccines produced?
by killing the disease causing microbe with chemicals, heat or radiation
Advantages of inactivated vaccines
- more stable and safer than live vaccines
- do not require refrigeration
Disadvantages of inactivated vaccines
stimulate a weaker immune system response than liv vaccines
- may require and adjuvant
- boosters likely required
What are 4 examples of inactivated vaccines?
- bubonic plague
- typhoid
- hep A
- rabies
What are acellular vaccines?
use only the antigenic part of the disease causing organism
What are the characteristics of acellular vaccines?
- don’t induce the strongest immune response
- may require boosters
- cannot cause disease
When are toxoid vaccine used?
when a bacterial toxin is the main cause of illness- when bacteria secrete toxins or harmful chemicals
How are toxins inactivated?
treating them with formalin
What is an example of a toxoid vaccine?
DTaP (diphtheria, tetanus and pertussis)
What is a BCG?
a vaccine against Mycobacterium bovis to protect against Mycobacterium tuberculosis
What is a subunit vaccine?
- a vaccine that only includes the antigens that best stimulate the immune system
- in some cases they use epitopes- parts of the Ag that Ab or T cells recognise
What is a conjugate vaccine?
A vaccine which links antigens or toxoids from the microbe that an infant’s immune system can recognise to polysaccharides
What problem do conjugate vaccines solve?
- many harmful bacteria have an outer coating of polysaccharides
- -polysaccharide coatings disguise bacterial antigens so that the immature immune system of infants and children can’t recognise or respond to them
What do conjugate vaccines defend against?
- hepB
- hib
- pertussis
- HPV
How do DNA vaccines work?
- use only genetic material
- when the genes for a microbe’s antigens are introduced into the body, some cells will take up that DNA and some cells make the antigen molecules.
- the cells secret the antigens and display them on their surfaces
- this evokes a strong antibody response to the free-floating antigen secreted by cells
- stimulates a strong cellular response against the microbial antigens displayed on cell surfaces
Adjuvant
a substance which enhances the body’s immune response to an antigen
What is the primary aim of vaccination?
to protect the individual who receives the vaccine
How does herd immunity occur?
- Vaccinated individuals are less likely to be a source of infection to others
- this reduces the risk of unvaccinated individuals being exposed to infection
- therefore individuals who cannot be vaccinated will still benefit from routine vaccination programmes
