Vaccines (Princ. immunisation) Flashcards
How is active immunity produced?
A foreign antigen triggers an adaptive immune response int he body.
This creates immunological memory (memory cells).
Whats the difference between the initial response & response with active immunirt?
The intitial response is slow & uses not great IgM antibodies.
The future response is much faster, larger & uses more effective IgG antibodies.
Name the 5 types of vaccine that cause active immunity:
Toxoids Conjugate vaccines Attenuated vaccines Killed vaccines Recombinant vaccines
What is an attenuated vaccine?
Organisms that are live but no longer pathogenic.
Produce full immune response but no disease.
How are pathogens attenuated?
Passes through non-human cell cultures repeatedly till they become non-pathogenic.
Why arnt attenuated vaccines given to the immunocompromised or pregnant?
Chance they could still revert to their pathogenic state.
What are the limitations of Attentuated vaccines?
- Needs refrigeration so hard in developing countries.
- Easier for viruses than bacteria
Give an example of an attenuated vaccine?
MMR
BCG (TB) (Bacillus Calmete-Guerin)
How is a pathogen deactivated for a dead vaccine?
Formaldehyde causes chemical deactivation
In what way is a dead vaccine better than live?
Can’t revert to wild-type so not a danger to the immuno-compromised or pregnent.
Why use adjuvants in dead vaccines?
They produce a wekaer immune rseponse so adjuvants reduce the doses needed.
Define Adjuvant
A substance that enhances antibody response
Why wouldnt you always use adjuvants?
They can have inflammatory responses against other proteins/antigens int he vaccine
Give an example of a dead vaccine:
Polio
HEP A
Rabies
What is a toxoid?
A pathogen’s toxin thats been treated with formalin.
Is a toxoid acellular?
Yes its an acellular vaccine
How is a toxoid vacccine different to others?
IT induces immunit against the toxin not the pathogen.
Give an example of a toxoid vaccine:
TDP
- Tetanus
- Diptheria
- Pertussis
Whats a subunit vaccine?
Part of a pathogen e.g. antigen or nucleic acid
Why is a subunit vaccine safe?
Because its only part of a pathogen so it cant form an infectious agent
Whats a benefit of a subunit vaccine?
Its easy to produce in large amounts
Whats the main type of subunit vaccine?
Recombinant vaccine
How is a recombinant vaccine produced?
Recombinate DNA technology.
- DNA that encodess antigen is inserted into yeast chromosome.
- Antigen is harvested & purified
Example of Recombinant vaccine
HEB B surface antigen for the HBV vaccine
What is a conjugate vaccine>
A poor antigen is conjugated to a stronger antigen to enhance the immune repsosne to the poor antigen. Most commonly a polysaccharide conjugated to a protein.
Give an example of pathogens affected by conjugate vaccines:
- Streptococcus Pneumoniae
- Neisseria meningitidis C
What is a DNA vaccine?
- An experimental vaccine
- The genes that encode a pathogen’s antigens.
How do DNA vaccines work?
Genes are taken up by cells
The cells prduce the antigen.
Either released or displayed on the surface.
How does the body respoond to a DNA vaccine?
Evokes a strong cellular response against the cell surface antigens.
Evokes a strong antibody response against the free-floating antigens.
What DNA vaccines are being tested in people?
Influenza & herpes vaccines.
What is passive immunisation?
Quick & immediate protection but with no memory
How is passive immunisation created?
By innoculating the patient with antibodies from another person or animal.
What are the 2 types of passive immunity injections?
Human normal immunoglbulin
Human specific immunoglobulin
Whats the difference between HNI & HSI vaccines?
Human Normal Immunoglobulin vaccines contain antibodies from an unselected pool of random donors.
Human specfic immunoglobulin antibodies use blood donors with a high antibody level against the target organism.
