Types of vaccine and the principles of vaccination Flashcards
What does passive immunisation refer to?
The transfer of pre-formed antibodies to provide temporary resistance
What are the problems with passive immunity?
- Potential for hypersensitivity if given repeatedly
- Preformed antibody prevents recipient immune response
Define active immunisation?
Delivery of an antigen to induce an immune response & establish immunological memory
What are the properties of an ideal vaccine?
- Cheap to produce
- Stable
- No side effects
- Induce a protective immune response
- Include a multiple range of epitopes to stimulate multiple clones of T & B cells
- Induce immunological memory
What are Live vaccines and examples
Contain whole pathogen
- virulent
- attenuated
- heterologous
What are attenuated vaccines?
Vaccines where the pathogen is altered in some way so that it cannot cause disease
What are heterologous live vaccines?
When an antigenically-related pathogen is used to vaccinate against another pathogen
What is a killed/inactivated vaccine?
Where the organism is antigenically intact but unable to replicate
Compare live & killed vaccines
- Live induces better immunity
- Live require fewer doses
- Live doesn’t need an adjuvant
- Greater risk of reversion to virulence in live
- Live are less stable
What are the 2 types of subunit vaccines?
- Contain only specific metabolites or structural proteins from an organism that are known to stimulate a protective immune response
- Synthetic peptide vaccines
What is immunogenicity?
The ability of a foreign substance to provoke an immune response
What are the issues with synthetic peptide vaccines?
Have low immunogenicity so need an adjuvant
What are virus vectored vaccines?
Harmless viruses are used to deliver the genetic code of antigens to cells of the body resulting in the production of protein antigens which stimulate an immune response
Describe RNA vaccination
mRNA is injected into the body and taken up by cells where it is translated by the cell into antigen which stimulates an immune response. mRNA only lasts for a short time and is broken down naturally & removed by the body
What are the advantages and disadvantages of RNA vaccination?
- Can be produced more rapidly than conventional vaccines
- More flexible because the code used to create the vaccine can be changed in responses that are seen in the pathogen
- Not very stable so have to be stored at very low temperatures
