Vaccination and Immunisation Flashcards
Pasteur Principle
- ISOLATE
- INACTIVATE - or imitate
- INJECT
Essential characteristics
of vaccines
- Must provide effective protection without risk of causing disease or severe side effects
- Protection should be long-lived
- Should stimulate correct arm of immune response, ie antibodies or effector T cells
- Stimulate neutralising antibodies to prevent re- infection
- Stable for long-term storage and transport
- Economically affordable for widespread use
Live vaccines
organisms capable of normal infection and replication. Not used against pathogens that can cause severe disease
Attenuated vaccines
Organism is live, but ability to replicate and cause disease reduced by chemical treatment or growth-adaptation in non-human cell lines. (measles, mumps, rubella)
killed vaccines
organism killed by physical or chemical treatment. Incapable of infection or replication, but still able to provoke strong immune response (B.pertussis, typhoid)
extract vaccines
materials derived from disrupted or lysed organism, eg capsular polysaccharides. Used when risk of organism surviving inactivation steps (flu, pneumococcal, diptheria, tetanus)
Recombinant vaccines
genetically engineered to alter critical genes. Often can infect and replicate but does not induce associated disease
DNA vaccine
naked DNA injected. Host cells pick up DNA and express pathogen proteins that stimulate immune response
What vaccine is best?
live or attenuated
• Paradoxically, the safer the vaccine, the
less effective some have been
• Living or attenuated organisms express proteins and stimulate the immune response in a manner which most closely resembles normal infection
Dendritic cells in vaccination
express Pattern Recognition Receptors (PRR), members of the Toll-like receptor Family (TLR)
role of dendritic cells
- encounters antigen in periphery and becomes activated
- migrates to lymph node
- activates T cells to become effector cells
