2.03 - Vaccinations Flashcards
What is the difference between active and passive immunisation?
Active: administration of vaccine that elicits a protective immune response
Passive: administration of antibodies that protect the recipient
What are the three roles that antibodies play in host defense?
Neutralisation of pathogenic toxins
Opsonisation for phagocytosis
Complement activation
What are the different types of active immunisations?
Killed/inactivated preparation of pathogen Live-attenuated pathogen Conjugate vaccines Subunit vaccines DNA vaccines Peptide vaccines
How effective are live attenuated vaccines? Do they confer a risk of restoration of virulence?
Most effective of all vaccines, confer a long lasting immunity.
They have a risk of restoration of virulence or reversion, particularly in immunosuppressed or immunodeficient. Genetic engineering has been undertaken to ensure reversion does not occur
How effect are killed/inactivated vaccines?
Less effective than live attenuated - limited cellular immune response to due to absence of replicating organism, predominantly humoral –> antibody production.
More effective if antigen is a protein
What are conjugate vaccines? Who are they important to vaccinate with?
Polysaccharide conjugated with carrier protein that immune system has already been exposed to –> immune response T-cell dependent.
Important to vaccinate <2yrs and those without spleen/hyposplenism
What are subunit vaccines?
Present antigen to immune system without introducing viral particles. Spontaneous aggregation into virus like particles –> increased immunogenicity.
What type of vaccine if the HPV vaccine?
It is a virus like particle. Self assembles when L1 protein of HPV produced in isolation. Comprises a mixture of virus types, highly immunogenic. Results in production of virus neutralising antibodies.
What are the advantages and disadvantages of inactivated vaccines?
Advantages: safety, easy to produce and store, less effected by pre-existing antibodies
Disadvantages: require boosters, may not preserve immunoprotective antigen, poor induction of T-cell immunity, poor inducers of mucosal immunity, potential for immune dysregulation, potential for immune response to tissue antigens derived from cells to which vaccine produced (allergy)
What is an adjuvant and what is its role?
Substances that have the ability to increase the immune response to an antigen, such as alum precipitation with the use of aluminium hydroxide.
They act as a depot for slow release, recruit APCs, enhance production of co-stimulatory molecules, act as PAMPs.
However, increase risk of side effects.
Examples: aluminium salts, toxins from cholera and pertussis, cell wall extracts and bacterial polysaccharides etc.
What are some adverse events associated with vaccination?
Bordetella Pertussis (whole cell preparation) --> localised erythema, pain, swelling, fever. 1/2000-3000 risk of febrile convulsion, rarely neurological complications Live attenuated --> increased risk of disease in immunodeficient Rotavirus --> intussuception Allergy to growth media or antibiotics used in egg culture --> influenza, yellow fever
