L11: Immunisation Flashcards
Explain passive immunity
- short lived (half life of IgG ~3 weeks)
- hypogammaglobunlinaemia in infants as maternal IgG declines
- can be gained by plasma infusion (Ab from recovered patients)
- IgG can be infused every 2/3 weeks for immunodefieciency to maintain protection
Explain active immunity
- exploits immunological memory
- secondary response is faster to develop, greater in magniutde and may be qualitatively better (e.g. higher affinity Ab)
How can herd immunity protect an individual and the gen population
Disease declines if majority of population is immune
Explain the pathology of measles
- highly infectious viral disease where patients develop fever and rash
- can cause ear infections ( which can lead to hearing loss), pneumonia (particularly in young kids), sub acute scelerosing panecephalitits (SSPE)
What percentage range need to be vaccinated to prevent MMR outbreaks?
83-94%
List the requirements for an effective vaccine
- vaccine being safe& stable
- high level of protection
- long lasting protection
- right type of response
- low cost
- easy to administer
- minimal side effects
What are the 5 main typpes of vaccines?
- Inactivted: dead organisms
- Attenuated: live but virulence disabled organisms e.g. yellow fever
- Subunit: protein fragments e..g Hep B
- Toxoid: bacterial toxin e.g. tetanus
- Conjugate: something with low antigenic property covalently bound to something with high e.g. s. pneumoniae+ diptheria
Name advantages of using live vaccines
- single dose effective
- may be given by natural route
- may induce local and sytemic immunity
- may induce right type of response
Name cons of using live vaccines
- can revert to virulence
- possibility of contaminatin
- susceptible to inactivation
- causes disease in immunocompromised host
How is polio caused?
By an enterovirus spread through the faceo-oral route
Explain the cell biology of polio
Member of the picornaviridae: +ve sense RNA translated into large polypeptide which is cleaved post translation
How do polio infections present?
Most infections are subclinical and are small # are accompanied by flu like symptoms
How many strains of polio cause symptoms?
3
Give examples of diseases that are treated with subunit vaccines
- hep B: surface Ag of virus
- pneumoccal polysacc: from the capsule of s. pneumoniae (pneumovax) & may get non responders
- tetanus toxoid: inactivated form of a protein exotoxin seecreted by bacteria
Explain how subunit vaccines work
T dependent response
- MHC interaction with TCR ables T cells to help and stimulate B cells by production of their cytokine panel
What is ‘reverse vaccinology’?
Where the whole genome is screened to identify proteins that could be used as vaccines
- used to develop vaccine against neisseria meningitidis group B
What are other important considerations for vaccines?
- Importance of inducing ‘right type’ of immunity e.g. HIV may need to induce CTL response
- Wrong type of immune response may do more harm than good e.g. 1960s RSV vaccine
What are adjuvants?
Substances administered with an Ag to promote immune response
- pure Ags often eliicit weak immune response
- enhances immune response by providing a ‘depot’ and by immunostimulatory properties
Explain how adjuvants can act in the immune response
- Activate dendritic cells via TLRs or NLRs
- Cause release of endogenous danger singals
- Promote Ag uptake by dendritic cells, which can then locate their lymph nodes & help stimulate B and T cells
- Stimulate release of chemokines/ cytokines
- Promote cross presentation of exogenous Ag by class I MHC, geeting CD8 and CTL cells involced and produce those cytokines and engage with macrophages
Adjuvants are licensed for use in humans and animals. True or false?
True, but they are not all interchangable
Give examples of adjuvants used in animals
- Freunds adjuvant: oil in water emulsion, quite immunogenic and can cause bad localised reactions
- Freunds complete adjuvant: also contains mycobacteria and is v stimulatory
What is ‘alum’?
Its the most commonly used adjuvant in humans
- contains aluminium containig compounds
- been shown to be better in stimulating Ab response (Th2) compared to Th1 mediated response
