Vaccination Flashcards
What is natural passive immunity
Transfer of maternal antibodies across the placenta to the breast milk
Define passive immunisation
Transfer of preformed antibodies
Name three conditions the natural immunity from mother protects us from
- Tetanus
- Rubella
- Mumps
- Poliovirus
What is artificial passive immunisation
Treatment with pooled normal human IgG
What is agammaglobulinaemia
B cell defects
Role of antisera
Neutralise toxins after immune system eliminates primary infection
What is the problem with treatment using passive immunity
Does not activate immunological memory so no long-term protection
What type of passive immunisation is given to people exposed to Botulism, Tetanus or Diphtheria
Anti-toxins
What type of passive immunisation is given to people exposed to Hepatitis, Measles and Rabies
Used prophylactically to reduce the chance of establishing infection after exposure
What is given to people with jellyfish stings
Anti-venoms
Define active immunisation/vaccination
Manipulating the immune system to generate a persistent protective response against pathogens by safely mimicking natural infections (IgG or IgA)
Define inoculation
Introduction of viable microorganisms into the subject
What are the aims of a ‘perfect’ vaccine
- Achieve long-term protection
- Stimulate both B and T cells
- Induce memory B and T cells
- Stimulate high affinity IgG and IgA production
What is the issue with influenza
Becomes established before immunological memory can activate
How do we overcome the immunological issues faced with influenza
Maintain high levels of neutralising antibodies by repeated immunisation
How long does it take for polio to establish infection in the nervous system
3 days
What is a consequence of the 3 day lag to establish infection of polio in the nervous system
Provides opportunity for memory to be activated and production of neutralising antibodies
What is the first stage of innate immune system
- Elicit ‘danger’ signals that activate the immune system such as PAMPs which engage the TLRs on T cells
- APC
- Engage the adaptive immune system
Example of an APC
Dendritic cells
What four conditions do we use attenuate pathogens to cause immunity with
TB
Polio
Typhoid
Mumps
Where are attenuated organisms for polio collected from
Monkey kidney epithelial cells
Where are attenuated TB pathogens collected from
BCG
What are the advantages of attenuated organisms
- Sets up transient infection
- Activation of full natural immune response
- Stimulation of memory response in T and B cell compartments
- Prolonged contact with immune system
Disadvantages of attenuated organisms
- Immunocompromised patients can be infected
- Revert back to original form (measles)
- Difficult to store (refrigeration) so can’t be used in some areas of the world
Name three inactivated pathogens
- Anthrax
- Cholera
- Hepatitis A
Advantages of inactivated pathogens
- No risk of infection
2. Storage is less critical
Disadvantages of inactivated pathogens
- Just activate the humoral response
- Lack of T cell involvement
- Without transient infection the immune response can be weak
- Repeated booster vaccines required (patient compliance issue)
What are toxoids
Inactivated exotoxins
What is the role of exotoxins
Produce symptoms of a disease
Exotoxins in diphtheria
Inhibits translation by inactivating EF2 factor = necrosis of heart and liver
Exotoxins in tetanus
Neurotoxin resulting in uncontrolled contraction of voluntary muscles
What are the advantages of using toxoids
- Safer than handling pathogens
- No risk of infection
- Easier to store and preserve
Disadvantages of using toxoids
- Immune response is less powerful than to live attenuated vaccines
- Repeat vaccinations required and adjuvants
Define adjuvant
Any substance that is added to a vaccine to stimulate the immune system
Ensures powerful immune response
How do toxoids work
Trigger immune system and send out ‘danger signals’
How do microbes work
Trigger immune system and send out danger signals
How do aluminium salts work
Extend half life of immunogen in site of infection resulting in depot effect - slow release of vaccine
Role of DNA vaccines
Aim to transiently express genes from pathogens in host cells
Generates immune response similar to natural infection leading to T and B cell memory responses
Advantages of DNA vaccines
- DNA vaccines do not require complex storage
2. Delivery can be simple and adaptable to widespread programs (no refrigeration is necessary)
Disadvantages of DNA vaccines
As with ‘killed’ vaccines and subunit vaccines there is no transient infection
DNA vaccination is likely to produce a mild immune response and requires subsequent boosting
Role of recombinant vector vaccine
Imitates effect of transient infection with pathogen but using a non-pathogenic organism
How does recombinant vector vaccine work
Genes for major pathogen antigens are introduced into non-pathogenic microbes and then into the host
Can be viral or bacterial
Advantages of recombinant vector vaccines
Produces immunological memory
Safe
Disadvantages of recombinant vector vaccines
Require refrigeration
Immune response to virus can negate effectiveness
How is the pathogen attenuated for polio
Prolonges culture of virus weakens their potency
How is BCG attenuated for TB
Grown for 13 years on medium containing bile
What are three types of subunit vaccines
- Toxoids
- Capsular polysaccharides
- Recombinant microbial antigens
How is Men C treated
Using capsular polysaccharides
Role of capsular polysaccharides
Protective immunity to encapsulated bacteria
How do capsular polysaccharides provide protective immunity
Block opsonisation
What is opsonisation
Coating of the organism with specific antibodies and complements which allows phagocytosis
Property of capsular polysaccharides
Highly polar, hydrophilic cell surface polymers.
What is the problem with synthetic peptides as vaccines
Peptides can either be stimulatory or supressive
