Vaccination Flashcards
What is the goal behind vaccination?
Stimulate memory in the immune system
So encounter with the same antigen protects from disease
What concept in nature does vaccination play on?
Encounter with a pathogen leads to disease, but also protection from the same pathogen through formation of memory
Who was the documented inventor of vaccines?
Jenner
Surgeon
In 1796
Why was Jenner not the true inventor of vaccines?
Jetsy the farmer discovered vaccines before Jenner
1774
Describe the first vaccine discovered
Smallpox
Using innoculations of scabs from milkmaids with cowpox
What is the most effective means of controlling infectious disease?
Vaccination
Which diseases have been eradicated by vaccines?
Smallpox
Rinderpest
What are vaccines?
Harmless versions of disease-causing organisms
Advantages of the specific immune responses induced by vaccines
Prevents infection
Controlling existing infection
Prevent disease developing post-exposure
Prevent foetal infection through vaccinating the mother
Prevent or control cancer
Which cells do successful vaccines boost?
T cells
B cells
CTLs
Describe how vaccines work
Small immune response is triggered upon vaccination
The response is not big enough to protect you
But production of memory cells
The second time, the immune system is poised to act against the antigen
What happens regarding T and B cells following infection?
B cells:
Some B cells become plasma cell factoriess for antibodies
Some B cells hide ready for the next encounter = memory B cells
T cells:
Some T cells become immediate effectors
Some become memory cells
Describe the immunological process following vaccination
- Vaccine delivery
- Uptake and processing by APCs (B cells and DC)
- B cell activation and proliferation, CD4 T cell response and CD8 T cell response
- B cell and T cell memory established
Describe why herd immunity works
If a lot of people are vaccinated, then the disease can’t spread very far
So the whole community stays safe
Attributes of an effective vaccine
Memory and specificity
Activate different T cells
Induces antibody production by plasma cells
Inexpensive
Safe
What are the different types of vaccine?
Live attenuated
Killed/ inactivated
Sub-unit
Peptide
Inactivated toxin
What is a live attenuated vaccine?
Anti-virulent, weaker form of the agent
Comprises of the whole organism undergoing treatment with acid or alkali
Protein coats are still there to cause immune response
Example of a live attenuated vaccine
MMR vaccine
What is a killed vaccine?
Chemically inactivated form of the agent
Example of a killed vaccine
Polio
What is a sub-unit vaccine?
Isolated components of the agent
Conjugated
Example of a sub-unit vaccine?
Hib
Hepatitis
What is a peptide vaccine?
Immunogenic peptide
Example of a peptide vaccine
Under development for autoimmune disease
What is an inactivated toxin vaccine?
Toxin inactivated to make a toxoid
Example of an inactivated toxin vaccine
Tetanus
Role of adjuvants
Make the antigen presenting cells interested in the antigen presented through the vaccine
In a non-specific way
Activation of these APCs cause them to secrete stimulatory factors
What is the disadvantage of live attenuated vaccines?
Still contain a small part of the weakened live virus
Cannot inject into an immunocompromised host
Since this could cause disease
Reversion/compensatory mutations
Spread disease to other immunocompromised hosts
How could peptide vaccines be used for autoimmune conditions?
Induces tolerance through stimulation of MHC II In the absence of co-stimulation
Advantages of live attenuated vaccines
Induces a systemic and local response
Long lasting
Often cheap
What are the advantages of inactivated/subunit/conjugate vaccines?
Helps to convert a T independent response to a T dependent response
No possible reversion
Safe to immunocompromised
What are the disadvantages of inactivated/subunit/conjugate vaccines?
Adjuvants required
Multiple doses - short-lived
CTL response is poor
IgG only - no local or mucosal response
Describe the two processes which makes it difficult for flu vaccine development
Antigenic drift
Antigenic shift
Describe antigenic drift
Mutations to epitopes in haemagglutinin so that neutralising antibodies no longer binds
Describe antigenic shift
Big chunks of DNA change
Antigenic shift occurs when RNA segments are exchanged between viral strains in a secondary host
No cross-protective immunity to virus expressing a novel hemagglutinin
What manufacturing process is used to make flu vaccines?
Egg-based process
The candidate viruses are injected into a fertilised hens eggs and incubated to allow the virus to replicate
The virus is isolated and killed and the virus antigen is purified
What flu vaccine is given to children?
Live attenuated
What flu vaccine is given to adults?
Inactivated
How is the strain of virus for the flu vaccine decided?
Sophisticated form of bioengineering using mathematical modelling
Inspired guess work - which vaccine is most useful
What tempetature are flu vaccines stored at?
4 degrees
What is important to look at when deciphering a vaccines efficacy?
Obtain data from elderly patients
Since this has higher social cost and is life-threatening
Which diseases do vaccines still need to be developed for?
Malaria
Schistosomiasis
Tuberculosis
HIV
What is the main hurdle in the development of an effective vaccine?
Development of an immunisation strategy that introduces:
- broad and long-lasting CTL immunity
- broadly neutralizing antibodies for all the proteins that the virus produces
What is important to consider when developing a new vaccine?
The impact of the vaccine
It is a very costly process
Need to develop vaccines for relevant conditions
How are vaccines and timing related?
It is important to employ vaccines at the correct timing
- travel vaccines
- elderly vaccines
- infant vaccines
Future goals of vaccine development
Eradication of polio
Effective vaccines for HIV, TB and malaria
Broadly-specific influenza vaccine
Vaccines against parasites
Which vaccines are recommended for the elderly?
Flu
Pneumococcus
Tetanus
Shingles
What is important regarding vaccines in the elderly?
Vaccination in the elderly results in lower antibody titre and reduced antibody efficacy
Evidence of decreased immunity during ageing
Increased infection rates amongst the elderly
Shingles reactivation due to immune senescence
Increased rates of cancer
Antibody profiles of primary, secondary and tertiary immune boosters
First vaccination = IgM
Second = more IgG
Third = increased affinity and quantity of IgG
Link between inflammageing and decreased immune responses
Inflammageing results in elevated baseline inflammation
This is bad for antigen specific immunity
What is inflammaging?
Nonspecific inflammation characteristic in the elderly
Considered a major target for anti-aging therapies
Way to assess the activation of the inflammatory pathway
Measuring the concentration of C-reactive protein
Clinical trial proving inflammageing as a good target for increasing the immune response in vaccination
VZV skin infection in elderly showed decreased response
The antibodies are present, but show reduced activity
Anti-inflammatory medication was used
Following immune suppression, reactivation of VZV infection on the skin showed increased response
= inflammatory suppression increases immune response
