14. Vaccination Flashcards
What is the primary aim of vaccination?
Stimulate production of memory T and B cells, without causing significant pathology
What types of antigens are used for vaccinations?
- Attenuated - alive but not able to cause substantial disease (not good to give to immunodeficient people)
- Dead organisms - not as good at stimulating immune response
- Subunits - protein/polysaccharides mixed with adjuvants
- Inactivated toxin - toxoid
What are adjuvants and carriers?
Adjuvant - something that nonspecifically stimulated specific immune response
Carrier - if using bits of organisms, then link them to much bigger protein which is taken up by dendritic cells and processed and presented to T cells (e.g. polysaccharides)
What are the adverse effects of vaccination?
Immunocompromised host, side-effects (especially neurological)
What is the difference between the primary and secondary immune response?
Primary immune response is weak and short lived, creation of memory cells (this is what you want to stimulate with vaccinations), secondary is more severe and lasts longer
What are the requirements for a successful vaccine?
Effective - right type of immune response
Available -
Stable - no everywhere has access to refrigeration
Inexpensive
Safe
What are the components of a vaccine?
Antigen (whole organism), carrier, adjuvant
Who developed the initial smallpox vaccine (first successful vaccine)?
Edward Jenner in 1798
When was Rinderpest and smallpox eliminated?
1979 - Smallpox
2011 - Rinderpest
What response does the live attenuated polio vaccine achieve?
Causes a very good IgA response in the area that the polio enters the body (if you used killed polio then doesn’t give the right response)
Which countries is polio still prevalent?
Afghanistan, some places in central Africa
What is the influenza problem?
Flu vaccines work well most of the time, but flu can change - point mutations (antigenic drift - antigens partly changed), exchange (antigenic shift - whole genomes switched - much more severe, antigens completely altered)
What are the two main antigens of influenza?
Hemoagglutinin, neuraminidase
How are flu vaccines produced?
In fertilised chicken eggs
How often does the flu vaccine production occur?
Twice a year, once for each flu season in the northern and southern hemisphere
What are the problems in developing an effective HIV vaccine?
Identification of immunogens (antigens which generate correct antibodies) and immunisation strategy which induce broad and long-lasting cytotoxic T cell immunity and broadly neutralising antibodies
What is an immunogen?
Antigen which generate correct antibodies
What has been the only slightly successful HIV vaccine?
4 priming injections of canarypox vector vaccine with HIV gag, pol & env genes, and 2 booster injections - shows limited effect (~30%)
What are conjugate vaccines? What diseases?
Carbohydrate vaccines - created by coupling a carbohydrate onto a protein (protein needed for activation of T cells) e.g. Haemophilia influenza type B (causes meningitis & pneumonia), Meningococcus group C
What are the vaccines/timings given to at risk groups?
BCG vaccine - 0-35years Chickenpox vaccine - any Flu vaccine - children & adults Pneumococcal vaccine - 2-65years Hepatitis B vaccine - birth onwards
What are the main travel vaccines?
Diphtheria, polio, tetanus, typhoid, Hep A, Hep B, cholera, japanese encephalitis, tick-borne encephalitis, meningococcal meningitis, rabies, tuberculosis, yellow fever
What is the ‘best’ vaccine?
no side effects, one shot protection for life
What is really great about the yellow fever vaccine?
Gives lifelong immunity
What is a gene gun? What are the benefits?
A method of vaccination which injects genes which encode proteins or the proteins themselves. Causes much greater cytotoxic T cell activation than regular vaccination - very effective in animals but not great in humans
What is the future of vaccination?
Polio eradication, effective HIV, TB, malaria vaccines, broad flu vaccine, therapeutic vaccines, DNA vaccines, vaccines against parasites
