Immunity and vaccines Flashcards
Active immunity
When the immune system produces its own antibodies after being stimulated by an antigen
How can active immunity occur?
Naturally = after catching a disease from a pathogen
Artificially = injection of vaccine containing attenuated antigen
Passive immunity
When antibodies given to you from a different organism that your body did not produce naturally
How can passive immunity occur?
Naturally when a baby is given antibodies via mother’s breast milk/placenta
Artificially by being injected antibodies in a medicine such as antivenom
Passive vs active immunity
Active requires exposure to antigen whereas passive doesn’t
Active takes a while for antibody to develop whereas passive is instant
Active produces memory cells but passive does not
Active gives long term protection as a result but passive does not
Why use vaccines?
Allows primary immune response to antigen so in case of reinfection with antigen, can lead to faster secondary response so wont experience the disease
Secondary response produces higher concentration of antibodies faster if infected with actual pathogen
What is in a vaccine?
An attenuated pathogen WITH ANTIGEN (GM to not cause disease)
Or RNA to encode for pathogen’s antigen by body cell
Or isolated antigen molecules
Herd immunity
Reducing occurrence of pathogen if the majority of the population is immune to pathogen since it reduces likelihood of infection of those not immune
Ethical issues of vaccines
Animal testing
Using animal based products from blood
Testing on humans can be risky if they believe they are immune
Epidemic means choosing who’s vaccinated first
Antigenic variation
When antigens on surface of pathogen change due to changes in base sequence of primary structure in DNA/RNA
Causing change in tertiary structure
How can antigenic variation be a problem for vaccines?
Vaccines will produce memory cells against a specific antigen
By changing antigen, a new primary response will have to occur
When is immunity against an antigen achieved?
achieved through the presence of antibodies against the antigens of that pathogen in a person’s body.
How do memory B cells lead to a faster secondary response?
Undergo clonal selection leading to the rapid development of plasma cells
leading to FASTER production of antibodies than with a primary immune response.
A HIGHER concentration of antibodies will be achieved.
Why are memory cells made instead of leaving Bcells and T helper cells in blood?
Waste of ATP for B cell and Th cells metabolic processes if antigen is not present but these cells remain in blood
Why is herd immunity important?
So the few unvaccinated people who are immune still have reduced chance of catching antigen
since occurance of pathogen has been reduced
