Viral vaccines Flashcards
What year was the last case of naturally acquired smallpox?
1977
What are the clinical presentations of smallpox?
Pustules that turn into scabs
What percentage of people would die in villages when smallpox was rampant?
40% of previously unexposed people would die. Mostly young.
What important observation did Edward Jenner make?
Milk maids in countrysides were immune to smallpox. Now we know because they gained immunity from being exposed to Cowpox
How did Edward Jenner invent vaccines?
Vacca = cow
Inoculated with cowpox postule taken from milk.
Then virolated the son of his friend a few months later with smallpox. The child became immune.
What control was used before the development of the smallpox vaccine?
The people would be inoculated with scabs from smallpox infected patients. The scabs would be dragged on skin or inhaled. This was very risky since 1% of the population died.
What is the goal of vaccines
To provide solid immunological memory in order to produce rapid secondary immune responses.
What are the signs of a good vaccine?
Formation of immunological memory
Creates threshold level of plasma antibodies to neutralise the virus
How do vaccines work?
Antigen from the vaccine is taken up by dendritic and antigen-presenting cells that present the antigen to B cells and T cells.
B cells activate and proliferate leading to the production of antibodies and B cell memory.
T cells differentiate into CD4 T cells and CD8 T cells.
The CD4 T cells produce cytokines that aid the B cell activation and proliferation and CD8 T cell antigen presentation. They also contribute to T cell memory.
CD8 T cells produce a CD8 T cell response and contribute to T cell memory.
Commonly used types of vaccines
Live attenuated
Inactivated
Sub-unit
What is a live attenuated vaccine?
A less virulent form of the agent that replicates.
Used in MMR - measles, mumps and rubella
What is an inactivated vaccine?
Chemically inactivated virus or lysates of cells infected with the virus.
Used in flu
What is a sub-unit vaccine?
An isolated recombinant component of an agent (as small as a single protein)
Used in HBV
Why was smallpox the ideal candidate for eradication?
- Worked when freeze-dried and easily transported
- Can see if someone is immune
- Everyone gets symptoms if infected. Not asymptomatic.
- No animal reservoir
- Once you have gained immunity it is lifelong
- Vaccine is easily delivered
What two concepts is surveillance containment based around?
R0 and herd immunity