April 2nd (Exam 3) Flashcards
How are memory cells different than naive T - cells?
What are most of them like?
They don’t require survival signals.
Most are quiescent
How do the memory cells get signalled to divide?
They have receptors for cytokines IL-7 and IL-15
What must a pathogen bypass in order to initiate a secondary immune response?
- Innate immune system
- Steady state level of pathogen specific abs
What are the cell surface molecules that distinguish naive T cells from memory T cells?
Which one has a produces a stronger signal when interacting with the TCR complex?
Naive - CD45RA
Memory - DC45RO
Memory has stronger signal
Explain the speed of the activation of the secondary immune response in relation to the various T cells that exist in the peripheral tissue.
They don’t require co-stimulatory signals
What are the two subtypes of memory T cells?
How are they different?
Central Memory T-cells - these hang out in the lymphoid organs (they are not differentiated)
Effector Memory T-cells - these hang out in the peripheral tissue and are pretty much differentiated and have lots of effector molecules already.
What happens to most of the CD8 T cells after a primary immune response?
Of the ones that survive what do they express?
95% die by apoptosis
5% live to be memory cells and they express IL-7R
How would you define a vaccine?
It is a non-infectious material that contains the pathogens antigens
What are the 6 types of vaccines?
- Live virus
- mRNA
- Killed/ inactivated
- Subunit
- Live attenuated
- Conjugate
What is vaccinia?
This is the live virus that is from cowpox (causes a mild infection in humans) that was given to prevent smallpox.
Explain how the small pox virus was eradicated in humans.
- Coordinated international program
- The antigenic epitopes (what we recognize) evolve slowly
- Live virus vaccine is highly effective.
- It only infects humans - no animal reservoir
Explain what a killed/inactivated virus vaccine is.
Examples?
Downsides?
This is when the virus is treated with formalin chemically or by heat so they can’t replicate..
Example: polio vaccine
Downside is that you have to make a bunch of real virus.
Explain what a live-attenuated virus vaccine is.
How are they made?
This is a mutant live virus that grows really poorly in humans and bc of this it is non-pathogenic
They are made by taking a virus from an infected person and then used to infect monkey cells. After a while, it gains mutations to work better there. Then we take it out and it doesn’t infect humans very well anymore.
What is the Salk vaccine for?
Why is it special?
It is an inactivated poliovirus vaccine that is trivalent meaning it protects against the three types of polio.
What is the Sabin vaccine for?
Why is it special?
What is better Salk or Sabin?
Downsides?
It is a live attenuated poliovirus vaccine that is also trivalent.
Sabin is better than Salk, but if the live virus displays back-mutation it can become pathogenic again.
What is a subunit vaccine?
This is a vaccination against one component or subunit of a virus
What are the two types of bacterial diseases that we talked about that are caused by the toxins released by those bacteria?
What do they release?
- Diphtheria - releases toxin
- Tetanus - releases toxin
How are vaccines made against bacterial toxins?
They are purified and then treated with formalin to destroy the toxic part - antigenic properties are retained.
The bacteria that causes meningitis…
What protections does your body naturally do?
What is the issue with making a vaccine?
How do we overcome this?
Your body makes high-affinity IgG against a polysaccharide on the surface of the bacteria - activating complement system.
Issue with making vaccine based on the sugar is that the MHC Class II molecules can’t present peptide to activate CD4 T cells.
This is overcome by linking it to something that an MHC Class II complex can bind like a peptide toxin.
What is a conjugate vaccine?
This is when different epitopes recognized by T and B cells are synthetically linked.
What type of responses do the live, inactivated, and attenuated virus vaccine activate?
What is necessary for producing memory?
They activate the innate and the adaptive.
Both of them.
What type of responses do the subunit and conjugate vaccines activate?
How do we get memory here?
They only activate the adaptive
We add an adjuvant like a microbial component that is recognized by TLRs to initiate an innate.
What is the idea that sequencing a pathogen’s genome leads to a better understanding of the pathogen and our response to it?
Reverse Virology
What type of virus is influenza?
What consequences does this have?
It is RNA
There are many mutant viruses
The immunological memory decays quickly
