Immunological Memory/ Vaccines Flashcards
What is an anamnestic immune response?
A secondary or ‘boosted’ response
What is the magnitude and duration of a secondary immune response relative to a primary resposne?
Longer and higher magnitude
Why are memory T cells preferentially activated during re-exposure to a pathogen?
Memory cells are 100x more abundant than naive cells and are activated more easily
What surface molecules are deferentially expressed on Memory and Naive T cells?
CD45RA is very highly expressed on naive but not memory, CD45RO is very highly expressed on memory cells but not on naive and one type of T memory cells expresses CCR5 not found on naive
What is the importance of CD45RO?
T cells with CD45RO are more readily activated through interaction with the CD3 complex
What are the two types of T memory cells? What’s the difference?
T central memory cells and T effector memory cells; Central memory cells patrol lymph nodes and effector memory cells act as sentinels in effector sites
What type of T memory cell expresses CCR5? What is the purpose of this molecule?
T effector memory cells- draws them into tissues
Why are secondary antibody responses of a higher quality than primary Ab responses?
Increased numbers of antigen-specific B cell clones with higher affinity BCR
True or False: The quality of antibodies improves with each exposure
True
Why are more memory B cells than naive B cells activated during the secondary response?
There are more memory cells that respond to a specific antigen than naive cells, and memory B cells are more easily activated due to higher BCR avidity, higher levels of MHC and costimulatory molecules, and greater amounts of intracellular TLR
Who ‘invented’ the vaccine? To what disease?
Edward Jenner; Smallpox
What is herd immunity?
When enough people have been vaccinated, then the odds are slim that a pathogen will find a susceptible host and be able to spread within the population therefore indirectly protecting the few who have not been vaccinated
What kind of vaccine are most vaccines against viral infection?
Live-attenuated vaccines
How are most live attenuated virus vaccine produced?
Produced by growing human virus in animal cells for many passages which mutates the virus to be less good at infecting humans
Why are live-attenuated vaccines better than killed vaccines?
Ability to replicated increases the antigen dose, the more antigen, the stronger the immune response, and so more plasma cells and memory B and T cells are generated; Plus, they elicit antibodies that recognize native structures on the surface of the pathogen
What are the disadvantages of live-attenuated vaccines?
Unsafe in immune-compromised individuals, need careful handling during manufacture, require refrigeration to maintain stability, and can inadvertently cause disease if the attenuated microbe reverts to a pathogenic form
What kind of vaccine is the Sabin Polio Vaccine? What is the major advantage of this vaccine?
An oral live attenuated vaccine; Induces IgA Ab in the intestine and serum
What kind of vaccine is the Salk Polio vaccine?
Inactivated polio vaccine
What are whole-inactivated vaccines?
Whole virus particles or bacteria that have been killed by heat, chemicals, or irradiation
What are adjuvants and why are they used?
Molecules or chemical compounds that enhance the magnitude of adaptive responses by stimulating innate responses at sites of immunization and activated DC, which migrate to draining lymphnodes to present antigen
What are toxoid vaccines?
Chemically inactivated bacterial toxins
What is a subunit vaccine?
A single component (usually protein) of a pathogen
What is a combination vaccine?
A mixture which provides protection against 2 or more pathogens in the one shot
What are conjugate vaccines and what pathogens are they typically directed against?
Consist of polysaccharide antigen fused to a T-dependent antigen; Encapsulated bacteria
What are virus-like particles?
Self-assembling viral particles that lack nucleic acids
What makes a pathogen difficult to vaccinate against?
Pathogens that cause latent, chronic infections or pathogens that have a high mutation rate in outer surface proteins
