Vaccine Development Flashcards
What is the purpose of vaccines?
Protection from infection
Or
Protection from disease-causing pathogens
What is herd immunity?
Disease being unable to spread in a population because enough people are immune to it
What condition(s) must be met for a vaccine to provide herd immunity?
Provide immunity for a long enough time (years rather than months)
Protect from infection rather than just reduce severity of illness
What 2 strategies does influenza use in antigenic variation that makes a long term single vaccines not feasible?
Antigenic drift
Antigenic shift
One of the reasons that influenza is hard to vaccinate against long term is because it mutates its surface antigens over time by altering epitopes in hemagglutinin. This changes causes neutralizing antibodies to be unable to bind to the mutated virus. What is this phenomenon called?
Antigenic drift
One of the reasons that influenza is hard to vaccinate against is because it is able to spontaneously mutate by exchanging RNA segments between strains in a secondary host. This causes there to be no cross-reactive immunity because the hemagglutinin is novel. What is this phenomenon called?
Antigenic shift
What type of vaccine is only able to confer immunity via antibodies?
Killed virus vaccine
What type of vaccine is able to confer immunity via antibodies and T cells?
Live attenuated and live recombinant
What are some benefits of the mRNA vaccine compared to killed and live/attenuated vaccines?
Confers the same type of immunity as live/attenuated vaccines without the risk of genetic reversion associated with live/attenuated vaccines
What are the disadvantages of live attenuated vaccines?
Reversion to wild type
Bc of risk cant be used in ppl with immunodeficiency or elders
What are the benefits of live attenuated vaccines?
Effective and long lasting
Activates both humeral and cell mediated immunity
Alternative routes of administration
Activates CD8 cells —> killer T cells for potent immune effector
What is a live recombinant vaccine?
Immunogenic parts of a target virus are placed onto another live (harmless) virus
What are the advantages of live recombinant vaccines over live attenuated?
No chance for reversion
Stimulates CD8 killer cells
Can be given to IC pts
What are the disadvantages of live recombinant vaccines?
Immunogenic part must create enough of a response to prevent infection by the target virus
What are the advantages of whole inactivated vaccines?
Has many antigenic determinants —> ↑ chance of broad immunogenicity in population
What are the disadvantages of whole inactivated vaccines?
risk of exo- or endotoxin effects
Needs adjuvant (risk of side effects)
Repeat administration needed
Mainly via IM injection
This type of vaccine is used for the HPV vaccine
Virus-like particles
The HPV vaccine is a VLP vaccine. What does this mean?
HPV capsid protein is present
No DNA present so no infection
Antigen processing is similar to a real viral infection
What are the disadvantages of virus-like particles?
Needs adjuvant
Multiple inoculations and boosting
What are the benefits of virus-like particles?
Better humeral immunity than natural infection
Toxicoids and the Hep B vaccine are an example of this type of vaccine
Subunit vaccine
What is a subunit vaccine?
Made by chemical synthesis, purification, or recombinant gene expression
This phase of the immune response in a vaccinated person can prevent infection if sufficient response present
Antibodies will prevent infection if titers are high enough
Usually within the 2-3 mo after vaccination
This phase of the immune system response eliminates a pathogen in a vaccinated person after it has established an infection in the person
Memory B and T cells
Effective years after vaccination
Who are the “vaccinated vulnerable”?
Elderly/frail
IC from genetics
CA pts (current or remission)
Anyone on autoimmunity tx
