Lecture 21 Flashcards
(15 cards)
What is a vaccine?
biological product that can be used to safely induce an immune response that confers protection against infection and/or disease on subsequent exposure
contains one or more protein antigens that induce immune response, exploiting memory of immune system
What are differences between killed (inactivated) and live-attenuated vaccines?
killed: mostly antibody-mediated, often requires multiple doses, safe for immunocompromised, more stable, easier to store
live-attenuated: strong antibody & cellular response, longer-lasting, not for immunocompromised, less stable, requires refrigeration, can revert to virulence
How are viruses traditionally attenuated? Why?
selecting for growth in nonhuman cells
isolation and culture in human cells –> infect nonhuman cells –> mutations enable it to grow in nonhuman –> no longer grows well in human cells so is attenuated
How can viruses be attenuated in the modern day?
recombinant DNA, mutating/splicing genes required for viral virulence
What is heterosubtypic immunity?
weak protection by previous infection with different strain of pathogens (like flu shot)
how are vaccines developed against bacteria or parasites?
attenuated bacterial vaccines: BCG
protect against disseminated tuberculosis in children
What is the problem with bacteria that have a polysaccharide outer capsule like S. pneumoniae
polysaccharide vaccines induce antibody-producing plasma cells by cross-linking BCR< but no affinity maturation or induction of memory B cells
How do conjugated vaccines work?
Link polysaccharide to a protein that can be recognized by T cells
How do RNA based vaccines work? (Like for SARS-CoV-2)
mRNA produced in vitro encapsulated into lipid based carrier, injected intramuscularly –> fusion of lipid carrier w muscle cells –> release of mRNA –> translation of spike protein –> antibody response
What are adjuvants? How do they work?
any substance that work to enhance immune response to an antigen, trigger viral/bacterial sensor pathways like TLR and NOD-like receptor families
What characteristics does an effective vaccine have?
safe, protective, sustained protection, induces protective T cells, practicality & perception
What are some diseases that do not have effective vaccines? Why?
rely on cell-mediated immunity
malaria, tuberculosis, HIV/AIDS
What are some routes of vaccination?
intramuscular, mucosal immunity may be enhanced in gastrointestinal/respiratory tracts through oral/aerosolized vaccines
What is herd immunity
protection conferred to unvaccinated individual in a population that is produced by vaccinated individual and reduced reservoir for infection
What are challenges to vaccine success?
access, commercial viability, immunological challenges, public concerns in safety/side effects
