Vaccines (E3) Flashcards
(22 cards)
How do vaccines work?
Vaccines activate the adaptive immune system and create immunity by safely introducing antigens for the immune system to train on.
What is a live attenuated vaccine?
A vaccine that introduces a weakened version of a living pathogen into the body, creating an immune response without causing disease.
What is a subunit (or recombinant) vaccine?
A vaccine that contains only part of the pathogen along with an adjuvant, making it safe for immunocompromised individuals but resulting in fewer memory cells.
What is herd immunity?
Herd immunity is created when a large percentage of a population is immune to a disease, breaking the chain of infection.
How many people in the US depend on herd immunity?
9 million people.
What must researchers do if the pathogen cannot be used?
Identify the pathogen’s antigens.
What do nucleic acid vaccines deliver?
Genetic templates for the antigens.
How do viral vector vaccines work?
They inject incomplete genetic material from a pathogen inside a harmless virus, which then delivers the genetic material into the body.
What does the COVID-19 virus use to enter our cells?
Spike protein on the surface.
How do COVID-19 mRNA vaccines teach the immune system?
COVID-19 mRNA vaccines give your cells instructions to make the virus’s spike protein. Your immune system sees this protein as foreign, triggering helper T cells, B cells (which make antibodies), and cytotoxic T cells. This creates memory cells, so your body can respond quickly if exposed to the real virus later.
What is mRNA?
Genetic material that instructs cells to make proteins.
mRNA (messenger RNA) is a molecule that carries genetic instructions from DNA to ribosomes, where it’s used to make proteins
What protects mRNA in vaccines and helps it enter cells?
A layer of fat.
What role do dendritic cells play in the immune response?
They capture antigens, process them, and present them to T cells to activate the adaptive immune response.
What do cytotoxic T cells do?
They learn to destroy infected cells.
What is attenuation in vaccine development?
The process of weakening a virus to create a live vaccine.
How do scientists weaken viruses for vaccines?
Scientists attenuate a virus by:
weakening it through genetic modification or
repeated growth in non-human cells so it can’t cause disease but still triggers an immune response.
What happens when a virus is reintroduced to the human body after attenuation?
The modified/weakened virus has trouble infecting human cells.
What does the immune system do when exposed to an attenuated virus?
When exposed to an attenuated virus, the immune system recognizes it as foreign, activates T and B cells, and mounts a full immune response without causing illness. This leads to the creation of memory cells that provide long-term protection.
How do nucleic acid vaccines such as mRNA work?
- The vaccine mRNA is taken up by immune cells (like dendritic cells).
- The cells translate the mRNA into viral protein (e.g., COVID spike protein).
- They then process that protein and present it on MHC class II.
- Helper T cells (CD4+) recognize the antigen on MHC II and become activated.
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Once activated, helper T cells:
• Help B cells make and improve antibodies.
• Help activate cytotoxic T cells (CD8+).
• Release cytokines to coordinate the immune response.
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What’s the difference between nucleic acid vaccines and viral vector vaccines?
Nucleic Acid Vaccines
What they use:
• Free-floating genetic material (either mRNA or DNA)
How it works:
• Injected directly (e.g., mRNA in lipid nanoparticles)
• Your cells take up the genetic code and make a viral protein
• That protein triggers an immune response
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Viral Vector Vaccines
What they use:
• A harmless virus (vector) that carries genetic instructions inside it
How it works:
• The virus enters your cells and delivers genetic material into the nucleus
• Your cells make the viral protein from that genetic material
• The protein triggers the immune response
Why are subunit vaccines described as “mostly B cell focused”?
They need to activate helper T cells but not cytotoxic T cells because the pathogen doesn’t enter cytoplasm of cells so it doesn’t need cytotoxic cells to induce apootosis.
They are designed to trigger strong antibody (humoral) responses, which is a B cell function.
Compare and contrast subunit and attenuated vaccines
Attenuated (Live) Vaccines
• Use a weakened but living version of the pathogen
• The pathogen infects cells (mildly), so the immune response is very broad and strong:
• Activates B cells
• Activates helper T cells (CD4+)
• Activates cytotoxic T cells (CD8+) via MHC I
• Often gives long-lasting immunity with fewer doses
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Subunit Vaccines
• Use only pieces of the pathogen (like surface proteins)
• Can’t infect cells, so they mainly:
• Activate B cells (with help from helper T cells)
• Do not activate cytotoxic T cells (since there’s no MHC I presentation)
• Often need booster shots and adjuvants to strengthen the response
• Safer for immunocompromised people, but sometimes less durable immunity
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Summary:
• Attenuated vaccines = broader, longer-lasting immunity
• Subunit vaccines = safer, but more limited immune activation
