Vaccination Flashcards
What is the difference in the adaptive immune response between bacterial and viral cells?
Bacterial and viral infection have the same B cell response, but in bacterial infection, TH1 and Th17 are produced, whereas viral involves Cytotoxic T cells and TH1 mostly
How can pathogens avoid the immune response?
Concealment of antigens, antigenic variation, immunosuppression, resistance to the immune response
What ways does concealment of antigens occur?
Intracellularly: pathogens inhibit antigen presentation by MHC class I Privileged sites: hiding dormant in the CNS Uptake of host molecules: cloak effect
How does antigenic variation occur?
Antigenic shift via mutation or drift via recombination
How does infliuenza avoid the immune response?
antigenic variation
What kind of antigenic variation produces a worse illness?
Antigenic shift, as there is no crossover protection
How does immunosuppression occur?
Shielding or inhibition of opsonisation, inhibition of the inflammatory response, induction of T regulatory cells which inhibit antigen presenting to T cells.
How does immunosuppression occur in HIV?
CD4 T cells are blocked
Why is there usually 2 doses of vaccine required?
Because the first dose stimulates the primary response mediated by B cells and T cells, to produce memory cells. The second dose stimulates the secondary immune response by memory B and T cells
What are the different types of vaccination?
Live attenuated secreted toxins conjugated killed/inactivated subunit RNA
What is a live attenuated vaccine and give an example?
Mutant form of live virus/bacteria that grows poorly in humans. Gives better protective immunity as the virus can replicate real infection. They are fragile, and should not be given to children with weakened immune systems.
EXAMPLE: MMR vaccine
What is a killed/inactivated vaccine and give an example?
Virus particles which are unable to replicate in humans because they have been treated chemically or physically. You will always need multiple doses/booster
EXAMPLE: Polio, Hep B
What is a secreted toxin vaccine
Secreted toxin vaccines involve purifying bacterial toxins and treating them with formalin to destroy their toxic activity. Inactivated toxoids have sufficient antigenic activity to provide protection against disease
What is a Conjugated vaccine
Conjugating bacterial polysaccharide to tetanus/diphtheria. Use capsule to escape CD4/TFH
Produce highly specific IgG antibodies which leads to complement fixation and killing of bacteria.
What is a subunit vaccine
Only one part/subunit of the virus rather than the full virus is injected
What is an RNA vaccine and give an example?
mRNA vaccines use mRNA created in a laboratory to teach our cells how to make a protein—or even just a piece of a protein—that triggers an immune response inside our bodies
EXAMPLE: COVID-19 vaccine
What is the new vaccine for meningitis B based on? How does it work?
Reverse immunology. FHbp prevents activation of the complement. Antibodies with ant FHbp induced with vaccination block FHbp inhibitory functions and allow activation of the complement cascade
What is passive vaccination and when is it indicated?
IM/IV injection of antibodies. Indicated for the prophylaxis of infectious disease, to prevent symptoms, protect during incubation period, treat antibody deficiences
What is active vaccination and when is it indicated?
iM/IV/SC, introducing the antigen to stimulate a specific response. Indicated as usual vaccines are.
What is the purpose of adjuvants and what must they do?
Additional components of vaccines which increase the immunogenicity. Important in subunit vaccines. Must provide appropriate immune response but not induce a response against themselves, but be stable with long shelf, biodegradable, cheap to produce, and reduce vaccine cost.
What is the purpose of excipients?
Additives in vaccines to prevent microbial contamination or to stabilise vaccines. Can potentially cause allergic reactions.
What makes a good vaccine?
SAFE: vaccine itself must not cause illness or death
PROTECTIVE: vaccine must protect against illness resulting from exposure to live pathogen
GIVES SUSTAINED PROTECTION: protection against illness must last for years
INDUCES NEUTRALISING ANTIBODY: essential to prevent infection
INDUCES PROTECTIVE T CELLS
PRACTICAL: low cost/dose, stability, easy administration, few side effects
What is the purpose of the vaccine delivery system?
Protects vaccine from being degraded, a good delivery system can be used to make a prolonged release formulation.
What are the different routes of administration of vaccines?
Injection
Intranasal
oral
pros and cons of injection delivery
prevent person to person transmission, produce a sytstemic response but they are painful, expensive and they do not mimic pathogen route of entry
pros and cons of mucosal vaccination (intranasal/oral)
Produce antibodies in the usual route of delivery but provide less organ protection
