Vaccines and Immunity Flashcards
Which immune mediators are transferred via mother’s milk?
- TGF-β in humans, cattle, possibly other species
- lactoferrin in humans, cows - part of innate immune system (anti-microbial)
What is increased and decreased in breast-fed children serum?
- increased regulatory TGF-β
- decreased regulatory TGF-α
What is breast feeding associated with?
- lower hypersensitivities - not all and not absence
- reduced GI, respiratory infections in infants
What are some examples of anti-sera/passive immunity?
- tetanus and other toxoid-releasing pathogens
- hepatitis A and B
- immunodeficient individuals
How does passive immunity end?
end eventually due to catabolism of antibodies
Describe the Janaka et al 2021 case study
- donor anti-spike immunity related to recipient recovery and can predict efficacy of convalescent plasma units
- of those with severe covid, only 65% created plasma reached protective levels
- less hospital death with anti-spike antibody titre, more with anti-nucleocapsid
What needs to balanced in vaccines and how is it achieved?
- need to mimic natural infection
- activate innate immune system -> adaptive immune system
- one way to help is mixing the vaccine with an adjuvant
Describe adjuvants
- any substance that, when given with an antigen, enhances the immune response to that antigen
- activates the innate immune response
Describe Alum
- main adjuvant method is slow release of antigen
- also can lead to damage (DAMPs) activating DCs and macrophages
- aggregates which makes easily phagocytosed
- mainly Th2 activation - not cell mediated
Describe immunostimulatory adjuvants
- dsRNA, CpG, saponins
- called QuilA - stimulates cytokine production
- Th1 stimulatory - used in horse, cat, dog, cattle vaccines
- e.g., FeLV recombinant vaccine
Describe Covid-19 vaccines
- no reported adjuvants
- astra zeneca oxford - actual virus - can activate innate immune response
- moderna & pfizer/biotech - lipid nanoparticle/mRNA
What are the 3 types of vaccine?
- live attenuated
- killed
- subunit
Describe the live attenuated vaccine
- still viable pathogen but reduced pathogenicity
- can cause infection but not disease
- attenuated by deliberate passage
Describe the effects of live attenuated vaccines on the general immune response
- strong, appropriate response
- cellular immunity
- humoral immunity - including secretory IgA depending on pathogen
- long-lasting memory
What are the advantages of live attenuated vaccines?
- multiple antigens
- single immunisations
- easy to produce without a genome of pathogen
- may not require an adjuvant
What are the disadvantages of live attenuated vaccines
- reversion to wild type
- persistent infection
- severe disease in immunocompromised
- hypersensitivity to egg antigens
Describe killed vaccines
- also referred to as inactivated
- killed by heat - can denature many protein antigens
- killed by chemical - formaldehyde
What is the effect of killed vaccines on the immune response?
- weaker response than live vaccines
- good serum antibody response, little secretory IgA
- poor cell-mediated immunity created
- booster shots usually required
What are the advantages of killed vaccines?
- multiple antigens
- stable
- safer than live vaccine
- no refrigeration
What are the disadvantages of killed vaccines?
- vaccines sometimes not killed
- lack of understanding about why it protects
- contamination with animal viruses
- initial preparation requires working with pathogen
Describe subunit vaccines
- specific, purified pathogen subunit/molecule
- toxoid vaccines induce antibodies against bacterial exotoxins - can cause major symptoms
Describe the effects of subunit vaccines on the immune response
- weak immune response
- good serum antibody response
- no cell-mediated immunity created
- booster shots usually required
What are the advantages of subunit vaccines?
- limited antigens - less chance of cross-reactivity
- higher levels of safety and reproducibility
- safer than live vaccine - no chance of accidental infection
- no need for refrigeration
What are the disadvantages of subunit vaccines?
- toxoid vaccines - limited to a few bacterial diseases
- limited number of antigenic targets - evolution
- difficult to develop
- adjuvant required
