Nucleic Acid Vaccinations

Question 1

Describe how DNA vaccines work

Answer 1

• plasmid carrying pathogen genes injected into muscle tissue
• host cells take up DNA and express it internally
• antigen presented via MHC I = stimulates T cytotoxic

Question 2

Nucleic acid vaccines: pros and cons

Answer 2

Pros:
- humoral AND cell-mediated immunity
- prolongs expression, enhancing memory

Cons:
- presently unknown

Question 3

AstraZeneca DNA vaccine

Answer 3

• modified non-replicating chimpanzee adenovirus
• E1 gene replaced with COVID-19 spike gene

Question 4

Rare but serious side effect of AstraZeneca

Answer 4

• antibodies produced against PF4 = Vaccine-induced immune thrombotic thrombocytopenia

Question 5

How do mRNA vaccines work ?

Answer 5

• mRNA encapsulated in lipid nano particle fuse with cells
• mRNA produces spike protein = MHC I presentation
• secreted antigen taken up by macrophages = MHC II presentation
• TLR3 involvement

NOTE: cross-presentation