Vaccines 2 Flashcards
Three Components of a Vaccine
- Antigen (target)
- Adjuvant (primer)
- Route and Dose
What is an antigen?
The specific target seen by the Adaptive immune system
What are the 3 main kinds of vaccines?
- Live attenuated
- Killed
- Subunit or Toxoid
What is a live attenuated vaccine?
Weakened or less virulent pathogen
How does a live attenuated vaccine work?
Weakened pathogen actually infects the host
Attenuated microbes multiply in the recipient, leading to a more robust and long-lasting immune response
What type of response does a live attenuated vaccine elicit?
A strong cellular and humoral response
How long is immunity for live attenuated vaccines?
Lifelong with only one or two doses
What are the 2 risks associated with live attenuated vaccines?
- Possibility that attenuated vaccine strain could revert to an active pathogen
- Cannot be given to health professionals or immunocompromised individuals
Why can you not give a live attenuated vaccine to a healthcare worker?
Could pass to a patient
Why can you not give a live attenuated vaccine to an immunocompromised individual?
It is possible that the weakened pathogen could still win
Immunocompromised
Recognizes pathogen as self
Autoimmune
Recognizes self as pathogen
What are the 2 logistical problems to live attenuated vaccines?
- need to be refrigerated to stay potent
- Difficult to produce live attenuated vaccines in bacteria b/c of the greater number of genes and thus, the chance of them reverting is greater
Why do we not have attenuated bacterial vaccines?
Bacteria have too many genes and thus, the chance of them reverting is too high
What is arguably the safest vaccine?
Killed
What is a killed vaccine?
A vaccine containing inactivated organisms or parts of them
Give an example of an attenuated vaccine
Measles, mumps
Give an example of a killed vaccine
Hep A
Influenza
Polio
How do you inactivate - for killed vaccines?
Heat/chemical/radiation
Boil, UV
What is an advantage killed has over attenuated?
Pose no risk of reverting
How are killed stored?
Dried and stored (up to 10 yrs)
Stable and do not require cold chain
What is a drawback of killed?
- Provide weak or short lived immune response
May require boosters
What type of vaccine consists of whole pathogens?
Killed
Is a killed vaccine able to infect host cells?
No
What types of vaccines require boosters?
Killed
Subunit or Toxoid
What does a subunit vaccine consist of ?
Antigens (targets) that best stimulate the immune system or specific toxins that mediate disease
What are the 3 methods of preparation for a subunit ?
- Chemical extraction of pathogen
- Recombinant DNA tech
- Chemically synthesized
What type of immune response does a subunit elicit?
Antibody responses
What type of immune response does a subunit not elicit?
Cytotoxic T
So we do not make T-cells
What type of antigens do we chose for subunit vaccines
Conserved antigens
They won’t escape vaccine
What is a major problem of subunit?
Pathogens that are antigenically diverse
Thye can mutate and escape the vaccine
Why does a subunit not work for Malaria?
Malaria can change its outercoating
How do we generate a subunit vaccine that works on a pathogen that changes?
We chose suface antigens so that even if the pathogen changes the surface of the spike protein sticks to the host
When do we use a toxoid vaccine?
When a bacterial toxin is the main cause of illness
Give an example of a toxoid vaccine
Diptheria or Tetanus
How does tetanus harm us?
It secrets a toxin and the toxin causes paralysis
So we vaccinate against the toxin and not the bacteria
What are the 2 new vaccine strategies?
- Engineered
2. DNA/RNA
How does an engineered vaccine work?
Attach targets from a highly virulent pathogen to the surface of a weak pathogen
Does an engineered vaccine infect the host?
Yes
What type of vax technique so we dress up a pathogen to look like a more virulent pathogen?
Engineered
What vaccine has no pathogen?
DNA/RNA
How does a DNA/RNA vax work?
Inoculate w/ a gene encoding a pathogen or targer
How does a recombinant vector vax work?
Introduce genes encoding microbial antigens into a non-cytopathic or attenuated virus/bacteria and infect individuals
Does a rec vector generate a true infection?
Yes
What type of immune response does a recombinant vector elicit?
Full complement immune response, including strong CTL responses
Can we use engineered vaccines on health care workers and immunocompromised?
No, it is STILL an infection
Is there any pathogenic machinery in an engineered vax?
No
Give an example of a recombinant vector vaccine
VSV-EBoV
J/J
Astrazenica
Give an example of DNA/RNA vax
Moderna
Pfizer
What are 4 advantages to a DNA/RNA vax?
- Elicit designer immune response
- Easy to produce and purify
- Stability
- Low cost
Theoretical concerns over DNA/RNA (2)
- Potential for genomic integration into host chromosomal DNA and induce mutagenesis and insertional carcinogenisi
AKA introduce into the wrong cells and create cancer - Potential for induction of ant-ds-DNA or antibodies against other nucelar antigens, leading to autoimmunity
What type of vax uses our cell machinery?
DNA/RNA
What does a killed usually consist of ?
Components often consists of surface molecules of pathogens that mediate host cell invasion
How does a DNA/RNA vax work? 4 steps
- Gene antigen of interest is cloned into a bacterial plasmid that is engineered to increase the expression of the inserted gene in mammalian cells
- After being injected, the plasmid enters a host cell where it remains in the nucleus
- Using the host cell machinery, the plasmid DNA directs the synthesis of the protein it encodes
- The microbial protein may be presented in the context of MHC molecules to elicit T-cell responses
