Vaccines Flashcards
What are the six categories of traditional vaccine preparations?
- Live attenuated bacteria
- dead or inactivated bacteria
- inactivated virus
- live attenuated viruses
- toxoids
- pathogen-derived antigens
What are the advantages that genetic engineering has over conventional vaccine production methodologies?
It offers advantages such as:
- a clinically safe product
- unlimited supply
- consistent production of a defined product.
How has recombinant DNA technology impacted vaccine technology?
Has enabled the large-scale production of polypeptides present on the surface of pathogens, which can be used as subunit vaccines.
What was the first recombinant subunit vaccine approved for medical use?
Recombinant hepatitis B surface antigen (rHBsAg), which gained FDA approval in 1986.
What were the disadvantages of using HBsAg purified directly from the blood of hepatitis B sufferers in hepatitis B vaccines?
- Restricted vaccine supply due to the availability of infected human plasma
- Likelihood of contamination with intact viable hepatitis B viral particles.
Which subunit vaccine, containing purified recombinant hepatitis B surface antigen (rHBsAg), gained FDA approval in 1998?
Engerix B
- gained FDA approval in 1998
- indicated for active immunization against infection caused by all known serotypes of hepatitis B virus.
What is the largest group of biopharmaceuticals approved for animal use?
Recombinant vaccines
Which recombinant vaccine targets pigs?
Porcilis PESTI
contains a recombinant form of the classical swine fever virus E2 antigen.
Bayovac CSF E2
What is the alternative approach to the production of subunit vaccines mentioned?
Direct chemical synthesis of subunit vaccines. - peptide vaccines
In the 1960s, what was found to confer immunological protection against subsequent administration of the intact tobacco mosaic virus?
A hexapeptide purified from the enzymatic digest of tobacco mosaic virus
Besides viral vaccines, what other type of vaccines have been constructed using direct chemical synthesis?
Synthetic vaccines
confer immunological protection against bacterial toxins, including
- diphtheria
- cholera toxins.
Which regulatory agency was the first to approve an mRNA vaccine?
The UK’s Medicines & Healthcare products Regulatory Agency (MHRA)
What are the advantages of RNA vaccines?
- They elicit both humoral and cellular immune responses.
- They are easily designed based on genetic sequencing alone.
- They can be quickly updated to target emerging variants.
- The cell-free manufacturing process is cheap and straightforward.
- The mRNA fragments themselves are non-infectious and quickly broken down.
- The mRNA platform is flexible and can encode multiple viral proteins into a single vaccine.
- They do not require the systematic use of adjuvants.
What are the two main categories of mRNA vaccines?
- conventional (non-amplifying)
- self-amplifying mRNA (saRNA).
What is the mechanism of action of mRNA vaccines?
- mRNA is in vitro transcribed (IVT) from a DNA template.
- IVT mRNA transfects dendritic cells (DCs) through endocytosis.
- mRNA escapes the endosomes and enters the cytosol.
- The mRNA is translated into antigenic proteins.
- The proteins are released from the cell or presented on MHC I via the endoplasmic reticulum
- The MHC I-peptide epitope complexes stimulate an antigen-specific CD8+ T-cell response.
- Exogenous proteins are degraded in endosomes and presented via the MHC II pathway.
- This induces an antigen-specific CD4+ T-cell response.
- The CD8+ and CD4+ T-cell responses contribute to cellular and humoral immunity, respectively.
