L17- Vaccines (2)

Question 1

What is the hierarchy of vaccines?

Answer 1

1st generation: Whole organism (live or weakened or killed)
2nd generation: sub-unit or recombinant
3rd generation: DNA vaccines

Question 2

What are inactivated organisms?

Answer 2

• Killed
• By heat/chemical
• Chemical usually better- inactivated but still immunogenic
• Induces antibody (humoural) response
• Requires booster
e.g polio inactivated by formaldehyde treatment, flu

Question 3

What are live attenuated organisms?

Answer 3

• Lose the ability to cause significant disease it can still grow
• Prolonged immune system exposure to antigenic epitopes
• Single immunisation
• Possibility of reversion to pathogenic strain
e.g BCG vaccine

Question 4

How are pathogens attenuated?

Answer 4

• Growth in unusual conditions e.g BCG
• Growth in unusual host cells e.g Rubella
• Animal homologue of human pathogen e.g vaccinia
• Molecular biology to knock out virulence genes

Question 5

What are subunit vaccines?

Answer 5

Consist of specific, purified macromolecules derived from pathogens, inactivated toxins or antigens purified from microbes e.g tetanus toxoid, diptheria vaccine (toxoid)

Question 6

What are conjugate vaccines?

Answer 6

Certain bacteria have polysaccharide outer coats that are poorly immunogenic (T cell independent antigens).

By linking these outer coats to proteins (e.g. toxoids), the immune system can be lead to recognise the polysaccharide as if it were a protein antigen.

Question 7

How are genetically engineered attenuated vaccines produced?

Answer 7

By mutating or deleting virulence genes

Question 8

How is a DNA vaccine/recombinant protein produced?

Answer 8

By cloning genes encoding antigens

Question 9

What are the non-viral targets of cancer vaccines?

Answer 9

Neoantigens

Overexpressed antigens