microbes lecture 9- vaccines

Question 1

what is the definition of a vaccination?

Answer 1

A means of producing immunity against pathogens,
such as viruses and bacteria, by the introduction of
live, killed, or altered antigens that stimulate the body
to produce antibodies against more dangerous forms

Question 2

who was Edward Jenner?

Answer 2

• Jenner was a Gloucester GP
• Routinely practiced variolation (and was variolated himself)
• 1765 - The potential for cowpox (vaccinia) to protect
  against smallpox (variola) was known (Fewster)
• 1796 - Performed the first protection trial with James Phipps

Question 3

what are the stages of inducing memory cells?

Answer 3

1- antigen recognising
2- lymphocyte activation
3- antigen elimination
4- contraction
5- memory

Question 4

memory vs naive b lymphocytes

Answer 4

• Long Lived
• Increased frequency
• Rapid proliferation
• Produce more Ab
• Produce higher affinity Ab
• Class switching
  – IgG & IgA have better effector functions than IgM

Question 5

memory vs naive t lymphocytes…

Answer 5

• Long Lived
• Increased frequency
• Rapid proliferation
• Lower activation threshold
• Better effector functions

Question 6

secondary Ab responses..

Answer 6

• Faster
• Higher
• Isotype Switched
• Higher Affinity

Question 7

what is the germinal centre reaction?

Answer 7

drives affinity maturation and class switching of Memory B
cells and Long Lived Plasma Class

Question 8

how do most vaccines work?

Answer 8

by inducing long lived
plasma cells and plasma antibody responses

Question 9

examples of virus attenuation…

Answer 9

1. Pathogenic virus is isolated and cultured on
   host (e.g human) cells.
2. Virus is incubated on cells from another
   host (eg.Monkey).
3. Virus spontaneously mutates and grows
   on monkey cells.
4. Virus can be used as a vaccine as it cannot grow on human cells.

Question 10

vaccine associated poliomyelitis…

Answer 10

• Last case of natural polio infection acquired in the UK
  was in 1984.
• Between 1985 and 2002, a total of 40 cases of paralytic
  polio were reported in the UK
  –Thirty cases were VAPP;
  –six cases had wild virus infection acquired overseas;
  –four cases unknown but wild virus was not detected.
• 2004 - killed (Salk) vaccine introduced

Question 11

what is a killed vaccine?

Answer 11

• Usually use chemicals or heat
• These kill the organism and render it completely uninfective
• Killed organism can still induce immunity
• e.g. whole cell pertussis vaccine

Question 12

what is a subunit vaccine?

Answer 12

• Toxins are the pathogenic fragments of bacteria
• Antibodies to toxins can protect from infection
• Chemically inactivated toxins are called toxoids
• e.g. acellular pertussis vaccine

Question 13

what are recombinant subunit vaccines?

Answer 13

• Certain viruses/bacteria/parasites are very hard to grow
  –e.g. they grow in host cells that are not readily cultivated
  –e.g. Human Papilloma Virus

Question 14

what is a live attenuated influenza virus?

Answer 14

• Fluenz (AstraZeneca/MedImmune)
• Uses multiple attenuated master virus (ca - cold-adapted only replicate efficiently at 25°C; ts-
  restricts replication at 37°C or 39°C; att - doesn’t produce illness)
• Effective in children over 2 years
• Well-tolerated in children and adults
• Ease of administration
• Known limitations:
  –ineffective in over 50s
  –issues with safety in children with asthma/wheezing
  –not for immunocompromised

Question 15

what is the vaccine design process?

Answer 15

1) antigen identification
2) vaccine delivery
3) immune activation

Question 16

what is an adjuvant?

Answer 16

Agents which act non-specifically to increase the specific immune response or responses to an antigen