Defence and vaccination against bacteria

Question 1

What is a good vaccine?

Answer 1

Provides substanital benefit to health at low cost and low risk

Question 2

What is innate and acquired immunity mediated by?

Answer 2

Innate: monocytes and PMNs
Acquired: lymphocytes (B and T cells), and monocytes and dendritic cells

Question 3

What are the 2 sub types of acquired immunity?

Answer 3

-Humoral immunity:
directly mediated by antibodies
-Cell mediates:
not primarily mediated by antibodies but by T lymphocytes and NK cells

Question 4

What are some of the roles of the antibodies?

Answer 4

• Toxin neutralisation
• as a focus for complement binding
• as an opsonin promoting phagocytosis.

Question 5

what are the different phases in clinical trials

Answer 5

Phase 1: priamrily for saftey and to assess immunogenicity
phase 2: primarily for assessing immune response but also expand safety database
Phase 3: protections studies, usually placebo- vaccine efficacy, blinded etc

Question 6

Define vaccine efficacy and which phase is it done and the formula for it

Answer 6

The reduction in the incidence of dieases among people who have recieved a vaccine compared to the incidence in unvaccinated people.
-Phase 3 trials
Vaccine efficacy= 1- attack in vaccinated group/attack rate in unvaccinated group
usually expressed as %

Question 7

Define herd immunity and give the formula

Answer 7

Form of immunity that occurs when the vaccination of a significant portion of the population provides a measure of protection for indivuals who have not yet developed immunity
Herd effect= 1- Attack rate vaccinated post introduction/attack rate unvaccianted pre-introduction

Question 8

What are the 3 elements to a vaccine

Answer 8

• Antigen: to stimulate the immune response to the target disease
• Adjuvant: to enhance and modulate the immune response
• Excipients: buffer, salts, saccharids to maintain the pH, osmolarity and stability of the vaccine. Preservative

Question 9

What are the 4 antigenic components that could be in vaccines

Answer 9

Live attenuated organisms: vaccine prepared from live microorganism whose disease producing ability has been wekeaned but whose immunogenic properties have not
Killed whole organism: organisms is killed and then killed either chemically or by heating
Component vaccines:
DNA vaccines: antigen gene is cloned in a vector. once DNA is injected, host expresses the antigen and mounts and immune response.

Question 10

What are conjugate vaccines adn when is it effective

Answer 10

• carbohydrate chemically linked to immunogenic protein

- effective when humoral immunity is required

Question 11

How does cunjugate vaccine work?

Answer 11

the prolysaccharide capsule of bacteria is binded to a protein carrier.

• T cell recognition of preotin carriers enhances B cell activation
• prmotoes efficient antibody response to polysaccharide