Immunity And Vaccines - Tutorial 3

Question 1

Name the four different types of vaccines

Answer 1

• Live attenuated microbes
• Killed whole microbes
• Portions of microbes
• Toxoids

Question 2

Name the four types of acquired immunity & describe how immunity is achieved for each type

Answer 2

Naturally acquired:
* Active - natural exposure to the antigen (e.g viruses, cuts, etc)
* Passive - antibodies passed to foetus via placenta or to infant via breast milk

Artificially acquired:
* Active - antigens introduced via vaccines - body makes antibodies and memory cells
* Passive - preformed antibodies injected (e.g tetanus, Hep B)

Question 3

Identify which type of vaccine would give the most effective response
and explain why

Answer 3

Live attenuated vaccines, often provide life -long immunity, without the need for boosters, thus are more effective than other vaccines

Question 4

Explain why a booster vaccine might be needed

Answer 4

• When a vaccine involves killed whole bacterial cells, toxoids, inactivated microbes or sub-units the immune system does not respond as powerfully as when a live attenuated vaccine is given
• Boosters are needed to intensify the immune response.

Question 5

Describe the concept of herd immunity

Answer 5

Herd immunity results when most of a population is immune to a disease, if most people are immune they will not be carriers, so herd immunity protects those who are immune

Question 6

List the undesirable responses of the immune system

Answer 6

1. Hypersensitivity reaction:
   - Allergy is a hypersensitivity to an environment antigen.
   - Anaphylaxis is the most severe and rapid reaction. It is life-threatening as it causes construction of the bronchial smooth muscle and oedema of the throat
2. Autoimmune disorder:
   - The immune system attacks the body’s own cells when it fails to recognise ‘self’ eg. Rheumatoid arthritis
3. Immuno-compromised persons are at risk from minor infections
   - Very young, elderly, severe illness, stress
4. Reactions to transplanted or foreign tissue including blood transfusion reactions, donated organs, etc
5. Chronic inflammation
   - Asthma is a disorder characterised by chronic airways inflammation (as well as hypersensitivity to a variety of stimuli). Inhalers which act as preventers reduce inflammation.
   Chronic inflammation of arteries plays a key role u the development of atherosclerotic plaque in response to damage to the endothelial lining of the artery (through smoking, high BP, high BGL)