ANSWERS

1. What is the definition of immunology?
   Immunology is the study of the body's defence systems against foreign material and "non-self" invasion.
2. What is meant by innate defence?
   The natural defences of the body.
3. List 3 examples of innate defences.
   • Barriers (hair, saliva, skin, tears).
   • Enzymes (lysozyme in saliva and tears kills Gram-positive bacteria).
   • Phagocytes (specialised cells such as neutrophils and macrophages which identify and remove foreign material).
4. What is an antigen?
   A foreign material that the immune system can recognise; ie. any substance, bacterial or otherwise, which in suitable conditions can stimulate the production of antibodies.
5. What is acquired immunity?
   Immunity developed after birth and throughout life; i.e. not inherited immunity.
6. What is natural immunity?
   The continuous process of recognition of foreign material and the body's response by the production of antibodies, thus providing protection from future infection.
7. What is meant by passive immunity?
   Immunity derived from means other than the animal producing its own antibodies.
8. List 3 ways in which passive immunity may be achieved.
   • Maternally derived immunity - from colostrum.
   • Administration of antisera.
   • Administration of antitoxins.
9. How is active immunisation achieved?
   By vaccination; i.e. immunity is produced by the animal in response to the stimulus of an antigen (vaccine).
10. List 4 criteria essential for the safe use of vaccines.
    • Store as directed on the data sheet (many vaccines must be refrigerated).
    • Never use if past expiry date.
    • Administer the product as directed on the data sheet (always use sterile needles and syringes for injectable preparations).
    • Do not mix with unrelated products.
      The above criteria all endeavour to ensure that the animal is presented with an undamaged antigen. This is essential since vaccines may contain viruses or bacteria which could prove harmful.
11. Why are booster vaccinations necessary?
    In order to remind the memory lymphocytes of the antigen, thus ensuring that the next time the animal meets the same antigen a rapid and effective response is produced.
12. What is meant by an ELISA test? Give an example.
    Enzyme-linked immunosorent assay. ELISA tests may be used to diagnose feline leukaemia (FeLV).