1. Rumours (or previously known as Chinese whispers).. What does this show?
I was given an extra vaccine for whooping cough for the baby

2. Aim of this lesson is to Answer these questions 1
Aim of this lesson is to Answer these questions 1. Why is there a new vaccine for the flu every year? 2. Is there any way to evade the immune system?

3. What do you notice here?

4. What is a mutation again?
Antigenic variation
Mutations in the nucleic acid which can eventually lead to the altering of the surface markers (antigen)
New antigen
So new
Vaccine needed
Called Antigenic variation

5. A mutation is a change in the DNA sequence
Mutations can occur through;
copying errors
-exposure to mutagens (like UV light, ionising radiation, chemicals or certain viruses)

6. Pairs please ....
Bacteria, viruses and protozoa all have the ability to undergone antigenic variation.
MODEL IT USING PLASTICINE/PIPE CLEANERS ETC.
Partner up;
one of you find out about trypansomiasis (p341)
ONE OF YOU FIND OUT ABOUT MALARIA (P342)

7. DIRECT ATTACK ON THE IMMUNE SYSTEM
The immune system can be hijacked;
Tb (mycobacterium tuberculosis) hides inside the phagocytes
Hiv (human immunodeficiency virus) hides inside t helper cells ( t lymphocytes)
HOT QUESTION – what are the problems with hiding in t helper cells? (function of T helper cells are to .....)

8. hiv Retrovirus – with rna not dna
Glycoprotein receptors help it bind to t lymphocytes

9. hiv
Uses protein synthesis of cell to reproduce
Leaves through budding

10. Hiv avoidance
B cells do make antibodies, however ineffective as hiv “hides” in helper T cells.
T helper cells needed in activation of the rest of the immune system, so down regulate immune system
Thus opportunistic infections can become major problem
Down regulation stage know as aids – acquired immunodeficiency.

11. Translate the writing into pictures
Immune system is like ....
HIV is like .....
tb is like .....

12. Put these cards into order now come up with a series for tb
Demonstrate your understanding
Put these cards into order now come up with a series for tb

13. Review – can you answer these?
1. Why is there a new vaccine for the flu every year? 2. Is there any way to evade the immune system?

14. Summary slide
Evasion of the immune system
- Many pathogens have evolved mechanisms that evade the specific immune system which has consequences for vaccination strategies.
- Some pathogens can change their antigens avoiding the effect of immunological memory Antigenic variation occurs in diseases like malaria and trypanosomiasis and is one of the reasons why they are still so common in many parts of the world. - Antigenic variation also occurs in the influenza virus explaining why it remains a major public health problem and why at risk individuals require to be vaccinated every year.

15. Summary slide
EVASION of immune system
The absence or failure of some component of the immune system results in increased susceptibility to infection.
HIV attacks lymphocytes and is the major cause of acquired immunodeficiency in adults.
Tuberculosis (TB) survives within phagocytes and avoids immune detection.