RUMOURS OR PREVIOUSLY KNOWN AS CHINESE WHISPERS WHAT

RUMOURS (OR PREVIOUSLY KNOWN AS CHINESE WHISPERS). . WHAT DOES THIS SHOW?

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?

WHAT DO YOU NOTICE HERE?

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

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) http: //nature. ca/genome/04/0413_e. cfm#010

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 (P 341) • ONE OF YOU FIND OUT ABOUT MALARIA (P 342)

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. . . )

HIV • RETROVIRUS – WITH RNA NOT DNA • GLYCOPROTEI N RECEPTORS HELP IT BIND TO T LYMPHOCYTES

HIV • USES PROTEIN SYNTHESIS OF CELL TO REPRODUCE • LEAVES THROUGH BUDDING

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.

TRANSLATE THE WRITING INTO PICTURES • IMMUNE SYSTEM IS LIKE. . • HIV IS LIKE. . . • TB IS LIKE. . .

DEMONSTRATE YOUR UNDERSTANDING PUT THESE CARDS INTO ORDER NOW COME UP WITH A SERIES FOR TB

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?

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.

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.