Lesson plan 22: Antigenic variation
Resources
Plasticine, pipe cleaners (optional: digital cameras/mobile phones).
Lesson content
(e)
Evasion of specific immune responses by pathogens
Many pathogens have evolved mechanisms that evade the specific immu ne
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.
Introduction (5 min)
Learning outcome
Today we are learning about the methods pathogens can use to avoid the
immune response.
Success criteria
We will know we are successful when we can:



describe the process of antigenic variation
give examples of pathogens that use antigenic vari ation
describe why antigenic variation poses a problem to public health.
Activity 1 (5 min)
Chinese whispers. Pass a message round the room. Use this to introduce the
idea of antigenic variation – over time the message can change and over time
a pathogen can change its antigen. Remind students of the specificity of the
immune response. Discuss the benefits of antigenic variation to a pathogen.
Direct teaching of malaria, trypanosomiasis and flu as examples of pathogens
that exhibit antigenic variation.
IMMUNOLOGY AND PUBLIC HEALTH (H, HUMAN BIOLOGY)
© Learning and Teaching Scotland 2011
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Activity 2 (30 min)
In co-operative groups students should use plasticine and pipe cleaners to
produce a model flu virus (complete with antigens) and antibodies. They
should model the action of the antibody recognising the antigen and binding
together. Students should then use the same model virus but change the
antigen and show how the antibody no longer recognises the virus. A digital
camera/mobile phone could be used to take pictures at each stage. The
pictures could then be uploaded onto a computer and displayed as students
talk about what is happening at each stage.
Activity 3 (10 min)
Groups should share their presentations with the class.
Plenary (5 min)
Refer to the learning outcome and success criteria for the lesson – have the
success criteria been achieved?
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IMMUNOLOGY AND PUBLIC HEALTH (H, HUMAN BIOLOGY)
© Learning and Teaching Scotland 2011