Have students read On Guard, which introduces students to the processes by which the immune system provides protection from viral and bacterial infections. Students read a short overview about the components of the immune system and how these components interact in their response to infection. Students then watch a video that clearly and concisely demonstrates this response.

Videos

Our Immune System

This video produced by Cortical Studios and Pfizer uses striking graphics to describe the inflammatory response of the immune system to bacterial infection.

The Immune System Explained 1 - Bacterial Infection

An animation that illustrates the immune response to bacteria in greater detail.

Activity

Have students select a disease from the Timeline of Infectious Diseases and model how the immune system would respond to the pathogenic agent of that disease using information from Reading 3 (On Guard), Table 1: The Immune Response to Infection.

Encourage students to take careful notes, particularly while watching the video and to watch the videos more than once, pausing when needed.

The immune system is extremely complex. For simplicity students may choose to model only a cellular response or a humoral response for the sake of clarity and simplicity. They should be reminded that in most cases both responses are occurring. Alternatively you may want to have students play the Immune System Game, which gives students a feel for the complexity of the immune response.

Going Further

Have students read Mimicking an Infection, which explores how vaccines work to activate the immune response against specific viruses and bacteria. Students should recognize that vaccines mimic an actual infection and provide protection against infection in a similar fashion without the dire consequences of the disease. In Module 3 – Viruses Go “Viral”, students learn about the impact of vaccines on infectious diseases and consider the implications and ethics of mandatory vaccinations.

Discussion

After students have read On Guard and Mimicking Infection you may want stimulate discussion of the questions posed after Reading 4

• How are vaccinations similar to contracting the actual disease in establishing immunity to the disease? How do they differ? (They are similar in the way they activate the immune response and produce long term protection through memory B cells

  They are similar in the way they activate the immune response and produce long term protection through memory B cells. They differ in that the pathogen causes a disease and the vaccine does not.

• Which do you think is preferable, contracting the disease or being vaccinated? Explain your response.

  Answers will vary. This question may generate discussion about the safety of vaccines and bring up student concerns. This issue is addressed in greater depth in Module 3 – Viruses Go “Viral”.

• The eradication of smallpox by vaccination was achieved through worldwide vaccination programs and also because smallpox virus has no animal reservoir. In Reading 1 you learned that polio has been eliminated from many countries but not eradicated from Earth. What other viral diseases could be candidates for eradication? Which would not be candidates?

  Eradication of a disease requires an effective vaccine for that disease and no animal reservoir that would harbor the virus. Provided students had experienced Module 1, they should recognize that measles would be a good candidate since an effective vaccine is available and no reservoir host exists. Other candidates for eradication include measles, chicken pox, mumps and rubella.

  Ebola would not be a good candidate since there is no vaccine and bats provide a reservoir host. SARS and Zika are also not candidates since they have animal reservoirs and no effective exists to date. You may want to have students do further research on this question.