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THE IMMUNE SYSTEM AND DISEASE

6 April, 2016 - 17:26
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Figure 17.1 This smallpox (variola) vaccine is derived from calves exposed to cowpox virus. Vaccines provoke a reaction in the immune system that prepares it for a subsequent infection by smallpox. (b) Viewed under a transmission electron microscope, you can see the variola’s dumbbell- shaped structure that contains the viral DNA.