Edward Jenner’s smallpox inoculation experiment was based on his observation that some dairymaids who worked with cows had suffered lesions on their hands, but that these dairymaids were immune to the more severe smallpox. He inoculated James Phipps with material from the lesions on a dairymaids’ hands. Which best explains why Jenner decided to infect Phipps?
Answer
A
The material contained antibodies that could destroy the smallpox pathogen.
B
The material contained pathogens that were similar to but weaker than the smallpox pathogen.
C
The material had oxygen that could help the cells of the body fight off smallpox infection.
D
The material contained a pathogen that could attack the smallpox pathogen.
Explanation
The lesions were caused by cowpox, a disease related to smallpox but generally much less severe. Jenner reasoned that exposure to the cowpox pathogen could train the immune system to protect against smallpox. So the best choice is that the material contained pathogens similar to, but weaker than, the smallpox pathogen.
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