Joe Smith had the flu last year. This winter he \"caught\" the flu again. Why wa

Question

Joe Smith had the flu last year. This winter he "caught" the flu again. Why wasn't he immune the second time?

Select one:

a. Memory cells produced in response to viral infections only last for a short period of time, usually only several weeks.

b. Joe obviously has a weak immune system.

c. Many viruses, such as influenza viruses are able to rapidly change their surface antigens thereby avoiding the previously produced memory cells.

d. Memory cells are only effective against bacteria and protozoans and are not able to recognize viral antigens.

Explanation / Answer

Many viruses, such as influenza viruses are able to rapidly change their surface antigens thereby avoiding the previously produced memory cells. This is why we get cold and cough again and again during our life time, in spite of having a secondary immune response.

Hence, the correct option is C.

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