Why do rhinoviruses infect the upper respiratory tract, particularly the nose, but not the lower respiratory tract?
A. They replicate most effectively at the cooler temperatures of the upper respiratory tract.
B. IgA antibodies in lower respiratory tract secretions prevent them from becoming established in the lower respiratory tract.
C. The prevalence of alveolar macrophages in the lower respiratory tract prevents them from becoming established there.
D. They are unable to attach to receptors on the pulmonary cells in the lower respiratory tract.
Answer: A
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