Virology USMLE Step 1 Practice Question
A 3-year-old girl with unknown vaccination status presents to the emergency department with a 4-day history of fever, bilateral parotid swelling, and jaw pain. Her temperature is 38.9°C, heart rate 112/min, respiratory rate 24/min, and blood pressure 98/60 mmHg. On examination, she has tender, symmetric parotid gland enlargement bilaterally. Laboratory studies show serum amylase 156 U/L and positive IgM antibodies against mumps virus. The patient's mother reports that the child has not received any MMR vaccinations. Which of the following best explains how the MMR vaccine would have prevented this clinical presentation?
Answer choices
- AInactivated mumps virus particles stimulate B lymphocytes to produce neutralizing antibodies without generating memory T cells
- BLive attenuated mumps virus replicates in lymphoid tissues, activating both CD8+ T cells and germinal center B cells to produce IgG antibodies and long-lived plasma cellsCorrect answer
- CRecombinant mumps surface glycoproteins presented on dendritic cells induce only mucosal IgA responses in Peyer's patches
- DPassive transfer of maternal IgG antibodies provides lifelong protection against mumps virus infection
- ELive attenuated virus stimulates innate lymphoid cells to release interferon-gamma, which blocks viral replication in the parotid glands
- FInactivated mumps antigen complexed with aluminum adjuvant triggers antibody-dependent cellular cytotoxicity through NK cell activation
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