Virology USMLE Step 1 Practice Question

A 35-year-old man with a CD4+ count of 45 cells/μL presents to the emergency department with a 10-day history of profuse watery diarrhea (8-10 stools daily), severe crampy abdominal pain, and a 5-kg weight loss. He denies bloody stools, recent antibiotic use, or travel outside the United States. Vital signs include temperature 37.9°C, heart rate 105/min, blood pressure 115/72 mmHg, and respiratory rate 18/min. Physical examination reveals mild dehydration. Stool culture is negative for bacterial pathogens. Electron microscopy of stool demonstrates characteristic wheel-shaped viral particles with double-stranded RNA. Which of the following viruses is most likely responsible for this patient's gastroenteritis?