Fibromatosis is primarily caused by which virus?

The primary cause of fibromatosis is the Shope fibroma virus. This virus specifically infects rabbits and is known for causing fibromas, which are benign tumors that can develop on the skin and other tissues. The Shope fibroma virus is a poxvirus, and its role in the development of fibromatosis has been well-documented in veterinary pathology.

While calicivirus, myxomavirus, and rotavirus are all important in the context of rabbit diseases, they are associated with different conditions. Calicivirus is responsible for diseases like rabbit hemorrhagic disease, while myxomavirus causes myxomatosis, which leads to severe swelling and skin lesions. Rotavirus primarily affects the gastrointestinal tract in various species, including rabbits, but is not linked to the development of fibromas. Thus, the Shope fibroma virus is the definitive cause of fibromatosis in rabbits, making it the correct choice for this question.