Induction of undifferentiated brain tumors in rats by a human polyomavirus (JC virus).

Newborn SD rats were inoculated intracranially with JC virus (Tokyo-1), a human polyomavirus, isolated from the autopsied brain of a patient with progressive multifocal leukoencephalopathy. Twenty-one to 61 weeks later, 20 of 27 rats developed tumors in the cerebrum, but not in the cerebellum. The undifferentiated neuroectodermal nature of the tumors was histologically, immunohistochemically and ultrastructurally confirmed.