JC virus is a ubiquitous polyomavirus that causes progressive multifocal leukoencephalopathy (PML). PML is associated with severely immunocompromised states. Most cases are seen in patients with AIDS. The disease can have a very rapid course, progressing over days or weeks. A CD4 count less than 100 is an especially poor prognostic sign in these patients. Characteristic histologic findings include giant astrocytes, and oligodendrocytes with enlarged nuclei and nuclear inclusions. Radiographic findings include numerous white matter lesions of varying sizes in the cerebral and cerebellar hemispheres. Answer (A)
2. ureter -water under the bridge.