Lack of JC viral genomic sequences in multiple sclerosis brain tissue by polymerase chain reaction.

With DNA extracted from brain specimens from 19 multiple sclerosis, 5 progressive multifocal leukoencephalopathy, 1 Alzheimer's disease, and 8 nonneurological control subjects, polymerase chain reaction was performed using nested sets of primer pairs amplifying segments of the large T and VPI antigen-encoding sequences of JC virus. Both sequences were detected in each of the 5 brain specimens of progressive multifocal leukoencephalopathy but in none of the 19 multiple sclerosis, 1 Alzheimer's disease, or the 8 control brain specimens.