BK virus and JC virus shed during pregnancy have predominantly archetypal regulatory regions.

Twenty-three BK virus and JC virus DNA samples obtained from urine of pregnant women had almost exclusively archetypal transcriptional control regions. Rearrangements characteristic of laboratory strains are apparently not required for reactivation in humans. Unexpectedly, alignment shows that many elements identified previously in the BK virus enhancer are conserved in the JC virus archetype.