High incidence of BK virus large-T-antigen-coding sequences in normal human tissues and tumors of different histotypes

T-antigen (TAg) coding sequences specific for BK virus (BKV) were detected, by PCR amplification followed by Southern-blot hybridization, in a high percentage of human tumors and tumor-cell lines, as well as in normal tissues, by analysis of 189 specimens. Specifically, the BKV early region was detected in 85\% of brain tumors and in all normal brain tissues, in 78\% of osteosarcomas, in 38\% of Ewing's tumors, in 40\% of normal bone specimens and in 71\% of normal peripheral blood cell samples. Wilms' tumor tissues used as a control were all negative for BKV sequences. RT-PCR analysis indicated that TAg coding sequences were expressed in specimens carrying BKV early region, ranging from 64\% of the osteosarcomas to 100\% of glioblastomas, Ewing's tumors, peripheral blood cells and normal bone. Moreover, DNA sequencing performed in 12 different positive samples revealed that the amplified PCR products are identical to the early-region sequence of wild-type BKV. The role of BKV TAg and its possible mechanism of action in human tumorigenesis are discussed.