Cloning of SV40 genomes from human brain tumors

From two human brain tumors SV40 genomes were isolated by recombinant DNA techniques. The SV40 genome cloned from a human meningioma DNA was shown to be indistinguishable from wild-type SV40. In contrast, the SV40 genome cloned from a human astrocytoma proved to be a nonviable deletion mutant with a truncated early region removing most of the large T-coding region. In addition, this mutant also carries a tandem duplication of an intact origin of replication.