Nucleotide sequences in human chromosomal DNA from nonhepatic tissues homologous to the hepatitis B virus genome.

DNA extracted from human nonhepatic tissues (placenta and kidney) have been digested with restriction endonucleases and examined by the Southern procedure with cloned 32P-labelled DNA of hepatitis B virus (HBV). In placental DNAs of women with the history of a hepatitis B infection and in one out of four cases of patients with no known HBV exposure or manifestation, HBV-related chromosomal nucleotide sequences were detected. The integration of HBV-related sequences was observed also in human kidney DNA. Moreover, in the placenta of women who had hepatitis B infection prior to delivery, unusual unintegrated forms of HBV have been found. We conclude that HBV sequences can be found not only in hepatic tissue but also in placental and kidney DNA, both of HBV-exposed and in one case even of a nonexposed patient.