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M Ziemer

Publications and source records attributed to M Ziemer.

6 recordsLinked to original sources
PubMed1985

Sequence of hepatitis B virus DNA incorporated into the genome of a human hepatoma cell line.

Seven copies of integrated hepatitis B virus (HBV) DNA and contiguous genomic DNA from a human hepatoma cell line (PLC/PRF/5) have been isolated by molecular cloning and have been partially sequenced. The HBV sequences are fragmented and rearranged. Thus, the surface antigen gene is the only intact HBV transcription unit present in these integrated sequences. The sites of integration-recombination are dispersed over the entire viral genome; there is some preference for integration within the double-stranded portion of the genome. There are no repeats at the ends of the integrated HBV DNA fragments. Thus, recombination does not take place in a manner resembling the integration of retroviruses. The sequence data suggest that each HBV fragment is of the adw subtype. However, the integrated DNAs show an unexpected degree of sequence divergence. Direct evidence for the duplication, transposition, and subsequent divergence of two sequences is presented. The data surprisingly suggest that infection-integration of four distinct adw strains occurred.

Base Sequence↗
PubMed1984

Cloning and analysis of integrated hepatitis virus sequences from a human hepatoma cell line.

We report here the isolation by molecular cloning and the analysis by heteroduplex and restriction enzyme mapping of seven distinct DNA fragments containing hepatitis B virus (HBV) sequences from genomic DNA of the PLC/PRF/5 human liver carcinoma cell line (the Alexander cell). No intact full-length HBV genomes were present. Three different patterns of organization of HBV fragments were detected. These included two linear fragments without detectable rearrangement, three other HBV fragments with internal deletions, and two HBV fragments containing long inverted duplications. HBsAg sequences are preferentially included in the integrated fragment, whereas the core gene is preferentially eliminated. Several of the integrated HBV fragments might act as templates for the synthesis of functional HBsAg mRNA, whereas only one clone could produce a full core antigen transcript.

Base Sequence↗