The HBV-producing cell line HepG2-4A5: a new in vitro system for studying the regulation of HBV replication and for screening anti-hepatitis B virus drugs.

All tissue culture systems for propagating HBV employed so far make use of tandemly arranged HBV genomes usually under the control of strong foreign promoters. Thus these systems are helpful for virus production but are of limited value in the investigation of the regulation of HBV replication or of the extent to which the expression of viral genes might be influenced by cellular signal transduction pathways. To overcome this barrier we established an HBV-producing cell line (HepG2-4A5) by stably transfecting HepG2 cells with a replication-competent, terminally redundant HBV plasmid (pSPT1.

Two-dimensional crystallization of a bacterial surface protein on lipid vesicles under controlled conditions.

The solubilized surface protein of the Gram-negative bacterium Comamonas acidovorans was reconstituted on lipid vesicles by means of controlled dialysis. To this end, a multichamber dialysis apparatus was built which allows one to control the temperature and the dialysis rate, to apply various temperatures or buffer systems and sample conditions in a single experiment, and to monitor the turbidity of the sample by means of light scattering. The reconstitution conditions were optimized such that the surface protein formed two-dimensional crystals suitable for electron crystallography.