COMPARISON OF 3 DIFFERENT RECOMBINANT HEPATITIS-B VIRUS CORE PARTICLES EXPRESSED IN ESCHERICHIA-COLI

The properties of three different recombinant hepatitis B virus core p roteins expressed in Escherichia coli were compared: an N-terminal fus ion protein, a C-terminally truncated protein and a sequence-authentic protein. All three proteins assembled into capsid-like particles with typical HBc-antigenicity, sedimentation behavior and distinctive elec tron microscopical images. Apart from this, however, variant HBc prote ins displayed properties different from sequence-authentic HBc protein p21.4. Unlike p21.4, the particles of the N-terminal fusion protein p 22.2 were sensitive to proteolytic attack by trypsin at variable sites within its arginine-rich C-terminus but not in its extended N-terminu s. We therefore conclude that the C-terminal region is located on the surface of the p22.2 particle. These particles also showed increased H Be-antigenicity, as did the C-terminally truncated core particles p17. 6, and to an even greater extent p18 particles which were derived fro m p22.2 by tryptic digestion. This might be interpreted as evidence fo r an - albeit minor - structural change. All variant core particles we re less stable and contained less RNA. Electron microscopic indication for DNA binding of C-terminal deleted p17.6 particles was obtained us ing an aqueous spreading technique.