Structural features of HBc CLPs.

<p><b>(A) The spikes on HBc CLPs comprise the immunodominant c/e1 epitope.</b> The picture shows a section from a cryo EM derived 3D reconstruction of a 120 dimer (triangulation number T = 4) HBc CLP (B. Böttcher and MN, unpublished data). <b>(B) X-ray derived structure of a HBc149 dimer.</b> The structure is based on pdb accession number 1QGT. Two core protein subunits associate into a symmetric dimer. One subunit is shown in grey, in the other the ascending central helix a3, the descending helix a4 and the connecting loop comprising the c/e1 epitope are colored white, blue and red. (<b>C) Correlation between the 3D structure of a HBc monomer and schematic representations of contiguous chain HBc versus SplitCore HBc. (D) HBc as carrier for heterologous proteins.</b> A foreign protein X with compatible 3D structure may be fused into c/e1 via both termini. A foreign protein Y with far apart termini may interfere with folding and CLP formation when fused over both ends but be compatible when fused over one end only in the SplitCore system. Fusions can be made to the coreN or the coreC segment, or both.