Mosaic hepatitis B virus core particles presenting the complete preS sequence of the viral envelope on their surface

Abstract

The sequence of the preS domain of the hepatitis B virus (HBV, genotype D) envelope was inserted into the major immunodominant region (MIR) of the C-terminally truncated HBV core (HBc) protein. In Escherichia coli, the HBc-preS fusion protein was partially soluble and did not produce particles. Co-expression of the wild-type HBc as a helper protein along with the fusion protein led to the formation of mosaic HBc particles that exhibited HBc, preS1 and preS2 antigenicity. Two alternative combinations of medium-and high-copy plasmids were used for co-expression of fusion and helper proteins, in an attempt to improve mosaic particle production. However, the preS fusion content of the particles remained the same in both expression combinations. In a third co-expression in which the modified HBc helper lacked aa 76-85 in the MIR, the incorporation level of HBc-preS fusion into the particles was noticeably lower. Purified chimeric particles were immunogenic in mice.

Construction and Immunological Evaluation of Multivalent Hepatitis B Virus (HBV) Core Virus-Like Particles Carrying HBV and HCV Epitopes

“…Moreover, practically full-length pre-S1, with deletion of the inner hydrophobic membrane-targeting fragment, was exposed on the surfaces of the HBc and HBc⌬ VLPs (35). In addition, numerous variants of mosaic HBc particles carrying the complete pre-S sequence at the MIR have been constructed with and without MIR deletions (16). In regard to the immunogenicity of the pre-S1 epitope in our present study, the surprising thing is that the bivalent chimera HBc⌬-pre-S1-HCV core induces stronger anti-pre-S1 antibody response than the monovalent HBc⌬-pre-S1.…”

Engineering of virus-like particles for alternative vaccine candidate targeting a hypervariable peptide antigen element

“…Modularisation of an antigen module bearing a hydrophobic stretch in a viral capsid protein has been considered to be challenging as it promotes incorrect folding of the capsid protein (Kazaks et al 2004), and consequently increases the tendency of the capsid proteins to aggregate (Aleksaitė andGedvilaitė 2006, Shin andFolk 2003). By doing so, the hydrophobic antigen module prevents the proper self-assembly of the modular capsid protein into VLPs.…”

“…A hydrophobic stretch has been known to cause formation of insoluble aggregates, as well as incorrect folding of proteins. Although the negative effects of a hydrophobic stretch 8 have been widely recognised (Aleksaitė and Gedvilaitė 2006, Chiti et al 2003, Esler et al 1996, Karpenko et al 2000, Kazaks et al 2004, Otzen et al 2000, approaches to minimise its effects on VLP assembly still rely on simultaneous expression of modular and unmodularised viral capsid proteins, which yields mosaic VLPs (Karpenko et al 2000, Loktev et al 1996.Various approaches have been commonly utilised to improve the solubility of proteins. These approaches can be classified into two classes, i.e.…”

“…Although the influences of hydrophobic antigen modules are known, approaches to minimise these impacts are still limited to the use of mosaic VLPs (Karpenko et al 2000, Kazaks et al 2004. Mosaic VLPs are VLPs composed of a modular capsid protein and sterically less challenging capsid protein, e.g.…”

“…They can be obtained in vivo in E. coli by performing the co-expression of wild-type and modular capsid protein at a determined ratio using two compatible plasmids (Beterams et al 2000) or limited translational read-through (Kazaks et al 2004, Koletzki et al 1997). …”