A fusion product of the complete Borrelia burgdorferi outer surface protein A (OspA) and the hepatitis B virus capsid protein is highly immunogenic and induces protective immunity similar to that seen with an effective lipidated OspA vaccine formula

Abstract

The immunogenicity of peptides and protein fragments can be considerably enhanced by their presentation on particulate carriers such as capsid‐like particles (CLP) from hepatitis B virus (HBV). Here we tested the suitability of the HBV capsid protein as a carrier for a relevant full‐length pathogen‐derived protein antigen. The entire 255‐amino acid ectodomain of the outer surface protein A (OspA) from Borrelia burgdorferi, the causative agent of Lyme disease, was inserted into the major B cell epitope of the HBV capsid, yielding a multimerization‐competent fusion protein, termed coreOspA. CoreOspA, consisting only in part of regular CLP, induced antibodies to OspA, including the Ig isotype profile and specificity for the protective epitope LA‐2, with an efficiency similar to that of recombinant lipidated OspA, the first generation vaccine against Lyme disease. Moreover, coreOspA actively and passively protected mice against subsequent challenge with B. burgdorferi. The data demonstrate the capacity of the HBV capsid protein to act as a potent immunomodulator even for full‐length and structurally complex polypeptide chains and thus opens new avenues for novel vaccine designs.

Norovirus P Particle, a Novel Platform for Vaccine Development and Antibody Production

“…Through genetic engineering, the self-assembled viral particles have been used as vaccine platforms for antigen presentation. Successful examples have been reported for several viruses, including a Flock House virus (FHV) virus-like particle (VLP) containing an antigen of Bacillus anthracis (20), hepatitis B virus (HBV) capsid-like particle (CLP) containing a surface antigen (OspA) of Borrelia burgdorferi (13,22,23), and the cowpea mosaic virus (CPMV) presenting a number of different antigens (4,5,10,16,17,25,26,38), although limitations in these presentation systems have also been described.In our previous study of human noroviruses, we discovered a unique subviral particle, the P particle, which can be used for antigen presentation. Noroviruses cause epidemics of acute gastroenteritis in humans.…”

A Structural Model for Duck Hepatitis B Virus Core Protein Derived by Extensive Mutagenesis

“…The interdimer contacts are mainly provided by the "hand region" (6) consisting of ␣5 (residues 112 to 127) onto which downstream residues to about position 140 fold back. Although the individual interdimer contacts are weak (58), the intact particles are so stable that even complete foreign proteins can be inserted into the c/e1 epitope (28,35,44); this is achieved by an inherent flexibility within the subunits, as well as in their arrangement on the icosahedral lattice (5,7). Such structural plasticity may be crucial for the active role of the capsid in reverse transcription, although only subtle differences between HBV CLPs and genome-containing nucleocapsids were detected in a recent cryo-electron microscopic (cryo-EM) study (40).…”

Internal Core Protein Cleavage Leaves the Hepatitis B Virus Capsid Intact and Enhances Its Capacity for Surface Display of Heterologous Whole Chain Proteins

“…However, analogous insertion of OspA, another important B. burgdorferi antigen (31,32), caused insolubility and pre-vented CLP formation, unless the insert was flanked by very long connecting linkers (10 and 22 aa on the N and C proximal side, respectively); even then the major products were nonregular multimers (33). Though they still induced potent, protective anti-OspA antibodies, the extra linker sequences may have an antigenic potential on their own and thus not be desirable for vaccine applications (33).…”

“…Though they still induced potent, protective anti-OspA antibodies, the extra linker sequences may have an antigenic potential on their own and thus not be desirable for vaccine applications (33).…”

“…As shown below, this was indeed the case. Moreover, the approach was also applicable to core protein fusions carrying a 65-residue heterologous peptide and, most importantly, the entire 256-aa OspA ectodomain, with strongly enhanced CLP formation compared with the contiguous chain coreOspA fusion (33). Hence single-sided protease cleavage of an insertion is a promising novel means of broadening the applicability of HBcAg CLPs, and by inference also other carrier systems, to the display of whole proteins regardless of their three-dimensional structure.…”