Hepatitis B virus capsid-like particles can display the complete, dimeric outer surface protein C and stimulate production of protective antibody responses against Borrelia burgdorferi infection.
Hepatitis B virus capsid-like particles (CLPs), icosahedral assemblies formed by 90 or 120 core protein dimers, hold promise as immune-enhancing vaccine carriers for heterologous antigens. Insertions into the immunodominant c/e1 B cell epitope, a surface-exposed loop, are especially immunogenic. However, display of whole proteins, desirable to induce multispecific and possibly neutralizing antibody responses, can be restrained by an unsuitable structure of the foreign protein and by its propensity to undergo homomeric interactions. Here we analyzed CLP formation by core fusions with two distinct variants of the dimeric outer surface lipoprotein C (OspC) of the Lyme disease agent Borrelia burgdorferi. Although the topology of the termini in the OspC dimer does not match that of the insertion sites in the carrier dimer, both fusions, coreOspCa and coreOspCb, efficiently formed stable CLPs. Electron cryomicroscopy clearly revealed the surface disposition of the OspC domains, possibly with OspC dimerization occurring across different core protein dimers. In mice, both CLP preparations induced high-titered antibody responses against the homologous OspC variant, but with substantial cross-reactivity against the other variant. Importantly, both conferred protection to mice challenged with B. burgdorferi. These data show the principal applicability of hepatitis B virus CLPs for the display of dimeric proteins, demonstrate the presence in OspC of hitherto uncharacterized epitopes, and suggest that OspC, despite its genetic variability, may be a valid vaccine candidate.
Skamel
Claudia
C
University Hospital Freiburg, Internal Medicine II/Molecular Biology, D-79106 Freiburg, Germany.
Ploss
Martin
M
European Molecular Biology Laboratory, D-69117 Heidelberg, Germany.
Böttcher
Bettina
B
European Molecular Biology Laboratory, D-69117 Heidelberg, Germany.
Stehle
Thomas
T
Max Planck Institute of Immunobiology, D-79108 Freiburg, Germany.
Wallich
Reinhard
R
University Hospital Heidelberg, Institute of Immunology, D-61920 Heidelberg, Germany.
Simon
Markus M
MM
Max Planck Institute of Immunobiology, D-79108 Freiburg, Germany.
Nassal
Michael
M
University Hospital Freiburg, Internal Medicine II/Molecular Biology, D-79106 Freiburg, Germany. Electronic address: nassal2@ukl.uni-freiburg.de.
D000818:Animals; D000942:Antigens, Bacterial / Q000737:chemistry*; D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry*; D001428:Bacterial Vaccines / Q000737:chemistry; D025065:Borrelia burgdorferi / Q000472:pathogenicity*; D019281:Dimerization; D018985:Epitopes, B-Lymphocyte / Q000737:chemistry; D014644:Genetic Variation; D051379:Mice; D008807:Mice, Inbred BALB C; D016513:Mice, SCID; D008958:Models, Molecular; D019590:Nucleocapsid Proteins / Q000737:chemistry*; D010957:Plasmids / Q000378:metabolism; D011487:Protein Conformation; D017434:Protein Structure, Tertiary
D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins; D001428:Bacterial Vaccines; D018985:Epitopes, B-Lymphocyte; D019590:Nucleocapsid Proteins; C079616:OspC protein; C099600:nucleocapsid protein, Hepatitis virus