Currently there is no human
vaccine against
Lyme borreliosis, and most research focuses on
recombinant protein vaccines, as such a
vaccine has been proven to be successful in the past. The expression of recombinant
antigens in meningococcal Outer Membrane Vesicles (OMVs), with the OMV functioning both as adjuvant and delivery vehicle, greatly enhances their potential. Immunization studies in mice have shown that OMV-based
vaccines can protect against various pathogens and an OMV-based
meningococcal vaccine is approved and available for human use. Because of its surface localization in Borrelia and the detailed knowledge regarding its immunogenicity and structure, OspA was chosen as a suitable
lipoprotein to be tested as an OMV-based
vaccine against
Lyme borreliosis. We have previously shown that the OMV-
OspA vaccine was immunogenic in mice and here we assessed the efficacy of OMV-OspA. We generated a second-generation OMV-
OspA vaccine and vaccinated C3H/HeN mice with (
EDTA extracted) meningococcal OMVs expressing OspA from B. burgdorferi strain B31. The adjuvant effect of empty OMVs on recombinant OspA was tested as well. We subsequently challenged mice with a
subcutaneous injection of B. burgdorferi. Average antibody end-point titers against the OspA-OMV construct were high, although lower compared to the
antibodies raised against recombinant OspA. Interestingly, antibody titers between recombinant OspA adjuvanted with
aluminum hydroxide and recombinant OspA with OMV as adjuvant were comparable. Finally, qPCR and culture data show that both the OspA-OMV and the
vaccine based on recombinant OspA with OMV as adjuvant provided significant, yet partial protection, against
Borrelia infection. OMV-based
vaccines using Borrelia (lipo)
proteins are an easy and feasible vaccination method protecting against B. burgdorferi
infection and could be a promising strategy in humans.