Evaluation of immunogenicity and efficacy of Borrelia burgdorferi derived peptide (PepB) antigen formulated in a protein scaffold in mice against Lyme disease

Abstract

Lyme disease (LD) is the most prevalent tick-borne disease in both Europe and North America. The development of effective Lyme disease vaccines is complicated by the complex biology of Borrelia species and alterations in the expression of outer surface membranes. In this work, PepB, which is Borrelia burgdorferiBB0172-derived peptide was evaluated in scaffolded formulation as a vaccine candidate in murine model of LD. In brief, four groups of 6-8 weeks old C3H/HeN breed of mice (n=6 per group) were immunized subcutaneously with BBA34: PepB (BP), outer surface protein C (OspC), BBA34 and a naïve control group. In 8 weeks, post-priming blood samples were collected, and specific IgG titers were evaluated by ELISA. After that, A dose of 105 B. burgdorferi/mouse was administered subcutaneously to all animals as a challenge. The mice were euthanized at 4 weeks post-challenge and then blood and tissue samples were collected to evaluate bacterial burden by real time qPCR, and bacterial recovery from tissues. Taken together, and considering both bacterial burden and bacterial recovery, immunization with BP was not able to confer protection against borreliosis in this experiment, and consequently it was not considered as a potential vaccine formulation in subsequent studies. It was concluded, that other alternative antigen platforms and delivery methods might be considered to improve the immunogenicity of the PepB-based vaccine candidate.