Design and development of a novel vaccine for protection against Lyme borreliosis.

Pär Comstedt,Urban Lundberg,Wolfgang Schüler,Markus Hanner,Andreas Meinke,Catherine A Brissette

doi:10.1371/journal.pone.0113294

Abstract

There is currently no Lyme borreliosis vaccine available for humans, although it has been shown that the disease can be prevented by immunization with an OspA-based vaccine (LYMErix). Outer surface protein A (OspA) is one of the dominant antigens expressed by the spirochetes when present in a tick. The Borrelia species causing Lyme borreliosis in Europe express different OspA serotypes on their surface, B. burgdorferi (serotype 1), B. afzelii (serotype 2), B. garinii (serotypes, 3, 5 and 6) and B. bavariensis (serotype 4), while only B. burgdorferi is present in the US. In order to target all these pathogenic Borrelia species, we have designed a multivalent OspA-based vaccine. The vaccine includes three proteins, each containing the C-terminal half of two OspA serotypes linked to form a heterodimer. In order to stabilize the C-terminal fragment and thus preserve important structural epitopes at physiological temperature, disulfide bonds were introduced. The immunogenicity was increased by introduction of a lipidation signal which ensures the addition of an N-terminal lipid moiety. Three immunizations with 3.0 µg adjuvanted vaccine protected mice from a challenge with spirochetes expressing either OspA serotype 1, 2 or 5. Mice were protected against both challenge with infected ticks and in vitro grown spirochetes. Immunological analyses (ELISA, surface binding and growth inhibition) indicated that the vaccine can provide protection against the majority of Borrelia species pathogenic for humans. This article presents the approach which allows for the generation of a hexavalent vaccine that can potentially protect against a broad range of globally distributed Borrelia species causing Lyme borreliosis.

Highlights

Lyme borreliosis (LB) is an emerging disease and the most common vector-borne infection in the Northern hemisphere
Fifty sites geometrically suitable for the formation of disulfide bonds based on their distance and orientation, as determined from three crystal structures [7,34,35], were identified in the C-terminal part of Outer surface protein A (OspA) from B. burgdorferi
When mice were immunized with fulllength OspA from B. burgdorferi and subsequently challenged with feral ticks from an LB endemic area in Europe, both B. afzelii and B. garinii strains could be isolated from the challenged mice [45]

Summary

Introduction

Lyme borreliosis (LB) is an emerging disease and the most common vector-borne infection in the Northern hemisphere. The Center for Disease Control and Prevention (CDC) recently presented an updated estimate of 300,000 cases annually in the US [1]. This is almost a 10-fold increase to earlier estimations and would indicate that the disease is much more prevalent than previously thought. Outer surface protein A (OspA) has been the basis for at least two different vaccines targeting LB; LYMErix (SmithKline Beecham) and ImuLyme (PasteurMerieux-Connaught). Both vaccines contained only OspA from B. burgdorferi as antigen, but only LYMErix was licensed and available for customers from 1998–2002, when it was voluntarily withdrawn from the market. OspA is a surface exposed lipoprotein of ,28.5 kD [5], which is attached to the outer membrane by its N-terminal lipid moiety [6]

Methods

Results

Conclusion