Borrelia burgdorferi, a tick-borne bacterial pathogen, causes a disseminated
infection involving multiple organs known as
Lyme disease.
Surface proteins can directly participate in microbial virulence by facilitating pathogen dissemination via interaction with host factors. We show here that a fraction of the B. burgdorferi chromosomal gene product BB0337, annotated as
enolase or phosphopyruvate
dehydratase, is associated with spirochete outer membrane and is surface exposed. B. burgdorferi
enolase, either in a recombinant form or as a membrane-bound native
antigen, displays enzymatic activities intrinsic to the glycolytic pathway. However, the
protein also interacts with host
plasminogen, potentially leading to its activation and resulting in B. burgdorferi-induced fibrinolysis. As expected,
enolase displayed consistent expression in vivo, however, with a variable temporal and spatial expression during
spirochete infection in mice and ticks. Despite an extracellular exposure of the
antigen and a potential role in host-pathogen interaction, active immunization of mice with recombinant
enolase failed to evoke protective immunity against subsequent B. burgdorferi
infection. In contrast,
enolase immunization of murine hosts significantly reduced the acquisition of spirochetes by feeding ticks, suggesting that the
protein could have a stage-specific role in B. burgdorferi survival in the feeding vector. Strategies to interfere with the function of surface
enolase could contribute to the development of novel preventive measures to interrupt the
spirochete infection cycle and reduce the incidences of
Lyme disease.