Over the past decade, numerous Borrelia burgdorferi proteins have been cloned and sequenced, while clinical and animal studies have delineated the basic microbiological events of Lyme disease. In contrast, we have a comparatively poor understanding of B. burgdorferi membrane biology and how general features of borrelial membrane architecture facilitate immune evasion during infection. Based upon extensive data obtained during the current funding period, the investigators have developed a new model of B. burgdorferi molecular architecture which helps to explain the bacterium's remarkable """"""""immunoevasiveness"""""""". According to this model (1) the B. burgdorferi outer membrane contains uncharacterized poorly immunogenic membrane proteins in addition to well characterized outer surface lipoproteins, (2) the preponderance of outer surface proteins (Osps) A and B is sequestered within the periplasmic space (and therefore unavailable as targets for borreliacidal antibody), and (3) novel membrane proteins may be expressed during infection. Their first two Specific Aims describe two complimentary approaches for the molecular characterization of novel borrelial outer membrane proteins. The first is based upon a recently developed procedure for isolating B. burgdorferi outer membranes, while the second identifies candidate outer membrane proteins whose export signals are fused with an E. coli alkaline phosphatase (PhoA) reporter. Studies in Specific Aim 1 will be expedited by the fact that three conserved B. burgdorferi outer membrane proteins already have been identified in isolated outer membranes.
Specific Aim 2 also includes detailed studies of three novel candidate outer membrane proteins, including an OspF homologue (designated BbK2.10) which is expressed only in vivo and which appears to be a member of a lipoprotein family. Experiments in our third Specific Aim will explore key ramifications of our findings that only small amounts of OspA and OspB are surface-exposed. Taken as a whole, these Specific Aims encompass our long term goal which is to integrate studies of B. burgdorferi membrane biology, Lyme disease pathogenesis, and vaccine development.
Showing the most recent 10 out of 98 publications
