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DNA of Borrelia burgdorferi was cleaved by the endonuclease EcoRI and ligated with the bacteriophage expression vector lambda gt11. After infection of the Escherichia coli strain Y1089, the plaques of recombinant phages were screened with a B. burgdorferi antiserum (human) for fusion proteins containing borrelia antigen.s A positive clone produced a hybrid protein (p200) of c. 200 Kda. The corresponding native borrelia protein (p97) was identified as having an Mr of 97 Kda. To localise protein p97 in the B. burgdorferi cell, immunoelectronmicroscopy and a Western blot of isolated flagella were used. Antibodies directed against proteins p200 and p97 recognised epitopes associated with the flagella.

We recently characterized the three-dimensional shape of Treponema phagedenis periplasmic flagella (PFs). In the course of these studies, we observed protrusions on swimming cells that resembled PFs. Here we present a detailed characterization of the shape, structure, and motion of these protrusions. Although protrusion formation occurred primarily in wild-type cells during the stationary phase, a large fraction of exponential-phase cells of cell cylinder helicity mutants (greater than 90% of mutant T-52) had protrusions. These results suggest that cells bearing protrusions can still participate in cell division. T. phagedenis protrusions had the identical helix handedness, pitch, and diameter to those of purified PFs. Protrusions were not present on mutants unable to synthesize PFs, but were present in all motile revertants which regained PFs. These results, taken together with electron microscope observations, suggest that protrusions consist of PFs surrounded by an outer membrane sheath. To analyze protrusion movements, we held cells against a coverglass surface with optical tweezers and observed the motion of protrusions by video-enhanced differential interference contrast light microscopy. Protrusions were found to gyrate in both clockwise and counterclockwise directions, and direct evidence was obtained that protrusions rotate. Protrusions were also observed on Treponema denticola and Borrelia burgdorferi. These were also left-handed and had the same helix handedness, pitch, and diameter as purified PFs from their respective species. The PFs from T. denticola had a helix diameter of 0.26 microns and a helix pitch of 0.78 micron; PFs from B. burgdorferi had a helix diameter of 0.28 micron and a helix pitch of 1.48 microns. Protrusions from these spirochete species had similar structures and motion to those of T. phagedenis. Our results present direct evidence that PFs rotate and support previously proposed models of spirochete motility.

A nonmotile mutant of Borrelia burgdorferi, the etiologic agent of Lyme disease, was isolated and characterized. The mutant was compared with the wild-type predecessor as well as with a motile back-revertant of the same genetic background. The mutant lacked, by morphologic, biochemical, and immunologic criteria, the major structural protein of flagella, flagellin. This mutation was not associated with major DNA rearrangements or with failure of transcription. An apparent consequence of a loss of flagella was reduced ability to penetrate human endothelial cell layers in vitro. In another assessment of functional significance, the flagella-less mutant was equal if not superior to flagella-bearing, isogenic isolates when examined in an enzyme-linked immunosorbent assay for anti-B. burgdorferi antibodies in the sera of Lyme disease patients. These studies of a mutant, the first among pathogenic Borrelia spp. to be characterized, indicate that the flagellum and motility it confers play a role in B. burgdorferi's invasion of human tissues. A flagella-less B. burgdorferi may be useful as the basis of a more specific immunoassay and a vaccine for protection against Lyme disease.

The flagellum associated polypeptide p41 is an immunodominant antigen of Borrelia burgdorferi in the early and late stages of Lyme borreliosis. p41 was prepared by affinity chromatography using monoclonal antibody specific for p41. An immunoglobulin class specific ELISA (IgM-, IgG-ELISA) was established with purified p41 as antigen and compared to the conventional ELISA with whole cell ultrasonic antigen. Whereas the sensitivity of IgM- and IgG-ELISA was comparable in both antigen preparations, crossreactivity of sera from syphilitic patients was reduced in the p41 IgG-ELISA. Discrepant results obtained by use of ultrasonic antigen or p41 antigen, were controlled by Western blots. A correlation between the results of p41-ELISA and Western blot was shown.