Comparative antigenic analysis of Treponema pallidum laboratory and street strains

The polypeptide and antigenic profiles of Treponema pallidum Nichols strain and two other more recently isolated 'street' strains of T. pallidum have been compared. PAGE and immunoblotting identified a 34.5 kDa polypeptide present in the Nichols strain which was absent from one of the other street strains. This polypeptide was shown to be associated with the axial filament in T. pallidum. Three other axial-filament-associated polypeptides of 37, 33 and 30 kDa were present in all strains examined. Axial filaments of all three strains were morphologically identical and all three strains were equally motile.     

Production of murine monoclonal antibodies to the major axial filament polypeptide of Treponema pallidum

A suitable immunization protocol for the stimulation of a murine antibody response to the axial filament polypeptides of Treponema pallidum was established. A range of monoclonal antibodies (Mabs) specific for different epitopes of the major axial filament polypeptide (37 kDa) was generated which demonstrated diversity in their ability to react with other treponemal species. Immunogold electron microscopy located the 37 kDa antigen on the surface of the axial filament structure. The early appearance of specific antibody to this polypeptide in infected man and rabbit indicates that such Mabs are potentially useful for the diagnosis of early syphilis.     

Molecular and immunochemical analysis of Treponema pallidum

Abstract Molecular analysis of polypeptides and antigens of Treponema pallidum has been used increasingly during the past 5 years in investigation of the immunology, pathogenicity and molecular biology of this organism. Failure to culture the organism has severely limited our knowledge of its constituent polypeptides and antigens, but many profiles of these unknown constituents, revealed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting techniques have been published. In order to compare meaningfully the results obtained by different groups, we have identified a standard pattern of prominent 'landmark' polypeptides in such gel profiles and where possible have assigned functional identities to them. A preliminary nomenclature for the prominent polypeptides of T. pallidum is proposed. These are: P1, 80 kDa; P2, 60 kDa; P3, 47 kDa, an outer membrane-associated polypeptide; P4, 40 kDa; P5, 37 kDa, the major polypeptide of the axial filament; P6, 34 kDa; and P7, 31.5 kDa.     

Correlation of treponemicidal activity in normal human serum with the presence of IgG antibody directed against polypeptides of Treponema phagedenis biotype Reiter and Treponema pallidum, Nichols strain

Normal human serum (NHS) was shown to have complement-dependent treponemicidal activity against both Treponema pallidum and Treponema phagedenis biotype Reiter (TPR) by employing in vitro-in vivo neutralization and TPR plaque assays, respectively. The molecular basis of NHS treponemicidal activity was studied by immunoblot analysis in conjunction with treponemicidal assays. Five major T. pallidum polypeptide bands (47kDa, 35kDa, 33kDa doublet, and 30 kDa) and three major TPR polypeptide bands (47kDa and 33kDa doublet) bound IgG present in NHS. Absorption of NHS with TPR completely removed both TPR and T. pallidum treponemicidal activity; corresponding immunoblots demonstrated a significant removal of IgG antibody against all three TPR polypeptide bands as well as four T. pallidum polypeptide bands (30kDa, 33kDa doublet, and 35kDa). In contrast, T. pallidum absorption of NHS was found to remove treponemicidal activity against T. pallidum but not TPR; corresponding Western blots showed the complete removal of IgG antibody against all but one T. pallidum polypeptide band (47kDa) but no detectable loss in IgG antibody against the TPR polypeptides. These results suggest that antibody in NHS generated against nonpathogenic, indigenous treponemes is responsible for the T. pallidum treponemicidal activity. Furthermore, the treponemicidal activity against T. pallidum correlated with the presence of IgG antibody against T. pallidum polypeptides of 30kDa, 35kDa, and a 33kDa doublet.     

Cloning and sequence analysis of flaA, a gene encoding a Spirochaeta aurantia flagellar filament surface antigen.

Spirochaeta aurantia DNA that coded for an antigenic determinant of the flagellin associated with the filament surface of the periplasmic flagella was isolated. When expressed in Escherichia coli, the antigenic polypeptide had an apparent molecular weight of 37,000. Sequence analysis of the antigen-encoding DNA revealed the presence of an open reading frame that determined a polypeptide with a predicted molecular weight of 31,241. This polypeptide showed a region of identity with the N-amino-terminal region of the 39,000- and 37,000-dalton flagellins of the distantly related spirochetes Treponema phagedenis and Treponema pallidum, respectively (S. J. Norris, N. W. Charon, R. G. Cook, M. D. Fuentes, and R. J. Limberger, J. Bacteriol. 170:4072-4082, 1988). The region of identity in the deduced S. aurantia polypeptide was preceded by a possible signal sequence and signal peptidase cleavage site.     

The periplasmic flagella of Serpulina (Treponema) hyodysenteriae are composed of two sheath proteins and three core proteins.

The major components of the periplasmic flagella of the spirochaete Serpulina (Treponema) hyodysenteriae strain C5 were purified and characterized. We demonstrate that the periplasmic flagella are composed of five major proteins (molecular masses 44, 37, 35, 34 and 32 kDa) and present their location, N-terminal amino acid sequence and immunological relationship. The 44 kDa and the 35 kDa protein are on the sheath of the periplasmic flagellum, whereas the 37, 34 and 32 kDa protein reside in the periplasmic flagellar core. The two sheath flagellar proteins are immunologically related but have different N-terminal amino acid sequences. The N-terminus of the 44 kDa protein shows homology with the sheath flagellins of other spirochaetes, but the 35 kDa protein does not. The three core proteins are immunologically cross-reactive and their N-terminal amino acid sequences are almost, but not completely, identical, indicating that the core proteins are encoded by three distinct genes. The core proteins show extensive N-terminal sequence similarities and an immunological relationship with periplasmic flagellar core proteins of other spirochaetes.     

Antigenic complexity of Treponema pallidum: antigenicity and surface localization of major polypeptides

The protein structure of Treponema pallidum was characterized by two-dimensional electrophoresis (2DE), consisting of isoelectric focusing (IEF, pH 5 to 7) in the first dimension and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) in the second dimension. Up to 85 major polypeptide species could be detected in the organisms in 2DE gels by Coomassie Blue staining. The antigenicity of the individual polypeptides was determined by transferring the 2DE pattern to nitrocellulose paper and utilizing a sensitive immunoperoxidase procedure to demonstrate the reactivity of immunoglobulins in sera obtained from rabbits infected intratesticularly at least 6 mo previously. The infected rabbit serum reacted with virtually every major polypeptide detectable by protein staining techniques, indicating that infected rabbits produce antibodies against nearly all major T. pallidum proteins at the time when the animals exhibit systemic resistance to reinfection. Surface radioiodination of freshly purified T. pallidum by an Iodogen procedure yielded preferential labeling of a major polypeptide with an apparent m.w. of 39,000. The results of this study indicate that the antigenic complexity of T. pallidum is much greater than described previously. The 39-kd polypeptide appears to be a major surface constituent of T. pallidum and as such may play an important role in the induction of immunity to syphilis.     

Fine Structure of Spirochaeta stenostrepta, a Free-living, Anaerobic Spirochete

The fine structure of Spirochaeta stenostrepta strain Z1, a free-living anaerobic spirochete, was studied by electron microscopy. The organism possessed a coiled protoplasmic cylinder, an axial filament inserted subterminally, and a loosely fitting sheath which enclosed both the protoplasmic cylinder and the axial filament. The axial filament consisted of two fibrils partially overlapping in a 1-2-1 arrangement. The axial fibrils appeared to possess a sheath surrounding an inner core. Both inner core and sheath were apparently enclosed in a cross-striated tubular structure, which was itself surrounded by an outer sheath. The axial filament exhibited a basal hook. A disc- or mushroom-shaped structure, possibly consisting in part of cytoplasmic membrane, was observed at the insertion end of isolated filaments. The protoplasmic cylinder had a distinctive surface structure consisting of an array of tightly packed, longitudinally arranged helices measuring 2.0 to 2.5 nm in diameter. This layer of helices lay below the outer cell sheath and the axial filament. Ballistic disintegration loosened the helical array, causing individual helices or segments of helices to become separated from the cell. The function of this layer of helices is still obscure.     

The antigenic interrelationship between the endoflagella of Treponema phagedenis biotype Reiter and Treponema pallidum Nichols strain. I. Treponemicidal activity of cross-reactive endoflagellar antibodies against T. pallidum

Treponemicidal activity against Treponema pallidum, Nichols strain, by anti-endoflagellar antibodies and the presence of antigenic interrelationships between the endoflagella of Treponema phagedenis biotype Reiter (TPR) and T. pallidum have been demonstrated. SDS-PAGE profiles of purified endoflagella from both organisms were similar, identifying five polypeptide bands for TPR (37,000, 33,000 doublet, 30,000, and 27,000 daltons) and five polypeptide bands for T. pallidum (35,000, 33,000 doublet, 30,000, and 27,000 daltons). Antiserum against TPR endoflagella identified identical bands on Western blots of TPR, T. pallidum, and the respective endoflagellar preparations. Western blots confirmed the presence of antibodies in normal human serum (NHS) against the 33,000 dalton treponemal endoflagellar proteins. The complement-dependent treponemicidal activity of NHS against T. pallidum was completely removed by absorption with purified TPR endoflagella. Furthermore, rabbit antisera against TPR endoflagella were reactive in the Treponema pallidum immobilization (TPI) test. These findings demonstrate that anti-endoflagellar antibodies are treponemicidal against T. pallidum. A possible mechanism for this activity is discussed in relation to the subsurface location of endoflagella.     

Antigenic relatedness and N-terminal sequence homology define two classes of periplasmic flagellar proteins of Treponema pallidum subsp. pallidum and Treponema phagedenis

The periplasmic flagella of many spirochetes contain multiple proteins. In this study, two-dimensional electrophoresis, Western blotting (immunoblotting), immunoperoxidase staining, and N-terminal amino acid sequence analysis were used to characterize the individual periplasmic flagellar proteins of Treponema pallidum subsp. pallidum (Nichols strain) and T. phagedenis Kazan 5. Purified T. pallidum periplasmic flagella contained six proteins (Mrs = 37,000, 34,500, 33,000, 30,000, 29,000, and 27,000), whereas T. phagedenis periplasmic flagella contained a major 39,000-Mr protein and a group of two major and two minor 33,000- to 34,000-Mr polypeptide species; 37,000- and 30,000-Mr proteins were also present in some T. phagedenis preparations. Immunoblotting with monospecific antisera and monoclonal antibodies and N-terminal sequence analysis indicated that the major periplasmic flagellar proteins were divided into two distinct classes, designated class A and class B. Class A proteins consisted of the 37-kilodalton (kDa) protein of T. pallidum and the 39-kDa polypeptide of T. phagedenis; class B included the T. pallidum 34.5-, 33-, and 30-kDa proteins and the four 33- and 34-kDa polypeptide species of T. phagedenis. The proteins within each class were immunologically cross-reactive and possessed similar N-terminal sequences (67 to 95% homology); no cross-reactivity or sequence homology was evident between the two classes. Anti-class A or anti-class B antibodies did not react with the 29- or 27-kDa polypeptides of T. pallidum or the 37- and 30-kDa T. phagedenis proteins, indicating that these proteins are antigenically unrelated to the class A and class B proteins. The lack of complete N-terminal sequence homology among the major periplasmic flagellar proteins of each organism indicates that they are most likely encoded by separate structural genes. Furthermore, the N-terminal sequences of T. phagedenis and T. pallidum periplasmic flagellar proteins are highly conserved, despite the genetic dissimilarity of these two species.     

Selective release of the Treponema pallidum outer membrane and associated polypeptides with Triton X-114.

The effects of the nonionic detergent Triton X-114 on the ultrastructure of Treponema pallidum subsp. pallidum are presented in this study. Treatment of Percoll-purified motile T. pallidum with a 1% concentration of Triton X-114 resulted in cell surface blebbing followed by lysis of blebs and a decrease in diameter from 0.25-0.35 micron to 0.1-0.15 micron. Examination of thin sections of untreated Percoll-purified T. pallidum showed integrity of outer and cytoplasmic membranes. In contrast, thin sections of Triton X-114-treated treponemes showed integrity of the cytoplasmic membrane but loss of the outer membrane. The cytoplasmic cylinders generated by detergent treatment retained their periplasmic flagella, as judged by electron microscopy and immunoblotting. Recently identified T. pallidum penicillin-binding proteins also remained associated with the cytoplasmic cylinders. Proteins released by Triton X-114 at 4 degrees C were divided into aqueous and hydrophobic phases after incubation at 37 degrees C. The hydrophobic phase had major polypeptide constituents of 57, 47, 38, 33-35, 23, 16, and 14 kilodaltons (kDa) which were reactive with syphilitic serum. The 47-kDa polypeptide was reactive with a monoclonal antibody which has been previously shown to identify a surface-associated T. pallidum antigen. The aqueous phase contained the 190-kDa ordered ring molecule, 4D, which has been associated with the surface of the organisms. Full release of the 47- and 190-kDa molecules was dependent on the presence of a reducing agent. These results indicate that 1% Triton X-114 selectively solubilizes the T. pallidum outer membrane and associated proteins of likely outer membrane location.     

Immunity in experimental syphilis. IV. Serological reactivity of antigens extracted from gamm-irradiated Treponema pallidum and Treponema reiteri

Miller, James N. (University of California School of Medicine, Los Angeles), J. H. De Bruijn, and J. H. Bekker. Immunity in experimental syphilis. IV. Serological reactivity of antigens extracted from gamma-irradiated Treponema pallidum and Treponema reiteri. J. Bacteriol. 91:583-587. 1966.-Ultrasonic lysate preparations extracted from virulent Treponema pallidum, Nichols strain, suspensions exposed to 652,800 R of gamma-irradiation exhibited a loss in the serological reactivity of their heat-labile antigens; the heat-stable components of both the lysate and residue antigens were unaffected. The activity of heat-stable, cardiolipin T. pallidum complement-fixing antigen obtained from similarly irradiated organisms was also unaltered. gamma-Irradiation of the cultivable Treponema reiteri with dosages as high as 6,500,000 R failed to alter serologically either the heat-labile or heat-stable component of its lipopolysaccharide-protein (Reiter protein) antigen. The reactivity of the lipopolysaccharide portion of the Reiter protein complex with an antiserum to T. pallidum Nichols indicates previously unsuspected antigenic differences between the rabbit-adapted Nichols strain of the organism and so-called "wild" human strains of T. pallidum in which this antigen is generally absent.     

Isolation of the outer membranes from Treponema pallidum and Treponema vincentii.

The outer membranes from Treponema pallidum subsp. pallidum and Treponema vincentii were isolated by a novel method. Purified outer membranes from T. pallidum and T. vincentii following sucrose gradient centrifugation banded at 7 and 31% (wt/wt) sucrose, respectively. Freeze fracture electron microscopy of purified membrane vesicles from T. pallidum and T. vincentii revealed an extremely low density of protein particles; the particle density of T. pallidum was approximately six times less than that of T. vincentii. The great majority of T. vincentii lipopolysaccharide was found in the outer membrane preparation. The T. vincentii outer membrane also contained proteins of 55 and 65 kDa. 125I-penicillin V labeling demonstrated that t. pallidum penicillin-binding proteins were found exclusively with the protoplasmic cylinders and were not detectable with purified outer membrane material, indicating the absence of inner membrane contamination. Isolated T. pallidum outer membrane was devoid of the 19-kDa 4D protein and the normally abundant 47-kDa lipoprotein known to be associated with the cytoplasmic membrane; only trace amounts of the periplasmic endoflagella were detected. Proteins associated with the T. pallidum outer membrane were identified by one- and two-dimensional electrophoretic analysis using gold staining and immunoblotting. Small amounts of strongly antigenic 17- and 45-kDa proteins were detected and shown to correspond to previously identified lipoproteins which are found principally with the cytoplasmic membrane. Less antigenic proteins of 65, 31 (acidic pI), 31 (basic pI), and 28 kDa were identified. Compared with whole-organism preparations, the 65- and the more basic 31-kDa proteins were found to be highly enriched in the outer membrane preparation, indicating that they may represent the T. pallidum rare outer membrane proteins. Reconstitution of solubilized T. pallidum outer membrane into lipid bilayer membranes revealed porin activity with two estimated channel diameters of 0.35 and 0.68 nm based on the measured single-channel conductances in 1 M KCl of 0.40 and 0.76 nS, respectively.     

Monoclonal antibodies directed against surface-associated polypeptides of Treponema pallidum define a biologically active antigen

Murine monoclonal antibodies (Mabs) were raised against two outer-membrane-associated polypeptides of Treponema pallidum (47 and 44 kDa). Three Mabs against each polypeptide were investigated further and only those directed against the 44 kDa polypeptide were demonstrated to have immobilizing activity. The specificity of the Mabs for T. pallidum was determined by Western blotting procedures and the surface association of the antigens was inferred by immunogold electron microscopy. The clear distinction between these two polypeptides in their biological activity could help to explain the pathobiology of syphilis infections as the 47 kDa antigen has been shown to be associated with the outer membrane of this organism. Inactivity of such a surface-located protein in antibody-mediated anti-treponemal mechanisms could account for the observed ability of this organism to survive in the face of strong antibody responses in infection.     

Ultrastructure of Treponema microdentium and Borrelia vincentii

Bladen, Howard A. (National Institute of Dental Health, Bethesda, Md.), and Edward G. Hampp. Ultrastructure of Treponema microdentium and Borrelia vincentii. J. Bacteriol. 87:1180-1191.-A small oral Treponema (FM) and Borrelia vincentii (N9) were harvested after 3 to 7 days of incubation and either embedded in Vestopal W or negatively stained with phosphotungstate. The protoplasmic cylinders of both strains were identical except for size, and had a triple-structured cell wall as well as intracellular concentric laminations. Protoplasmic cylinders of both strains were enclosed in a cell envelope which appeared amorphous in negatively stained preparations, but which had a triple-structured wall when viewed in thin sections. The cell envelope of strain FM also acted as an envelope for the terminal filament; no filament envelope was evident in strain N9. Large structures which contained variable numbers of organisms and which were representative of spirochetal granules were observed. Protoplasmic cylinders contained within such granules frequently were devoid of cell envelopes. The axial filament consisted of several individual fibers which usually terminated in small end knobs. Occasionally, a fiber of the axial filament became a fiber of the terminal filament. Fibers of the terminal filament originated in end knobs similar to, but separate from, those to which the axial filament was attached. A periodicity of 60 A was occasionally observed in the terminal filament envelope of strain FM. A microperiodicity of approximately 20 A was also observed. The fibers of the terminal filament of strain N9 were composed of a large number of fibrils approximately 15 A wide. The periodicity and fibrillar structure of the terminal filament is discussed with reference to proposed models of bacterial flagella suggested by X-ray diffraction data.     

Antigenic and structural analysis of Treponema denticola

Polypeptide and Western immunoblot profiles of subcellular fractions of Treponema denticola ATCC 33520 have been determined by SDS-PAGE of Triton X-100-soluble and -insoluble fractions, a lipopolysaccharide-enriched fraction and purified flagella. Major Triton X-100-soluble polypeptides of 72, 68, 54 and 52 kDa were detected. The 54 kDa polypeptide appeared to be a breakdown product of a larger, heat-modifiable polypeptide. Based on the results of SDS-PAGE analysis and immunoblotting of proteinase K digests of T. denticola, a 'rough' lipopolysaccharide appeared to be present. Electron microscopy has been used to monitor the effect of detergent treatment on the morphology of the organism and to examine the detailed structure of the flagella. Treatment with Triton removed the T. denticola outer membrane, resulting in exposure of the flagella. The flagella were shown to have a complex sheath and core structure and polypeptide composition characteristic of that observed for other treponemes. Polypeptides of 38, 35, 32 and 28 kDa were present in purified flagella preparations. Immunoelectron microscopy, iodine-labelling and Western blotting were used to demonstrate the exposure of antigens on the T. denticola surface. Surface iodination located polypeptides of 72, 68 and 54 kDa. Antiserum raised against whole cells of T. denticola recognized these polypeptides and an additional polypeptide of 52 kDa. These data provide a basis for future detailed molecular analysis of the ultrastructure and antigenicity of T. denticola.     

Characterization of the periplasmic flagellum proteins of Leptospira interrogans.

The structure and composition of periplasmic flagella (PF) from Leptospira interrogans serovar pomona type kennewicki were characterized. Electron microscopic observations showed that leptospiral PF were complex structures composed of an 11.3-nm-diameter core surrounded by two sheath layers with 21.5- and 42-nm diameters. Two-dimensional gel electrophoresis of isolated PF showed the presence of seven different proteins ranging in mass from 31.5 to 36 kDa. Rabbit polyclonal and mouse monoclonal antibodies against PF proteins were prepared and were used to localize specific proteins to portions of the PF structure by immunoelectron microscopy. A 34-kDa protein was associated with the 11.3-nm-diameter core filament, while a 36-kDa protein was associated with a PF sheath (21.5-nm-diameter filament). The amino termini of the 34- and 35.5-kDa proteins were homologous to PF core proteins of other spirochetes. The experimental data suggested that L. interrogans PF contains 2 proteins (34 and 35.5 kDa) in the PF core.     

Comparative analysis of proteins from the fibrous sheath and outer dense fibers of rat spermatozoa

The protein composition of the fibrous sheath (FS) and the outer dense fibers (ODF), two cytoskeletal components of the tail of spermatozoa, was compared by using polyacrylamide gel electrophoresis and immunochemistry applied to Western blots and to spermatozoa. Isolated FS and ODF, the purity of which were verified by electron microscopy (EM), were denatured and either run on sodium dodecyl sulfate-polyacrylamide gels or used to raise antibodies. The gels revealed at least 18 and 14 polypeptide bands for the FS and ODF, respectively. The major bands of the FS had molecular masses of 75, 27.5, and 14.4 kDa, whereas the major bands of the ODF-connecting piece had molecular masses of 32-26, 20, 14.4, 84, and 80 kDa. Several prominent FS and ODF bands were found to comigrate on gels, and the 14.4 kDa polypeptides had similar electrophoretic properties. Anti-FS serum reacted with the majority of Western blot-transferred FS polypeptides, but also cross-reacted strongly with a major 14.4 kDa ODF polypeptide and with less affinity to other major ODF polypeptides. Anti-ODF serum reacted with the majority of ODF polypeptides, but also cross-reacted strongly with a major 14.4 kDa FS polypeptide, and with less affinity to several other FS polypeptides including the 75 kDa band. Antibodies affinity-purified from the 14.4 kDa FS polypeptide only cross-reacted with the 14.4 kDa ODF polypeptide, whereas antibodies purified from the 14.4 kDa ODF polypeptide cross-reacted with 14.4, 27.5, 57, and 63 kDa FS polypeptides. The immunocross-reactions observed on Western blots were confirmed by immunocytochemical methods applied to spermatozoa. This study demonstrates that the FS and ODF, both composed of many polypeptides, several having similar molecular weights, are related cytoskeletal structures as they have epitopes in common, and both contain 14.4 kDa polypeptides with common antigenic and electrophoretic properties.     

Development of cellular immunity to individual soluble antigens of Treponema pallidum during experimental syphilis

The contribution of individual specific molecules of Treponema pallidum subspecies pallidum to cellular immunity in experimental syphilis was evaluated by combining the techniques of Ag identification and purification with the lymphocyte proliferation assay. Proliferative responses of splenic lymphocytes from syphilitic rabbits to complex treponemal Ag and Con A were vigorous throughout the course of intratesticular infection (6, 10, 17, 30, and 210 days). Normal rabbits did not respond to any treponemal preparations and all rabbits failed to respond to normal rabbit testicular Ag (NRT). Seven defined treponemal Ag (47 kDa, 37 kDa, 35, 33-kDa, 30-kDa, 14 kDa, and 12 kDa) stimulated lymphocytes from infected rabbits. Cellular responses to the 37-kDa and 30-kDa fractions were evident by day 6 of infection and responses to the 35, 33-kDa and 14-kDa Ag were first detected on day 10; responsiveness to these Ag continued throughout the observation period. Cellular responses to the 47-kDa molecule were detectable but lower when compared with other individual Ag. Responsiveness to the 12-kDa Ag was not evident until 7 mo postinfection. Specific immunoblot reactivity of serum from rabbits used in this study generally correlated with the development of cellular reactivity to individual Ag of T. pallidum.