Unique lipid composition of Treponema pallidum (Nichols virulent strain).

The lipid composition of Treponema pallidum (Nichols virulent strain) was determined after purification of the organisms from the infected testes of corticosteroid-treated rabbits by differential centrifugation, filtration through Nuclepore membranes, and sedimentation in Hypaque density gradients. The total lipids were comprised of 32.2% neutral lipids, mainly cholesterol, and 67.8% phospholipids consisting of phosphatidylcholine (32.1%), sphingomyelin (14.8%), cardiolipin (13.0%), phosphatidylethanolamine (6.2%), phosphatidylinositol-serine (1.2%), and lysophosphatidylcholine (0.4%). Monoglycosyldiglyceride, a glycolipid comprising 25 to 50% of thetotal lipid of all Treponema previously examined, was not detected. The fatty acid composition was similar but quntitatively distinct from that of the infected testes tissue.     

Capacity of virulent Treponema pallidum (Nichols) for deoxyribonucleic acid synthesis.

Treponema pallidum (Nichols) was extracted from infected rabbit tissue, and cell lysates were prepared for monitoring thymidine kinase and deoxyribonucleic acid polymerase activities. No thymidine kinase could be demonstrated in preparations of T. pallidum or the cultivable T. phagedenis biotype Reiter. Significant levels of deoxyribonucleic acid polymerase were detected in both treponemal samples. Interestingly, comparisons of polymerase activity among a spectrum of bacterial genera revealed a direct correlation between enzyme concentrations and estimated generation time. Incorporation of [3H]uridine and [3H]thymidine into macromolecules by intact T. pallidum and the Reiter treponeme was examined. Selective ribonuclease-deoxyribonuclease digestion and cesium chloride gradient banding demonstrated that T. pallidum, independent of the host, and T. phagedenis were capable of synthesizing deoxyribonucleic acid only from the [3H]-uridine precursor.     

Molecular specificities of monoclonal antibodies directed against virulent Treponema pallidum.

Radioimmunoprecipitation (RIP) and Western blot analyses with specific anti-Treponema pallidum subsp. pallidum monoclonal antibodies were used to identify antigens with apparent masses of 102, 84, 54, 53, 52, 47, 32, 29, and 24 kilodaltons (kDa). Cross-reactivity of these antibodies with T. pallidum subsp. pertenue antigens and lack of cross-reactivity with T. phagedenis biotype Reiter, T. vincentii, T. refringens, T. scoliodontum, and T. denticola were also demonstrated by RIP and Western blot analyses. Reactivities in the T. pallidum immobilization test, along with the RIP of lactoperoxidase-catalyzed iodination products, suggested that the identified antigens were surface associated. The abundance and surface association of the 47- and 84-kDa antigens were supported by reactivity in the microhemagglutination test for T. pallidum and by strong reactivity of monoclonal antibodies upon indirect immunofluorescence assays with rabbit-cultivated T. pallidum subsp. pallidum, respectively, but not with T. phagedenis biotype Reiter. Anti-47-kDa and anti-84-kDa monoclonal antibodies were also reactive in indirect immunofluorescence assays using treponemes found in dark-field-positive smears of human genital ulcers.     

Inhibition of macromolecular synthesis in cultured rabbit cells by Treponema pallidum (Nichols).

Treponema pallidum partially inhibited the synthesis of DNA, RNA, and protein by rabbit cells in vitro. The inhibition of DNA synthesis was proportional to treponemal concentration and persisted during the period of exposure to T. pallidum. The toxic effect was not dependent on treponemal metabolism or on whole treponemes, since heat- and penicillin-killed treponemes and a cell-free sonicate of treponemes had similar toxicities. The toxic factor(s) was also detected in extracts of syphilitic rabbit testes but not in extracts of normal rabbit testes or testes inflamed by chemical means. The T. pallidum-derived toxic material had a molecular weight greater than 20,000 as determined by dialysis. Protein and DNA synthesis were most rapidly inhibited; RNA synthesis continued at normal rates for up to 2 h after exposure to treponemes. Protein synthesis or a necessary precursor of protein synthesis appeared to be the primary target of the T. pallidum toxin(s).     

Prolonged survival of virulent Treponema pallidum (Nichols strain) in cell-free and tissue culture systems.

Survival of Treponema pallidum was found to be prolonged in the presence of tissue culture. Of the 12 cultures studied, cottontail rabbit epithelium (Sf1Ep) supported T. pallidum for the longest time. In horizontal Leighton tubes with reduced medium and an atmosphere of 5% CO2 in N2, the 50% survival time (ST50) was 5 to 6 days for treponemes associated with monolayers of Sf1Ep cells. Comparable cell-free tubes had ST50 values of less than 4 days. In vertical Leighton tubes containing 6 ml of prereduced medium incubated aerobically, gradients of O2 tension and redox potential were established. Attachment and survival of T. pallidum were greatest at a depth of about 10 to 20 mm. Motility was between 70 and 95% in this area throughout the first 14 days of incubation. Occasionally, greater than 50% motility was observed for as long as 21 days. The redox potential and O2 tension in the optimal area of gradient cultures were reproduced by adjusting the medium depth in a shell vial culture system containing cells on a horizontal cover slip. Treponemes associated with the cell monolayer in both gradient and shell vial cultures were still virulent after 21 days in vitro. The dilution of testis extract and the concentration of T. pallidum were found to be important factors in survival of T. pallidum.     

Radiolabeling of Treponema pallidum (Nichols virulent strain) in vitro with precursors for protein and RNA biosynthesis.

We observed uptake of [U-14C]serine, U-14C-labeled amino acid hydrolysates, and [2-14C]uracil by virulent Treponema pallidum in vitro for at least 96 h. No uptake of [2-14C]thymine, [1-14C]pyruvate, [U-14C]pyruvate, and [2-14C]uridine was detected. Treponemal protein and RNA biosynthetic activity was identified by erythromycin inhibition of amino acid and uracil uptake. Radioactivity due to uptake of radiolabeled amino acids by residual testicular cells in the cultures remained at background levels regardless of the presence or absence of cycloheximide. Accumulation of the radiolabeled substrates by T. pallidum proceeded at a linear rate for 48 to 96 h during incubation in vitro. The longevity of substrate uptake using the system of incubation described will facilitate future studies on the metabolism of the microorganism to help determine essential growth factors and environmental conditions for multiplication of T. pallidum in vitro.     

Development of monoclonal antibodies that recognize Treponema pallidum.

We developed a panel of monoclonal antibodies to Treponema pallidum (Nichols) antigens, some of which recognize treponemal antigens on T. pallidum (Nichols), T. pallidum strain 14, and Treponema phagedenis biotype Reiter. The antibodies were detected by either an enzyme-linked immunosorbent assay or a radioimmunoassay.     

Sensitivity and specificity of monoclonal antibodies directed against antigenic determinants of Treponema pallidum Nichols in the diagnosis of syphilis.

Murine anti-Treponema pallidum monoclonal antibodies were employed in studies on sensitivity and specificity of binding to examine their potential for use in the detection of low numbers of pathogenic treponemes present in various body fluids. Monoclonal antibodies were used as a primary antibody source in a solid-phase immunoblot assay system. All monoclonal antibodies assayed were capable of detecting ca. 1.0 X 10(3) to 2.5 X 10(3) treponemes. Of 13 monoclonal antibodies examined, 3 were able to detect 10(3) virulent treponemes, and 1 of these antibodies was able to reveal the presence of as few as 500 organisms. Western blot analyses showed that all anti-T. pallidum monoclonal antibodies exhibiting high sensitivities for the detection of T. pallidum cells were directed against an abundant, 47,000-dalton surface-exposed antigen of the organism (S. A. Jones, K. S. Marchitto, J. N. Miller, and M. V. Norgard, Abstr. Annu. Meet. Am. Soc. Microbiol. 1984, B173, p. 46; K. S. Marchitto, S. A. Jones, and M. V. Norgard, Abstr. Annu. Meet. Am. Soc. Microbiol. 1984, B182, p. 48). Differences in binding properties of the various monoclonal antibodies were most likely a reflection of differential binding affinities or their specificities for different epitopes on the 47,000-dalton surface antigen. With two possible exceptions, the monoclonal antibodies tested reacted specifically with T. pallidum, either purified or found within a high-contaminating tissue background, and not with Treponema phagedenis biotype Reiter, Haemophilus ducreyi, Neisseria gonorrhoeae, herpes simplex virus type 2, or normal rabbit testicular tissue. The high sensitivity and specificity exhibited by these anti-T. pallidum monoclonal antibodies make them excellent candidates for employment in new syphilis or other treponemal diagnostic tests designed to detect very low numbers of pathogenic treponemes in lesion exudates or other body fluids.     

Examination of various cell culture techniques for co-incubation of virulent Treponema pallidum (Nichols I strain) under anaerobic conditions.

Treponema pallidum (Nichols virulent) was incubated with and without cells in cell culture medium reduced to -275 mV Ecal, pH 7.3, under deoxygenated conditions. Five to ten percent of the treponemes attached to cells and remained motile for at least 120 h in cell-treponeme systems of co-incubation. Virulent treponemes could be detected after 120 to 144 h in the supernatant fluids of cell-treponeme co-incubation cultures and in cell-free tubes containing medium harvested from aerobically cultivated mammalian cells. Medium supplemented with ox serum ultrafiltrate, pyruvate, and sodium thioglycolate and gas mixtures containing H2 and CO2 enhanced treponemal survival. Increases in treponemal numbers were observed using dark-field microscopy but were not substantiated using the rabbit lesion test. Continuous passage of the treponeme was not achieved in vitro.     

Anabolic potential of virulent Treponema pallidum.

Acrylamide gel autoradiography of 3H-labeled proteins from Treponema pallidum demonstrates that virulent treponemes incubated in vitro synthesize a spectrum of high-molecular-weight proteins. A comparison of the protein profiles of T. pallidum with the Reiter treponeme shows that T. pallidum possesses significant anabolic competence.     

Depression of lymphocyte response to concanavalin A in rabbits infected with Treponema pallidum (Nichols strain).

Peripheral blood lymphocytes isolated from rabbits in the early stages of Treponema pallidum infection responded poorly when exposed to concanavalin A in vitro. Maximal depression of blastogenesis occurred when lymphocytes were cultured in the presence of autologous serum in comparison with fetal calf or normal homologous rabbit serum.     

Preliminary evaluation of an immunochromatographic strip test for specific Treponema pallidum antibodies

We evaluated a prototype immunochromatographic strip (ICS) test for qualitative detection of Treponema pallidum antibodies in 353 sera from 157 patients. For sera from 43 syphilis patients, the ICSs were reactive, while for sera from 114 patients without syphilis, including 22 with biologically false-positive Rapid Plasma Reagin test results, the ICSs were nonreactive. The ICS test may expand the available options for serological testing for syphilis.     

Carbon sources utilized by virulent Treponema pallidum.

Carbon sources utilized by virulent Treponema pallidum organisms extracted from infected rabbit tissue have been investigated. Utilization of 14C-labeled compounds by T. pallidum was monitored by degradation of these compounds to 14CO2. Experiments have consistently shown that of 22 carbon sources examined, [14C]glucose and [14C]pyruvate are selectively degraded to 14CO2 under the experimental conditions employed. When [1-14C]pyruvate, [2-14C]pyruvate, and [3-14C]pyruvate are tested, virulent T. pallidum preferentially degrade and release the carboxyl group as 14CO2. End product analyses indicate that CO2 and acetate are the major products of pyruvate degradation by T. pallidum.     

Intracellular Location of Treponema pallidum (Nichols Strain) in the Rabbit Testis

During investigations designed to obtain purified suspensions of virulent Treponema pallidum (Nichols strain), infected rabbit testicular tissue was routinely examined in the electron microscope. Morphologically typical T. pallidum were found intracellularly within the cytoplasmic substance of fibroblasts, interstitial and Leydig cells, and of spermatocytes. The importance of these observations to latency and treatment is discussed.     

Antigenic and structural characterization of Treponema pallidum (Nichols strain) endoflagella.

Purified endoflagella from Treponema pallidum, Nichols strain, were characterized both structurally and antigenically. Structural analysis showed T. pallidum endoflagella are composed of 35- and 33-kilodalton (kDa) subunits which lack cysteine and do not share N-terminal amino acid sequence homology (20 residues). Intact endoflagella were dissociated into the composite subunits by incubation, which disrupts noncovalent bonds. Antiserum raised against purified T. pallidum endoflagella identified shared epitopes on the endoflagellar polypeptides of the nonpathogen, Treponema phagedenis biotype Reiter. Pathogen-specific epitopes were also found on the 35- and 33-kDa polypeptides by using affinity-purified endoflagellar antibodies. The pathogen-specific epitopes were localized by immunoblotting analysis of chymotryptic digests of the endoflagellar subunits; 18- and 26-kDa fragments derived from the 35-kDa subunit were found to possess a majority of the pathogen-specific epitopes. Both the 35- and 33-kDa subunits had surface exposure, as determined by immunoelectron microscopy, although additional immunochemical data indicated that the surface exposure of the 35-kDa subunit was greater.     

Die Anordnung der Außenfibrillen bei Treponema pallidum (Stamm Nichols)

Zusammenfassung Die Außenfibrillen von Treponema pallidum (Stamm Nichols) bilden zwei gegenläufige Spiralbänder, die sich über den ganzen Zelleib des Erregers erstrecken und sich in regelmäßigen Abständen kreuzen.

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Summary The outer fibrils of treponema pallidum (tribe Nichols) form two bundles twisting around the entire length of treponema and crossing each other in regular distances.

     

Ribosomal ribonucleic acid synthesis by virulent Treponema pallidum.

Ribosomal ribonucleic acid (rRNA) synthesis by virulent Treponema pallidum was monitored by incorporation of [(3)H]uridine into trichloroacetic acid-precipitable counts and examination of radiolabeled rRNA on polyacrylamide gels. Verification that rRNA synthesis originated with T. pallidum was based upon co-electrophoresis with Escherichia coli rRNA, proportionate reductions in the amount of rRNA synthesized when numbers of treponemes were decreased, and inclusion of appropriate animal cell controls. The rate of treponemal rRNA synthesis was greater at temperatures of 37 and 39 degrees C than at 33 degrees C; rRNA synthesis was inhibited at 4 and 42 degrees C and was effectively inhibited by actinomycin D. Kinetic experiments indicated that the majority of rRNA synthesis occurred early after extraction of treponemes from infected rabbit testicular tissue. Polyacrylamide gel profiles demonstrated the capacity of virulent T. pallidum to synthesize and process RNA to 23s, 16s, and 4 to 5s classes. Although motility of T. pallidum appeared unaffected during longer periods of incubation, pulselabeling experiments confirmed significant reductions in the rate of rRNA synthesis. When the effect of various environmental conditions upon rRNA synthesis was investigated, optimal synthesis was found to occur in an atmosphere of 20% oxygen whereas virtually no synthesis was observed under anaerobic or low-oxygen conditions.     

Immune response to Treponema pertenue and Treponema pallidum Nichols in patients with yaws.

Human sera from African patients with acute yaws were analysed by Western blot (WB) against antigens of Treponema pallidum Nichols and two Treponema pertenue isolates. The Western blot patterns were remarkably similar from one patient to another, and strains of both subspecies exhibited exactly the same banding pattern. Sera from yaws patients failed to detect at least one antigen in T. pertenue which was absent from T. pallidum.     

Competitive enzyme-linked immunosorbent assay for Treponema pallidum antibodies

A competitive enzyme-linked Treponema pallidum immunosorbent assay (CETPIA) was compared with the standard serological tests for syphilis. Of 3081 serum samples submitted, 2883 gave negative results in the CETPIA and the routine screening tests. Positive results were obtained in the CETPIA and in one or more of the specific treponemal tests with 115 samples. Discrepancies in the results of the CETPIA and standard serological tests were found with 83 serum samples, most of these were attributed to biological false positive reactions in the Venereal Disease Research Laboratory (VDRL) test. CETPIA may have a role in the serological diagnosis of syphilis.     

Retention of motility of Treponema pallidum (Nichols virulent strain) in an anaerobic cell culture system and in a cell-free system.

Optimum parameters for retention of motility of Treponema pallidum (Nichols virulent strain) were found by anaerobic co-incubation of the treponeme with rat glial cells and anaerobic incubation in spent medium obtained from glial cells originally grown aerobically.