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J D Radolf

Publications and source records attributed to J D Radolf.

At least 73 records · Page 4Linked to original sources
PubMed1995

Dermal inflammation elicited by synthetic analogs of Treponema pallidum and Borrelia burgdorferi lipoproteins.

The membrane lipoproteins of Treponema pallidum and Borrelia burgdorferi have potent immunostimulatory properties in vitro, implicating them as major inflammatory mediators in syphilis and Lyme disease. Recently, we reported that synthetic lipohexapeptide analogs (lipopeptides) of the lipoproteins could be used as surrogates for native spirochetal lipoproteins in immune cell activation studies in vitro. The present study was designed to evaluate the inflammatory properties of the lipopeptides in vivo and to correlate the cellular responses to these synthetic analogs with the histopathology of syphilis and Lyme disease. Lipopeptides corresponding to the 47-kDa major membrane lipoprotein of T. pallidum and the outer surface protein A of B. burgdorferi injected intradermally induced dose-dependent dermal inflammation in mice; the initial predominantly neutrophilic (mice) or heterophilic (rabbits) cellular infiltrates were followed by infiltrates consisting predominantly of mononuclear cells. The intradermal response of rabbits to the 47-kDa lipopeptide was strikingly similar to that observed for animals infected intradermally with T. pallidum. In all cases, lipopolysaccharide was substantially more potent as an inflammatory mediator than the spirochetal lipopeptides. In contrast to the lipopeptides, nonacylated hexapeptides elicited minimal or no dermal lesions in mice or rabbits, underscoring the importance of acyl modification to the inflammatory properties of the lipopeptides. This study provides the first in vivo evidence that the spirochetal lipoproteins/lipopeptides contribute to the immunopathogenesis of syphilis and Lyme disease.

Amino Acid Sequence↗
PubMed1995

Use of tissue culture and animal models to identify virulence-associated traits of Haemophilus ducreyi.

To identify virulence-associated properties of Haemophilus ducreyi, 34 strains of this sexually transmitted pathogen were evaluated for in vitro phenotypic characteristics of potential relevance to chancroid pathogenesis and for their ability to produce lesions in the temperature-dependent animal model for chancroid. Of the 34 strains tested, all but three produced a cytopathic effect on human foreskin fibroblasts (HFF) and all but six strains formed large microcolonies on HFF monolayers. A subset of 12 selected strains underwent more extensive analyses and, when evaluated for both their cytadherence kinetics and growth in the presence of HFF monolayers, it was found that several of these strains had a very limited ability to attach to HFF cells. When the same 12 strains were tested in the temperature-dependent rabbit model, only the seven strains which were positive in all of these in vitro-based tests readily produced lesions. In contrast, the five strains that were noted to be deficient in one or more of the phenotypic characteristics scored in the in vitro systems did not produce lesions. This association between the traits measured in vitro and the ability to produce dermal lesions was significant (P = 0.0012). These results suggest that in vitro behavior may be used to predict the virulence potential of H. ducreyi strains. Moreover, the phenotypic characteristics described in this study are appropriate focal points for efforts to determine the molecular basis of the virulence of this pathogen.

Animals↗
PubMed1995

Characterization of outer membranes isolated from Borrelia burgdorferi, the Lyme disease spirochete.

The lack of methods for isolating Borrelia burgdorferi outer membranes (OMs) has hindered efforts to characterize borrelial surface-exposed proteins. Here we isolated OMs by immersion of motile spirochetes in hypertonic sucrose followed by isopycnic ultracentrifugation of the plasmolyzed cells. The unilamellar vesicles thus obtained were shown to be OMs by the following criteria: (i) they contained OspA and OspB; (ii) they did not contain flagellin, NADH oxidase activity, or the 60-kDa heat shock protein; and (iii) their morphology by freeze-fracture electron microscopy was identical to that of OMs of intact organisms. Consistent with previous studies which employed immunoelectron microscopy and detergent-based solubilization of B. burgdorferi OMs, only small proportions of the total cellular content of OspA or OspB were OM associated. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) fluorography of OMs from spirochetes metabolically radiolabeled with [3H]palmitate or 35S-amino acids demonstrated that the OMs contained both nonlipidated and lipidated proteins. This fractionation procedure was also used to isolate OMs from virulent and avirulent isolates of the well-characterized B. burgdorferi N40 strain. SDS-PAGE fluorography revealed that OMs from the two isolates differed with respect to both nonlipoprotein and lipoprotein constituents. When whole cells, protoplasmic cylinders, and OMs were immunoblotted against sera from mice persistently infected with B. burgdorferi N40, the majority of antibody reactivity was directed against intracellular proteins. The availability of isolated OMs should facilitate efforts to elucidate the complex relationship(s) between B. burgdorferi membrane composition and Lyme disease pathogenesis.

Animals↗
PubMed1995

Membrane topology of Borrelia burgdorferi and Treponema pallidum lipoproteins.

A critical issue regarding the molecular architectures of Treponema pallidum and Borrelia burgdorferi, the agents of venereal syphilis and Lyme disease, respectively, concerns the membrane topologies of their major lipoprotein immunogens. A related question is whether these lipid-modified membrane proteins form intramembranous particles during freeze fracture electron microscopy. To address these issues, native borrelial and treponemal lipoproteins were reconstituted into liposomes of diverse composition. The importance of the covalently associated lipids for membrane association of lipoproteins was revealed by the observation that nonlipidated recombinant forms of both B. burgdorferi OspA and the T. pallidum 47-kDa immunogen (Tpp47) showed very weak or no binding to model bilayer vesicles. In contrast to control liposomes reconstituted with bacteriorhodopsin or bovine rhodopsin, two well-characterized transmembrane proteins, none of the lipoprotein-liposomes contained particles when examined by freeze fracture electron microscopy. To extend these findings to prokaryotic lipoproteins with relatively amphiphilic polypeptides, similar experiments were conducted with a recombinant nonlipidated form of Escherichia coli TraT, a lipoprotein which has putative transmembrane domains. The nonlipidated TraT oligomers bound vesicles derived from E. coli lipids but, surprisingly, did not form particles in the freeze-fractured liposomes. These findings support (i) a proposed topology of spirochetal lipoproteins in which the polypeptide is extrinsic to the membrane surface and (ii) the contention that particles visualized in freeze-fractured spirochetal membranes represent poorly characterized transmembrane proteins.

Antigens, Surface↗
PubMed1995

A system for generalized mutagenesis of Haemophilus ducreyi.

The lack of a generalized mutagenesis system for Haemophilus ducreyi has hampered efforts to identify virulence factors expressed by this sexually transmitted pathogen. To address this issue, the transposable element Tn1545-delta 3, which encodes resistance to kanamycin, was evaluated for its ability to insert randomly into the H. ducreyi chromosome and produce stable, isogenic mutants. Electroporation of H. ducreyi with 1 microgram of plasmid pMS1 carrying Tn1545-delta 3 resulted in the production of 10(4) kanamycin-resistant transformants; Southern blot analysis of a number of these transformants indicated that insertion of the transposon into the chromosome occurred at a number of different sites. This pMS1-based transposon delivery system was used to produce an H. ducreyi mutant that expressed an altered lipooligosaccharide (LOS). Passage of this mutant in vitro in the presence or absence of kanamycin did not affect the stability of the transposon insertion. To confirm that the observed mutant phenotype was the result of the transposon insertion, a chromosomal fragment containing Tn1545-delta 3 was cloned from this H. ducreyi LOS mutant. Electroporation of the wild-type H. ducreyi strain with this DNA fragment yielded numerous kanamycin-resistant transformants, the majority of which had the same altered LOS phenotype as the original mutant. Southern blot analysis confirmed the occurrence of proper allelic exchange in the LOS-deficient transformants obtained in this backcross experiment. The ability of Tn1545-delta 3 to produce insertion mutations in H. ducreyi should facilitate genetic analysis of this pathogen.

Cloning, Molecular↗
PubMed1994

The 47-kDa major lipoprotein immunogen of Treponema pallidum is a penicillin-binding protein with carboxypeptidase activity.

The recent model of Treponema pallidum molecular architecture proposes that the vast majority of the bacterium's integral membrane proteins are lipoprotein immunogens anchored in the cytoplasmic membrane while the outer membrane contains only a limited number of surface-exposed transmembrane proteins. This unique model explains, in part, the organism's remarkable ability to evade host immune defenses and establish persistent infection. Our strategy for refining this model involves demonstrating that the physiological functions of treponemal membrane proteins are consistent with their proposed cellular locations. In this study, we used an ampicillin-digoxigenin conjugate to demonstrate by chemiluminescence that the 47-kDa lipoprotein immunogen of T. pallidum (Tpp47) is a penicillin-binding protein. Reexamination of the Tpp47 primary sequence revealed the three amino acid motifs characteristic of penicillin-binding proteins. A recombinant, nonlipidated, soluble form of Tpp47 was used to demonstrate that Tpp47 is a zinc-dependent carboxypeptidase. Escherichia coli expressing Tpp47 was characterized by cell wall abnormalities consistent with altered peptidoglycan biosynthesis. Though the inability to cultivate T. pallidum in vitro and the lack of genetic exchange systems continue to impede treponemal research, this study advances strategies for utilizing E. coli molecular genetics as a means of elucidating the complex relationships between syphilis pathogenesis and T. pallidum membrane biology.

Amino Acid Sequence↗
PubMed1994

Induction of protective immunity to Haemophilus ducreyi in the temperature-dependent rabbit model of experimental chancroid.

The temperature-dependent rabbit model for chancroid, a sexually transmitted disease caused by the fastidious Gram-negative bacterium Haemophilus ducreyi, was used to investigate the abilities of previous infection and immunization with an acellular preparation of H. ducreyi to induce protective immunity. In the first set of experiments, animals were infected intradermally with either the 35000 or Cha-1 strains of H. ducreyi and then rechallenged 30 days later with both the homologous and heterologous strains. In animals infected with the 35000 strain, statistically significant protective immunity occurred only against the homologous strain, whereas protection against both homologous and heterologous challenge was obtained in rabbits previously infected with strain Cha-1. In a separate series of experiments, rabbits were immunized with cell envelopes from either strain 35000 or strain Cha-1 and then challenged with both the homologous and heterologous strains. In rabbits immunized with strain 35000 cell envelopes, significant protective immunity was observed only against challenge with the homologous strain. In animals immunized with strain Cha-1 cell envelopes, protection was obtained against both homologous and heterologous challenge. Histopathologic analysis of sites inoculated with strain 35000 (10(5) CFU) demonstrated that the inflammatory response in control animals was predominantly suppurative (i.e., heterophilic), whereas that of immunized animals was predominantly mononuclear and, at later time points, largely histiocytic. ELISA and Western blot analyses revealed that immunization produced a better humoral immune response than did infection and provided evidence for antigenic cross-reactivity between these two strains. These results provide the experimental basis for continued efforts to identify potential H. ducreyi vaccinogens.

Animals↗
PubMed1994

Role of outer membrane architecture in immune evasion by Treponema pallidum and Borrelia burgdorferi.

Combined ultrastructural and molecular studies have revealed that the syphilis and Lyme-disease spirochetes, Treponema pallidum and Borrelia burgdorferi, have distinctive molecular architectures. Both organisms persist in their hosts and have strategies for immune evasion that include the use of rare, poorly immunogenic surface-exposed proteins as potential virulence determinants.

Animals↗
PubMed1994

Southwestern Internal Medicine Conference: brucellosis: don't let it get your goat!

Brucellosis is a highly pleomorphic zoonotic infection caused by one of the following four species of gram-negative facultative intracellular coccobacilli: Brucella melitensis, B. abortus, B. suis, or B. canis. The disease is a worldwide public health problem and a significant cause of economic losses in domestic live-stock. Although largely eradicated in most industrialized countries, in the United States there has been an upsurge of B. melitensis cases associated with the ingestion of unpasteurized goat's milk or goat's milk cheese from Mexico. Brucellosis can be either insidious or abrupt in onset and can affect virtually every organ system; skeletal involvement (spondylitis, arthritis) is the most frequent metastatic complication. Cases are diagnosed either by isolation of the bacterium (usually from blood) or by serologic testing. Treatment of brucellosis requires the administration of two antimicrobial agents. Doxycycline plus streptomycin or rifampin or trimethoprim-sulfamethoxazole plus rifampin appear to be the most effective regimens.

Animals↗
PubMed1994

Digoxigenin-ampicillin conjugate for detection of penicillin-binding proteins by chemiluminescence.

This paper describes a highly sensitive new method for the identification of penicillin-binding proteins (PBPs) that is based on the use of an ampicillin-digoxigenin conjugate (DIG-AMP conjugate) which is detected by immunoblotting and chemiluminescence. The sensitivity of chemiluminescence permitted X-ray film exposure times to be decreased to minutes, as opposed to the days or weeks which are requisite when conventionally radiolabeled beta-lactams are used. Coupling of ampicillin to digoxigenin yielded a product containing digoxigenin (detected by chemiluminescence) which also was inhibitory for Staphylococcus aureus and Escherichia coli. Unconjugated digoxigenin at concentrations of up to 100 micrograms/ml was not inhibitory for either organism. For S. aureus the MICs of DIG-AMP (0.7 microgram of conjugated ampicillin per ml) and of free ampicillin (0.5 microgram/ml) were comparable, indicating that ampicillin retained its bioactivity when coupled to digoxigenin. However, for E. coli the MICs of DIG-AMP (70 micrograms of conjugated ampicillin per ml) and of free ampicillin (8 micrograms/ml) were widely disparate, suggesting that the DIG-AMP conjugate was too large and/or hydrophobic to traverse the E. coli outer membrane via porins. DIG-AMP binding assays with E. coli and S. aureus cell envelopes revealed profiles of PBPs similar to those detected with 125I-ampicillin or [3H]penicillin. DIG-AMP binding to PBPs was completely inhibited in competition experiments with free ampicillin or penicillin, supporting the specificity of the DIG-AMP conjugate for PBPs. DIG-AMP thus represents an advantageous alternative to radioactive beta-lactams for the identification and analysis of PBPs.

Ampicillin↗
PubMed1994

Virulent Treponema pallidum promotes adhesion of leukocytes to human vascular endothelial cells.

Perivasculitis and endothelial cell abnormalities are characteristic histopathologic features of syphilis, a sexually transmitted disease caused by Treponema pallidum. To extend earlier studies demonstrating that T. pallidum activates endothelial cells, we now show that virulent T. pallidum, but not heat-killed T. pallidum or nonpathogenic Treponema phagedenis, promotes increased adherence of lymphocytes and monocytes to human umbilical vein endothelial cells. Lymphocytes and monocytes are the two cell types prominent in the histopathology of syphilis. Recognition that T. pallidum can stimulate endothelial cells to bind leukocytes provides important insights into the early mechanisms of syphilis immunopathogenesis.

Cell Adhesion↗
PubMed1994

Similarity between the 38-kilodalton lipoprotein of Treponema pallidum and the glucose/galactose-binding (MglB) protein of Escherichia coli.

The recent discovery that abundant and immunogenic lipoproteins constitute the integral membrane proteins of Treponema pallidum has prompted efforts to investigate their importance in the physiology and ultrastructure of the organism and in immune responses during infection. Earlier studies identified a 38-kDa lipoprotein of T. pallidum believed to be specific to the pathogen. In the present study, monoclonal antibodies generated against the 38-kDa lipoprotein of T. pallidum reacted with cognate 37-kDa molecules in the nonpathogens Treponema phagedenis, Treponema denticola, and Treponema refringens. Cloning and expression of the 38-kDa-lipoprotein gene of T. pallidum in Escherichia coli revealed that the recombinant product displayed a slightly larger (39-kDa) apparent molecular mass but remained reactive with anti-38-kDa-protein monoclonal antibodies. The recombinant product was processed and acylated in E. coli. DNA and amino acid sequence analyses indicated an open reading frame encoding 403 amino acids, with the first 25 amino acids corresponding to a leader peptide terminated by a signal peptidase II processing site of Val-Val-Gly-Cys. The predicted mature protein is 378 amino acids in length with a deduced molecular weight of 40,422 (excluding acylation). Southern blotting failed to demonstrate in nonpathogenic treponemes genomic sequences homologous with the 38-kDa-lipoprotein gene of T. pallidum. Computer analysis revealed that the 38-kDa lipoprotein of T. pallidum had 34.2% identity and 58.9% similarity with the glucose/galactose-binding protein (MglB) of E. coli and Salmonella typhimurium. Furthermore, of the 19 amino acids of MglB involved in carbohydrate binding, the 38-kDa lipoprotein had identity with 11. These studies have allowed the first putative functional assignment (carbohydrate binding) to a T. pallidum integral membrane protein. Recognition of this potential physiological role for the 38-kDa lipoprotein underscores the possibility that the membrane biology of T. pallidum may more closely resemble that of gram-positive organisms, which also utilize lipoproteins as anchored transporters, than that of gram-negative bacteria to which T. pallidum often is analogized.

Amino Acid Sequence↗
PubMed1994

Analysis of Borrelia burgdorferi membrane architecture by freeze-fracture electron microscopy.

Freeze-fracture electron microscopy was used to investigate the membrane architectures of high-passage Borrelia burgdorferi B31 and low- and high-passage isolates of B. burgdorferi N40. In all three organisms, fractures occurred almost exclusively through the outer membrane (OM), and the large majority of intramembranous particles were distributed randomly throughout the concave OM leaflet. The density of intramembranous particles in the concave OM leaflet of the high-passage N40 isolate was significantly greater than that in the corresponding leaflet of the low-passage N40 isolate. Also noted in the OMs of all three organisms were unusual structures, designated linear bodies, which typically were more or less perpendicular to the axis of the bacterium. A comparison of freeze-fractured B. burgdorferi and Treponema pallidum, the syphilis spirochete, revealed that the OM architectures of these two pathogens differed markedly. All large membrane blebs appeared to be bounded by a membrane identical to the OM of B. burgdorferi whole cells; in some blebs, the fracture plane also revealed a second bilayer closely resembling the B. burgdorferi cytoplasmic membrane. Aggregation of the lipoprotein immunogens outer surface protein A (OspA) and OspB on the bacterial surface by incubation of B. burgdorferi B31 with specific polyclonal antisera did not affect the distribution of OM particles, supporting the contention that lipoproteins do not form particles in freeze-fractured OMs. The expression of poorly immunogenic, surface-exposed proteins as virulence determinants may be part of the parasitic strategy used by B. burgdorferi to establish and maintain chronic infection in Lyme disease.

Antigens, Bacterial↗
PubMed1994

Treponema pallidum rare outer membrane proteins: analysis of mobility by freeze-fracture electron microscopy.

Freeze-fracture and deep-etch electron microscopy were used to investigate the molecular architecture of the Treponema pallidum outer membrane (OM). Freeze-fracture electron microscopy of treponemes freshly harvested from rabbit testes revealed that the intramembranous particles (IMPs) in both the concave and convex OM leaflets were distributed into alternating areas of relatively high and low particle density; in many OM fractures, IMPs formed rows that ran either parallel to or obliquely across the fracture faces. Statistical analysis (runs test) confirmed that the IMPs were nonrandomly distributed in both OM leaflets. Examination of deep-etched specimens revealed that the particles observed in freeze-fractured OMs also were surface exposed. Combined analysis of deep-etched and cross-fractured treponemes revealed that the OM particles were located in regions of the OM away from the endoflagella and closely apposed to the cytoplasmic membrane-peptidoglycan complex. When treponemes were incubated for extended periods with heat-inactivated immune rabbit syphilitic serum, no alteration in the distribution of OM IMPs was detected. In further experiments, approximately 1:1 mixtures of T. pallidum and Escherichia coli or separate suspensions of the nonpathogenic Treponema phagedenis biotype Reiter were fixed at 34 degrees C or after cooling to 0 degree C (to induce lateral phase separations that would aggregate IMPs). Only particles in the T. pallidum OM failed to aggregate in cells fixed at the lower temperature. The combined data suggest that the mobility of T. pallidum rare OM proteins is limited, perhaps as a result of interactions between their periplasmic domains and components of the peptidoglycan-cytoplasmic membrane complex.

Animals↗
PubMed1994

Fatty acids of Treponema pallidum and Borrelia burgdorferi lipoproteins.

A fundamental ultrastructural feature shared by the spirochetal pathogens Treponema pallidum subsp. pallidum (T. pallidum) and Borrelia burgdorferi, the etiological agents of venereal syphilis and Lyme disease, respectively, is that their most abundant membrane proteins contain covalently attached fatty acids. In this study, we identified the fatty acids covalently bound to lipoproteins of B. burgdorferi and T. pallidum and examined potential acyl donors to these molecules. Palmitate was the predominant fatty acid of both B. burgdorferi and T. pallidum lipoproteins. T. pallidum lipoproteins also contained substantial amounts of stearate, a fatty acid not typically prevalent in prokaryotic lipoproteins. In both spirochetes, the fatty acids of cellular lipids differed from those of their respective lipoproteins. To characterize phospholipids in these organisms, spirochetes were metabolically labeled with [3H]palmitate or [3H]oleate; B. burgdorferi contained only phosphatidylglycerol and phosphatidylcholine, while T. pallidum contained phosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, phosphatidylinositol, and cardiolipin. Although palmitate predominated in the lipoproteins, there were no apparent differences in the incorporation of these two fatty acids into phospholipids (putative acyl donors). Phospholipase A1 and A2 digestion of phosphatidylcholine from B. burgdorferi and T. pallidum labeled with either [3H]palmitate or [3H]oleate also revealed that neither fatty acid was incorporated preferentially into the 1 and 2 positions (potential acyl donor sites) of the glycerol backbone. The combined findings suggest that fatty acid utilization during lipoprotein synthesis is determined largely by the fatty acid specificities of the lipoprotein acyl transferases. These findings also provide the basis for ongoing efforts to elucidate the relationship between lipoprotein acylation and the physiological functions and inflammatory activities of these molecules.

Animals↗
PubMed1993

Evaluation of molecular methodologies and rabbit infectivity testing for the diagnosis of congenital syphilis and neonatal central nervous system invasion by Treponema pallidum.

IgM immunoblotting and polymerase chain reaction (PCR) were evaluated for use in diagnosing congenital syphilis, and the prevalence of central nervous system (CNS) invasion by Treponema pallidum during congenital infection was examined. The results of rabbit infectivity testing (RIT) on serum and cerebrospinal fluid (CSF) of 19 infants born to mothers with untreated early syphilis were compared with results of PCR and IgM immunoblotting. Seven infants had clinical evidence of congenital syphilis supported by positive serum IgM immunoblot (7/7), PCR (6/7), and RIT (3/3). Six symptomatic infants (86%) had T. pallidum isolated from CSF by RIT; 5 of 6 RIT-positive CSF samples were positive by PCR, and 2 also were reactive by IgM immunoblot. In 12 asymptomatic infants, 5 (42%) had a reactive serum IgM immunoblot and in 4 of these IgM reactivity was the only evidence of congenital infection. CNS invasion by T. pallidum was uncommon among asymptomatic infants; only 1 (8%) was positive by CSF RIT. The excellent agreement between RIT and PCR further substantiates the use of PCR as a surrogate for RIT. Our data indicate that the diagnosis of asymptomatically infected neonates will require a comprehensive approach using assays for both specific neonatal IgM and T. pallidum DNA in serum and CSF.

Adolescent↗
PubMed1993

Lipid modification of the 17-kilodalton membrane immunogen of Treponema pallidum determines macrophage activation as well as amphiphilicity.

A murine monoclonal antibody specific for a 17-kDa major membrane immunogen of Treponema pallidum was used to select recombinant Escherichia coli clones expressing the molecule from a T. pallidum genomic library. Sequence analysis of the structural gene for the immunogen (designated tpp17) revealed a 468-bp open reading frame encoding a polypeptide of 156 amino acids with a calculated molecular mass of 16,441 Da. The deduced amino acid sequence included a putative leader peptide terminated by a consensus tetrapeptide for the modification and processing of prokaryotic lipoproteins. Immunoprecipitation of the cloned immunogen radiolabeled with [3H]palmitate confirmed that it was a lipoprotein. The amino acid sequence also predicted that the mature protein contains four cysteine residues in addition to the lipid-modified cysteine of the N terminus. The existence of disulfide-bonded multimeric forms of the native immunogen was demonstrated by immunoblotting T. pallidum solubilized in the presence and absence of 2-mercaptoethanol. Triton X-114 phase partitioning of a nonlipidated form of the 17-kDa immunogen cleaved from a glutathione S-transferase fusion protein demonstrated that lipid modification is responsible for the immunogen's hydrophobic character. The same nonlipidated form of the immunogen also was used to demonstrate that lipid modification is essential for the molecule's ability to stimulate production of tumor necrosis factor alpha by murine macrophages. We conclude that covalently attached fatty acids not only anchor T. pallidum lipoproteins to spirochetal membranes but also confer upon these molecules the ability to activate immune effector cells.

Amino Acid Sequence↗