Immunodominant extracellular loops of Treponema pallidum FadL outer membrane proteins elicit antibodies with opsonic and growth-inhibitory activities.

The global resurgence of syphilis has created a potent stimulus for vaccine development. To identify potentially protective antibodies against Treponema pallidum (TPA), we used Pyrococcus furiosus thioredoxin (PfTrx) to display extracellular loops (ECLs) from three TPA outer membrane protein families (outer membrane factors for efflux pumps, eight-stranded β-barrels, and FadLs) to assess their reactivity with immune rabbit serum (IRS). We identified five immunodominant loops from the FadL orthologs TP0856, TP0858 and TP0865 by immunoblotting and ELISA.

Immunodominant extracellular loops of FadL outer membrane proteins elicit antibodies with opsonic and growth-inhibitory activities.

The global resurgence of syphilis has created a potent stimulus for vaccine development. To identify potentially protective antibodies (Abs) against (), we used thioredoxin (Trx) to display extracellular loops (ECLs) from three outer membrane protein families (outer membrane factors for efflux pumps, eight-stranded β-barrels, and FadLs) to assess their reactivity with immune rabbit serum (IRS). Five ECLs from the FadL orthologs TP0856, TP0858 and TP0865 were immunodominant.

Treponema pallidum genetic diversity and its implications for targeted vaccine development: A cross-sectional study of early syphilis cases in Southwestern Colombia.

Background: Venereal syphilis, caused by the spirochete Treponema pallidum subsp. pallidum (TPA), is surging worldwide, underscoring the need for a vaccine with global efficacy. Vaccine development requires an understanding of syphilis epidemiology and clinical presentation as well as genomic characterization of TPA strains circulating within at-risk populations.

Use of Epivolve phage display to generate a monoclonal antibody with opsonic activity directed against a subdominant epitope on extracellular loop 4 of BamA (TP0326).

Introduction: Syphilis, a sexually transmitted infection caused by the spirochete (), is resurging globally. 's repertoire of outer membrane proteins (OMPs) includes BamA (β-barrel assembly machinery subunit A/TP0326), a bipartite protein consisting of a 16-stranded β-barrel with nine extracellular loops (ECLs) and five periplasmic POTRA (polypeptide transport-associated) domains. BamA ECL4 antisera promotes internalization of by rabbit peritoneal macrophages.

Extracellular Loops of the Treponema pallidum FadL Orthologs TP0856 and TP0858 Elicit IgG Antibodies and IgG-Specific B-Cells in the Rabbit Model of Experimental Syphilis.

The resurgence of syphilis in the new millennium has called attention to the importance of a vaccine for global containment strategies. Studies with immune rabbit serum (IRS) indicate that a syphilis vaccine should elicit antibodies (Abs) that promote opsonophagocytosis of treponemes by activated macrophages. The availability of three-dimensional models for Treponema pallidum's () repertoire of outer membrane proteins (OMPs) provides an architectural framework for identification of candidate vaccinogens with extracellular loops (ECLs) as the targets for protective Abs.

Macrophage mediated recognition and clearance of Borrelia burgdorferi elicits MyD88-dependent and -independent phagosomal signals that contribute to phagocytosis and inflammation.

Background: Macrophages play prominent roles in bacteria recognition and clearance, including Borrelia burgdorferi (Bb), the Lyme disease spirochete. To elucidate mechanisms by which MyD88/TLR signaling enhances clearance of Bb by macrophages, we studied wildtype (WT) and MyD88 Bb-stimulated bone marrow-derived macrophages (BMDMs).

Results: MyD88 BMDMs exhibit impaired uptake of spirochetes but comparable maturation of phagosomes following internalization of spirochetes.

Evidence that immunization with TP0751, a bipartite Treponema pallidum lipoprotein with an intrinsically disordered region and lipocalin fold, fails to protect in the rabbit model of experimental syphilis.

Deconvolution of syphilis pathogenesis and selection of candidate syphilis vaccinogens requires detailed knowledge of the molecular architecture of the Treponema pallidum outer membrane (OM). The T. pallidum OM contains a low density of integral OM proteins, while the spirochete's many lipoprotein immunogens are periplasmic.

Sequence Variation of Rare Outer Membrane Protein β-Barrel Domains in Clinical Strains Provides Insights into the Evolution of subsp. , the Syphilis Spirochete.

In recent years, considerable progress has been made in topologically and functionally characterizing integral outer membrane proteins (OMPs) of subspecies , the syphilis spirochete, and identifying its surface-exposed β-barrel domains. Extracellular loops in OMPs of Gram-negative bacteria are known to be highly variable. We examined the sequence diversity of β-barrel-encoding regions of , , and in 31 specimens from Cali, Colombia; San Francisco, California; and the Czech Republic and compared them to allelic variants in the 41 reference genomes in the NCBI database.

IFNγ Enhances CD64-Potentiated Phagocytosis of Opsonized with Human Syphilitic Serum by Human Macrophages.

Syphilis is a multi-stage, sexually transmitted disease caused by the spirochete (). Considered broadly, syphilis can be conceptualized as a dualistic process in which spirochete-driven inflammation, the cause of clinical manifestations, coexists to varying extents with bacterial persistence. Inflammation is elicited in the tissues, along with the persistence of spirochetes to keep driving a robust immune response while evading host defenses; this duality is best exemplified during the florid, disseminated stage called secondary syphilis (SS).

A Homology Model Reveals Novel Structural Features and an Immunodominant Surface Loop/Opsonic Target in the Treponema pallidum BamA Ortholog TP_0326.

Unlabelled: We recently demonstrated that TP_0326 is a bona fide rare outer membrane protein (OMP) in Treponema pallidum and that it possesses characteristic BamA bipartite topology. Herein, we used immunofluorescence analysis (IFA) to show that only the β-barrel domain of TP_0326 contains surface-exposed epitopes in intact T. pallidum.

Human TLR8 is activated upon recognition of Borrelia burgdorferi RNA in the phagosome of human monocytes.

Phagocytosed Borrelia burgdorferi (Bb), the Lyme disease spirochete, induces a robust and complex innate immune response in human monocytes, in which TLR8 cooperates with TLR2 in the induction of NF-κB-mediated cytokine production, whereas TLR8 is solely responsible for transcription of IFN-β through IRF7. We now establish the role of Bb RNA in TLR8-mediated induction of IFN-β. First, using TLR2-transfected HEK.

Serine lipids of Porphyromonas gingivalis are human and mouse Toll-like receptor 2 ligands.

The total cellular lipids of Porphyromas gingivalis, a known periodontal pathogen, were previously shown to promote dendritic cell activation and inhibition of osteoblasts through engagement of Toll-like receptor 2 (TLR2). The purpose of the present investigation was to fractionate all lipids of P. gingivalis and define which lipid classes account for the TLR2 engagement, based on both in vitro human cell assays and in vivo studies in mice.

Phagosomal signaling by Borrelia burgdorferi in human monocytes involves Toll-like receptor (TLR) 2 and TLR8 cooperativity and TLR8-mediated induction of IFN-beta.

Phagocytosed Borrelia burgdorferi (Bb) induces inflammatory signals that differ both quantitatively and qualitatively from those generated by spirochetal lipoproteins interacting with Toll-like receptor (TLR) 1/2 on the surface of human monocytes. Of particular significance, and in contrast to lipoproteins, internalized spirochetes induce transcription of IFN-β. Using inhibitory immunoregulatory DNA sequences (IRSs) specific to TLR7, TLR8, and TLR9, we show that the TLR8 inhibitor IRS957 significantly diminishes production of TNF-α, IL-6, and IL-10 and completely abrogates transcription of IFN-β in Bb-stimulated monocytes.

Phagocytosis of Borrelia burgdorferi, the Lyme disease spirochete, potentiates innate immune activation and induces apoptosis in human monocytes.

We have previously demonstrated that phagocytosed Borrelia burgdorferi induces activation programs in human peripheral blood mononuclear cells that differ qualitatively and quantitatively from those evoked by equivalent lipoprotein-rich lysates. Here we report that ingested B. burgdorferi induces significantly greater transcription of proinflammatory cytokine genes than do lysates and that live B.

Phagocytosis of Borrelia burgdorferi and Treponema pallidum potentiates innate immune activation and induces gamma interferon production.

We examined the interactions of live and lysed spirochetes with innate immune cells. THP-1 monocytoid cells were activated to comparable extents by live Borrelia burgdorferi and by B. burgdorferi and Treponema pallidum lysates but were poorly activated by live T.

TP0453, a concealed outer membrane protein of Treponema pallidum, enhances membrane permeability.

The outer membrane of Treponema pallidum, the non-cultivable agent of venereal syphilis, contains a paucity of protein(s) which has yet to be definitively identified. In contrast, the outer membranes of gram-negative bacteria contain abundant immunogenic membrane-spanning beta-barrel proteins mainly involved in nutrient transport. The absence of orthologs of gram-negative porins and outer membrane nutrient-specific transporters in the T.

The Treponema pallidum tro operon encodes a multiple metal transporter, a zinc-dependent transcriptional repressor, and a semi-autonomously expressed phosphoglycerate mutase.

The Treponema pallidum tro operon encodes an ABC transporter (TroABCD), a transcriptional repressor (TroR), and the essential glycolytic enzyme phosphoglycerate mutase (Gpm). The apparently discordant observations that the solute binding protein (TroA) binds Zn2+, whereas DNA binding by TroR in vitro is Mn2+-dependent, have generated uncertainty regarding the identities of the ligand(s) and co-repressor(s) of the permease. Moreover, this operonic structure suggests that Gpm expression, and hence glycolysis, the sole source of ATP for the bacterium, would be suspended during TroR-mediated repression.