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Syphilis vaccine: up-regulation of immunogenicity by cyclophosphamide, Ribi adjuvant, and indomethacin confers significant protection against challenge infection in rabbits.

Many unsuccessful attempts have been made to develop effective vaccines against experimental syphilitic infection. The focus of this report was to evaluate newer approaches to up-regulate immune responses following immunization with Treponema pallidum. Rabbits were injected once on day 0 with heat-inactivated treponemes suspended in the Ribi adjuvant system containing monophosphoryl lipid A (MPL) and trehalose dimycolate; animals were challenged dermally on day 29 with viable organisms. Various up-regulating agents were then tested using this general immunization protocol. When rabbits were pretreated on day -2 with cyclophosphamide (CYC), no protection was apparent. CYC pretreatment exhibited some protection when combined with a daily course of indomethacin on days 29 to 36. When rabbits were injected on day 0, then given a boost of MPL alone on day +2 plus indomethacin on days 29 to 36, minor protection was again apparent. Excellent protection was achieved when the vaccine protocol involved a combination of CYC pretreatment on day -2, an MPL boost on day +2, and indomethacin on days 29 to 36. Ninety-two percent of the subsequent lesions were atypical as indicated by their flat appearance, small size, lack of ulceration, and rapid healing. Importantly, this vaccine regimen also decreased dissemination of T. pallidum to distant tissues. These results suggest a new perspective in understanding immune responses in syphilis. We propose that vaccination, like infection, generates immune down-regulation that counter-balances immune stimulation. THus, effective vaccines will depend on removal and/or neutralization of treponemal components that down-regulate immune reactivity.

Adjuvants, Immunologic↗

Novel recombinant-antigen enzyme immunoassay for serological diagnosis of syphilis.

Enzyme immunoassay (EIA) is an ideal method for screening large numbers of patients for syphilis. We evaluated a novel immune-capture EIA (ICE Syphilis; Murex Diagnostics) that uses three recombinant Treponema pallidum antigens (TpN15, TpN17, and TpN47) and compared the results with those obtained by the native T. pallidum antigen EIA (Captia SelectSyph-G; Centocor) that we currently use for the serodiagnosis of syphilis. Specificity was evaluated by screening 1,184 unselected serum specimens in parallel by the ICE Syphilis and SelectSyph-G assays, while sensitivity was tested with a panel of 101 serum specimens containing antitreponemal antibodies (treated and untreated) from patients with various stages of infection. The specificity of the ICE Syphilis EIA (99.8%) on screening was significantly higher (P < 0.02) than that of the SelectSyph-G EIA (99.2%). The sensitivity of the ICE Syphilis EIA was significantly higher (P < 0.01) than that of the SelectSyph-G EIA on both initial (99 versus 91.4%) and repeat (100 versus 92.4%) testing. The ICE Syphilis EIA was also significantly more sensitive (P < 0.01) than the fluorescent treponemal antibody-abs (92.4%) but not the T. pallidum hemagglutination assay (97.1%). Sera containing antitreponemal antibodies gave a much higher antibody index (absorbance of test serum/kit cutoff) by the ICE Syphilis EIA than by the SelectSyph-G EIA. This combined with the overall high sensitivity makes the ICE Syphilis EIA an ideal test for excluding or detecting treponemal infection in human immunodeficiency virus (HIV)-infected patients. The ICE Syphilis EIA was positive with sera from all 15 HIV-infected patients in the study, whereas sera from 3 HIV-infected patients were negative by the SelectSyph-G EIA. We conclude that the high sensitivity and specificity of the ICE Syphilis EIA and its suitability for automation make it an ideal screening test.

Antigens, Bacterial↗

In vitro and in vivo activities of sedecamycin against Treponema hyodysenteriae.

Sedecamycin (lankacidin A), one of the lankacidin-group antibiotics, showed potent activity against Treponema hyodysenteriae. The MICs of sedecamycin against 79 field isolates of T. hyodysenteriae ranged from 0.78 to 12.5 micrograms/ml, the MIC for 90% of the strains tested (MIC90) being 3.13 micrograms/ml. The protective and therapeutic effects of sedecamycin were compared with those of carbadox, tiamulin, and lincomycin against experimental infection with T. hyodysenteriae in mice. The protective effect of sedecamycin was similar to that of carbadox, two times more potent than that of tiamulin, and three times greater than that of lincomycin. In the therapeutic test, sedecamycin showed activity similar to that of carbadox and was two times more active than both tiamulin and lincomycin. At doses of 10 mg or more of sedecamycin per kg, the recurrence of shedding of T. hyodysenteriae into the feces of mice was not detected for at least 8 weeks postmedication.

Animals↗

Clinical and epidemiological features of syphilis in pregnant women: the course and outcome of pregnancy.

Clinical and epidemiological features of syphilis and the course and outcome of pregnancy were studied in 155 pregnant women infected with syphilis; 95 (61%) women were unemployed, 47% were unmarried. Syphilis proceeded without clinical manifestations in 121 cases (78%). Discordant results of complement fixation (Wassermann) test, precipitation test, Treponema pallidum immobilization test, and fluorescent antibody test were observed in 22 (14%) of the women. Pregnancy pathology was observed in 75 cases (48.8%) and more often appeared as anemia in 49 (31.5%), stillborn in 46 (29.8%) and toxicosis in 44 (28.4%). Fetal ultrasonic stigmas of infection were evident in 23 cases (49%). There was distension of the brain ventricle system and hepatomegaly each in 1 case (2%), transvascular infiltration of liver in 2 cases (4%), dilation of intestinal loops, gastromegaly, ventriculomegaly and petrifaction in lungs each in 1 case; ultrasonic changes in vessels of organs: of the liver in 4 cases (8%), intestines and stomach in 16 cases (32%), lungs in 4 cases (8%), kidneys in 10 cases (21%) and of the ventricular system in 9 cases (19%). Fetus development retardation was revealed in 3 cases (6%), fetal hypoxia in 1 (2%), hypohydrosis in 2 (4%) and hydropsy in 1 case (2%). The pregnancy pathology in women with syphilis was considered not pathognomonic.

Adolescent↗

Laboratory diagnosis of sexually transmitted infections in estonia in 2001-2002: shortcomings with impact on diagnostic quality and surveillance.

OBJECTIVES: The objectives of this study were to comprehensively characterize the range, content, and performance of sexually transmitted infection (STI) testing services in Estonia during the period 2001 to 2002 and to determine if the observed diagnostic laboratory practices and methods adhered to international evidence-based recommendations. STUDY: Survey data, focusing on organization and performance characteristics of STI diagnostics services, were assessed using questionnaires, telephone interviews, and site visits to all responding facilities providing STI diagnostics services in Estonia. Guidelines of international evidence-based recommendations for STI testing were used as references. RESULTS: There were significant shortcomings in STI testing availability and practices. Among all participating laboratories diagnosing STIs, only a minority (n = 16, 28%) offered testing for the full minimum range of relevant STIs in Estonia, i.e., Treponema pallidum, Neisseria gonorrhoeae, Chlamydia trachomatis, and Trichomonas vaginalis. In addition, because testing methods used were not properly selected, confirmation of several infections in accordance with evidence-based requirements was not possible, which has an impact both on STI diagnostic quality and surveillance.

Animals↗

[The preservation of strains of pathogenic Treponema pallidum in BALB/c mice].

A clinical and serologic follow-up of 307 BALB/c mice and 12 rabbits injected with the blood and brain and spinal tissue of mice infected with 5 strains of T. pallidum has demonstrated the possibility of a prolonged (up to 465 days) preservation of pathogenic T. pallidum strains in these mice, as well as the regularity of a syphilitic infection development in rabbits. This permits recommending T. pallidum pathogenic strains to be maintained in mice at laboratories of institutions for skin and sexually transmitted diseases where experimental and diagnostic studies with the use of specific serologic tests for syphilis are carried out.

Animals↗

Comparison of in vitro culture and polymerase chain reaction for detection of Borrelia burgdorferi in tissue from experimentally infected animals.

A polymerase chain reaction (PCR) was developed for identification of Borrelia burgdorferi in biological specimens. The diagnostic efficiency was compared with that of in vitro culture. A primer set specifying a 791-bp DNA fragment of the B. burgdorferi B31 flagellin gene was used. Amplified DNA sequences were analyzed by agarose gel electrophoresis, and the identity of amplified DNA was confirmed by restriction enzyme cleavage and Southern blot hybridization with a 32P-labeled probe. By using purified B. burgdorferi DNA, the detection limit of the assay was approximately 0.002 pg of DNA, corresponding to one copy of the B. burgdorferi genome. By using in vitro-cultivated B. burgdorferi without prior DNA purification as the template DNA, 2 to 20 organisms could be detected. A 791-bp DNA fragment was amplified from all of 18 different B. burgdorferi strains tested, as well as from Borrelia hermsii and Borrelia anserina but not from Treponema pallidum. The efficacy of the PCR assay was evaluated on spleen, renal, and urinary bladder tissue specimens from eight experimentally infected gerbils. Specimens from the same organs were cultured in BSK medium in parallel. Of 24 organs, 21 (88%) were PCR positive and 17 (71%) were culture positive. All culture-positive specimens were also PCR positive. Compared with B. burgdorferi cultivation, PCR had at least a comparable diagnostic sensitivity, it was less laborious, and results were available within 1 to 2 days.

Animals↗

Use of the skin protection assay in experimental syphilis to assess protective immunity against a specific Treponema pallidum surface epitope.

We have recently shown that a monoclonal antibody, designated M131, that binds a surface phosphorylcholine epitope on Treponema pallidum possesses complement-dependent killing activity and confers partial protection in rabbits following passive immunization (Blanco et al., 2005, Infect. Immun. 73:3083-3095). In this study, the protective potential of M131 was further tested using the rabbit skin protection assay of Titus and Weiser. Both M131 and infection-derived immune rabbit serum resulted in significant lesion delays corresponding to at least a 90% reduction of the treponemal challenge inoculum. The skin protection assay provides a way to assess the protective potential of specific immunogens while using far less antibody than in passive immunization protocols.

Animals↗

The hyaluronidase associated with Treponema pallidum facilitates treponemal dissemination.

Treponema pallidum contains hyaluronidase (Hase) associated with its surface. Experiments were performed to determine the functional role of this enzyme in syphilitic infection. The effects of incubating organisms with rabbit anti-bovine Hase or normal or immune sera were compared. Preincubation of treponemes with anti-Hase resulted in inhibition of treponemal degradation of hyaluronic acid, indicating that these antisera did in fact retard enzyme activity. Anti-Hase did not immobilize or neutralize T. pallidum. In addition, rabbits were immunized with bovine Hase and then challenged intradermally with organisms; subsequent lesion development was not affected. Anti-Hase did not block treponemal attachment to cultured testicular fibroblasts but did inhibit attachment to isolated capillaries. Rabbit amnions were used as an in vitro model for dissemination of T. pallidum. Anti-Hase retarded the penetration of organisms through the amnions. This inhibitory effect was dependent on the presence of amniotic hyaluronic acid. When this glycosaminoglycan was selectively removed, the anti-Hase lost its ability to inhibit treponemal penetration. When exogenous hyaluronic acid was added back to treated amnions, the inhibitory effect of anti-Hase was restored. Evans blue experiments were used to characterize treponeme-induced vascular leakage following intradermal inoculation of T. pallidum. Prior treatment of organisms with anti-Hase reduced dermal leakage of the dye, indicating the involvement of the treponemal Hase in causing vessel leakage. Finally, rabbit testicular infections were used as an in vivo model for dissemination; one testis was infected, and after 10 to 13 days, treponemes in the opposite testis were quantitated. The anti-Hase restricted dissemination of organisms. These findings point to the functional role of the treponemal Hase in facilitating disseminated syphilis.

Amnion↗

A novel 62-kilodalton egg antigen from Schistosoma mansoni induces a potent CD4(+) T helper cell response in the C57BL/6 mouse.

In infection with Schistosoma mansoni, hepatic granuloma formation is mediated by CD4(+) T helper (Th) cells sensitized to schistosomal egg antigens. There is considerable variation among infected individuals with respect to both severity of disease and the T-cell response to egg antigens. In the BL/6 mouse, the egg granulomas are relatively small and the relevant sensitizing egg antigens are largely unknown. We investigated the CD4(+) Th cell response of infected BL/6 mice to egg antigens fractionated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and found a prominent lymphoproliferative response to be directed against a 62-kDa component. With the aid of a specific T-cell hybridoma, 4E6, the 62-kDa antigen was isolated; following partial digestion with endoproteinase Glu-C, an internal amino acid sequence was found to be identical with one present in the enzyme phosphoenolpyruvate carboxykinase (PEPCK) of the organisms Caenorhabditis elegans and Treponema pallidum and to differ by one residue from PEPCK of various other species. In CD4(+) Th cells from 7.5- 8.5-week-infected BL/6 mice, the purified 62-kDa molecule elicited a potent proliferative response which, based on cytokine analysis, was of a mixed Th-1 and Th-2 type. Our results reveal a novel egg antigen of particular prominence in the BL/6 mouse and suggest that the immune response in schistosomiasis is a product of sensitization to egg antigens that may vary considerably in immunogenicity from strain to strain.

Animals↗

Treponema pallidum and the quest for outer membrane proteins.

Treponema pallidum, the syphilis spirochaete, has a remarkable ability to evade the humoral and cellular responses it elicits in infected hosts. Although formerly attributed to the presence of an outer coat comprised of serum proteins and/or mucopolysaccharides, current evidence indicates that the immuno-evasiveness of this bacterium is largely the result of its unusual molecular architecture. Based upon a combination of molecular, biochemical, and ultrastructural data, it is now believed that the T. pallidum outer membrane (OM) contains a paucity of poorly immunogenic transmembrane proteins ('rare outer membrane proteins') and that its highly immunogenic proteins are lipoproteins anchored predominantly to the periplasmic leaflet of the cytoplasmic membrane. The presence in the T. pallidum OM of a limited number of transmembrane proteins has profound implications for understanding syphilis pathogenesis as well as treponemal physiology. Two major strategies for molecular characterization of rare outer membrane proteins have evolved. The first involves the identification of candidate OM proteins as fusions with Escherichia coli alkaline phosphatase. The second involves the characterization of candidate OM proteins identified in outer membranes isolated from virulent T. pallidum. Criteria to define candidate OM proteins and for definitive identification of rare OM proteins are proposed as a guide for future studies.

Antibodies, Monoclonal↗

Treponema pallidum in nerve fibres.

Ultrathin sections of a rabbit scrotal syphiloma were examined by electron microscopy. Treponemes were observed in the endo-, peri-, and epineurium of the nerve fibre. The significance of these findings, in that infection may be transmitted via the nerve fibres and pain reduced by damage to the afferent fibres, are discussed.

Animals↗

Syphilis.

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Adult↗

Microbiological shifts in intra- and extraoral habitats following mechanical periodontal therapy.

OBJECTIVES: The aim of the present study was to analyze the intra- and extraoral colonization dynamics of periodontal pathogens following supra- and subgingival debridement. MATERIAL AND METHODS: Thirty five patients with chronic periodontitis were enrolled in the study. Supra- and subgingival plaque samples, saliva, and swab samples from mucosa and extraoral sites were taken at baseline and 6 weeks, 3 months and 6 months after mechanical periodontal therapy. Actinobacillus actinomycetemcomitans (Aa), Porphyromonas gingivalis (Pg), Eikenella corrodens (Ec), Tannerella forsythensis (Tf), Prevotella intermedia (Pi), Prevotella nigrescens (Pn), and Treponema denticola (Td) were identified by PCR. RESULTS: Supra- and subgingival debridement decreased the number of subgingival sites infected with the analyzed pathogens only transiently, if at all. However, the detection frequencies of Tf, Td, Ec, Pi, and Pn in the supragingival region, of Pg, Td, and Pn at the oral mucosa sites (mostly the tongue), and of all pathogens except Aa in saliva increased over the 6-month observation period. Td was the only pathogen recorded in notable quantities in the extraoral habitat (external ear canal). CONCLUSION: The results indicate that supra- and subgingival debridement results in a dissemination of periodontal pathogens within the oral cavity.

Bacteria, Anaerobic↗

Antigenic variability of Borrelia burgdorferi.

Borrelia burgdorferi strains (six isolates from North America and 28 isolates from Europe) were analyzed by physicochemical and immunological methods. By SDS-PAGE, all Borrelia burgdorferi strains tested had two major proteins with constant molecular weights of 60 and 41 kDa and one, two, or three variable low molecular weight proteins (OspA = 30-32 kDa, OspB = 34-36 kDa, pC = 21-22 kDa). All combinations--except OspB alone or OspB/pC--were observed. Borrelia burgdorferi strains were different from relapsing fever borreliae by strong reactivity with OspA- and/or pC-specific polyclonal antibodies, whereas relapsing fever borreliae were only weakly reactive. Among 25 Borrelia burgdorferi isolates, seven different serotypes of Borrelia burgdorferi were defined according to their reactivity in the Western blot with three monoclonal OspA-specific antibodies (H5332, H3TS, and LA5), four OspA- or OspB-specific polyclonal antibodies, and 12 polyclonal antibodies against whole borreliae. Antigenic differences between European CSF and skin isolates were observed, all skin isolates (n = 11) belonging to serotype 2 in contrast to only two out of seven CSF isolates. CSF isolates were antigenically heterogenous (serotypes 1, 2, 3, 4, and 5). Serotypes 6 and 7 were represented by two tick isolates, and the other European tick isolates are not yet fully characterized. Antigenic differences between European and North American strains may play a role in differences in the clinical picture of Lyme borreliosis.

Antigens↗