Syphilis testing in blood donors, France, 2007 to 2022.

BackgroundSyphilis in blood donors (BD) has increased in many countries.AimWe aimed to describe trends in syphilis seroposivity in BD in France, to identify risk factors and assess if a non-treponemic test (NTT) could define BD having recovered from syphilis for more than 1 year.MethodsThe analysis covered the period 2007 to 2022 and 45,875,939 donations. Of the 474 BD syphilis-positive in 2022, 429 underwent additional investigations with an NTT. History of syphilis was obtained at the post-donation interview or based on serology results for repeat donors.ResultsUntil 2021, positivity rates remained stable (mean: 1.18/10,000 donations, range: 1.01-1.38). An increased rate was observed in 2022 (1.74/10,000; p = 0.02). Over the whole study period, prevalence was 2.2 times higher in male than in female BD (4.1 times higher in 2022). The proportion of males with an identified risk factor who have sex with men increased from 16.7% in 2007 to 64.9% in 2022. Based on NTT, 79 (18%) of the donors who were seropositive in 2022 were classified as having been infected in the previous year. History of syphilis was available for 30 of them. All had an infection within the previous 3 years. Among seven donors with a syphilis < 12 months before testing, one had an NTT titre ≥ 8, three a titre between 1 and 4, three were negative.ConclusionSyphilis seropositivity increased considerably in BDs in 2022, mostly in males, notably MSM. Available data did not allow appropriate evaluation of the NTT to distinguish recent from past infection.

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. The aim of this study was to describe the clinical, demographic, and molecular features of early syphilis cases in Cali, Colombia. METHODS AND FINDINGS: We conducted a cross-sectional study to identify individuals with early syphilis (ES) in Cali, Colombia through a city-wide network of public health centers, private sector HIV clinics and laboratory databases from public health institutions. Whole blood (WB), skin biopsies (SB), and genital and oral lesion swabs were obtained for measurement of treponemal burdens by polA quantitative polymerase chain reaction (qPCR) and for whole-genome sequencing (WGS). Among 1,966 individuals screened, 128 participants met enrollment criteria: 112 (87%) with secondary (SS), 15 (12%) with primary (PS) and one with early latent syphilis; 66/128 (52%) self-reported as heterosexual, while 48 (38%) were men who have sex with men (MSM). Genital ulcer swabs had the highest polA copy numbers (67 copies/µl) by qPCR with a positivity rate (PR) of 73%, while SS lesions had 42 polA copies/µl with PR of 62%. WB polA positivity was more frequent in SS than PS (42% vs 7%, respectively; p = 0.009). Isolation of TPA from WB by rabbit infectivity testing (RIT) was achieved in 5 (56%) of 9 ES WB samples tested. WGS from 33 Cali patient samples, along with 10 other genomic sequences from South America (9 from Peru, 1 from Argentina) used as comparators, confirmed that SS14 was the predominant clade, and that half of all samples had mutations associated with macrolide (i.e., azithromycin) resistance. Variability in the outer membrane protein (OMP) and vaccine candidate BamA (TP0326) was mapped onto the protein's predicted structure from AlphaFold. Despite the presence of mutations in several extracellular loops (ECLs), ECL4, an immunodominant loop and proven opsonic target, was highly conserved in this group of Colombian and South American TPA isolates. CONCLUSIONS: This study offers new insights into the sociodemographic and clinical features of venereal syphilis in a highly endemic area of Colombia and illustrates how genomic sequencing of regionally prevalent TPA strains can inform vaccine development.

Improved efficiency using sequential automated immunoassays for syphilis screening in blood donors.

Using sequential immunoassays for the screening of blood donors is well described for viral serology testing but not for the screening of syphilis. In this study, we report the evaluation results and 2-year sequential testing data using two highly sensitive automated serology assays, the Alinity s Syphilis chemiluminescent immunoassay for screening, with all repeatedly reactive samples then tested on the Elecsys Syphilis electrochemiluminescence immunoassay. We screened 1,767,782 blood donor samples between 7 July 2021 and 6 July 2023 and found the Alinity false-positive rate to be low at 0.08% (1,456/1,767,782). The common false-positive rate between the two assays was also low (3.83%, 58/1,514). Concordantly reactive samples were further tested using a Treponema pallidum particle agglutination test, a rapid plasma reagin test, and a fluorescent treponemal antibody absorption test. There were 262/1,376 concordantly reactive Alinity and Elecsys blood donor samples with reactivity on one or more of the confirmatory tests. A total of 26/1,376 donors had a current syphilis infection, 152/1,376 reported a past history of syphilis and had been treated, and 84/1,376 did not report a past history of syphilis. We suggest that future studies could explore the use of sequential immunoassays to aid in the serodiagnosis for syphilis. IMPORTANCE: The serodiagnosis for syphilis usually follows two methodologies-a "traditional" algorithm using a non-treponemal test followed by confirmation using a treponemal test, or a "reverse" algorithm using a treponemal test followed by a non-treponemal test. There are limited reports in the literature of using a modified reverse algorithm (treponemal test followed by a second treponemal test), and to the best of knowledge, there are currently no published articles using two highly sensitive automated immunoassays to aid the serodiagnosis of syphilis. In addition, the Treponema pallidum particle agglutination (TPPA) assay is commonly used as a confirmatory test for the diagnosis of syphilis. With the withdrawal of the TPPA assay from Australia and presumably from the global market also, alternative testing algorithms are now required. This study provides proof of concept for using sequential immunoassays in the diagnosis of syphilis.

A novel syphilis Treponema pallidum lipoprotein peptide antigen diagnostic assay using red cell kodecytes in routine blood centre column agglutination testing platforms.

BACKGROUND AND OBJECTIVES: The detection of treponemal antibodies, which are used to make a diagnosis of syphilis, is important both for diagnostic purposes and as a mandatory blood donor test in most countries. We evaluated the feasibility of using Kode Technology to make syphilis peptide red cell kodecytes for use in column agglutination serologic platforms. MATERIALS AND METHODS: Candidate Kode Technology function-spacer-lipid (FSL) constructs were made for the Treponema pallidum lipoprotein (TmpA) of T. pallidum, using the peptide and FSL selection algorithms, and then used to make kodecytes. Developmental kodecytes were evaluated against a large range of syphilis antibody reactive and non-reactive samples in column agglutination platforms and compared against established methodologies. Overall, 150 reactive and 2072 non-reactive Syphicheck assay (a modified T. pallidum particle agglutination) blood donor samples were used to evaluate the agreement rate of the developed kodecyte assay. RESULTS: From three FSL-peptide candidate constructs, one was found to be the most suitable for diagnostics. Of 150 Syphicheck assay reactive samples, 146 were TmpA-kodecyte reactive (97.3% agreement), compared with 58.0% with the rapid plasmin reagin (RPR) assay for the same samples. Against the 2072 expected syphilis non-reactive samples the agreement rate for TmpA-kodecytes was 98.8%. CONCLUSION: TmpA-kodecytes are viable for use as cost-effective serologic reagent red cells for the detection of treponemal antibodies to diagnose syphilis with a high level of specificity in blood centres. This kodecyte methodology also potentially allows for introduction of the reverse-algorithm testing into low-volume laboratories, by utilizing existing transfusion laboratory infrastructure.

Seroinfection of Antibodies to Toxoplasma gondii, Parvovirus B19, Treponema pallidum, and HIV in a Pregnant Attending a Medical Center in Northern Peru.

Introduction: Transplacental infections are frequent, especially in developing countries, where limited screening is performed to find infectious agents in the pregnant population. We aim to determine the clinical and epidemiological characteristics and seroinfection of antibodies against Toxoplasma, parvovirus B19, T. pallidum, and HIV in pregnant women who attended the Motupe Health Center in Lambayeque, Peru during July-August 2018. Methods: A descriptive cross-sectional study was conducted in 179 pregnant women interviewed with a standardized questionnaire. ELISA was used to determine antibodies to Toxoplasma and parvovirus B19. The detection of syphilis and HIV was conducted using immunochromatography, while the detection of hepatitis B was conducted using FTA-ABS and immunofluorescence, respectively. Results: Of 179 pregnant women, syphilis and HIV infections routinely included in the screening of pregnant women presented a seroinfection of 2.2 and 0.6%, respectively. Toxoplasmosis seroinfection was 25.1%, while IgM antiparvovirus B19 was 40.8%, revealing that pregnant women had an active infection at the time of study. Conclusion: The level of seroinfection of toxoplasmosis reveals the risk to which pregnant women who participated in the study are exposed. The high seroinfection of parvovirus B19 could explain the cases of spontaneous abortion and levels of anemia in newborn that have been reported in Motupe, Lambayeque, Peru. However, future causality studies are necessary to determine the significance of these findings.

"Syphilitic Hepatitis": A Comprehensive Review of Clinical Features, Diagnostic Approaches, and Management Considerations.

Syphilitic hepatitis is a very rare presentation of syphilis infection, characterized by inflammation of the liver due to the invasion of hepatic tissue by the bacterium Treponema pallidum. This review article provides an in-depth analysis of the existing body of information pertaining to syphilitic hepatitis. The article primarily concentrates on key aspects such as the epidemiology, clinical manifestations, diagnostic methods, and therapeutic approaches associated with this condition. Despite its rarity, awareness of syphilitic hepatitis is vital for accurate diagnosis and appropriate intervention. The clinical presentations frequently exhibit similarities with many liver illnesses, hence presenting difficulties in making an accurate diagnosis. Common symptoms include fatigue, stomach pain, and jaundice. Diagnostic procedures encompass the use of serological assays, including rapid plasma reagin (RPR) and fluorescent treponemal antibody absorption (FTA-ABS), in conjunction with imaging modalities to evaluate hepatic engagement. The primary therapeutic approach is the prompt initiation of antibiotic therapy, with a particular emphasis on penicillin, to eradicate the causative bacterial infection and facilitate the restoration of liver function. Failure to swiftly manage this condition may result in substantial morbidity. In summary, syphilitic hepatitis is a very uncommon but medically relevant manifestation of syphilis infection. The significance of increased clinical suspicion, precise diagnostic techniques, and prompt antibiotic administration is emphasized in this review since these are crucial in reducing the potentially severe outcomes associated with this illness.

Early neurosyphilis with serofast state.

We report a rare case of confirmed early neurosyphilis with serofast state in HIV-negative patient, with uncontrolled type 2 diabetes mellitus. Syphilitic meningitis was diagnosed initially on serology and cerebrospinal fluid (CSF) analysis. The patient had persistently raised non-treponemal titres on serum with negative CSF venereal disease research laboratory result, following treatment during 3 years of follow-up.

Treponema pallidum Periplasmic and Membrane Proteins Are Recognized by Circulating and Skin CD4+ T Cells.

BACKGROUND: Histologic and serologic studies suggest the induction of local and systemic Treponema pallidum-specific CD4+ T-cell responses to T. pallidum infection. We hypothesized that T. pallidum-specific CD4+ T cells are detectable in blood and in the skin rash of secondary syphilis and persist in both compartments after treatment. METHODS: Peripheral blood mononuclear cells collected from 67 participants were screened by interferon-γ (IFN-γ) ELISPOT response to T. pallidum sonicate. T. pallidum-reactive T-cell lines from blood and skin were probed for responses to 89 recombinant T. pallidum antigens. Peptide epitopes and HLA class II restriction were defined for selected antigens. RESULTS: We detected CD4+ T-cell responses to T. pallidum sonicate ex vivo. Using T. pallidum-reactive T-cell lines we observed recognition of 14 discrete proteins, 13 of which localize to bacterial membranes or the periplasmic space. After therapy, T. pallidum-specific T cells persisted for at least 6 months in skin and 10 years in blood. CONCLUSIONS: T. pallidum infection elicits an antigen-specific CD4+ T-cell response in blood and skin. T. pallidum-specific CD4+ T cells persist as memory in both compartments long after curative therapy. The T. pallidum antigenic targets we identified may be high-priority vaccine candidates.

Seroprevalence of Treponema pallidum infection among high-risk populations from Brazil.

Syphilis is a significant public health concern worldwide. According to the 2020 estimates, nearly 7.1 million new cases of syphilis have been reported globally, with over 30 % of these cases reported from American nations, particularly Brazil. Concerns have been raised regarding the susceptibility of specific groups to syphilis due to challenges and vulnerabilities that place these groups at a higher risk of infections or complications in the treatment outcomes. The present study aimed to compare the seroprevalence and the factors associated with syphilis among such high-risk groups. The study was designed as a cross-sectional one and was conducted with pregnant women, people living with HIV (PLHIV), people living with tuberculosis (PLTB), indigenous and healthy populations in Mato Grosso do Sul, Brazil. The study was conducted between June 2019 and August 2022, during which the included patients were subjected to treponemal and non-treponemal serological assays. The study also included a survey conducted through a self-reported questionnaire to collect information regarding the participants' demographics and sexual behaviors. A total of 550 samples were collected, with 110 participants in each of the five groups. The results of the study revealed that the seroprevalence of Treponema pallidum infection in pregnant women, PLHIV, PLTB, indigenous and healthy populations of the study region was 10 % (n = 11/110), 41.81 % (n = 46/110), 17.27 % (n = 19/110), 5.45 % (n = 6/110), and 8.18 % (n = 9/110), respectively. Homosexual orientation (p = 0.04) and a history of sexually transmitted infection (STI) (p = 0.01) were associated with the seroprevalence of T. pallidum infection in PLHIV. However, no such associations were noted in the remaining four groups. The seroprevalence of T. pallidum infection was observed to vary significantly among the different high-risk groups, which highlighted the persistent concern of syphilis, particularly among vulnerable populations. These findings underscore the significance of focused interventions and public health strategies customized to the specific requirements of each of the groups evaluated in the present study to decrease the number of cases of syphilis and thereby prevent future complications in patients with other serious infections.

Serofast status in syphilis: Pathogenesis to therapeutics.

Syphilis, a sexually transmitted infection caused by Treponema pallidum, has been experiencing a rise in prevalence in recent years. "Syphilis serofast" describes a unique serological reaction in patients with syphilis whose clinical symptoms have resolved following consistent anti-syphilitic therapy, but the non-Treponema pallidum antigen serologic test is still positive. Syphilis serofast is a risk factor for syphilis recurrence, neurosyphilis, and multisystem involvement. Considering the current lack of comprehensive knowledge about the epidemiological characteristics, pathogenesis, and therapies of syphilis serofast, we conducted an online search of research relating to syphilis serofast over the last twenty years. Previous research has shown that the pathogenesis of syphilis serofast is mainly related to clinical factors, immune factors, syphilis subtypes, and T.pallidum membrane protein repeat gene antigen. There are two distinct viewpoints on the treatment of serofast: no excessive treatment and active treatment. In addition, serofast patients also showed two clinical outcomes: syphilis recurrence and persistent serofast status. This article systematically reviews the related factors, treatment, and clinical outcomes of syphilis serofast, provides a theoretical basis for its research, diagnosis, and treatment, and helps clinicians develop a follow-up treatment management plan for syphilis serofast.

Platelet-derived major histocompatibility complex class I coating on Treponema pallidum attenuates natural killer cell lethality.

The evasive tactics of Treponema pallidum pose a major challenge in combating and eradicating syphilis. Natural killer (NK) cells mediate important effector functions in the control of pathogenic infection, preferentially eliminating targets with low or no expression of major histocompatibility complex (MHC) class I. To clarify T. pallidum's mechanisms in evading NK-mediated immunosurveillance, experiments were performed to explore the cross-talk relations among T. pallidum, NK cells, and platelets. T. pallidum adhered to, activated, and promoted particle secretion of platelets. After preincubation with T. pallidum, platelets expressed and secreted high levels of MHC class I, subsequently transferring them to the surface of T. pallidum, potentially inducing an immune phenotype characterized by the "pseudo-expression" of MHC class I on the surface of T. pallidum (hereafter referred to a "pseudo-expression" of MHC class I). The polA mRNA assay showed that platelet-preincubated T. pallidum group exhibited a significantly higher copy number of polA transcript than the T. pallidum group. The survival rate of T. pallidum mirrored that of polA mRNA, indicating that preincubation of T. pallidum with platelets attenuated NK cell lethality. Platelets pseudo-expressed the MHC class I ligand on the T. pallidum surface, facilitating binding to killer cell immunoglobulin-like receptors with two immunoglobulin domains and long cytoplasmic tail 3 (KIR2DL3) on NK cells and initiating dephosphorylation of Vav1 and phosphorylation of Crk, ultimately attenuating NK cell lethality. Our findings elucidate the mechanism by which platelets transfer MHC class I to the T. pallidum surface to evade NK cell immune clearance.

Persistence of Treponema pallidum IgM antibodies in serum: What is their meaning?

We studied the detection of Treponema pallidum (TP)-IgM antibodies in the serum of 69 patients treated for syphilis. The persistence of TP-IgM antibodies in serum for more than 3 years was the only clue to suspect an active infection and, therefore, to investigate a central nervous system involvement.

Immunophenotypic variations in syphilis: insights from Mendelian randomization analysis.

Background: Infection with Treponema pallidum instigates complex immune responses. Prior research has suggested that persistent Treponema pallidum infection can manipulate host immune responses and circumvent host defenses. However, the precise role of immune cells in Treponema pallidum infection across different stages remains a contentious issue. Methods: Utilizing summary data from genome-wide association studies, we employed a two-sample Mendelian randomization method to investigate the association between 731 immunophenotypes and syphilis. Syphilis was categorized into early and late stages in this study to establish a more robust correlation and minimize bias in database sources. Results: Our findings revealed that 33, 36, and 27 immunophenotypes of peripheral blood were associated with syphilis (regardless of disease stage), early syphilis and late syphilis, respectively. Subsequent analysis demonstrated significant variations between early and late syphilis in terms of immunophenotypes. Specifically, early syphilis showcased activated, secreting, and resting regulatory T cells, whereas late syphilis was characterized by resting Treg cells. More B cells subtypes emerged in late syphilis. Monocytes in early syphilis exhibited an intermediate and non-classical phenotype, transitioning to classical in late syphilis. Early syphilis featured naive T cells, effector memory T cells, and terminally differentiated T cells, while late syphilis predominantly presented terminally differentiated T cells. Immature myeloid-derived suppressor cells were evident in early syphilis, whereas the dendritic cell immunophenotype was exclusive to late syphilis. Conclusion: Multiple immunophenotypes demonstrated associations with syphilis, showcasing substantial disparities between the early and late stages of the disease. These findings hold promise for informing immunologically oriented treatment strategies, paving the way for more effective and efficient syphilis interventions.

Evaluation of rapid diagnostic test kits for detection of Treponema pallidum antibody.

Rapid syphilis testing plays a crucial role in global health strategies, addressing the urgent need for prompt and accurate diagnostics, especially in settings with limited resources. Despite their practical utility, these tests often lack thorough validation, leading to concerns about their efficacy and reliability. This study aims to evaluate two prototypes of the Onsite Syphilis Ab Combo Rapid Test (Fd and Ff) and compare their performance with the established chemiluminescent microparticle immunoassay (CMIA) method. Employing a reverse algorithm approach, the study analyzed 450 serum samples, including those from syphilis patients, healthy individuals, and cases with potential cross-reactions. Results of the rapid test kit were then correlated with CMIA findings, RPR, and TPPA titers. The results showed that prototype Fd exhibited a sensitivity of 100.0%, specificity of 98.8%, positive predictive value (PPV) of 8.4%, negative predictive value (NPV) of 100.00% and accuracy of 98.8%. Similarly, prototype Ff exhibited sensitivity of 100.0%, but with a slightly higher specificity of 99.6%, PPV of 21.5%, NPV of 100.0% and accuracy of 99.6%. Moreover, both prototypes Fd and Ff of the Onsite Syphilis Ab Combo Rapid Test demonstrated significant efficacy diagnostic tool, offering clear and straightforward interpretation for clinicians in varied CMIA, RPR and TPPA titer scenarios. The Onsite Syphilis Ab Combo Rapid Test prototypes, Fd and Ff, demonstrated high sensitivity and specificity, comparable to CMIA methods. The effectiveness highlights their suitability for syphilis screening, particularly in non-laboratory settings or situations requiring immediate results. The validation of these prototypes supports their integration into current syphilis diagnostic algorithms, potentially contributing to improved public health outcomes.

Seroprevalence of Treponema pallidum infection in Brazilian indigenous people: a cross-sectional study.

Indigenous communities in Brazil have a complex epidemiological profile, which increases their chances of contracting sexually transmitted diseases. However, limited data is available on Treponema pallidum infections in this population. We investigated the seroprevalence and risk factors associated with T. pallidum infection in an indigenous population of Dourados, Mato Grosso do Sul. Blood samples were collected from September 2017 to March 2020, and the participants were interviewed to obtain comprehensive data on demography and sexual behavior. Serological tests were performed to detect T. pallidum infection. Besides conducting descriptive analysis, we performed Chi-squared tests and determined the bivariate odds ratio. The data were also analyzed using logistic regression. Among the 2190 invited individuals, 1927 (88%) were included in this study. The seroprevalence of T. pallidum infection was 2.91%. The results of a multivariate analysis showed that individuals who were 30-39 years old, with up to 4 years of school education, living in households without piped water, with a history of genital lesions, multiple sexual partners, and having a history of STIs had the highest seroprevalence of T. pallidum. This study showed that behavioral, social, and economic factors play an important role in the transmission of T. pallidum within the indigenous population. Thus, targeted intervention, including imparting education in the native language, mass testing initiatives, and implementing public policies to improve socioeconomic indicators, is needed to reduce the cases of syphilis in this community.

Single-test syphilis serology: A case of not seeing the forest for the trees.

INTRODUCTION: There have been few empirical studies for diagnostic test accuracy of syphilis using a sequence of rapid tests in populations with low prevalence of syphilis such as pregnant women. This analysis describes syphilis test positivity frequency among pregnant women at an antenatal clinic in Zambia using a reverse-sequence testing algorithm for antenatal syphilis screening. METHODS: Between August 2019 and May 2023, we recruited 1510 pregnant women from a peri-urban hospital in Lusaka, Zambia. HIV positive and HIV negative women were enrolled in a 1:1 ratio. Blood collected at recruitment from the pregnant mothers was tested on-site for syphilis using a rapid treponemal test. Samples that tested positive were further tested at a different laboratory, with rapid plasma reagin using archived plasma. RESULTS: Of the total 1,421 sera samples which were screened with a rapid treponemal test, 127 (8.9%) were positive and 1,294 (91.1%) were negative. Sufficient additional samples were available to perform RPR testing on 114 of the 127 (89.8%) RDT positive specimens. Thirty-one (27.2%) of these 114 were reactive by RPR and 83 (72.8%) were negative, resulting in a syphilis overtreatment rate of 3 fold (i.e, 84/114). Insufficient sample or test kit availability prevented any testing for the remaining 89 (5.9%) participants. CONCLUSION: Use of only treponemal tests in low prevalence populations, like pregnant women, subjects individuals with non-active syphilis to the costs and possible risks of overtreatment. The use of the dual treponemal and non-treponemal tests would minimize this risk at some additional cost.

Performance Assessment of Treponemal and Nontreponemal Tests for the Diagnosis of Acquired Syphilis.

There are a variety of nontreponemal test (NTT) and treponemal test (TT) kits for the serologic diagnosis of syphilis. Because of the complexity of the infection (multiple clinical stages) and the different antigens used in these kits, a systematic evaluation of the accuracy of the currently available commercial tests is warranted. Our objective was to evaluate the performance of commercially available tests for the diagnosis of syphilis infection. In this study, we analyzed one NTT (Venereal Disease Research Laboratory [VDRL] test, Wiener Laboratories, Rosario, Argentina) and two TTs (fluorescent treponemal antibody absorption [FTA-ABS] test, Euroimmun, Lübeck, Germany, and syphilis recombinant ELISA v. 4.0 test [ELISA], Wiener Laboratories, Rosario, Argentina) using a panel of 187 samples, including serum samples from 31 individuals with primary syphilis, 77 with secondary syphilis, and 79 with latent syphilis. An additional 192 samples from uninfected individuals and 323 serum samples from individuals with other diseases were included. The sensitivities of the VDRL, ELISA, and FTA-ABS tests were 97.9%, 100%, and 96.3%, respectively. The VDRL and ELISA tests showed a specificity of 100%, and the FTA-ABS test showed a specificity of 99.5%. Accuracy was 98.9% for the VDRL test, 100% for the ELISA, and 97.9% for the FTA-ABS test. For primary, secondary, and latent syphilis, the ELISA achieved a diagnostic performance of 100%, whereas the sensitivity for the VDRL and FTA-ABS tests ranged from 96.8% to 98.7% and 93.7% to 98.7%, respectively. No difference was observed when the tests were used as traditional or reverse algorithms. In general, all three tests are able to discriminate positive and negative samples for syphilis, regardless of the diagnostic algorithm.

Serological evaluation of recombinant protein antigen Tp0608 for the diagnosis of syphilis.

OBJECTIVE: To evaluate the serological diagnosis value of recombinant protein antigen Tp0608 for syphilis. METHOD: 406 patients with various stages of syphilis were enrolled. A recombinant protein antigen Tp0608 was established and ELISA was used to detect patients with various stages of syphilis. The results were compared with the conventional rapid plasma reagin test (RPR) and Treponema pallidum particle agglutination test (TPPA). The sensitivity of Tp0608 recombinant protein and RPR+TPPA screening was 96.6 % and 93.1 % respectively for patients with various stages of syphilis. For patients who may have cross reactivity, the specificity of Tp0608 recombinant protein screening is 98.9 %, and the AUC of the ROC curve is 0.99; The specificity of RPR+TPPA screening was 97.3 %, and the AUC of the ROC curve was 0.96. The sensitivity and specificity of Tp0608 recombinant protein in syphilis screening are higher than conventional RPR+TPPA methods, especially in congenital syphilis and primary syphilis. CONCLUSION: The Tp0608 recombinant protein is a promising diagnostic antigen for syphilis screening, but its intracellular location and protective response have not been determined, and further verification is needed.