Large-Scale Comparative Analyses of Tick Genomes Elucidate Their Genetic Diversity and Vector Capacities.

Among arthropod vectors, ticks transmit the most diverse human and animal pathogens, leading to an increasing number of new challenges worldwide. Here we sequenced and assembled high-quality genomes of six ixodid tick species and further resequenced 678 tick specimens to understand three key aspects of ticks: genetic diversity, population structure, and pathogen distribution. We explored the genetic basis common to ticks, including heme and hemoglobin digestion, iron metabolism, and reactive oxygen species, and unveiled for the first time that genetic structure and pathogen composition in different tick species are mainly shaped by ecological and geographic factors. We further identified species-specific determinants associated with different host ranges, life cycles, and distributions. The findings of this study are an invaluable resource for research and control of ticks and tick-borne diseases.

Treponema pallidum membrane protein Tp47 induced autophagy and inhibited cell migration in HMC3 cells via the PI3K/AKT/FOXO1 pathway.

The migratory ability of microglia facilitates their rapid transport to a site of injury to kill and remove pathogens. However, the effect of Treponema pallidum membrane proteins on microglia migration remains unclear. The effect of Tp47 on the migration ability and autophagy and related mechanisms were investigated using the human microglial clone 3 cell line. Tp47 inhibited microglia migration, the expression of autophagy-associated protein P62 decreased, the expression of Beclin-1 and LC3-II/LC3-I increased, and the autophagic flux increased in this process. Furthermore, autophagy was significantly inhibited, and microglial cell migration was significantly increased after neutralisation with an anti-Tp47 antibody. In addition, Tp47 significantly inhibited the expression of p-PI3K, p-AKT, and p-mTOR proteins, and the sequential activation of steps in the PI3K/AKT/mTOR pathways effectively prevented Tp47-induced autophagy. Moreover, Tp47 significantly inhibited the expression of p-FOXO1 protein and promoted FOXO1 nuclear translocation. Inhibition of FOXO1 effectively suppressed Tp47-induced activation of autophagy and inhibition of migration. Treponema pallidum membrane protein Tp47-induced autophagy and inhibited cell migration in HMC3 Cells via the PI3K/AKT/FOXO1 pathway. These data will contribute to understanding the mechanism by which T. pallidum escapes immune killing and clearance after invasion into the central nervous system.

Serum Ubiquitin C-Terminal Hydrolase-L1, Glial Fibrillary Acidic Protein, and Neurofilament Light Chain Are Good Entry Points and Biomarker Candidates for Neurosyphilis Diagnosis Among Patients Without Human Immunodeficiency Virus to Avoid Lumbar Puncture.

BACKGROUND: Laboratory tests to diagnose neurosyphilis using cerebrospinal fluid (CSF) are currently disadvantageous as a lumbar puncture is required, which may result in patients with neurosyphilis missing an opportunity for early diagnosis. Thus, blood biomarker candidates that are more convenient and minimally invasive to collect for diagnosing neurosyphilis is urgently needed. METHODS: This observational study aimed to analyze serum ubiquitin C-terminal hydrolase-L1 (UCH-L1), glial fibrillary acidic protein (GFAP), and neurofilament light chain (NF-L) levels in 153 patients without human immunodeficiency virus (HIV) and to evaluate their diagnostic performance in neurosyphilis compared with CSF. RESULTS: Serum UCH-L1, GFAP, and NF-L levels were significantly higher in patients with neurosyphilis compared with patients with uncomplicated syphilis or non-syphilis. For the diagnosis of neurosyphilis, serum UCH-L1, GFAP, and NF-L revealed sensitivities of 90.20%, 80.40%, and 88.24%, and specificities of 92.16%, 78.43%, and 80.39%, respectively, at cutoff levels of 814.50 pg/mL, 442.70 pg/mL, and 45.19 pg/mL, respectively. In patients with syphilis, serum UCH-L1, GFAP, and NF-L levels correlated strongly or moderately with those in the CSF, with similar or better diagnostic performance than those in the CSF. The testing algorithms' sensitivity and specificity increased to 98.04% and 96.08%, respectively, when subjected to parallel and combination testing, respectively. CONCLUSIONS: To avoid lumbar puncture, each serum UCH-L1, GFAP, and NF-L is a good entry point and biomarker candidate for the diagnosis of neurosyphilis among patients without HIV. These proteins used in concerto can further improve the diagnostic sensitivity and specificity.

Response and duration of serum anti-SARS-CoV-2 antibodies induced by the third dose of an inactivated vaccine: A prospective longitudinal cohort study at 21 serial time points over 641 days.

Given the prevalence of low-pathogenic but highly infectious Omicron variants, a cohort study was conducted to assess the response and duration of novel coronavirus-inactivated vaccine-induced antibodies 1 year after the third dose (Day 641). Blood samples were collected and anti-spike neutralizing antibodies (neutralizing antibody), total antibodies against the receptor-binding domain of the spike protein (total antibody), and immunoglobulin G antibodies against the spike protein (IgG antibody) were determined. Antibody kinetics and attenuation were evaluated. The results showed that the levels of neutralizing, total, and IgG antibodies on Day 641 were 98.05 IU/mL, 152.8 AU/mL, and 7.68 S/CO, respectively. Levels of anti-SARS-CoV-2 antibodies were higher in the younger subgroup than in the older subgroup at several time points after the second and third doses. The seropositive rate of neutralizing antibodies providing protection from infection or severe infection was 46.87% and 87.5%, and the seropositive rates of total antibody and IgG antibody were maintained at 100% and 90.63%, respectively. The half-lives of neutralizing, total, and IgG antibodies were 186.89, 363.04, and 417.50 days, respectively. Collectively, anti-SARS-CoV-2 antibodies may provide a certain degree of protection from infection 1 year after the third dose and high protection from severe infection.

Treponema pallidum membrane protein Tp47 promotes angiogenesis through ROS-induced autophagy.

BACKGROUND: Pathological angiogenesis is an important manifestation of syphilis, but the underlying mechanism of Treponema pallidum subspecies pallidum (T. pallidum)-induced angiogenesis is poorly understood. OBJECTIVES: The objective of this study is to investigate the role and related mechanism of the T. pallidum membrane protein Tp47 in angiogenesis. METHODS: The proangiogenic activity of recombinant T. pallidum membrane protein Tp47 in human umbilical vein endothelial cells (HUVECs) was assessed by tube formation assay, three-dimensional angiogenesis analysis and experiments with a zebrafish embryo model. The effects of mitochondrial ROS and NADPH oxidase on intracellular ROS induced by Tp47 were further investigated. Furthermore, the levels of autophagy-related proteins and autophagic flux were measured. Finally, the role of ROS-induced autophagy in angiogenesis was studied. RESULTS: Tp47 promoted tubule formation and the formation of angiogenic sprouts in vitro. In addition, a significant increase in the number of subintestinal vessel branch points in zebrafish injected with Tp47 was observed using a zebrafish embryo model. Tp47 also significantly increased intracellular ROS levels in a dose-dependent manner. Tp47-induced tube formation and angiogenic sprout formation were effectively prevented by the ROS inhibitor NAC. In addition, Tp47 enhanced the production of mitochondrial ROS and expression of the NADPH oxidase-related proteins Nox2 and Nox4. The production of mitochondrial ROS and intracellular ROS was reduced by the NADPH oxidase inhibitors DPI and apocynin. Furthermore, Tp47 significantly increased expression of the autophagy-related proteins P62 and Beclin 1 and the LC3-II/LC3-I ratio and promoted an increase in autophagic flux, which could be effectively rescued by coincubation with the ROS inhibitor NAC. Further intervention with the autophagy inhibitor BafA1 significantly inhibited tube formation and angiogenic sprout formation. CONCLUSIONS: Tp47-induced NADPH oxidase enhanced intracellular ROS production via mitochondrial ROS and promoted angiogenesis through autophagy mediated by ROS. These findings may contribute to our understanding of pathological angiogenesis in syphilis.

Study on Doppler Spectra of Electromagnetic Scattering of Time-Varying Kelvin Wake on Sea Surface.

In general, it is more practical to detect ship wake under the background of a complicated sea state than the ship directly. Thus, in this paper, the Doppler spectra of time-varying Kelvin wake on a time-varying sea surface are numerically investigated by considering the change of ship wake with time in ocean environments. For this purpose, the linear superposition model of a time-varying sea surface and a time-varying Kelvin wake is established. Combined with the facet scattering field model of sea surface and Kirchhoff approximation (KA), the Doppler of the radar scattering echo signal of the time-varying wake on the sea surface is simulated and analyzed under different polarizations, incident angles, ship speeds, and wind speeds, as well as wind directions. It can be observed that the Doppler spectrum changes as the conditions change. This study provides a reference for extracting motion features of ship wakes in a sea clutter environment.

Characterisation of the novel clinical isolate X-4 containing a new tp0548 sequence-type.

OBJECTIVES: A novel tp0548 sequence-type was identified in one clinical isolate (X-4) from a patient diagnosed with primary syphilis in Xiamen, China. To precisely define and characterise a new clinical isolate, we performed further genome-scale molecular analysis. METHODS: The pooled segment genome sequencing method followed by Illumina sequencing was performed. RESULTS: This novel sequence-type contained a unique nucleotide substitution 'T' at position 167 and belonged to the SS14-like clade of TPA strains, as determined by phylogenetic analysis. Multi-locus sequence analysis of nine chromosomal loci demonstrated that the X-4 isolate was clustered within a monophyletic group of TPA strains. Whole-genome phylogenetic analysis subsequently corroborated the TPA strain classification of the X-4 isolate and revealed that the isolate was closely related to the SS14 strain, with 42 single-nucleotide variations and 12 insertions/deletions. In addition, high intrastrain heterogeneity in the length of the poly G/C tracts was found in the TPAChi_0347 locus, which might indicate that this gene of the X-4 isolate is likely involved in phase variation events. The length heterogeneity of the poly A/T tracts was lower than the genetic variability of the poly G/C tracts, and all the observed intrastrain variations fell within coding regions. CONCLUSION: The novel tp0548 sequence-type was determined to belong to a new TPA isolate, X-4. The identification of variable length in homopolymetic tracts (G/C and A/T) could provide a snapshot of the genes that potentially involved in genotype-phenotype variations. These findings provide an unequivocal characterisation for better understanding the molecular variation of this emerging isolate.

Tp0136 targets fibronectin (RGD)/Integrin ß1 interactions promoting human microvascular endothelial cell migration.

Lesion healing without treatment is a unique clinical characteristic of the early stages of syphilis infection. Angiogenesis, which involves endothelial cell migration, is an important process in wound healing. Tp0136, an outer membrane protein of T. pallidum, has the ability to bind host fibronectin-producing cells, which plays a crucial role in the pathogenesis of syphilis. In this research, we purposed to analyze the role of Tp0136 in the migration of human microvascular endothelial (HMEC-1) cells and to explore the related mechanism. First, Tp0136 significantly promoted HMEC-1 cell migration. Furthermore, the levels of C-C motif ligand 2 (CCL2) mRNA and protein expression rose with the concentration and time increasing of Tp0136. The migration of HMEC-1 cells was significantly suppressed by an anti-CCL2 antibody and a CCR2 (the CCL2 receptor) inhibitor. Further study revealed that, in cells pretreated with anti-fibronectin antibody, anti-integrin ß1 antibody or RGD (Arg-Gly-Asp), the expression levels of CCL2 induced by Tp0136 were notably decreased. Additionally, after pretreatment with an anti-fibronectin antibody, an anti-integrin ß1 antibody or RGD, the migration of HMEC-1 cells treated with Tp0136 was obviously suppressed. These results show that Tp0136 promots the migration of HMEC-1 cells by inducing CCL2 expression via the interaction of the fibronectin RGD domain with integrin ß1 and the CCL2/CCR2 signaling pathway, and these interactions may contribute to the mechanisms that increase the capacity for self-healing syphilis infection.

Recombinant Treponema pallidum protein Tp47 promotes the migration and adherence of THP-1 cells to human dermal vascular smooth muscle cells by inducing MCP-1 and ICAM-1 expression.

Vascular inflammation is a complex and multifactorial pathophysiological process that plays a crucial role in all stages of syphilis and is responsible for tissue damage. Little is known about the interactions of infiltrating immunocytes with human dermal vascular smooth muscle cells (HDVSMCs) in arterioles during the immunopathogenesis of syphilis. The Treponema pallidum subsp. pallidum membrane protein Tp47 is considered a major inducer of inflammation initiation and development. In this study, we demonstrated that Tp47 promoted the migration and adhesion of THP-1 cells to HDVSMCs. Furthermore, Tp47 increased monocyte chemoattractant protein-1 (MCP-1) and intercellular adhesion molecule-1 (ICAM-1) mRNA and protein expression levels in a dose- and time-dependent manner. The migration and adhesion of THP-1 cells to HDVSMCs were significantly suppressed by anti-MCP-1 and anti-ICAM-1 neutralizing antibodies, respectively. Further studies revealed that treatment of HDVSMCs with Tp47 activated the PI3K/Akt, p38 MAPK and NF-κB signalling pathways. Inhibition of PI3K/Akt, p38 MAPK and NF-κB suppressed the MCP-1 and ICAM-1 expression induced by Tp47. In addition, the migration and adhesion of THP-1 cells to Tp47-treated HDVSMCs were significantly decreased by pretreatment with PI3K/Akt, p38 MAPK and NF-κB inhibitors. These findings demonstrate that Tp47 promotes the migration and adherence of THP-1 cells to HDVSMCs by inducing MCP-1 and ICAM-1 expression, which is mediated by activation of the PI3K/Akt, p38 MAPK and NF-κB pathways. This study provides a novel potential therapeutic strategy for controlling the vascular inflammatory response in syphilis patients.

Changes of T lymphocyte subsets in patients with HIV-negative symptomatic neurosyphilis.

OBJECTIVES: The host immune response could be an imperative factor in the pathogenesis of neurosyphilis, but the role of T lymphocyte subsets remains unclear. In the present study, we assessed the CD4+ T and CD8+ T cell subsets in the peripheral blood of patients with HIV-negative symptomatic neurosyphilis and then explored the clinical application value of neurosyphilis. METHODS: In total, 24 patients with HIV-negative symptomatic neurosyphilis and 22 patients with syphilis/non-neurosyphilis were included in this study and cerebrospinal fluid (CSF) and blood samples were obtained. Th1, Th2, Th17, Th9, CD8+IFN-γ+, CD8+IL-4+, CD8+IL-9+, and CD8+IL-17 + cells were identified by flow cytometry. RESULTS: The levels of CD8+IFN-γ+ were significantly increased in the peripheral blood of neurosyphilis patients compared to that in syphilis/non-neurosyphilis patients, but it was opposite to Th2, Th9, CD8+IL-4+, CD8+IL-9+, and CD8+IL-17 + cells. Dendritic cells (DCs) of neurosyphilis matured by T. pallidum induced the development of a combination of IFN-γ-producing Th1 cells. The number of CD8+IL-17 + cells was significantly correlated with the CSF RPR and CSF TPPA levels. ROC curve analysis revealed that the number of CD8+IFN-γ+ cells could be a potential biomarker for neurosyphilis from non-neurosyphilis/syphilis. CONCLUSIONS: High expression of CD8+IFN-γ+ cells and low expression of CD8+IL-17 + cells in patients with symptomatic neurosyphilis, which explains the pathogenesis of symptomatic neurosyphilis, meanwhile CD8+IFN-γ+ cells may be a better indicator in classifying symptomatic neurosyphilis from non-neurosyphilis/syphilis among patients without HIV infection.

Metabolic Disorders in Patients with Central Nervous System Infections: Associations with Neurosyphilis.

INTRODUCTION: Recently, neurosyphilis was found to be associated with diabetes mellitus (DM). Whether the association was specific to neurosyphilis among central nervous system (CNS) infections, and whether neurosyphilis is associated with other prevalent metabolic disorders deserves further study. METHODS: An in-depth cross-sectional study was conducted with 74 neurosyphilis patients and 74 sex- and age-matched patients with other CNS infections. DM-, hypertension-, and dyslipidemia-related factors were compared between patients with neurosyphilis and those with other CNS infections. RESULTS: The prevalence rates of hypertension and hyperlipidemia in neurosyphilis patients were 45.9 and 21.4%, respectively, which were higher than those in patients with other CNS infections (45.9 vs. 28.4%, p = 0.027; 21.4 vs. 8.3%, p = 0.028). In addition, neurosyphilis patients had significantly higher systolic blood pressure (BP; median 139 mm Hg; interquartile range [IQR] 121-151 mm Hg), -diastolic BP (median 83 mm Hg; IQR 76-89 mm Hg), total cholesterol (median 4.86 mmol/L; IQR 3.80-5.51 mmol/L), low-density lipoprotein (median 3.39 mmol/L; IQR 2.52-3.95 mmol/L), and apolipoprotein A1 (apoA1; median 1.31 g/L; IQR 1.06-1.52 g/L) levels and lower apoB/A1 ratios (median 0.67; IQR 0.49-0.99) than patients with other CNS infections (p< 0.05). There were no differences in the DM-related factors between patients with neurosyphilis and those with other CNS infections (p> 0.05). CONCLUSION: Potential association between neurosyphilis and metabolic disorders was found among CNS infections. The results could have important implications for clinical practice, alerting more clinicians to this issue.

Origin of Nontreponemal Antibodies During Treponema pallidum Infection: Evidence From a Rabbit Model.

The origin of nontreponemal antibodies during syphilis infection is hotly debated. Here, we analyzed the immune response in rabbits immunized with various antigens. Inactivated treponemes elicited the production of low-titer nontreponemal antibodies in some rabbits. Cardiolipin combined with bovine serum albumin also induced anticardiolipin antibody production. These findings indicate that Treponema pallidum contained a cardiolipin antigen with weak immunogenicity. However, active T. pallidum induced higher nontreponemal antibody production with strong immunogenicity at an earlier time point, and the antibody titer was consecutive, suggesting the high nontreponemal antibody titer resulted from the combined effects of both the T. pallidum cardiolipin antigen and the damaged host-cell cardiolipin antigen during syphilis infection, the latter of which plays a major role in the induction of nontreponemal antibody production. Our study provides direct animal evidence of the origin of nontreponemal antibodies during T. pallidum infection.

Treponema pallidum promotes macrophage polarization and activates the NLRP3 inflammasome pathway to induce interleukin-1ß production.

BACKGROUND: The involvement of inflammasome activation and macrophage polarization during the process of syphilis infection remains unknown. In this study, A series of experiments were performed using human macrophages to research the role of NLRP3 inflammasome regulation in interleukin (IL)-1ß production and its influence on macrophage polarization triggered by T. pallidum. RESULTS: The results showed that in M0 macrophages treated with T. pallidum, the M1-associated markers inducible nitric oxide synthase (iNOS), IL-1ß and TNF-α were upregulated, and the M2-associated markers CD206 and IL-10 were downregulated. In addition, we observed NLRP3 inflammasome activation and IL-1ß secretion in T. pallidum-treated macrophages, and the observed production of IL-1ß occurred in a dose- and time-dependent manner. Moreover, the secretion of IL-1ß by macrophages after T. pallidum treatment was notably reduced by anti-NLRP3 siRNA and caspase-1 inhibitor treatment. NAC, KCl, and CA074-ME treatment also suppressed IL-1ß release from T. pallidum-treated macrophages. CONCLUSIONS: These findings showed that T. pallidum induces M0 macrophages to undergo M1 macrophage polarization and elevate IL-1ß secretion through NLRP3. Moreover, the process of NLRP3 inflammasome activation and IL-1ß production in macrophages in response to T. pallidum infection involves K+ efflux, mitochondrial ROS production and cathepsin release. This study provides a new insight into the innate immune response to T. pallidum infection.

Assessing effects of different processing procedures on the yield of Treponema pallidum DNA from blood.

In this work, we employed real-time PCR analysis targeting tp0574 to investigate the effects of different processing procedures on the yield of T. pallidum DNA from blood to improve assay sensitivity. The T. pallidum DNA yields following red blood cell lysis pretreatment were 40.4 times greater from whole blood and 32.4 times greater from residual hematocytes than yields without pretreatment. For the simulated whole-blood experiments, the T. pallidum DNA yields from the lower layer were 2.8, 4.6, 7.3, 12.6, 15.24, 16.7, 65.1 and 73.1 times those from the upper layer following centrifugation at 500×, 1000×, 2000×, 4000×, 5000×, 7000×, 10,000× and 20,000 × g, respectively. However, the T. pallidum DNA yields from blood clots were only 1.0% at different centrifugal forces. The experiment with infected rabbit blood showed results similar to those mentioned above. In addition, sample processing time (within 48 h) and storage temperature (4 °C and 25 °C) did not affect T. pallidum DNA extraction efficiency. The T. pallidum DNA yield can be significantly improved by red blood cell lysis pretreatment and appropriate centrifugation. Furthermore, the T. pallidum DNA extraction yield is greater from whole blood or residual hematocytes from anti-coagulated blood than from plasma, serum or blood clots.

Development of tissue inflammation accompanied by NLRP3 inflammasome activation in rabbits infected with Treponema pallidum strain Nichols.

BACKGROUND: The inflammasome responses in Treponema pallidum infection have been poorly understood to date. This study aimed to investigate the expression of the nucleotide-binding leucine-rich receptor protein 3 (NLRP3) inflammasome in the development of tissue inflammation in rabbits infected with T. pallidum. METHODS: Forty-five rabbits were randomly assigned to a blank group or an infection group, and the latter was divided into no benzathine penicillin G (BPG) and BPG treatment subgroups. Rabbits in the infection group were injected intradermally with 0.1 mL of a 107/mL T. pallidum suspension at 10 marked sites along the back, and the blank group was treated with normal saline. The BPG treatment subgroup received 200,000 U of BPG administered intramuscularly twice, at 14 d and 21 d post-infection. The development of lesions was observed, and biopsies of the injection site and various organs, including the kidney, liver, spleen, lung, and testis, were obtained for NLRP3, caspase-1, and interleukin-1ß (IL-1ß) mRNA analysis during infection. Blood was also collected for the determination of IL-1ß concentration. RESULTS: Rabbits infected with T. pallidum (both the BPG treatment and no BPG treatment subgroups), exhibited NLRP3 inflammasome activation and IL-1ß secretion in cutaneous lesions, showing a trend in elevation to decline; NLRP3 mRNA expression reached a peak at 18 d in the BPG treatment subgroup and 21 d in the no BPG treatment subgroup and returned to "normal" levels [vs. the blank group (P > 0.05)] at 42 d post-infection. The trend was similar to the change in cutaneous lesions in the infected rabbits, which reached a peak at 16 d in the BPG treatment subgroup and 18 d in the no BPG treatment subgroup. NLRP3, caspase-1, and IL-1ß mRNA expression levels were slightly different in different organs. NLRP3 inflammasome activation was also observed in the kidney, liver, lung, spleen and testis. IL-1ß expression was observed in the kidney, liver, lung and spleen; however, there was no detectable level of IL-1ß in the testes of the infected rabbits. CONCLUSIONS: This study established a clear link between NLRP3 inflammasome activation and the development of tissue inflammation in rabbits infected with T. pallidum. BPG therapy imperceptibly adjusted syphilitic inflammation.

Comparison of Clinical and Laboratory Characteristics of General Paresis and Non-Neurosyphilis Dementia.

BACKGROUND: The differential diagnosis of general paresis (GP) and non-neurosyphilis (NS) dementia is not clearly defined. The present study examined the differences in clinical and laboratory features of GP and non-NS dementia. MATERIALS AND METHODS: We retrospectively examined clinical and laboratory features of 85 GP patients and 196 non-NS dementia patients. Data were collected from Zhongshan Hospital between June 2005 and June 2014. RESULTS: The GP group had a higher percentage of males (83.53%, 71/85) and younger median age ([52 [interquartile range 47.0-61.0] vs. 76 [68.3-82.0] years) than the non-NS dementia group. GP have higher Mini-Mental State Examination (MMSE; Z = -5.809; p = 0.000) than non-NS dementia. Distribution of CDR scores were significantly higher in the non-NS group than GP group (χ2 = 29.153; p = 0.000). The laboratory findings showed significantly different total cholesterol (CH), low-density lipoprotein CH and homocysteine levels between the 2 groups. Serologic testing for syphilis revealed that the GP group had higher seropositive rapid plasma reagin (RPR) and Treponema pallidum particle agglutination (TPPA) rates than the non-NS dementia group (96.47% [82/85] vs. 0.51% [1/196], Z = -2.663, p = 0.008; 100% [85/85] vs. 1.02% [2/196], Z = -2.663, p = 0.008). Interestingly, cerebrospinal fluid (CSF) biochemical indices, including pleocytosis rates, increased protein levels, and positive RPR and TPPA rates in the GP group were higher than that in the non-NS dementia group. CONCLUSIONS: Based on these preliminary data, patients with clinically evident symptoms of dementia, especially middle-aged males, should undergo blood tests for syphilis. All patients with positive serology results should undergo CSF examinations to diagnose GP dementia before further pharmaceutical and behavioral interventions.

Novel predictors of neurosyphilis among HIV-negative syphilis patients with neurological symptoms: an observational study.

BACKGROUND: Known predictors of neurosyphilis were mainly drawn from human immunodeficiency virus (HIV)-infected syphilis patients, which may not be applicable to HIV-negative populations as they have different characteristics, particularly those with neurological symptoms. This study aimed to identify novel predictors of HIV-negative symptomatic neurosyphilis (S-NS). METHODS: From June 2005 to June 2015, 370 HIV-negative syphilis patients with neurological symptoms were recruited, consisting of 191 S-NS patients (including 123 confirmed neurosyphilis and 68 probable neurosyphilis patients) and 179 syphilis/non-neurosyphilis (N-NS) patients. Clinical and laboratory characteristics of S-NS were compared with N-NS to identify factors predictive of S-NS. Serum rapid plasma reagin (RPR), Treponema pallidum particle agglutination (TPPA), and their parallel testing format for screening S-NS were evaluated. RESULTS: The likelihood of S-NS was positively associated with the serum RPR and TPPA titers. The serum TPPA titers performed better than the serum RPR titers in screening S-NS. The optimal cut-off points to recognize S-NS were serum RPR titer ≥1:4 and serum TPPA titer ≥1:2560 respectively. A parallel testing format of a serum RPR titer ≥1:2 and serum TPPA titer ≥1:1280 screened out 95.8% of S-NS and all confirmed cases of neurosyphilis. S-NS was independently associated with male sex, serum RPR titer ≥1:4, serum TPPA titer ≥1:2560, and elevated serum creatine kinase. Concurrence of these factors increased the likelihood of S-NS. CONCLUSIONS: Quantitation of serum TPPA is worthwhile and performs better than serum RPR in screening S-NS. Serum RPR, serum TPPA, male sex, and serum creatine kinase can predict S-NS. Moreover, patients with both a serum RPR titer <1:2 and a serum TPPA titer <1:1280 have a low probability of S-NS, suggesting that it is reasonable to reduce lumbar punctures in such individuals.

Evaluation of the boson chemiluminescence immunoassay as a first-line screening test in the ECDC algorithm for syphilis serodiagnosis in a population with a high prevalence of syphilis.

We developed a new Boson chemiluminescence immunoassay (CIA) and evaluated its application with cross-sectional analyses. Our results indicated that the Boson CIA demonstrated strong discriminatory power in diagnosing syphilis and that it can be used as a first-line screening test for syphilis serodiagnosis using the European Centre for Disease Prevention and Control algorithm or as a confirmatory test when combined with a patient's clinical history.

Analysis of 3 algorithms for syphilis serodiagnosis and implications for clinical management.

BACKGROUND: Algorithms for the diagnosis of syphilis continue to be a source of great controversy, and numerous test interpretations have perplexed many clinicians. METHODS: We conducted a cross-sectional study of 24 124 subjects to analyze 3 syphilis testing algorithms: traditional algorithm, reverse algorithm, and the European Centre for Disease Prevention and Control (ECDC) algorithm. Every serum sample was simultaneously evaluated using the rapid plasma reagin, Treponema pallidum particle agglutination, and chemiluminescence immunoassay tests. With the results of clinical diagnoses of syphilis as a gold standard, we evaluated the diagnostic accuracy of the 3 syphilis testing algorithms. The κ coefficient was used to compare the concordance between the reverse algorithm and the ECDC algorithm. RESULTS: Overall, 2749 patients in our cohort were diagnosed with syphilis. The traditional algorithm had the highest negative likelihood ratio (0.24), a missed diagnosis rate of 24.2%, and only 75.81% sensitivity. However, both the reverse and ECDC algorithms had higher diagnostic efficacy than the traditional algorithm. Their sensitivity, specificity, and accuracy were 99.38%-99.85%, 99.98%-100.00%, and 99.93%-99.96%, respectively. Moreover, the overall percentage of agreement and κ value between the reverse and the ECDC algorithms were 99.9% and 0.996, respectively. CONCLUSIONS: Our research supported use of the ECDC algorithm, in which syphilis screening begins with a treponemal immunoassay that is followed by a second, different treponemal assay as a confirmatory test in high-prevalence populations. In addition, our results indicated that nontreponemal assay is unnecessary for syphilis diagnosis but can be recommended for determining serological activity and the effect of syphilis treatment.