OBJECTIVETo assess the sensitivity, specificity, and feasibility of 4 recombinant Treponema pallidum antigen-based rapid tests in the diagnosis of syphilis.

METHODSA total of 970 outpatients were selected from the Sexually Transmitted Diseases Centre of Peking Union Medical College Hospital. Venous blood was collected and serum was extracted. T. pallidum antibodies in whole blood, anticoagulant whole blood, and serum were detected using 4 recombinant T. pallidum antigen-based rapid tests. T. pallidum haemagglutination test (TPHA) was considered as the gold standard for the detection of T. pallidum specific antibodies in serum. The sensitivities and specificities of four methods were analyzed.

RESULTSThe sensitivities and specificities of Abbott Determine Syphilis TP test, SD-BIOLINE Syphilis 3.0 test, VISITECT-SYPHILIS test, and Syphicheck-WB test for serum specimens were 100% and 98.9%, 95.7% and 98.0%, 94.6% and 98.2%, 68.1% and 98.9%; for whole blood were 74.1% and 99.5%, 87.9% and 99.4%, 73.2% and 99.7%, 64.7% and 99.7%. The observed sensitivities of the 4 rapid diagnosis tests were not significantly different with TPHA (P > 0.05).

CONCLUSIONSThe 4 rapid tests show good performance and characteristics in the diagnosis of syphilis. Furthermore, they are more sensitive for serum specimens than whole blood.

Antigens, Bacterial ; immunology ; Humans ; Quality Control ; Recombinant Proteins ; immunology ; Sensitivity and Specificity ; Syphilis ; diagnosis ; Treponema pallidum ; immunology

There are many serologic tests for syphilis. By means of the usual serologic tests, it is not possible to differentiate between patients who need therapy and those who are cured. In this paper I want to discuss the scientific developments and demonstrate the results of immunologic research in syphilis, which makes it possible to differentiate between treated and untreated cases.
Antibodies, Bacterial/analysis ; Chromatography, Gel ; Electrophoresis, Starch Gel ; Fluorescent Antibody Technique ; Hemagglutination Tests ; Human ; Immunoglobulin G/analysis ; Immunoglobulin M/analysis ; Syphilis/immunology* ; Syphilis Serodiagnosis* ; Treponema pallidum/immunology

OBJECTIVETo summarize the clinical features and analyze the serologic test results of latent syphilis.

METHODSThe clinical data of 601 patients with latent syphilis who were treated in the sexually transmitted disease centre of Peking Union Medical College Hospital between January 2001 and November 2007 were retrospectively analyzed.

RESULTSOf the 601 cases of latent syphilis, there were 174 cases of early latent syphilis(EL), 170 cases of late latent syphilis(LL), and 257 cases of unknown latent syphilis. Male to female ratio was 0.74:1256 males and 345 females, respectively). Patients aged 20-39 years accounted for the largest proportion. Non-marital sexual intercourse was the main route of infection. Forty-six patients (7.65%) were co-infected with other sexually transmitted diseases. A total of 251 cases of latent syphilis (41.76%) were confirmed when the patients were receiving tests for other sexually transmitted diseases or suspected sexually transmitted diseases. Of the 601 patients with EL, LL and unknown latency, the proportion of serum rapid plasma reagin(RPR) titers higher than or equal to 8 were 72.99% (127/174), 52.94% (90/170), and 60.31%(155/257), respectively. Compared with the early syphilis, serological negative conversion rate was significantly lower after treatment for l2 months in the early latent syphilis patients (P=0.044).

CONCLUSIONEducation and awareness raising on syphilis should be strengthened to lower the prevalence of latent syphilis.

Adult ; Female ; Humans ; Male ; Middle Aged ; Retrospective Studies ; Syphilis, Latent ; blood ; diagnosis ; immunology ; therapy ; Young Adult

OBJECTIVETo study the rate of human immunodeficiency virus (HIV) seroconversion, HIV transmission and related risk factors among injecting drug users (IDUs) in an area of Sichuan province.

METHODSIn November 2002, a community-based baseline survey was conducted to recruit 333 HIV-seronegative IDUs for a prospective cohort study in Xichang county of Sichuan province, China. Follow-up visits were carried out every 6 months to study the situation of drug use, sexual behaviors of the IDUs and blood specimens were collected to test for antibodies against HIV and syphilis.

RESULTSDuring a 24-month follow-up period, cohort retention rate and HIV incidence were 75.7% and 2.53 per 100 person-years [95% confidence interval (CI): 1.10-3.97)], respectively. Multivariate Poisson regression model showed that risk factors which were significantly associated with HIV seroconversion would include: ethnicity (RR = 12.42; 95% CI: 2.72-56.74, P = 0.0012) and needle or syringe sharing in the past 3 months (RR = 4.06; 95% CI: 1.29-12.81, P = 0.0168). Syphilis seroconversion in this cohort was 4.71 per 100 person-years (95% CI: 2.59-6.82). In multivariate Poisson regression being female (RR = 4.42; 95% CI: 1.78-10.99, P = 0.0014) appeared to be the only factor which was significantly associated with syphilis seroconversion.

CONCLUSIONOur study results showed that there was a rapid transmission of HIV and syphilis among IDUs in Sichuan province, suggesting that effective intervention should be urgently taken.

Cohort Studies ; HIV Seropositivity ; immunology ; transmission ; Humans ; Prospective Studies ; Risk Factors ; Sexual Behavior ; Substance Abuse, Intravenous ; Syphilis ; immunology ; transmission

OBJECTIVETo clone tpn17 and tpn47 genes of Treponema pallidum and then construct their prokaryotic expression systems,to establish ELISAs based on rTpN17 and rTpN47 as antigens and to evaluate the sensitivity and specificity of the ELISAs for detection of serological diagnosis of syphilis.

METHODSThe whole length of tpn17 and tpn47 genes was amplified by PCR and then their prokaryotic expression systems were constructed. SDS-PAGE was used to measure the expression of the target recombinant proteins rTpN17 and rTpN47. Ni-NTA affinity chromatography was applied to extract rTpN17 and rTpN47, while Western blot was performed to determine the specific immunoreactivity of rTpN17 and rTpN47. By using rTpN17 and rTpN47 as the coated antigen, respectively, ELISAs (rTpN17-ELISA and rTpN47-ELISA) were established to detect serum samples from 200 healthy individuals, 25 RA patients, 17 SLE patients and 211 syphilis patients. The detection effects of the ELISAs were compared to those of TRUST and TPHA.

RESULTThe sequence similarity of the cloned tpn17 and tpn47 genes was 100 % compared with the corresponding sequences in GenBank. The expression outputs of rTpN17 and rTpN47 were approximately 37.2 % and 26.8 % of the total bacterial proteins, respectively. Both the extracted rTpN17 and rTpN47 could take place remarkable conjugation reactions to the sera with positive antibody against Treponema pallidum.The positive detection rate of TPHA (99.1%) was the highest (P<0.001). The positive detection rates of rTpN17-ELISA (85.3 %) and rTpN47-ELISA (84.3 %) were similar (P>0.05). The positive detection rates of TRUST (72.5 %) was lower than that of rTpN17-ELISA (P=0.001) but similar to that of rTpN47-ELISA (P=0.014). The detection results of all the serum samples from healthy individuals, RA patients and SLE patients were negative, whereas 7.1 % (3/42) of the samples from RA or SLE patients were positive.

CONCLUSIONrTpN17 and rTpN47 are still maintaining their original immunoreactivity. The ELISAs using rTpN17 or rTpN47 as the antigen are rapid, simple and convenient, higher sensitivity and specificity methods for serological screening and detection of syphilis.

Antibodies, Bacterial ; Antigens, Bacterial ; Blotting, Western ; Enzyme-Linked Immunosorbent Assay ; methods ; Female ; Humans ; Male ; Syphilis ; diagnosis ; Syphilis Serodiagnosis ; Treponema pallidum ; chemistry ; immunology ; isolation & purification

Syphilis, a chronic bacterial infection caused by the spirochete Treponema pallidum subsp. pallidum, remains a public health concern worldwide. Syphilis control is largely dependent upon early identification and prompt treatment. The diagnosis of syphilis is mainly based on laboratory tests, especially serology and dark-field microscopy. In recent years, recombinant Treponema pallidum antigen-based rapid tests, polymerase chain reaction, and immunoglobulin M antibody detection have also shown certain sensitivities and specificities for syphilitic patients at different stages.
Antigens, Bacterial ; blood ; Humans ; Immunoglobulin M ; blood ; Polymerase Chain Reaction ; methods ; Sensitivity and Specificity ; Syphilis ; blood ; diagnosis ; Syphilis Serodiagnosis ; Treponema pallidum ; immunology ; isolation & purification

OBJECTIVETo investigate the incidence of seroresistance of syphilis and analyze its relevant factors.

METHODSThe clinical data of 131 patients with syphilis were retrospectively analyzed. The incidence of seroresistance was investigated and the correlation between seroresistance and factors including age, gender, original titer, disease course, and medications were analyzed.

RESULTSThe incidence of seroresistance was not significantly different among patients with different ages and genders, but was significantly different among patients with different disease courses, antibody titers, and medications. Patients with a baseline serum rapid plasma reagin (RPR) titer of greater than 1: 8, a latent course, or a macrolide therapy history had higher incidences of seroresistance (i. e., 61%, 45.6%, and 72.7% respectively) than those who had a lower RPR titer, a primary course, or a benzathine penicillin therapy history.

CONCLUSIONSyphilis patients with a high baseline RPR titer, a latent course, and a macrolides therapy are prone to be seroresistant.

Adolescent ; Adult ; Aged ; Female ; Humans ; Macrolides ; therapeutic use ; Male ; Middle Aged ; Reagins ; blood ; Syphilis ; blood ; diagnosis ; drug therapy ; immunology ; Syphilis Serodiagnosis ; methods ; Young Adult

Using recombinant TpNs proteins of Treponema pallidum as antigens, ELISAs are proved to be of higher sensitivity and specificity. However, they can be further increased by using multiple TpNs antigens. According to the epitope analysis, we firstly used linking primers PCRs to obtain an artificial fusion gene segment tpE17-47 containing epitopes of both TpN17 and TpN47. Subsequently, we conducted the prokaryotic expression systems of entire tpN17 and tpN47 genes and tpE17-47 fusion gene. SDS-PAGE analysis and BioRad Gel Image Analysis System showed that the recombinant proteins rTpN17, rTpN47 and rTpE17-47 expressed stably, with 36%, 20% and 28% yields of total bacterial protein, respectively. After purified by Ni-NTA affinity chromatography, all the three recombinant proteins could be recognized by T. pallidum antibody positive sera from syphilis patients. The positive rate of rTpE17-47-ELISA for detecting serum specimens in clinically 630 cases with syphilis was 98.6%. This rate was slightly higher than that by Treponema pallidum particle agglutination (TPPA) (97.9%) (P > 0.05), but significantly higher than those by rTpN17-ELISA (83.8%), rTpN47-ELISA (83.3%) and rapid plasma reagin (RPR) (72.1%) (P < 0.01). Furthermore, both ELISAs and TPPA for detecting the serum specimens in 25 cases with SLE, 36 cases with RA and 250 healthy cases were all negative. RPR showed positive in 1 case with SLE, 2 cases with RA and 2 healthy cases. This could be a novel serological screening or diagnostic method of syphilis with advantages of quickness, convenience, safety, sensitivity and specificity.
Amino Acid Sequence ; Antigens, Bacterial ; biosynthesis ; genetics ; Base Sequence ; Enzyme-Linked Immunosorbent Assay ; Humans ; Immunodominant Epitopes ; immunology ; Molecular Sequence Data ; Recombinant Fusion Proteins ; biosynthesis ; genetics ; immunology ; Sensitivity and Specificity ; Syphilis ; diagnosis ; microbiology ; Syphilis Serodiagnosis ; methods ; Treponema pallidum ; immunology

The changes of serum IgG antibody reactivity to protein antigens of Treponema pallidum after treatment of syphilis were observed using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blot. Until 9 to 12 months after treatment, it was seen that there was a loss of several antibodies and some diminution in their reactivity in primary, secondary and early latent syphilis, but no changes occurred in late latent and reinfected syphilis. In primary syphilis, there was a significant loss of two IgG antibodies to the treponemal antigens of molecular weights 68,500 and 47,000 at 11 months after treatment. According to our previous study, the treponemal antigen of molecular weight 68,500 was T. pallidum specific and appeared only in primary syphilis, and that of molecular weight 47,000 was one of the major antigens of T. pallidum. The reaction between serum IgG antibodies of 14 patients who had been treated for secondary, early latent and late latent syphilis 2 to 14 years ago and major antigens of T. pallidum was observed and any loss or decrease in reactivity was not discovered. From the results obtained, it was concluded that the observation of serum IgG antibody reactivity to protein antigens of T. pallidum is not helpful in evaluating the efficacy of treatment in secondary, early latent, late latent and reinfected syphilis. However, serum IgG antibodies to treponemal antigens of molecular weights 68,500 and 47,000 could possibly be useful in the assessment of the efficacy of treatment in primary syphilis.
Antibodies, Bacterial/*immunology ; Antigens, Bacterial/*analysis ; Blotting, Western ; Electrophoresis, Polyacrylamide Gel ; Humans ; Immunoglobulin G/*analysis ; Recurrence ; Syphilis/*diagnosis/immunology/therapy ; Time Factors ; Treponema pallidum/*immunology

Cell mediated immune responses play a prominent role in syphilis, which is caused by Treponema pallidum. The role of dendritic cells (DC) in the syphilitic infection is not well understood in human. In the present study, we studied interaction of T. pallidum with DC, generated from human peripheral blood mononuclear cells with GM-CSF and IL-4. After adding T. pallidum for 16 hours to immature DC at culture day 7, the change of surface antigens on DC was monitored by flow cytometry, the amount of IL-12 in culture supernatant of DC was measured by ELISA and T cell stimulatory capacity of DC was checked in mixed lymphocyte reaction (MLR). We have observed an efficient phagocytosis of T. pallidum by electron microscopy as early as 2 hours after addition of T. pallidum to DC. Interaction of DC with T. pallidum resulted in increased surface expression of CD83 which was proportionally increased according to the number of T. pallidum. Expressions of CD80, CD86 and HLA-DR on DC were slightly increased. The amount of IL-12 in the culture supernatant of DC was increased (1, 099pg/ml) after the addition of T. pallidum. T. pallidum-infected DC also displayed enhanced T cell stimulatory capacity in MLR. As seen from the above, we observed phagocytosis of T. pallidum by DC as early as 2 hours after addition of T. pallidum to DC and found that T. pallidum can stimulate DC maturation which mean that DC modulate an protective immune response during T. pallidum infection.
Cells, Cultured ; Dendritic Cells/cytology/*immunology/*microbiology ; Human ; Interleukin-12/metabolism/secretion ; Lymphocyte Culture Test, Mixed ; Microscopy, Electron ; Phagocytosis/immunology ; Receptors, Cell Surface/immunology/metabolism ; Support, Non-U.S. Gov't ; Syphilis/*immunology ; T-Lymphocytes/immunology ; Treponema pallidum/*immunology/ultrastructure