We utilized polyethylenimine (PEI) and Glu solution to immobilize the antibody of Treponema Pallidum on the silver electrode of piezoelectric quartz crystal and detect the standard antigen solution at different concentration. The antibody keeps the intrinsic Y type molecular structure revealed by AFM. The resonant range of the sensor is between 5 x 10(-5) - 1.25 x 10(-4) g/mL and the correlation coefficient is 0.9976, the optimal resonance pH is 7.5. We found the sensor having good selectivity in comparison with the method using BSA. At last, a discussion on the reproducibility of the sensor is presented.
Antibodies, Bacterial ; immunology ; Antigens, Bacterial ; analysis ; Biosensing Techniques ; instrumentation ; Equipment Design ; Immunoassay ; instrumentation ; methods ; Microelectrodes ; Polyethyleneimine ; Quartz ; Treponema pallidum ; 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 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

BACKGROUND: We compared the results of automated and quantitative methods for the diagnosis of syphilis, Mediace Rapid Plasma Reagin (RPR) and Mediace Treponema pallidum Latex Agglutination (TPLA) (Sekisui Chemical Co., Ltd, Japan) with those of conventional methods. METHODS: Sera from 3,896 persons who had health checkups between December 2005 and November 2006 were included in the evaluation of positive rates and biological false positives (BFP) for Mediace RPR and TPLA. In addition, 134 patients' sera positive for automated Mediace RPR or TPLA were tested for VDRL and TPHA. Discrepancies between TPLA and TPHA results were confirmed by the RecomBlot Treponemal IgG/IgM (Mikrogen GmbH, Germany). Automated Mediace RPR and TPLA were performed using the Hitachi 7600 chemistry autoanalyzer (Hitachi, Japan). Samples with positive Mediace RPR and negative TPLA results were defined as BFP. RESULTS: Positive rate of automated Mediace RPR was 0.23% (9/3,896). BFP of the Mediace RPR was 0.18%. Positive rate of automated TPLA was 1.62% (37/2,284). Among the 134 patients' sera, 33 (24.6%) showed a discrepancy between conventional VDRL and automated Mediace RPR results: Among 31 Mediace RPR(+)/VDRL(-) sera, 13 were positive and 18 were negative for TPLA. The remaining 2 sera of discrepancy with Mediace RPR(-)/VDRL(+) were all positive for TPLA. There were seven sera that showed a discrepancy between automated TPLA and TPHA results: Two sera with Mediace RPR(+)/TPLA(-)/TPHA(+) showed negative recomBlot Treponemal IgG/IgM results, and among five sera with TPLA(+)/TPHA(-), three demonstrated IgG or IgM by recomBlot Treponemal IgG/IgM. CONCLUSIONS: The results of comparison data demonstrated that automated TPLA results had a high concordance with recomBlot Treponemal IgG/IgM results. Moreover, there are additional advantages of automated methods such as quantitative detection, low infection risk, and no influence by human handling.
Adolescent ; Adult ; Aged ; Aged, 80 and over ; Agglutination ; False Positive Reactions ; Female ; Humans ; Immunoglobulin G/analysis ; Immunoglobulin M/analysis ; Latex Fixation Tests ; Male ; Middle Aged ; Reagent Kits, Diagnostic ; Reagins/*blood ; Syphilis/*diagnosis ; Syphilis Serodiagnosis/*methods ; Treponema pallidum/*immunology/isolation & purification