Researches On The Rapid Diagnosis, Immunology, And Molecular Biology Of Syphilis

Background & objectives: As a sexually transmitted infection, Syphilis has beenassociated with an increased risk of HIV transmission and acquisition. Most infectedindividuals have no symptoms. It leads to further transmission and prevalence ofinfection that patients can not receive early treatment. Cases on the reprevalence ofsyphilis have been reported in many countries including China for recent years. Thereports highlight the need for urgent medical approaches to stop syphilis transmissionin the world. Several simple, point-of-care Treponema-specific rapid diagnostic testswith high sensitivities and specificities have been selected by WHO. They willpopularize these rapid tests to the globe. These new rapid diagnostic tests based onrecombinant antigen will replace those traditional confirmatory tests and performwide bound screening of syphilis more efficiently. Although patients withseroresistance usually were considered as clinical cure, they have to continuously besuffered from the risk of relapse. The object of this study is to search the relationshipbetween seroresistence and immunological status. One of the final aims is to makepatients achieve the general health in psychology and physiology. At the beginning of1999, the CDC embarked on an effort to promote syphilis elimination as a nationalgoal. One facet of the plan was to monitor syphilis transmission in areas ofendemicity and prevent outbreaks that result from dissemination of syphilis into areasthat had not experienced recent transmission. Hence we must develop the molecularsubtyping of Tp to provide better thoughts and large number of data for studyingepidemiologic relationships of syphilis. Besides these, the Tp-DNA quantificationwould become an innovative method to observe curative effect and find the causation of seroresistence.Method:1.Rapid diagnosis of syphilis1) To Evaluate the performance and the operational characteristics of several rapidtests based on recombinant Tp antigen against treponema pallidum haemagglutinationassay.2) To compare syphilis rapid tests based on recombinant of Tp antigen with RPRtest in order to assess their sensitivities and specificities.2. Studies of immunology of treponema pallidum.1) To retrospectively analyze the incidence of seroresistance and relative fhctors, suchas age, gender, original titer, course of disease, various medication, and etc in 131syphilis patients.2) To analyze the immunological characteristics among three groups—pretreatmentgroup, seroresistence group and healthy group.3. Molecular biology of treponema pallidum.1) Amplification of the arp gene using nested PCR and RELP analysis for the tpr genein order to differentiate molecular subtyping of TP. Molecular subtyping is basic tostudy the endemic epidemiology of Tp.2) Comparing the variety of Tp DNA loads in blood between untreated patients andpatients who had been treated for six months. The half-quantification of Tp-DNA inperipheral blood were determined by RT-PCR.Results:1. 1) The rapid treponemal tests showed good performance especially their highsensitivities in serum tests. The serum sensitivity of Abbott Determine Syphilis Tp testis 100% and its specificity is 98.9%. The serum sensitivity of SD BIOLINE Syphilis3.0 test is 95.5% and its specificity is 97.9%. The serum sensitivity ofVISITECT-SYPHILIS test is 94.0% and its specificity is 98.1%. The serumsensitivity of Syphicheck-WB test is 67.4% and its specificity is 98.8%.2) TPHA was used as a gold standard for dectecton of TP. Results are shown asbelow: The serum sensitivity of Abbott Determine Syphilis Tp test is 100% and its specificity is 98.4%. The serum sensitivity of RPR test is 65.1% and its specificity is98.4%.2. 1) There was no significant difference in age and gender for seroresistantindividuals. There was a statistiacally significant difference among courses of disease,antibodies titer and medication categories. The patients who had original titer withmore than 1:8, latent course and mavcrolide therapy had higher risk for seroresistancethan those who had a lower titer, primary course and benzathine penicillin therapy.2) There was no significant difference among groups pretreatment, seroresistenceand normal groups by analysing of peripheral blood lymphocyte immunophenotypesin syphilitic patients with flow cytometry.3. 1) We were unable to detect TP in all seroresistent patients and 5 cases of beingcured. 5 cases of 30 patients who had not been treated were found posivtive for TP.Molecular subtype were detected by nested PCR as follows: 13c, 14b, 14b, 14d and14d.2) The Tp DNA loads in blood of untreated patients were much higher than thosewho had been treated for six months.Conclusions:1. These 4 syphilis rapid tests are more sensitive in serum than in whole blood. Basedon their performances and operational characteristics, they are suitable for using inSTD clinic settings for the diagnosis of syphilis. The rapid test based on therecombinant of Tp antigen shows significantly higher sensitivity than RPR test does.2. Latent group, high primary titer group, or group treated by mavcrolide therapy,with resistant syphilis present remarkable difference compared with others groups onstatistic. Analysis of lymphocyte immunophenotypes in syphilitic patients showed nodeference among groups. The reason is likely to be shortage of the sample.3. We should develop a more sensitive method to determine the DNA loads in theperipheral blood of syphilis patients. The relationship between seroresistence andDNA loads needs to be further demonstrated. The Tp DNA loads in the blood ofuntreated patients were remarkably different from the loads of patients who had beentreated.