献血人群梅毒螺旋体免疫印迹法IgG/IgM抗体检测及应用分析

Detection of IgG/IgM antibody of Treponema Pallidum by Western Blotting in blood donors and its application

目的了解广州地区献血人群ELISA梅毒抗体阳性中免疫印迹法TP-IgG/IgM抗体检测情况,探讨TP-WB在本地区献血者梅毒检测应用的意义。方法采用抗-TP ELISA试剂(A:北京万泰、B:上海科华)对本中心采集的无偿献血者血浆标本作抗-TP检测,2015年1—6月随机收集208例呈反应性标本(包括双试剂,单试剂,灰区)的抗-TP ELISA的S/CO值,进行梅毒螺旋体明胶颗粒凝集试验(TPPA)确认和欧蒙免疫印迹法(TP-WB)检测;分析TP-IgG-WB和TP-IgM-WB阳性的P15/P17/P45/P47条带情况;以WB为参照对A、B 2试剂检测结果的S/CO值进行ROC曲线分析。结果 208例TP-ELISA检测为单试剂阳性5例,TPPA与TP-WB均为阴性,ELISA双试剂阳性203例,TPPA检测阳性165例,阳性率为79.30%(165/208)。208例标本中全部进行TP-IgG-WB检测阳性147例,阳性率70.67%(147/208),不确定4例;其中只有106例标本同时进行了TP-IgM-WB检测,检出阳性为4.85%(5/103),同时为IgG阳性,不确定3例,TPPA与TP-WB检测阳性结果存在差异(P<0.01);147例TP-IgG-WB阳性条带抗体谱(P15/P17/P45/P47)阳性率比较高,其中条带P15/P45阳性率高达93.2%,5例TP-IgM-WB阳性中均检出P15/47条带;ROC曲线分析中,A试剂S/CO的ROC曲线曲线下面积AUC为0.902(95%CI:0.851—0.952,P<0.05),约登指数为0.745,S/CO最佳临界点为14.9;B试剂S/CO的ROC曲线AUC为0.946(95%CI:0.917—0.976,P<0.05),约登指数为0.784,S/CO最佳临界点为13.6。结论广州地区献血人群中梅毒螺旋体抗体不合格人群中主要以IgG抗体阳性为主,即多为既往感染;不同抗-TP ELISA试剂有其对应的最佳S/CO阈值,可以通过S/CO值预测梅毒感染确证试验的阳性结果;梅毒螺旋体抗体的免疫印迹法可作为采供血机构确认梅毒感染的有益补充。

Objective To evaluate the immunoglobulin M and G Western blotting(WB)and ELISA for screening antibodies to Treponema pallidum(TP)in blood donors,and to explore the application of TP-WB for syphilis screening in local blood donors.Methods Anti-TP ELISA reagents(A:Beijing Wantai,B:Shanghai Kehua)were used for anti-TP detection on plasma samples of voluntary blood donors collected at our center.From January to June 2015,208 reactive samples(including dual reagents,single reagent,gray areas)were randomly collected for S/CO values of anti-TP ELISA for TPparticle agglutinationassay(TPPA)confirmation and Oumeng TP-WBdetection.P15/P17/P45/P47 bands of TP-IgG-WB and TP-IgM-WB positive samples were analyzed.ROC curve analysis on the S/CO values of test results of A and B reagents was performed using WB as a reference.Results Among 208 ELISA reactive cases,5 cases,reactive to one assay,were all negative for TPPA and TP-WB,and 165 out of 203 cases,reactive to dual assays,were positive for TPPA,with a positive rate of 79.30%(165/208).All 208 ELISA reactive cases were subjected to IgG WB,147 were positive for TP-IgG,with a positive rate of 70.67%(147/208),and 4 were undetermined;only 106 samples were tested for TP-IgM-WB in parallel,5 were IgG positive,with a positive rate of 4.85%(5/103),and 3 were undetermined.There were statistically significant differences between positive results of TPPA and TP-WB(P<0.01).The positive rate of 147 TP-IgG-WB bands(P15/P17/P45/P47)was relatively high,of which the positive rate of P15/P45 bands was as high as 93.2%.P15/47 bands were detected in all the 5 TP-IgM-WB cases;In ROC curve analysis,the area under the ROC curve of A and B reagent S/CO was 0.902(95%CI:0.851—0.952,P<0.05)vs 0.946(95%CI:0.917—0.976,P<0.05),the Youden index was 0.745 vs 0.784,and the S/CO optimal cut-off point was 14.9 vs 13.6.Conclusion Positive anti-TP IgG was dominant in syphilis deferral among blood donors in Guangzhou,suggesting most of positive cases were past infections.Different anti-TP ELISA assays have their corresponding optimal S/CO thresholds,and the syphilis infection confirmation test can be predicted by the S/CO value;WB,as an additional test,is contribute to the safety of syphilis screeningin blood donors.