基于多聚化重组抗原的检测戊型肝炎病毒IgM与IgG抗体的ELISA的建立及初步评估

Development and Evaluation of ELISAs for Anti-hepatitis E Virus IgM and IgG Detection Based on Polymerized Recombinant Antigen

建立并评估分别检测戊型肝炎 (戊肝 )病毒IgM与IgG抗体的捕获法及间接法ELISA。以原核表达的多聚化重组HEV蛋白为抗原 ,建立戊肝捕获法IgMELISA(E2 -IgM )和间接法IgGELISA(E2 -IgG)。利用 2 9只实验感染猴系列血清及多份临床急性肝炎血清、正常人血清以及单克隆抗体评估所建立的方法的敏感性与特异性 ,并与商品化试剂 (Genelabs公司抗 -HEVIgG和IgM试剂 ,GL -IgG/GL -IgM )进行比较。 2 9只恒河猴E2 -IgM和E2-IgG的阳转率均为 10 0 % ,其中 75 %在感染后 4周内阳转 ,均早于ALT异常时间。E2 -IgM持续 2～ 14周 ,平均6周 ;E2 -IgG在 70周时仍无一阴转。GL -IgG阳转率为 79 3% ( 2 3/ 2 9) ,多数晚于ALT异常时间 ,平均持续约18周 ,但最长为 1只在感染后 70周时仍为阳性。用E2 -IgM试剂盒检测 92 8份正常人血清 ,仅 2份OD值略高于0 2。检测 5 10份临床急性肝炎血清 ,可明显将其区分为 2个部分 ,一个部分OD值小于 0 2 ,其OD值分布与正常人相似 ;另一个部分OD值大于 0 4,共 131份 ,其中 10 9份大于 1 0。可能分别对应于急性肝炎中的非戊肝患者和戊肝患者。 119份非甲～丙急性肝炎中 ,E2 -IgM阳性 5 7份 ,GL -IgM阳性 2 9份 (E2 -IgM均阳性 )。 5 0 6 0份普通人群血清的E2 -IgGOD值在 0 2以下 。

This paper focused on development and evaluation of anti-μ chain IgM ELISA and indirect ELISA for IgG antibodies against hepatitis E virus(HEV).Prokaryotic expressed polymerized recombinant HEV protein NE2 was used as antigen to develop two ELISA methods for anti-HEV IgM(E2-IgM)or IgG(E2-IgG)detection.Serial serum samples of twenty-nine HEV experimentally infected Rhesus monkeys were used to understand the dynamics of anti-HEV IgM and IgG detected by E2-IgM or E2-IgG as well as IgG detected by a generally used commercial kit(Genelabs, anti-HEV IgG,GL-IgG).Sera of 928 normal individuals and 510 clinical acute hepatitis patients were detected for anti-HEV IgM using E2-IgM,among them 200 patients were detected by E2-IgG at the same time.Sera of 5060 normal population were detected for anti-HEV IgG using E2-IgG.Sera of 119 non-A to C acute hepatitis cases were detected parallel for anti-HEV IgM using E2-IgM and a commercial IgM kit(GL-IgM).Two anti-HEV monoclonal antibodies which can capture HEV directly were used in blocking test for the evaluation of the specificity of E2-IgM and E2-IgG. The results showed the positive seroconversion rate of HEV by E2-IgM and E2-IgG methods in 29 HEV infected monkeys were both 100%,of which 75% were conversed within first 4 weeks post-infection,all earlier than the beginning time of ALT abnormality. Compared with 79.3% seroconversion rate by GL-IgG, 75% seroconversed within the first six weeks,much later than ALT abnormality. The seroconversion rate by E2-IgM lasted from two to fourteen weeks,with a mean of six weeks.Seroconversion by E2-IgG was a little later than E2-IgM, but none converted to negative at 70 weeks after infection. The average lasting time of GL-IgG was 18 weeks, only one monkey's IgG remained to be detectable by GL-IgG at 70weeks post infection. Among 928 normal people samples detected by E2-IgM,only 2 had OD value a little higher than 0.2.Two groups could be easily differentiated from 510 clinical acute hepatitis patients detected by E2-IgM ,one group was the same as detected in normal people with OD value lower than 0.2, the other group including 131 patients had OD value higher than 0.4,among them 109 samples were higher than 1.0. It suggested these two groups were corresponding to non-hepatitis E and hepatitis E patients.Patients with E2-IgM positive also had higher E2-IgG OD.Among 119 non-A to C acute hepatitis patients detected by E2-IgM and GL-IgM parallelly,57 were E2-IgM positive,including all the 29 patients who were positive by GL-IgM.Ten E2-IgM positive samples could be blocked by anti-HEV monoclonal antibodies(MAbs)from 66.4%～94.8%,with an average blocking rate of 86.6%.The OD values of 5060 normal population detected by E2-IgG formed a peak close to logarithm normal distribution with the mean of 0.022,and distributed evenly in samples with OD value higher than 0.4.Two groups also could be differentiated from 200 acute hepatitis patients,one with OD value lower than 0.2 as same as normal people,and the other with OD value higher than 1.0 formed another peak with peak OD value of 2.5,among the latter peak most were E2-IgM positive.Anti-HEV MAbs also could block E2-IgG effectively,and the blocking rate of Fab fragments of MAbs were the same as whole MAbs,which suggested that the blocking is epitope specific.The developed IgM and IgG ELISA methods have good specificity and sensitivity.IgM method is suitable for diagnosis of hepatitis E virus clinically infected,and the IgG method is suitable to diagnose hepatitis E virus infection in the past.