我国肠道病毒71型中和抗体标准品的国际单位赋值

Assignment of international unit for national enterovirus 71 neutralizing antibody standard in China

目的在率先创建了我国肠道病毒71型(EV-A71)中和抗体(NTAb)国家标准品(NS),之后建立国际标准品(IS)的背景下,对我国NS进行国际单位(IU)赋值.方法通过包括全球7个国家和地区,18个实验室(Lab)参加的国际协作标定研究,对NS和IS同时进行协作标定,并分别采用疫苗免疫婴幼儿血清和自然感染成人血清进行适用性研究,评价NS对实验室间和毒株间检测的影响,并对其进行国际单位赋值.结果共17个Lab应用统一的C4毒株完成了全部协作标定.其中,Lab14和Lab17还同时采用B4毒株完成全部标定.各实验室间检测结果具有相同趋势,NS(1000U/ml)和IS(1000IU/0.5ml)的NTAb几何平均滴度(GMT)分别为621和640.分别以NS和IS标化,当均应用C4毒株时,各实验室间检测变异系数(GCV)分别从原始效价的71%降至40%和38%;当采用不同毒株(C4、B4型)时,Lab14的检测差异从原始效价的2.11倍降至1.36、1.84倍;而Lab17的检测差异从2.49倍降至0.82、1.39倍.结论EV-A71NTAbNS中和活性良好,定量准确,能有效降低实验室间和毒株间检测误差,以IS标定应赋值1940IU/ml,用于EV-A71NTAb检测方法的质量控制和标化.

Objective To set up the Chinese enterovirus 71(EV-A71) neutralizing antibody (NTAb) National Standard with international unit (IU) based on our established EV-A71NTAb.Methods An international collaborative calibration study on EV-A71NTAb was carried out in 7countries/regions with a total of 18La-boratories (Lab) .Both National and International Standards of the EV-A71NTAb were calibrate at the same time to assign the National Standard by International Standard with the IU.The applicability of infant serum immunized with EV-A71vaccine and adult serum naturally infected EV-A71were studied to evaluate the effect of National Standard at laboratories and detection strains.Results There were 17Labs completed all calibra-ted detection with united C4EV-A71strain.Among them,Lab14and Lab17also used B4EV-A71to complete all detections at the same time.The tendency of results from different Labs was consistent,and GMTs of the National Standard and International Standard were 621 (1 000U/ml) and 640 (1 000IU/0.5ml),respective-ly.With the National Standard and International Standard,the GCV of NTAb among different Labs declined from 71% (titer) to 40%and 38% (relative potency),respectively.And the ratio of relative potency between C4and B4strain (C4/B4) declined from 2.11times (titer) to 1.36,1.84times in Lab14,and from 2.49times (titer) to 0.82,1.39times in Lab17,respectively.Conclusions EV-A71NTAb NS showed high EV-A71 neutralizing activity and accurate quantitative accuracy.It could reduce the error remarkably among different Labs and strains.Calibrated by International Standard,the National Standard should be assigned at 1 940IU/ml to be used for the quality control and standardization of EV-A71NTAb detections.