肠道病毒71型中和抗体的保护水平

目的通过检测乳鼠模型、健康婴幼儿和疫苗免疫后目标人群的肠道病毒71型(Enterovirus 71,EV71)中和抗体效价,为确定EV71疫苗保护水平提供基础数据。方法 6份不同EV71病毒株免疫血清经中和抗体准确定量后,分别通过两个EV71乳鼠攻毒模型,检测EV71中和抗体保护水平。采用标准化的中和抗体检测法和EV71中和抗体定值标准品,分别对健康婴幼儿及疫苗免疫后血清进行中和抗体准确定量。结果在2个乳鼠攻毒模型中,6份免疫血清的中和抗体保护水平接近,ED50分别为10～50 U和6.1～54.2 U;婴幼儿人群7、12和24月龄抗体阳性率分别为45.0%、48.8%和56.8%,阳性人群的抗体效价分别为113.8、120.3和330.6U/m(l均值为173.2 U/m)l,母亲抗体阳性率和效价分别为86.7%和114.3 U/ml;中、高剂量疫苗2针免疫后,婴幼儿抗体阳性率均为100%,效价为356.0和1 136.2 U/ml,较婴幼儿人群自然感染水平高2.1～6.6倍。结论应用标准化的中和抗体检测法和EV71中和抗体定值标准品,确定了以U/ml为单位的乳鼠攻毒抗体保护水平及婴幼儿人群抗体水平和疫苗免疫后抗体水平,为EV71疫苗免疫人群中和抗体保护水平的确定提供了依据。

Protection level of neutralizing antibody against enterovirus 71

Objective To measure the neutralizing antibody titer against enterovirus 71(EV71) in suckling mouse model,healthy infants and the target population after immunization and provide a basic data for determination of protection level of EV71 vaccine.Methods The neutralizing antibodies in six serum samples against various EV71 strains were quantified accurately,and evaluated for protection level by challenge test in two suckling mouse models.The neutralizing antibodies in serum samples of healthy infants and the target population after immunization were quantified accurately by standardized neutralization test in vitro and the standard substances for quantification of EV71 neutralizing antibody.Results The protection levels of EV71 neutralizing antibodies in 6 serum samples were similar in challenge tests in two suckling mouse models,with ED50 values of 10 ~ 50 U and 6.1 ~ 54.2 U,respectively.The antibody positive rates of infants at ages of 7,12 and 24 months were 45.0%,48.8% and 56.8%,while the neutralizing antibody titers in antibody positive infants were 113.8,120.3 and 330.6 U / ml(with a GMT of 173.2 U / ml),respectively.However,the antibody positive rate and the neutralizing antibody titer were 86.7% and 114.3 U / ml respectively in the infant's mothers.After immunization with two doses of vaccine at high and moderate dosages,the neutralizing antibody positive rates in infants were 100%,while the neutralizing antibody titers were 356.0 and 1 136.2 U / ml,respectively,which were 2.1 ~ 6.6 times higher than those in infants infected naturally.Conclusion The protection levels of EV71 neutralizing antibody on suckling mouse model,infants and the target population after EV71 vaccination were quantified as the unit of U / ml by using standardized neutralization test in vitro and the standard substances for quantification of EV71 neutralizing antibody,which provided a basis for determination of protection level of neutralizing antibody in vaccinated population.