流感减毒活疫苗诱导的粘膜反应IgA抗体检测方法的可行性分析

Feasibility of IgA antibody detection method for evaluating the mucosal response induced by live attenuated influenza vaccine

目的:对建立的检测流感病毒特异性IgA抗体检测方法进行验证,并且用于评价流感减毒活疫苗(LAIV)粘膜免疫反应。方法:使用来自英国生物制品所(NIBSC)的流感抗原国际参考品作为包被抗原,检测鼻咽拭子阳性样品,确定流感病毒型别特异性的IgA抗体滴度,考察该方法的特异性;通过对高低不同抗体滴度的阳性样本多次平行检测来评价该方法的重复性;在此基础上,对526份鼻咽拭子样本进行IgA抗体滴度检测。结果:只针对包被抗原阳性的样品检测到高滴度的IgA抗体,其他型别的抗体未检测到,方法特异性显著。鼻咽拭子IgA抗体检测方法的组间重复性、组内重复性、方法重复性良好。检测接种LAIV疫苗免疫前后的鼻咽拭子样本,疫苗组H1N1、H3N2以及B型IgA抗体几何平均滴度(GMT)接种前后的比值分别为1.15、1.45和1.18,均高于安慰剂组;疫苗接种组IgA抗体滴度高于免疫前2倍的比率,也高于安慰剂对照组(P<0.05)。鼻咽拭子IgA抗体检测结果与血清样本HI抗体结果缺乏相关性(P<0.001)。结论:建立的流感病毒特异性IgA抗体的检测方法能够满足LAIV粘膜免疫评价的需要。

Objective:To validate the established method for detecting influenza virus specific immunoglobulin A(IgA) antibody and to evaluate the mucosal immune responses induced by live attenuated influenza vaccine(LAIV).Methods:International reference strains from The National Institute for Biological Standards and Control(NIBSC) were used as coating antigen to test asopharyngeal swab positive samples in order to determine the influenza virus specific IgA antibody titer and the specificity of the method. Reproducibility was evaluated by parallel testing of nasal samples at high and low antibody titers.On the basis of the test, 526 nasopharyngeal swab samples were tested for IgA antibody titer. Results:Only high titers of IgA antibodies were detected for samples that were positive for the coating antigen, other types of antibodies were not detected, indicating that the method had good specificity. The intergroup reproducibility, intra-group reproducibility and method reproducibility were good. The ratios of GMTs for IgA titers against homologous H1N1, H3N2 and B virus in asopharyngeal swabs before and after the inoculation were 1.15, 1.45 and 1.18 respectively, which were higher than those in placebo group. The ratio of the subjects receiving LAIV with at least a 2-fold increase was higher than that of placebo subjects(P<0.05).There was no correlation between the results of IgA antibody detection in nasopharyngeal swabs and HI antibody results in serum samples(P<0.001). Conclusion:The established influenza-specific IgA antibody detection method can meet the detection requirements of LAIV, which can be applied for assessing the mucosal immune effects of influenza vaccine.