Objective To analyze the levels of human serum antibody against Neisseria meningitidis serogroup C measured by serum bactericidal assay (SBA) and ELISA.Methods SBA and a modified ELISA were applied to measure the serum bactericidal titer and the specific concentration of immunoglobulin G (IgG) against meningoeoccal serogroup C in sera samples.Seventy-five sera were from healthy adults without undertaking vaccination while another 429 and 388pre- and post- vaccinated sera were from 143 infants and 194 young children immunized with conjugate vaccine or polysaccharide vaccine,respectively.Correlation between serum bactericidal titer and the concentration of specific IgG against meningococcal serogroup C was analyzed.Results The concentration of meningococcal serogroup C specific IgG in healthy adults showed a strong correlation (r=0.814 33,P＜0.001 ) with serum bactericidal titer through linear regression analysis.Weak correlation was observed between SBA titers and IgG concentration in pre vaccinated sera of infants and children ( conjugate/polysaccharide vaccine ) ( infants:r =0.140 64,P ＞ 0.100/r =0.2899,P＜0.05; children:r=0.540 40,P＜0.05/r=0.194 36,P＜0.05).After immunization with 2-dose conjugate vaccine in infants and 1-dose in children,a strong correlation between the two panels of results was observed (r=0.809 38,P＜0.001 and r=0.837 23,P＜0.001 respectively).However after immunization with polysaccharide vaccine,the correlation between serum bactericidal titer and concentration of specific IgG was weak (r＜0.500 00).Conclusion Among healthy adults and post vaccinated infants or young children immunized with conjugate vaccine,the concentration of specific IgG was comparable to the serum bactericidal titer against meningococcal serogroup C.However,it was not unfavorable to use ELISA as the principal means of measuring serum antibody responses to polysaccharide vaccine for infants under 1 year old.%目的 比较血清杀菌试验(SBA)和酶联免疫吸附试验(ELISA)测定两种C群脑膜炎奈瑟菌(Nm)疫苗免疫后血清抗体滴度的差异.方法 采用SBA测定75名未免疫健康成年人(40～70岁)血清、143名3～8月龄婴儿及194名3～5岁儿童NmA和C群结合疫苗或A+C群多糖疫苗免疫前后血清中Nm杀菌抗体水平,然后用ELISA测定相应血清的Nm特异性IgG含量,并利用线性相关与回归分析两种测定结果的相关性.结果 未免疫健康成年人血清中Nm杀菌抗体水平和特异性IgG含量之间的相关性较高(r=0.814 33,P＜0.001)；3～8月龄婴儿和3～5岁儿童接种结合/多糖疫苗前,Nm杀菌抗体水平和特异性IgG含量之间相关性较差(3～8月龄:r=0.140 64,P＞0.l00/r=0.2899,P＜0.05;3 ～5岁:r=0.540 40,P＜0.05/r=0194 36,P＜0.05),接种1剂结合疫苗后,杀菌抗体水平和特异性IgG含量之间的相关性较好(r=0.809 38,P＜0.001和r=0.837 23,P＜0.001)；接种多糖疫苗后,杀菌抗体水平和特异性IgG含量之间的相关性较差(r＜0.500 00).结论 健康成年人血清和结合疫苗免疫后的婴幼儿血清中特异性C群Nm IgG含量可以间接反映血清杀菌抗体水平,ELISA方法可以替代SBA.但ELISA检测方法不适用于3～8月龄婴儿多糖疫苗免疫后的效果评价.
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