West Midlands Immunodeficiency Centre, University Hospitals Birmingham NHS Foundation Trust, Birmingham, UK.
The Binding Site Group Ltd, Birmingham, UK.
J Immunol Methods. 2020 Nov;486:112846. doi: 10.1016/j.jim.2020.112846. Epub 2020 Aug 31.
Assessment of pure polysaccharide response to the 23-valent pneumococcal polysaccharide vaccine (PPV23) can be biased by previous exposure to the conjugate vaccine (PCV). We applied pre-analytical modification to the existing ELISA by pre-incubating serum with PCV.
PCV-adsorbed and non-adsorbed sera were prepared before measuring the concentration of anti-pneumococcal capsular polysaccharide (PCP) IgG antibodies by the whole pneumococcal ELISA. Paired pre and post-pneumococcal vaccination sera from 73 subjects were analyzed and the baseline anti-PCP IgG for each sample was subtracted from the post-vaccination value to measure vaccine responses. Absolute change in titers and fold changes were then compared between both methods.
In the PCV-vaccinated group (n = 28), pre-adsorption with PCV significantly reduced the vaccine responses compared to non-adsorbed sera [median increase in anti-PCP titers: 27.55 mg/l and 45.98 mg/l, respectively]. In addition, the median fold change dropped significantly from 3.026 to 2.313. In PPV23-vaccinated immunocompetent subjects (n = 28) there was a significant difference in anti-PCP responses with PCV adsorption [median values: 73.71 mg/l without and 51.04 mg/l with adsorption]. All the antibody deficiency patients (n = 17) displayed poor PPV23 responses. Although PPV23 responsiveness was not statistically different between both methods, we have observed a trend for lower anti-PCP IgG titers in PCV-adsorbed sera compared to non-adsorbed ones. Serotype-specific IgG analysis using a multiplexed bead-based immunoassay performed on 10 paired samples confirmed that the adsorption observed is specific to PCV serotypes.
Pre-analytical modification to the conventional ELISA by removing the PCV-specific serotypes may differentiate true polysaccharide response from recall response induced by previous PCV vaccination.
对 23 价肺炎球菌多糖疫苗（PPV23）的纯多糖反应的评估可能会因先前接触结合疫苗（PCV）而产生偏差。我们通过在血清中预先孵育 PCV 对现有的 ELISA 进行了分析前修饰。
在通过全肺炎球菌 ELISA 测量抗肺炎球菌荚膜多糖（PCP） IgG 抗体的浓度之前，制备 PCV 吸附和未吸附的血清。分析了 73 名受试者的肺炎球菌疫苗接种前后配对血清，并从接种后值中减去每个样本的基线抗 PCP IgG，以测量疫苗反应。然后比较了两种方法之间的抗体效价绝对变化和倍数变化。
在 PCV 接种组（n=28）中，与未吸附血清相比，PCV 预吸附显着降低了疫苗反应[抗 PCP 效价的中位数增加：分别为 27.55 和 45.98 mg/l]。此外，中位数倍数变化从 3.026 显着降至 2.313。在免疫功能正常的 PPV23 接种受试者（n=28）中，PCV 吸附存在抗 PCP 反应的显着差异[无吸附时的中位数值为 73.71 mg/l，有吸附时为 51.04 mg/l]。所有抗体缺陷患者（n=17）均显示出较差的 PPV23 反应。尽管两种方法之间的 PPV23 反应无统计学差异，但我们观察到与未吸附血清相比，PCV 吸附血清中的抗 PCP IgG 效价较低的趋势。对 10 对配对样本进行的基于多重珠的免疫分析的血清型特异性 IgG 分析证实，观察到的吸附是针对 PCV 血清型的特异性。
通过去除 PCV 特异性血清型对常规 ELISA 进行分析前修饰，可以区分真正的多糖反应与先前 PCV 接种引起的回忆反应。
