Background

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.

Methods

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.

Results

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.

Conclusion

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.

中文翻译：

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通过预先吸附结合疫苗血清型分离多糖IgG肺炎球菌抗体应答：结合疫苗时代的改良方法。

背景

对23价肺炎球菌多糖疫苗（PPV23）的纯多糖反应的评估可能因先前接触缀合物疫苗（PCV）而产生偏差。通过将血清与PCV一起预孵育，我们对现有ELISA进行了分析前修饰。

方法

在通过整个肺炎球菌ELISA测量抗肺炎球菌荚膜多糖（PCP）IgG抗体的浓度之前，先制备PCV吸附和非吸附血清。分析了来自73名受试者的成对的肺炎球菌疫苗接种前后血清，并从疫苗接种后的值中减去了每个样品的基线抗PCP IgG，以测量疫苗反应。然后比较两种方法之间的滴度和倍数变化的绝对变化。

结果

在PCV疫苗接种组（n  = 28）中，与未吸附血清相比，预吸附PCV显着降低了疫苗反应（抗PCP滴度中位数增加：分别为27.55 mg / l和45.98 mg / l）。此外，中位数倍数变化从3.026大幅下降至2.313。在接种PPV23的免疫活性受试者（n  = 28）中，有PCV吸附的抗PCP反应存在显着差异[中位值：无吸附时为73.71 mg / l，有吸附时为51.04 mg / l]。所有抗体缺乏症患者（n = 17）显示出较差的PPV23响应。尽管两种方法之间PPV23的响应性在统计学上没有差异，但我们观察到PCV吸附血清中抗PCP IgG滴度较低的趋势与未吸附的相比。使用对10个配对样品进行的基于多重磁珠的免疫测定进行血清型特异性IgG分析，证实观察到的吸附对PCV血清型具有特异性。

结论

通过去除PCV特异性血清型对常规ELISA进行分析前修饰，可以将真正的多糖反应与以前的PCV疫苗诱导的召回反应区分开。