Department of Infectious Disease Surveillance and Control, National Institute for Health and Welfare, Turku, Finland.
Vaccine. 2012 Nov 6;30(48):6897-902. doi: 10.1016/j.vaccine.2012.09.003. Epub 2012 Sep 13.
Pertussis toxin (PT) is a specific virulence factor of Bordetella pertussis and it is included in all acellular pertussis vaccines (aP). Although immunity after infection seems to persist longer than that after vaccination, the exact mechanism(s) is not known. Primary aim of this study was to develop an ELISA method for measuring avidity index (AI) of IgG-anti-PT antibodies and to compare antibody responses after booster vaccination and infection. Secondary aim was to evaluate if the AI-ELISA has potential in the serodiagnosis of pertussis.
Serum samples from a total of 409 subjects were included in the study. Paired sera were taken from 97 adolescents who received booster vaccine ten years ago (dTpa-004) and from 80 young adults who received a second booster dose ten years after the previous booster vaccine (dTpa-040). Thirty-two paired sera from culture-confirmed pertussis patients, 161 single sera from serologically diagnosed patients and 39 single sera from healthy controls were included. AI of IgG-anti-PT antibodies were determined with newly developed ELISA using diethylamine (DEA) as a bond breaking agent. The IgG-anti-PT antibodies were measured by standardized ELISA.
A significant increase was found in antibody concentrations and AI between PRE and one month POST vaccination ten years ago [GMC for antibody: 7.9 IU/ml vs. 98.3 IU/ml (p=0.0001); for AI: 40.4% vs. 56.1% (p=0.0001)]. Similar result was observed after the second booster dose [GMC for antibody: 9.2 IU/ml vs. 92.4 IU/ml (p=0.0001); for AI: 36.1% vs. 59.5% (p=0.0001)] and between the first and second sera of culture-confirmed patients [GMC for antibody: 6.9 IU/ml vs. 285.1 IU/ml (p=0.0001); for AI: 40.5% vs. 68.4% (p=0.0001)]. Healthy controls showed lower levels of both antibodies and AI.
Our results suggest that there may be difference in quality and quantity of antibodies to PT after vaccination and after infection. Furthermore, AI could be a help for vaccine studies.
百日咳毒素（PT）是博德特氏菌的一种特定毒力因子，它存在于所有无细胞百日咳疫苗（aP）中。尽管感染后的免疫似乎比接种疫苗后的免疫持续时间更长，但确切的机制尚不清楚。本研究的主要目的是开发一种用于测量 IgG 抗-PT 抗体亲和力指数（AI）的 ELISA 方法，并比较加强疫苗接种和感染后的抗体反应。次要目的是评估 AI-ELISA 在百日咳血清诊断中的潜在应用。
本研究共纳入了 409 例血清样本。97 例青少年在 10 年前接受了加强疫苗（dTpa-004），80 例年轻人在 10 年前接受了加强疫苗后再次接受了第二剂加强疫苗（dTpa-040），采集了配对的血清样本。32 对来自培养确诊的百日咳患者的配对血清样本、161 例血清学诊断患者的单份血清样本和 39 例健康对照者的单份血清样本也被纳入研究。使用新开发的 ELISA 并以二乙胺（DEA）作为键断裂剂来测定 IgG 抗-PT 抗体的 AI。使用标准化 ELISA 测定 IgG 抗-PT 抗体。
10 年前加强疫苗接种前和接种后一个月，抗体浓度和 AI 均显著升高[抗体的 GMC：7.9IU/ml 比 98.3IU/ml（p=0.0001）；AI：40.4%比 56.1%（p=0.0001）]。第二次加强疫苗接种后也观察到类似的结果[抗体的 GMC：9.2IU/ml 比 92.4IU/ml（p=0.0001）；AI：36.1%比 59.5%（p=0.0001）]，以及培养确诊患者的第一份和第二份血清样本之间[抗体的 GMC：6.9IU/ml 比 285.1IU/ml（p=0.0001）；AI：40.5%比 68.4%（p=0.0001）]。健康对照组的抗体和 AI 水平均较低。
我们的结果表明，接种疫苗和感染后，PT 的抗体在质量和数量上可能存在差异。此外，AI 可能有助于疫苗研究。
