Mechanisms of Humoral Immune Protection Induced by Anthrax Vaccine Adsorbed

项目摘要 为了减轻生物恐怖主义造成的炭疽感染的持续威胁，现役军人接种了疫苗 炭疽疫苗吸附（Anthrax Vaccine Adsorbed，AVA）然而，部分AVA受助人可能仍然没有受到保护， 炭疽感染和更好地了解导致疫苗反应受损的机制， 免疫力下降是必要的。在最大的AVA疫苗接种者真实世界队列（> 2，900人）中， 50%的AVA疫苗接种者显示出显著的体外致死毒素中和， 中和能力在接种后迅速减弱。因此，本项目的目标是确定 AVA疫苗接种后中和不良的机制。AVA的主要抗原是保护性抗原 （PA）.我们以前的研究已经确定了血清抗PA识别的共同序列表位， 已经显示出中和与非中和应答的不同表位结合。中和不良 免疫应答还与抗PA的亲合力受损和IgG 4产生增强有关。在 此外，与欧洲裔美国人相比，非最佳AVA应答在非洲裔美国人中更常见。 初步数据表明，非裔美国人对非中和性的反应丰富， AVA疫苗接种后的抗原表位，在免疫细胞亚群和免疫途径方面存在显著差异 与美国人相比。关键问题仍然是理解的机制， 迅速减弱或受损的成人疫苗接种反应，如抗AVA的反应。该项目涉及 AVA免疫后保护受损的机制，通过比较高和低水平的抗PA抗体 上述AVA组群中的中和剂以及结构域特异性，抗PA亲合力， 和抗PA IgG 4应答，所有这些都可以抑制保护性人炭疽杆菌免疫（Aim 1）。 保护性反应的其他机制将使用中和PA特异性人免疫球蛋白来剖析。 我们实验室以前生产的单克隆抗体。此外，虽然抗PA结构域特异性是 与中和能力有关，中和剂血清结合的PA构象表位没有 被阐明。因此，本项目采用新型氢氘交换质谱技术， 使用来自高中和剂和低中和剂的血清绘制PA上的抗PA结合位点（目的2）。最后，Mech- 将在非洲裔美国人与欧洲裔美国人疫苗接种者中评价AVA应答受损的差异 (Aim 3）。抗体、免疫细胞谱和调控途径将通过质谱细胞仪进行比较 在AVA疫苗接种后的不同时间，细胞内细胞因子（CyTOF）、细胞内细胞因子产生、流式细胞术和ELISpot。 将测试表位特异性和抗PA反应受损的遗传易感性。这些研究将 提供新的见解，以优化未来的炭疽疫苗和其他跨种族群体的成人疫苗接种。

Project Summary To mitigate the ongoing threat of anthrax infection due to bioterrorism, active military members are vaccinated with Anthrax Vaccine Adsorbed (AVA). However, some AVA recipients may remain unprotected against anthrax infection and a better understanding of mechanisms leading to impaired vaccine response and rapidly waning immunity are needed. In the largest real-world cohort of AVA vaccinees (>2,900 individuals), less than 50% of AVA vaccinees showed significant in vitro lethal toxin neutralization, and both antibody levels and neutralization capacity waned quickly after vaccination. Therefore, the goal of this project is to identify mechanisms of poor neutralization after AVA vaccination. The primary antigen in AVA is protective antigen (PA). Our previous studies have identified common sequential epitopes recognized by serum anti-PA, and have shown differential epitope binding of neutralizing vs. non-neutralizing responses. Poorly neutralizing responses have also been associated with impaired avidity of anti-PA and enhanced IgG4 production. In addition, suboptimal AVA responses are more common in African American vs. European American vaccinees. Preliminary data suggest that African American individuals have enriched responses against non-neutralizing epitopes after AVA vaccination and have marked differences in immune cell subsets and immune pathways compared to European American individuals. Critical questions remain in understanding the mechanisms of rapidly waning or impaired adult vaccination responses, such as those against AVA. This project addresses mechanisms of impaired protection after AVA immunization by comparing anti-PA antibodies from high and low neutralizers in the AVA cohort described above as well as new recruits for domain specificity, anti-PA avidity, and anti-PA IgG4 responses, all of which may inhibit protective human Bacillus anthracis immunity (Aim 1). Additional mechanisms of protective responses will be dissected using neutralizing PA-specific human monoclonal antibodies previously generated by our lab. In addition, although anti-PA domain specificity is related to neutralizing capacity, the conformational epitopes of PA bound by the serum of neutralizers have not been elucidated. Therefore, this project uses novel hydrogen-deuterium exchange mass spectrometry tech- niques to map anti-PA binding sites on PA using sera from high and low neutralizers (Aim 2). Finally, mech- anisms of impaired AVA responses will be evaluated in African American vs. European American vaccinees (Aim 3). Antibodies, immune cell profiles, and regulatory pathways will be compared by mass cytometry (CyTOF), intracellular cytokine production, flow cytometry and ELISpot at various times after AVA vaccination. Epitope specificity and genetic predisposition to impaired anti-PA responses will be tested. These studies will provide new insights to optimize future anthrax vaccines and other adult vaccinations across racial groups.