Development of B Cell Responses and Markers of Immunity Following Oral Rotavirus Vaccination in Infants

项目总结 轮状病毒(RV)仍然是全球儿童腹泻病死亡的主要原因， 撒哈拉以南非洲和亚洲低收入国家严重和致命疾病造成的不成比例的负担。 口服RV疫苗，如葛兰素史克(GlaxoSmithKline)，在高收入国家非常有效，但对于 他们在低收入国家表现明显不佳的原因不明，这是减少的一个重大障碍 全球范围内的腹泻病。需要更好地理解为什么口服疫苗在这些环境中失败 提高疫苗性能，开发下一代疫苗。这项研究的目标是提炼 以轮状病毒(RV)为原型评估口服疫苗免疫应答的方法。 病原体特异性免疫记忆的产生是疫苗接种的基本目标，但几乎不是 知道轮状病毒疫苗能够做到这一点。由于抗体反应一直被证明是 对轮状病毒免疫至关重要，评估B细胞对轮状病毒疫苗的反应是至关重要的，特别是 RV特异性记忆B细胞的产生。然而，对RV特异性淋巴细胞反应的评估 目前完全缺乏获得许可的疫苗。假设是，在适当的条件下(例如，在高- 收入国家)，循环中反映免疫记忆的RV特异性B细胞亚群可识别如下 接种疫苗。同样，该项目提出，口服轮状病毒疫苗在低收入环境中表现不佳是 由于疫苗未能产生记忆B细胞反应，这可能部分是通过 由于这些环境所特有的肠道病原体负荷增加，早期B细胞耗尽。 为了验证这些假说，将使用流式细胞术来定义循环RV的免疫表型- 在口服轮状病毒疫苗后，美国佛蒙特州伯灵顿和孟加拉国达卡的婴儿中出现了特定的B型病毒。这些 队列代表疫苗应答优秀(VT)和减弱(孟加拉国)的人群。 由此确定的RV特异性亚群将与血清抗体反应和粪便疫苗相关 脱落，替代疫苗效果的标志物。接下来，该项目将评估辅助因素的贡献 认为影响RV疫苗性能的因素是RV特异性B细胞的发育。最后，计算性的 将开发轮状病毒特异性疫苗反应的模型，并将实验结果应用于 反复测试和提炼这些模型，以生成轮状病毒免疫的预测模型。 这些结果将有助于更好地了解轮状病毒和其他肠道病毒的免疫力的发展。 并确定干预措施的关键目标，以改善世界各地口服疫苗的效果。

PROJECT SUMMARY Rotavirus (RV) remains the leading cause of death due to diarrheal disease in children worldwide, with a disproportionate burden of severe and fatal disease in low-income countries of sub-Saharan Africa and Asia. Oral RV vaccines such as Rotarix (GlaxoSmithKline) are highly efficacious in high-income countries, but for unclear reasons they significantly underperform in low-income countries, a significant obstacle to the reduction of diarrheal disease worldwide. Greater understanding of why oral vaccines fail in these settings is needed to improve vaccine performance and develop next-generation vaccines. The goal of this study is to refine approaches for assessing immunological responses to oral vaccines, using rotavirus (RV) as a prototype. Generation of pathogen-specific immunological memory is the fundamental goal of vaccination, but little is known about the ability of RV vaccines to do this. Since antibody responses have consistently been shown to be critical for RV immunity, assessment of B cell responses to RV vaccination is paramount, particularly the generation of RV-specific memory B cells. However, evaluations of RV-specific lymphocyte responses to currently licensed vaccines are completely lacking. The hypothesis is that under proper conditions (e.g. in high- income countries), circulating RV-specific B cell subsets reflecting immune memory can be identified following vaccination. Similarly, the project proposes that oral RV vaccine underperformance in low-income settings is due to a failure of the vaccine to generate memory B cell responses, and that this may be mediated in part by early B cell exhaustion due to the increased gut pathogen burden unique to these settings. To test these hypotheses, flow cytometry will be used to define the immunophenotype of circulating RV- specific B among infants in Burlington, VT, USA and Dhaka, Bangladesh following oral RV vaccination. These cohorts represent populations in which vaccine responses are excellent (VT) and diminished (Bangladesh). RV-specific subsets thus identified will be correlated with serum antibody responses and fecal vaccine shedding, surrogate markers of vaccine effect. Next, the project will evaluate the contribution of cofactors thought to impact RV vaccine performance on the development of RV-specific B cells. Finally, computational models of RV-specific vaccine responses will be developed, and the experimental results will be applied to iteratively test and refine these models to generate a predictive model of RV immunity. These results will lead to greater understanding of the development of immunity to RV and other enteric viral infections and identify key targets for intervention to improve oral vaccine performance around the world.