Mapping the germinal center and memory B cell landscape to complex antigens

摘要 疫苗是过去一个世纪最成功的公共卫生干预措施之一。在28家获得许可的公司中 疫苗，几乎所有疫苗都是通过诱导能够中和病原体的保护性抗体来发挥作用的。 然而，我们对疫苗免疫反应的细胞动力学的理解，特别是对生物学的理解 生发中心(GC)周围B细胞竞争和记忆B细胞生物学对复合疫苗的影响 抗原，一直是有限的。对这些生物过程缺乏基本了解可能是一种 尽管进行了近30年的研究，但未能开发出有效的艾滋病毒疫苗。事实是， 少数HIV+个体产生广泛的中和抗体(BNAbs)，这给人们带来了新的希望 艾滋病毒疫苗确实是有可能的。最近的研究发现，许多艾滋病毒阴性的健康人类捐赠者 VRC01类前体B细胞。然而，来自这些研究的工作表明，这些潜在的bNab 前体B细胞以异常罕见的频率被发现，这表明免疫后这些B细胞 细胞的竞争将被更频繁的非中和B细胞所击败。回答免疫学问题 围绕这个问题，我开发了一个模型系统，利用含有人类基因的小鼠作为生殖系- 恢复的VRC01 bNab(VRC01gHL)，以及来自David Nemazee博士和William博士实验室的团队 军士长。通过这个B细胞转移模型，我们发现抗原亲和力、亲和力和前体频率都 在GCs中稀有的VRC01gHL B细胞的竞争成功中起着相互依赖的作用。关键的是，我们发现 具有生理亲和力的稀有VRC01gHL B细胞可以被激活，成功地在GC和 形式记忆。在这份K99/R00提案中，我将以这些发现为基础。我将探索前兆频率是如何 和亲和力影响来自GC的记忆B细胞和长期存活的浆细胞的平衡输出，以及TFH如何 HELP可以调节这些过程。我将评估这些参数如何影响召回和竞争成功 VRC01gHL记忆B细胞。此外，我将研究不同的代谢途径是否参与了 成功地将记忆VRC01gHL B细胞募集到继发性GC和继发性GC内。我将通过以下方式进一步培训 建立辅助性T细胞转移方法特异性研究不同转铁蛋白途径在竞争性中的作用 VRC01gHL B细胞的成功。K99阶段将在洛杉矶的Shane Crotty博士的实验室进行 Jolla Institute(LJI)。克罗蒂博士是一位理想的导师，因为他在研究疫苗方面有非常成功的历史 生物学，尤其是T滤泡辅助者(TFH)生物学。他还探索了与艾滋病毒疫苗相关的生物学。我 还将通过课程学习接受抗体表征的正式培训，并进一步开发 威廉·斯赫德博士作为访客在实验室接受免疫原生产和设计的真实培训 科学家。在R00阶段，我将带着我的实验模型，研究多个 影响记忆细胞生物学的参数。这些将包括研究循环抗体、记忆的作用 TFH和B细胞的“代谢记忆”。

ABSTRACT Vaccines are one of the most successful public health interventions over the past century. Of the 28 licensed vaccines, nearly all of them work by induction of protective antibodies capable of neutralizing the pathogen. However, our understanding of the cellular dynamics of immune responses to vaccines, particularly the biology surrounding B cell competition within germinal centers (GC) and memory B cell biology to complex vaccine antigens, has remained limited. This lack of fundamental understanding of these biological processes may be a contributor to the failure to develop an effective HIV vaccine, despite nearly 30 years of research. The fact that a small population of HIV+ individuals develop broadly neutralizing antibodies (bnAbs) gives renewed hope that an HIV vaccine is indeed possible. Recent work has found that many HIV negative healthy human donors have VRC01-class precursor B cells. However, work from these studies revealed that these potential bnAb precursor B cells are found at an unusually rare frequency, suggesting that following immunization these B cells would be outcompeted by more frequent non-neutralizing B cells. To answer immunological questions surrounding this problem, I developed a model system utilizing mice containing human genes for the germline- reverted VRC01 bnAb (VRC01gHL), together with teams from the labs of Dr. David Nemazee and Dr. William Schief. Through this B cell transfer model, we found that antigen affinity, avidity, and precursor frequency all played interdependent roles in competitive success of rare VRC01gHL B cells in GCs. Critically, we found that rare VRC01gHL B cells with physiological affinities could be primed to successfully compete within GCs and form memory. In this K99/R00 proposal I will build on these findings. I will explore how precursor frequency and affinity affect the balanced output of memory B cell and long lived plasma cells from GCs, and how Tfh help can modulate these processes. I will assess how these parameters affect recall and competitive success of VRC01gHL memory B cells. Moreover, I will investigate if different metabolic pathways are involved in successful recruitment of memory VRC01gHL B cells to and within secondary GCs. I will further my training by developing a co-T cell transfer method to specifically study the impact of different Tfh pathways in competitive success of VRC01gHL B cells. The K99 phase will be conducted in the laboratory of Dr. Shane Crotty at the La Jolla Institute (LJI). Dr. Crotty is an ideal mentor as he has a highly successful history in studying vaccine biology, particularly T follicular helper (Tfh) biology. He has also explored this biology related to HIV vaccines. I will additionally receive formal training in antibody characterization through coursework and further develop real world training in immunogen production and design in the laboratory of Dr. William Schief as a visiting scientist. During the R00 phase, I will take my experimental models with me and investigate multiple parameters affecting memory cell biology. These will include studying the roles of circulating antibody, memory Tfh, and “metabolic memory” of B cells.