Elicitation of HIV Broadly Neutralizing Antibodies from Engineered B cells

项目概要/摘要 HIV广泛中和抗体（bnAbs）对病毒有效，但不能通过 由于人类B细胞抗原受体（BCR）库所施加的遗传限制，疫苗接种是一个非常重要的问题。我们 最近显示，来自野生型小鼠的成熟原代B细胞可以离体工程化以表达 bnAb基因作为功能性抗原受体，并且这些细胞可以返回宿主并接种疫苗， 产生持久的bnAb应答。因为这种动物模型不能支持HIV感染，治疗或 这些反应的保护效力尚未得到评价。这里描述的建议：1）探索 新的B细胞靶向方法，旨在改善B细胞如何被工程化并在体内发挥功能; 2） 定义了疫苗参数和工程细胞的特性，这些特性是可重现地诱导 小鼠模型中持久的bnAb应答; 3）将我们成功的“工程化B细胞疫苗” 用于使用嵌合HIV/SIV病毒进行功效测试的恒河猴动物模型的EBcV原型 （SHIV）。将测试在非人灵长类动物（NHP）中引发的BnAb预防异源性免疫的能力。 2级病毒感染，抑制或维持对病毒血症的抑制，以评估EBcVs的可能性 作为预防性疫苗或HIV功能性治疗。这种方法可能具有重要意义。 这是优于其他基因治疗策略的优势，目的是从肌肉或肝细胞持久分泌bnAb。 当从修饰的B细胞中引发时，bnAb反应应该：1）能够在亲和力上成熟以响应A 快速进化的病原体; 2）在抗原存在下增加滴度; 3）表达为所有效应子 同种型; 4）被免疫系统耐受，因为它们来源于B细胞;和5）经受耐受 如果有害的话，这些机制应该抑制表达它们的细胞。本研究中设计的所有研究 建议支持我们的长期目标，开发安全，有效和经济可行的“工程 从基因组修饰的B细胞产生持久的HIV bnAb应答的“B细胞疫苗”作为一种策略 用于预防或HIV功能性治疗。

Project Summary/Abstract HIV broadly neutralizing antibodies (bnAbs) are effective against the virus, but cannot be elicited through vaccination due to genetic limitations imposed by the human repertoire of B cell antigen-receptors (BCRs). We have recently shown that mature primary B cells from wild-type mice can be engineered ex vivo to express bnAb genes as functional antigen receptors, and that these cells can be returned to the host and vaccinated to generate durable bnAb responses. Because this animal model cannot support HIV infection, therapeutic or protective efficacy of these responses have not yet been evaluated. The proposal described here: 1) Explores novel B cell targeting approaches that aim to improve how B cells are engineered and function in vivo; 2) Defines vaccine parameters and the properties of engineered cells required for reproducible elicitation of durable bnAb responses in the mouse model and; 3) Translates our successful ‘Engineered B cell Vaccine’ (EBcV) prototype to the rhesus macaque animal model for efficacy testing using chimeric HIV/SIV viruses (SHIVs). BnAbs elicited in non-human primates (NHP) will be tested for their ability to prevent heterologous tier-2 virus infection, suppress, or maintain suppression of viremia, in order to evaluate the potential for EBcVs to function as prophylactic vaccines or as an HIV functional cure. Such an approach may have significant advantages over other gene therapy strategies that aim to durably secrete bnAbs from muscle or liver cells. When elicited from modified B cells, bnAb responses should be: 1) able to mature in affinity in response to a rapidly evolving pathogen; 2) increase titers in the presence of antigen; 3) be expressed as all effector isotypes; 4) tolerated by the immune system because they originate from B cells and; 5) subject to tolerance mechanisms that should inactivate the cells expressing them if they are harmful. All studies designed in this proposal support our long-term goal, the development of safe, effective and economically feasible ‘Engineered B cell vaccines’ that would generate durable HIV bnAb responses from genome modified B cells as a strategy for prevention or HIV functional cure.