Engineering AAV Vectors to Evade Antibody Neutralization

描述(由申请人提供)：基因疗法在治疗和潜在治愈各种疾病方面具有巨大的潜力。然而，基因传递技术需要在安全性、有效性和表达稳定性方面有显著的改进，才能治疗这些疾病中的大多数。基于腺相关病毒(AAV)的载体在实验室和临床上都被证明是非常有前途的，但它们仍然存在一些缺点。特别是，大多数人已经接触了AAV 2型以及其他血清型，因此免疫系统已经准备好中和AAV。AAV载体的抗体中和是一个既定的问题，细胞免疫反应也可能是一个挑战。我们将尝试解决前者的问题，并将进一步研究后者涉及的基本机制。对于前者，我们开发了新的定向进化技术来产生具有新特性的AAV新突变体。具体地说，产生在编码病毒外壳蛋白的衣壳基因中具有随机点突变的大型病毒库，并使用高通量筛选来选择具有新特性的变体。我们利用这种方法来产生具有改变的受体结合性质的变异体，以及逃脱抗体的中和变异体，抗体极大地抑制了野生型衣壳或外壳蛋白的AAV基因传递。我们将研究人类抗体躲避变异体介导治疗性基因促红细胞生成素高效基因传递到携带抗AAV抗体的动物的肌肉和肝脏的可能性。此外，虽然AAV被抗体中和是一个既定的问题，但对AAV与免疫系统其他组成部分的相互作用知之甚少。因此，补体[和T细胞]免疫中和该病毒的基本机制将在体外和体内进行研究。总而言之，病毒是为了它们自己的目的而自然进化的，这并不总是满足人类治疗的需要。因此，在这项工作中开发的将病毒重新进化为增强型人类疗法的新方法将对增强型病毒基因输送载体的分子工程产生广泛和普遍的影响，包括替代AAV血清型以及其他载体。此外，它还将深入了解其他免疫系统组件对AAV的反应。

DESCRIPTION (provided by applicant): Gene therapy has vast potential for treating and potentially curing a wide variety of disorders. However, gene delivery technologies require significant improvements in safety, efficiency, and expression stability before the majority of these diseases can be treated. Vectors based on adeno-associated virus (AAV) have proven themselves to be highly promising, both in the laboratory and the clinic, but they still suffer from several shortcomings. In particular, the majority of the human population has been exposed to AAV serotype 2, as well as other serotypes, and as a result the immune system is primed to neutralize AAV. Antibody neutralization of AAV vectors is an established problem, and cellular immune responses may also be a challenge. We will attempt to solve the former problem and will further investigate basic mechanisms involved in the latter. For the former, we have developed novel directed evolution technology to generate new mutants of AAV with new properties. Specifically, large libraries of virus with random point mutations in the capsid gene encoding the viral coat protein are generated, and variants with novel properties are selected using high throughput screens. We have utilized this approach to generate variants with altered receptor binding properties, as well as variants that escape neutralization by antibodies that greatly inhibit AAV gene delivery by the wild type capsid or coat proteins. We will study the potential of human antibody evading variants to mediate high efficiency gene delivery of the therapeutic gene erythropoietin to the muscle and liver of animals carrying anti-AAV antibodies. In addition, while AAV neutralization by antibodies is an established problem, much less is known about AAV interactions with other components of the immune system. Therefore, the basic mechanisms of immune neutralization of this virus by complement [and T cells] will be investigated to both in vitro and in vivo. In summary, viruses have naturally evolved for their own ends, which do not always meet the needs of a human therapeutic. The novel approaches developed in this work to re-evolve viruses into enhanced human therapeutics will therefore have broad and general impact on the molecular engineering of enhanced viral gene delivery vehicles, including alternate AAV serotypes as well as other vectors. Furthermore, it will yield insights into the responses of other immune system components to AAV.