Whole Inactivated HIV-1; Stabilization and Immunogenicity

描述（由申请人提供）：传统上成功的病毒疫苗方法，全灭活病毒（WIV），在开发有效HIV/AIDS疫苗的总体努力中受到的关注相对较少。只有一种灭活病毒产品（Salk/IRC免疫原，“Remune”）已在人体中进行了测试，但该产品是包膜耗尽的，仅作为治疗性而非预防性免疫原进行测试。 由于抗体中和的主要靶表位在包膜糖蛋白中，因此通常认为它是预防性免疫原的不可缺少的组分。然而，到目前为止，用单体重组包膜糖蛋白（rgp 120）免疫人类导致相对类型特异性中和，对初级分离株的中和非常少，并且没有效力。少数表现出广泛的初级分离物中和的单克隆抗体通常识别构象表位。驱动这一提议的主要假设是这样的表位可以在WIV上保留，并以免疫原性形式呈递。 我们之前的工作集中在1）开发用于HIV-1的不同原代分离株的可扩展繁殖的方法，2）评估gp 120在各种繁殖、加工和灭活方法期间的保留和结构/功能，3）评估两种正交灭活程序的组合，以及4）使用一组可能的生产方案和疫苗制剂评估WIV的动物免疫原性。初步研究是有希望的，显示出相对广泛的异源中和的主要分离株，尽管相当小的剂量和低纯度的WIV。本提案的目的是评估有前景但未经证实的病毒稳定方法，以在不牺牲天然gp 120三聚体结构完整性的情况下大幅提高WIV的产率、纯度和免疫原性。这些用于病毒稳定化的新方法是基于对隐生物物种的研究，所述隐生物物种能够在剧烈但短暂的环境条件（例如高盐、高热、冷冻和干燥）下存活，这是由于高浓度的溶质，所述溶质通常被称为渗透剂、亲液剂或相容性溶质。其中研究得最好的是二糖海藻糖，它已被用于在冻干过程中稳定病毒疫苗。 我们假设，这种溶质的创新使用将产生显着改善的WIV免疫原性以及如果该候选人进行人体测试所需的可扩展性。除了这种方法对于WIV疫苗概念的益处之外，用于在加工和纯化期间提高完整病毒的纯度和产率的方法可以有助于许多其他HIV疫苗概念（例如，使用重组病毒载体如牛痘、禽痘、VSV、VEE等的那些）。并且还可能影响基因治疗领域，其中逆转录病毒通常用作递送载体并且产物产量是主要限制因素。 如果这一努力在提高WIV产量和免疫原性方面取得成功（R21阶段），我们将使用亚型C WIV作为疫苗在猕猴中进行原理验证有效性研究，然后用异源亚型C感染性和致病性SHIV进行攻毒（R33阶段）。因此，该提案代表了将这种艾滋病毒疫苗概念从临床前研究过渡到临床研究的关键一步。

DESCRIPTION (provided by applicant): A traditionally successful approach to viral vaccines, whole inactivated virus (WIV), has received relatively little attention in the overall effort to develop an effective HIV/AIDS vaccine. Only one inactivated virus product (the Salk/IRC Immunogen, "Remune") has been tested in humans but this product is envelope depleted and tested only as a therapeutic rather than a prophylactic immunogen. Since the primary target epitopes for antibody neutralization are in the envelope glycoprotein, it is generally considered an indespensible component of a prophylactic immunogen. Thus far, however, immunization of humans with monomeric recombinant envelope glycoprotein (rgp120) has resulted in relatively type-specific neutralization, very little neutralization of primary isolates, and no efficacy. The few monoclonal antibodies that demonstrate broad primary-isolate neutralization generally recognize conformational epitopes. The primary hypothesis driving this proposal is that such epitopes can be retained, and presented in an immunogenic form, on WIV. Our prior work focused on 1) developing methods for scalable propagation of diverse primary isolates of HIV-1, 2) assessing the retention and structure/function of gp120 during various methods for propagation, processing, and inactivation, 3) evaluating the combination of two orthogonal inactivation procedures, and 4) assessing the animal immunogenicity of WIV, using one set of possible production protocols and vaccine formulation. Preliminary studies were promising, showing relatively broad heterologous neutralization of primary isolates, despite rather small doses and low purity of the WIV. The objective of this proposal is to evaluate promising but unproven methods for virus stabilization, to achieve dramatic improvements in the yield, purity, and immunogenicity of WIV without sacrificing the structural integrity of the native gp120 trimers. These novel methods for virus stabilization are based on studies of cryptobiotic species that are capable of surviving drastic but transient environmental conditions (e.g. high salt, high heat, freezing, and desiccation) due to high concentrations of solutes, which are variably known as osmolytes, kosmotropes, or compatible solutes. The best studied of these is the disaccharide trehalose, which has been used to stabilize viral vaccines during lyophylization. We hypothesize that the innovative use of such solutes will yield dramatically improved WIV immunogenicity as well as the scalability that will be needed if this candidate were to proceed to human testing. In addition to the benefits of this approach for the WIV vaccine concept, methods for improving the purity and yield of intact viruses during processing and purification could contribute to many other HIV vaccine concepts (e.g. those using recombinant viral vectors such as vaccinia, avipox, VSV, VEE, etc.) and could also impact the gene therapy field where retroviruses are commonly used as the delivery vehicle and product yield is a major limiting factor. If this effort is successful at improving WIV yield and immunogenicity (R21 phase), we will conduct a proof-of-principle efficacy study in macaques using subtype-C WIV as the vaccine, followed by challenge with a heterologous subtype C infectious and pathogenic SHIV (R33 phase). Therefore, this proposal represents a critical step in qualifying this HIV vaccine concept for transition from pre-clinical to clinical studies.