Design of HIV VLPs with Enhanced Immunogenicity

描述(由申请人提供)： 迫切需要一种预防性的HIV-1疫苗，而能够引起针对病毒包膜糖蛋白的广谱中和抗体(NAB)反应的抗原将是一个重要的组成部分。然而，疫苗开发中的挑战包括HIV-1非凡的遗传多样性和免疫逃避能力，以及可用于广泛NAB的表位有限。模拟自然感染中的一个重要过程并启动适当的先天免疫反应的免疫原被认为是有利的。病毒样颗粒(VLP)代表了一种诱人的方法来呈现Env，其形式类似于其在病毒粒子上的暴露。我们最近报道了修饰的Env蛋白可以被设计成以非常高的水平整合到VLP中(Wang，2007)。我们假设，含有这种修饰的Env的VLP将引起增强的NAB反应，并正在提出其他新的方法来产生具有更强免疫原性的VLP。一种方法将侧重于加强将稳定的环境三聚体纳入VLP。或者，VLP的免疫原性将通过掺入分子佐剂来增强，包括膜锚定形式的鞭毛蛋白、Toll样受体5(TLR5)的天然配体或膜锚定形式的GM-CSF。我们预计，由此产生的VLP将引起更好的中和抗体反应，以及细胞介导的细胞免疫。我们假设，这些新的VLP将引起更高的广泛反应的NAB滴度和增强的粘膜免疫反应时，通过粘膜接种，我们将在豚鼠模型中测试这一假设。由于DNA疫苗在引发抗体反应和引发细胞反应方面是有效的(Singh等人，2005年)，作为比较，我们还将产生表达分支B和C环境和GAG的DNA构建体，用于DNA疫苗的启动，包括集中跨分支免疫的跨分支DNA Prime-VLP Boost方案。我们的目标是开发一种有效减少粘膜表面感染的艾滋病毒疫苗。天然状态的Env抗原递呈与膜锚定佐剂和粘膜递送相结合，为激发针对HIV的强大NAB反应提供了一种有前景的方法，旨在阻断感染过程的初始步骤。由于艾滋病毒在粘膜表面的传播效率相对较低，即使适度增强粘膜保护性反应，也可能对降低发病率产生重大影响。可能导致这种增强保护的结果包括：增加反应的幅度和/或持续时间，增加反应的交叉反应的广度，以及提高局部粘膜部位的反应水平。尽管作出了巨大努力，但预防艾滋病的有效疫苗仍然难以找到，需要新的方法。我们的研究集中在开发新的颗粒抗原，它将引起广泛的反应性中和抗体反应以及细胞介导的免疫。我们还将重点加强粘膜表面的免疫反应，大多数艾滋病毒感染都是在粘膜表面传播的。

DESCRIPTION (provided by applicant): A prophylactic HIV-1 vaccine is urgently needed, and an antigen that elicits strong broadly reactive neutralizing antibody (nAb) responses against the viral envelope glycoprotein would be an important component. However, the challenges in vaccine development include the extraordinary genetic diversity and immune evasion capacity of HIV-1 and the limited availability of epitopes for broadly nAbs. Immunogens that mimic an important process in natural infection and initiate appropriate innate immune responses are expected to be advantageous. Virus-like particles (VLPs) represent an attractive approach to present Env in a form similar to its exposure on virions. We recently reported that modified Env proteins can be designed to be incorporated into VLPs at very high levels (Wang, 2007). We hypothesize that VLPs containing such modified Env will elicit enhanced nAb responses, and are proposing additional new approaches to generate VLPs with greater immunogenicity. One approach will focus on enhancing the incorporation of stable Env trimers into VLPs. Alternatively, VLP immunogenicity will be enhanced by incorporation of molecular adjuvants, including a membrane -anchored form of flagellin, the natural ligand of the toll-like receptor 5 (TLR5), or a membrane- anchored form of GM-CSF. We expect that the resulting VLPs will elicit improved neutralizing antibody responses, as well as cell-mediated cellular immunity. We hypothesize that these novel VLPs will elicit higher titers of broadly reactive nAbs and enhanced mucosal immune responses when administered by mucosal inoculation, and we will test this hypothesis in a guinea pig model. Because DNA vaccines are effective in priming antibody responses as well as eliciting cellular responses (Singh et al., 2005), as a comparison we will also generate DNA constructs expressing clade B and C Env and Gag for use in priming by DNA vaccines, including a cross-clade DNA prime-VLP boost regimen to focus cross-clade immunity. Our goal is to develop an HIV vaccine that is effective at reducing the incidence of infection at mucosal surfaces. The combination of Env antigen presentation in its native state combined with a membrane-anchored adjuvant and mucosal delivery provides a promising approach to stimulate strong nAb response against HIV, designed to block the initial step in the infection process. Because of the relatively low efficiency of HIV transmission at mucosal surfaces, even a modest enhancement of protective mucosal responses could have a significant effect on reducing disease incidence. Among the possible outcomes which may result in such enhanced protection are: increasing the magnitude and/or duration of the response, increasing the breadth of cross-reactivity of the responses, and enhancing the levels of responses at local mucosal sites. Despite tremendous efforts, an effective vaccine for AIDS prevention remains elusive and novel approaches are needed. Our research is focused on developing novel particulate antigens that will elicit broadly reactive neutralizing antibody responses as well as cell-mediated immunity. We will also focus on enhancing immune responses at mucosal surfaces, where most HIV infections are transmitted.