Refocusing the Immune Response to the HIV Envelope Glycoprotein

描述(由申请人提供)：由于每天约有14,000名新感染者，迫切需要开发一种安全有效的艾滋病毒疫苗。然而，到目前为止，所有测试的战略都没有达到这一目标。因此，如果要开发安全有效的疫苗来预防艾滋病毒感染，就需要采取新的战略。最近于2008年3月在国立卫生研究院举行的艾滋病毒疫苗峰会列出了开发艾滋病毒疫苗所必需的九个高度优先的研究目标。这项拨款建议的工作直接涉及列出的九个最高研究优先事项之一，即：“确定为什么广谱中和抗体(BNAbs)不常见，以及如何激发它们”。我们解决这个问题的新方法是基于令人惊讶的初步结果，这些结果表明HIV gp120上的裂解位点是高度保守的，这些裂解位点被细胞内和分泌的酶识别，这些酶对抗原处理、肿瘤生长和寄生虫感染至关重要。令人惊讶的是，这些位点也位于受体结合或中和抗体结合重要的特定氨基酸上或其附近。由于病毒变异率很高，这些位点一定是由于强大的选择压力而被保守，可能是为了逃避免疫反应。在这项提议中，我们希望使HIV包膜蛋白上的这些保守的裂解位点失活，以产生抗蛋白酶的包膜糖蛋白。然后我们将以兔子免疫原性研究所需的数量表达这些蛋白。所产生的血清将被检测是否存在广谱中和抗体。我们推测，这些位点的失活将保留重要的表位，这些表位通常在体内降解，然后才能刺激强大的免疫反应。这些表位的保存应该允许我们将免疫反应重定向到HIV包膜蛋白，以改善广泛中和抗体的形成。这些实验有可能解释为什么到目前为止用测试的疫苗很难产生中和抗体，以及其他多年来困扰该领域的观察结果。 公共卫生相关性：在这些研究中，我们提出了一种开发艾滋病毒疫苗抗原的新方法。我们将尝试通过突变抗原处理酶识别的保守位点来提高被广泛中和抗体识别的包膜蛋白表位的免疫原性。

DESCRIPTION (provided by applicant): With approximately 14,000 new infections per day, there is an urgent need to develop a safe and effective HIV vaccine. However, all of the strategies tested to date have fallen short of this goal. Thus, new strategies are required if the development of a safe and effective vaccine to prevent HIV infection is ever to be realized. A recent HIV Vaccine Summit held at NIH in March 2008 listed nine high priority research objectives essential for the development of an HIV vaccine. The work proposed in this grant directly addresses one of the nine highest research priorities listed, namely: "Determine why broadly neutralizing antibodies (bNAbs) are uncommon and how they can be elicited". Our new approach to this problem is based on surprising preliminary results showing that cleavage sites on HIV gp120, recognized by intracellular and secreted enzymes known to be important for antigen processing, tumor growth, and parasitic infection, are highly conserved. Surprisingly, these sites are also located at, or adjacent to, specific amino acids important for receptor binding or the binding of neutralizing antibodies. Because of the high rate of virus variation, these sites must have been conserved as the result of strong selective pressure, possibly to evade the immune response. In this proposal we wish to inactivate these conserved cleavage sites on HIV envelope proteins to create protease resistant envelope glycoproteins. We will then express these in quantities required for rabbit immunogenicity studies. The resulting sera will be assayed for the presence of broadly neutralizing antibodies. We postulate that inactivation of these sites will preserve important epitopes that are normally degraded in vivo before they are able to stimulate robust immune responses. Preservation of these epitopes should allow us to redirect the immune response to HIV envelope proteins in a way that improves the formation of broadly neutralizing antibodies. These experiments have the potential to explain why it has been so difficult to elicit neutralizing antibodies with the vaccines tested to date, as well as other observations that have perplexed the field for many years. PUBLIC HEALTH RELEVANCE: In these studies we propose a new approach to the development of HIV vaccine antigens. We will attempt to improve the immunogenicity of epitopes on the envelope protein recognized by broadly neutralizing antibodies by mutation of conserved sites recognized by antigen processing enzymes.