Mechanisms of broadly neutralizing humoral immunity against influenza viruses

描述(由申请人提供)：人类疫苗通常是通过反复试验产生的，对它们提供的保护性免疫所涉及的分子机制知之甚少。这一疫苗开发系统对随时间变化很小的病原体非常有效；然而，显然需要一种更复杂的方法来开发针对持续结构变化的病原体的广泛保护性疫苗，如流感病毒。目前的流感病毒疫苗通过诱导抗体来提供保护，这些抗体通过病毒高度可变的结合区域来阻止病毒进入。为了使基于抗体的疗法和疫苗对广泛的结构多样化的流感病毒有效，必须通过阻止病毒复制的替代途径来获得明确的保护。我们小组成员和其他人鉴定出了针对病毒血凝素(HA)保守茎段的广谱中和单抗，这是一项突破性的进步，因为许多抗体能够阻止病毒和内体膜的融合，但结合相对抵抗结构变化的表位。我们小组成员的第二个重要发现是，低浓度的抗茎抗体介导的保护依赖于Fc-Fc受体(FCR)的相互作用；因此，抗体同型决定了低浓度抗茎抗体的保护活性。目前的建议是对分子机制进行多中心调查，这些分子机制可以被利用来提供针对流感病毒的广泛保护。我们的项目包括：1)精确定位介导病毒中和的病毒HA和神经氨酸酶糖蛋白上的表位，并剖析它们实现中和的机制。2)使用嵌合流感病毒蛋白的免疫研究，旨在确定能够介导广谱体液免疫的结构元件。3)Fc-FCR相互作用在病毒中和中的作用。4)在人体内研究在疫苗接种过程中如何产生具有有利Fc结构域的抗体。5)人类抗流感抗原B细胞特异性的自然进化研究。6)确定可引起广谱的抗流感体液免疫的流感抗原暴露的特定序列。总体而言，我们的目的是更好地了解针对流感病毒表面蛋白的广泛保护性体液免疫反应的机制，从而为推进新一代广泛保护性流感病毒疫苗和基于抗体的疗法创造一个蓝图。

DESCRIPTION (provided by applicant): Human vaccines have most often been generated by trial and error with little understanding of molecular mechanisms involved in the protective immunity that they provide. This system of vaccine development has been remarkably effective against pathogens that exhibit little variability over time; however, it has become evident that a much more sophisticated approach is required to develop broadly protective vaccines against pathogens that undergo continuous structural change, such as influenza viruses. Current influenza virus vaccines confer protection by eliciting antibodies that block viral entry by bindin regions of the virus that are highly mutable. In order for antibody-based therapies and vaccines to be effective against a breadth of structurally diverse influenza viruses, protection will clearl have to be gained through alternate routes of blocking viral replication. The identification of broadly neutralizing monoclonal antibodies against the conserved stalk domain of the viral hemagglutinin (HA), by members of our group and by others, was a groundbreaking advance, as many of these antibodies are able to block fusion of viral and endosomal membranes, yet bind epitopes that are relatively resistant to structural change. A second critical finding by members of our group was that protection mediated by anti-stalk antibodies at low concentrations is dependent on Fc-Fc Receptor (FcR) interactions; therefore, antibody isotype determines protective activity of anti-stalk antibodies at lower concentrations. The current proposal is for a multi-center investigation into molecular mechanisms that can be harnessed to provide broad-based protection against influenza viruses. Our projects include: 1) Precise mapping of epitopes on the viral HA and neuraminidase glycoproteins that mediate virus neutralization, and dissection of mechanisms by which they achieve neutralization. 2) Immunization studies using chimeric influenza virus proteins designed to identify structural elements able to mediate broad-spectrum humoral immunity. 3) Delineation of the roles of Fc-FcR interactions in viral neutralization. 4) Investigation in human subjects into how to elicit antibodies with favorable Fc domains during vaccination. 5) Studies on the natural evolution of human B cell specificities against influenza antigens. 6) Identification of specific sequences of influenza antigen exposures that elicit broad-spectrum, anti-influenza humoral immunity. Overall, our intention is to better understand the mechanisms of broadly protective humoral immune responses against the influenza virus surface proteins and thereby create a blueprint for advancing a new generation of broadly protective influenza virus vaccines and antibody-based therapeutics.