Influenza vaccines inducing broadly cross protective immunity

描述（由申请方提供）：目前的流感疫苗靶向诱导对可变抗原血凝素和神经氨酸酶的免疫应答，这两种抗原对毒株特异性保护有效。然而，这种疫苗接种不能提供针对抗原性不同菌株的出现的保护，如在2009年H1N1大流行爆发的早期阶段未能控制所示。我们计划的目标是开发新型流感疫苗，在没有佐剂的情况下，诱导广泛的交叉保护性免疫，对抗抗原漂移株。为了实现这一目标，将提出新的方法来开发免疫原性形式的高度保守的抗原靶标，并将其纳入流感疫苗接种中。作为保守抗原靶标的有希望的候选者是含有高度保守的胞外结构域的膜蛋白M2。膜锚定形式的病毒样颗粒（VLP）上的M2（M2 VLP）将处于使M2具有免疫原性的构象，并且即使在没有佐剂的情况下也赋予广泛的交叉保护性M2免疫。我们假设，含有高度保守的抗原靶点（如流感M2 VLP）的流感疫苗将诱导广泛的交叉保护和异亚型免疫。为了检验这一假设，在具体的目标1中，将产生含有膜锚定嵌合形式的四聚体M2胞外结构域的新构建体的重组VLP疫苗，并将与野生型M2蛋白相比评价其交叉保护效力。我们还将提出一种新的方法来克服目前疫苗的毒株特异性保护和对M2的弱交叉保护性免疫的限制。具体目标2将研究基于保守M2的免疫增强交叉保护广度的作用机制。此外，有助于交叉保护的免疫相关物将使用传统和新方法（包括特定免疫组分的消耗）来确定。在具体目标3中，将在雪貂中进一步评价有希望的候选疫苗的交叉保护效力和交叉保护的持续时间，雪貂是用于测试人类临床前疫苗的更相关的动物模型。在不使用佐剂的情况下提高疫苗接种后针对流感病毒的交叉保护性免疫的广度是适用于人类的理想且实用的方法，并且对于推进疫苗领域至关重要。

DESCRIPTION (provided by applicant): Current influenza vaccines are targeted to induce immune responses to the variable antigens hemagglutinin and neuraminidase, which are effective for strain-specific protection. However, such vaccination does not provide protection against the emergence of antigenically distinct strains as shown by the failure to control the 2009 H1N1 pandemic at the early stage of its outbreak. The goal of our proposed project is to develop novel influenza vaccines that will induce broadly cross protective immunity against antigenically drifted strains in the absence of adjuvants. To achieve this goal, novel approaches will be proposed to develop a highly conserved antigenic target in an immunogenic form and to incorporate this into the influenza vaccination. A promising candidate as a conserved antigenic target is the membrane protein M2 containing a highly conserved extracellular domain. M2 on virus-like particles (VLPs) in a membrane-anchored form (M2 VLPs) will be in a conformation enabling M2 to be immunogenic and confer broadly cross-protective M2 immunity even without an adjuvant. We hypothesize that influenza vaccines containing highly conserved antigenic targets such as influenza M2 VLPs will induce broadly cross-protective and heterosubtypic immunity. To test this hypothesis, in specific aim 1, recombinant VLP vaccines containing novel constructs of the tetrameric M2 extracellular domain in a membrane-anchored chimeric form will be generated and their cross protective efficacy will be evaluated in comparison with the wild type M2 protein. We will also propose a novel approach to overcome the limitation of strain-specific protection by current vaccines and weak cross-protective immunity to M2. Specific aim 2 will investigate action mechanisms by which conserved M2 based immunity enhances the breadth of cross protection. Also, immune correlates contributing to cross protection will be determined using traditional and novel approaches including depletion of specific immune components. In specific aim 3, the cross-protective efficacy of promising vaccine candidates and the duration of cross protection will be further evaluated in ferrets, which is a more relevant animal model for testing pre-clinical vaccines for humans. Improving the breadth of cross protective immunity against influenza viruses after vaccination without using adjuvant is a desirable and practical approach applicable to humans and critically important for advancing the vaccine field.