Surrogate endpoints for correlating protective immunity in response to influenza

描述（由申请方提供）：流感是人类最严重和最常见的大流行/流行性病毒性疾病之一。病毒基因组的快速突变和重排使病毒能够逃避宿主的免疫反应，这使得必须频繁开发针对新病毒变体的疫苗。我们开发了一种新的流感免疫方法，将单层脂质体载体与表达特异性抗原表位的重组蛋白相结合。该重组蛋白免疫原结合了结构M2蛋白的保守N-末端序列，该结构M2蛋白预期构建为代表多种流感H和N亚型。蛋白质的抗原组分与水溶性疏水蛋白结构域融合，该结构域促进抗原与脂质双层膜的有效整合。疏水性融合蛋白的水溶性特性允许使用商业上可行的制备程序对其进行分离和纯化。我们之前已经证明，基于M2 e的流感疫苗（L-IAVM 2 e1-HD）在小鼠中刺激主动保护性应答，我们目前的建议的目的是证实L-IAVM 2 e1-HD疫苗将在雪貂和非人灵长类动物中提供类似的保护性免疫。雪貂和非人灵长类动物中L-IAVM 2 e1-HD疫苗的比较评价是重要的研究，因为：1）雪貂是临床试验前广泛接受的流感候选疫苗试验模型; 2）在高等动物中基于M2的疫苗的保护性免疫的相关性是未知的，因此，建立用于监测保护性免疫应答的替代终点对于设定其他M2候选疫苗的临床试验标准至关重要，其中评价有效性，即，就像禽流感疫苗一样，是不可能的。我们相信LIAVM 2 e1- HD疫苗的测试将证明它是刺激针对结构保守病毒蛋白的保护性应答的高效手段，从而促进抗流感疫苗的开发，该疫苗不会因与流感H和N表面蛋白突变相关的抗原性变化和/或漂移而失效。基于重组蛋白技术的疫苗还提供了快速有效地适应病毒变化（无论是天然的还是人造的）的机会，以根据需要生产新疫苗。总的来说，这种疫苗技术的吸引人的特点是为了提供一个重大的改进，我们的能力，以应对流感感染和流感作为一种生物武器的潜在用途。公共卫生相关性：该疫苗计划的长期目标是开发一种独特的新方法来免疫IAV的大流行/流行株，该方法将提供保护以免受各种不同病毒亚型的感染。该方法基于使用基质2（M2 e）蛋白的N-末端胞外域片段作为血凝素（H或HA）或神经氨酸酶（N）抗原的替代品用于疫苗开发。我们的中心假设是，M2 e重组融合蛋白，当以多聚体构型作为脂质体复合物存在时，可以用作人疫苗，其将提供针对不同H和N流感亚型感染的更广泛的保护。指导我们假设的基本原理是M2 e结构蛋白是高度保守的，因此，能够刺激对N-末端氨基酸胞外域区段的主动免疫的疫苗的开发将提供针对多种IAV毒株感染的保护。在SBIR AT I期申请中提出的研究重点是证明基于M2 e的疫苗在雪貂和非人流感灵长类动物模型中刺激针对H1N1 IAV毒株的保护性免疫应答的能力。

DESCRIPTION (provided by applicant): Influenza represents one of the most serious and common pandemic/epidemic viral diseases of human populations. Rapid mutations and rearrangements of the viral genome allow the virus to evade host immune responses, making the frequent development of vaccines to new viral variants necessary. We have developed a new approach to immunization for influenza that combines a unilamellar liposome carrier with a recombinant protein expressing specific antigenic epitopes. The recombinant protein immunogen incorporates a conserved N-terminal sequence of the structural M2 protein prospectively constructed to represent a variety of influenza H and N subtypes. The antigenic component of the protein is fused to a water-soluble hydrophobic protein domain that facilitates efficient integration of the antigen to lipid bilayer membranes. The water solubility properties of the hydrophobic fusion protein allows for its isolation and purification using commercially viable preparative procedures. We have previously shown that a M2e-based influenza vaccine (L-IAVM2e1-HD) stimulates active protective responses in mice and the objective of our present proposal is to confirm that the L-IAVM2e1-HD vaccine will provide similar protective immunity in ferrets and non-human primates. Comparative evaluation of the L-IAVM2e1-HD vaccine in ferrets and non-human primates are important studies because: 1) the ferret is a widely accepted model for testing of influenza vaccine candidates prior to clinical testing and; 2) the correlates of protective immunity are unknown for M2-based vaccines in higher animals and thus, the establishment of surrogate endpoints for monitoring protective immune responses will be essential for setting the criteria for clinical testing of other M2 vaccine candidates where evaluation of efficacy, i.e., as in the case of an avian influenza vaccine, will not be possible. We believe that testing of the LIAVM2e1- HD vaccine will demonstrate that it is a highly effective means of stimulating protective responses against a structural, conserved viral protein, thereby facilitating the development of a vaccine against influenza that would not be rendered ineffective by antigenic shifts and/or drifts associated with mutations of the influenza H and N surface proteins. Vaccines based upon recombinant protein technologies also offer the opportunity to rapidly and efficiently adjust to changes in the virus, either natural or man-made, to generate new vaccines as needed. Taken together, the attractive features of this vaccine technology are designed to provide a major improvement in our ability to respond to influenza infections and the potential use of influenza as a biological weapon. PUBLICE HEALTH RELEVANCE: The long range goal of this vaccine program is to develop a unique new approach to immunization against pandemic/epidemic strains of IAV that will provide protection from infection by a variety of different viral subtypes. This approach is based on the use of the N-terminal ectodomain segment of the Matrix 2 (M2e) protein as an alternative to the haemagglutinin (H or HA) or neuraminidase (N) antigens for vaccine development. Our central hypothesis is that the M2e recombinant fusion protein, when presented in a multimeric configuration as a liposomal complex, can be used as a human vaccine that will provide broader protection against infection by different H and N influenza subtypes. The underlying rationale guiding our hypothesis is that the M2e structural protein is highly conserved and thus, the development of a vaccine that is capable of stimulating active immunity to the N-terminal amino acid ectodomain segment would provide protection against infection by multiple strains of IAV. The studies proposed in this SBIR AT Phase I application are focused on demonstrating the ability of an M2e-based vaccine to stimulate protective immune responses against an H1N1 strain of IAV in ferrets and a non-human influenza primate model.