Surrogate endpoints for correlating protective immunity in response to influenza

描述(申请人提供)：流感是人类最严重和最常见的大流行性/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免疫反应，因此有必要频繁开发针对新病毒变种的疫苗。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定抗原表位的重组蛋白相结合。重组蛋白免疫原含有一个保守的结构M2蛋白的N端序列，预期构建的M2蛋白代表多种流感H和N亚型。该蛋白质的抗原成分被融合到一个水溶性疏水蛋白结构域，该结构域促进了抗原与脂质双层膜的有效整合。疏水融合蛋白的水溶特性允许使用商业上可行的制备程序来分离和纯化它。我们之前已经证明了基于M2e的流感疫苗(L-IAVM2e1-HD)能在小鼠中激发主动保护性反应，我们目前建议的目的是证实L-IAVM2e1-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。在雪貂和非人灵长类动物中对L-IAVM2e1-HD疫苗进行比较评估是一项重要的研究，因为：1)雪貂是在临床测试之前对候选流感疫苗进行测试的一个被广泛接受的模型；2)高等动物中基于M2的疫苗的保护性免疫相关尚不清楚，因此，建立用于监测保护性免疫反应的替代终点对于设定其他M2候选疫苗临床测试的标准至关重要，在这些标准中，如禽流感疫苗一样，无法进行疗效评估。我们相信，对LIAVM2e1-HD疫苗的测试将证明，它是一种高度有效的手段，可以刺激针对结构保守的病毒蛋白的保护性反应，从而促进流感疫苗的开发，这种疫苗不会因流感H和N表面蛋白突变而导致的抗原转移和/或漂移而无效。基于重组蛋白质技术的疫苗还提供了迅速和有效地适应病毒变化的机会，无论是自然的还是人工的，以根据需要产生新的疫苗。综上所述，这项疫苗技术的诱人特征旨在大幅提高我们应对流感感染的能力，并可能将流感用作生物武器。公共卫生相关性：该疫苗计划的长期目标是开发一种针对大流行/流行毒株的免疫接种的独特方法，该方法将提供保护，使其免受各种不同病毒亚型的感染。这种方法是基于使用基质2(M2e)蛋白的N末端胞外结构域片段作为血凝素(H或HA)或神经氨酸酶(N)抗原的替代品来开发疫苗。我们的中心假设是，当M2e重组融合蛋白以多聚体配置作为脂质体复合体呈现时，可以用作人类疫苗，从而对不同H和N流感亚型的感染提供更广泛的保护。指导我们假设的基本原理是M2e结构蛋白是高度保守的，因此，能够刺激对N末端氨基酸胞外结构域片段的主动免疫的疫苗的开发将对多种IAV毒株的感染提供保护。在这项SBIR AT第一阶段申请中提出的研究重点是展示基于M2e的疫苗在雪貂和非人流感灵长类动物模型中刺激针对H1N1毒株IAV的保护性免疫反应的能力。

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.