Development of broadly-protective vaccines for influenza B viruses

项目总结 B型流感病毒(IBV)每年都会引起流行病，发病率和死亡率都很高，但一直以来 与甲型流感病毒(IAV)相比，研究不足。目前可用于IBV和IAV的疫苗是亚种 由于出现了新的抗原变异体，因此必须经常更新。到目前为止，努力 开发具有广泛保护性、可能“通用”的疫苗几乎完全集中在IAV上。RFA-AI-20- 因此，要求“开发和/或表征传染性支气管炎病毒疫苗成分 补充现有的主要IAV候选疫苗“。在目标1(R21阶段)，我们计划发展广泛的反应性 B型流感候选疫苗病毒。使用突变方法，我们已经产生了突变 IBV血凝素(HA，主要病毒抗原)，其抗原性介于两者之间 IBV的主要血统。因此，这些抗原可能会引发免疫反应，从而提供对病毒的保护。 两种传染性支气管炎病毒的血统。在这里，我们计划开发更多具有潜在更高交叉反应性的IBV HA突变体 比我们现在的候选人更多。此外，我们还将建立IBV HA的抗原图，以分析 IBV Has的抗原性(目前广泛用于IAV Has的抗原图，但尚未开发出来 对于IBV HA)。在目标2(R33阶段)，我们将评估B型流感候选疫苗的免疫原性 病毒。简而言之，来自目标1的前5名候选人将用于免疫雪貂。将进行免疫接种 用佐剂分泌的IBV HA(Sa)突变体(从而消除了其他IBV蛋白对 免疫反应)，或与佐剂IBV HA呈现在由自组装组成的纳米颗粒上 噬菌体蛋白(由佐治亚理工学院R.Kane博士产生)。将对接种疫苗的雪貂的血清进行检测 与IBV HA抗原的反应，这些数据将被整合到抗原图中。使用已建立的 通过噬菌体展示方法，S.Khurana博士(联邦药物管理局)将确定 我们的血凝素突变体引发的抗体。这一分析将使我们能够识别引起广泛反应的抗原。 针对保守表位的抗体。免疫学研究将由圣犹大的P.Thomas博士进行 儿童研究医院。根据AIM 2中获得的数据，排名前两位的IBV HA免疫原将是 用于评估B型流感候选疫苗病毒(AIM 3，R33阶段)的保护效果。雪貂 将按照AIM 2中的规定进行免疫，并用代表当前血统和 祖传病毒(在分离谱系之前分离)。病毒滴度和免疫反应将是 与对照动物相比。我们预计，用IBV HA突变体进行一次免疫将导致 比用野生型IBV HA单一免疫更广泛的保护性免疫。总而言之，在 完成这两个阶段，我们预计将开发出一种新的战略，以设计广泛的保护 IBV疫苗，并已在雪貂身上证明了其广泛的保护效果。

PROJECT SUMMARY Influenza B viruses (IBV) cause annual epidemics with appreciable morbidity and mortality, but have been understudied compared to influenza A viruses (IAV). Currently available vaccines for IBV and IAV are sub- optimal and must be updated frequently due to the emergence of novel antigenic variants. To date, efforts to develop broadly protective, potentially ‘universal’ vaccines have almost exclusively focused on IAV. RFA-AI-20- 003 therefore calls for the “development and/or characterization of IBV vaccine components that complement existing lead IAV vaccine candidates”. In Aim 1 (R21 phase), we plan to develop broadly reactive influenza B candidate vaccine viruses. Using mutagenesis approaches, we have already generated mutant IBV hemagglutinins (HA, the major viral antigen) whose antigenic properties are in-between those of the two major lineages of IBV. Thus, these antigens may elicit immune responses that confer protection against viruses of both IBV lineages. Here, we plan to develop additional IBV HA mutants with potentially higher cross-reactivity than that of our current candidates. In addition, we will establish an antigenic map for IBV HA to analyze the antigenic properties of IBV HAs (antigenic maps are now widely used for IAV HAs, but have not been developed for IBV HA). In Aim 2 (R33 phase), we will assess the immunogenicity of influenza B candidate vaccine viruses. Briefly, the top 5 candidates from Aim 1 will be used to immunize ferrets. Immunization will be carried out with adjuvanted, secreted IBV HA (sHA) mutants (thus eliminating the contribution of other IBV proteins to immune responses), or with adjuvanted IBV HA presented on nanoparticles composed of a self-assembling phage protein (generated by Dr. R. Kane, Georgia Tech). The sera from vaccinated ferrets will be tested for reactivity with IBV HA antigens, and these data will be integrated into the antigenic map. Using an established phage display approach, Dr. S. Khurana (Federal Drug Administration) will identify the epitopes targeted by the antibodies elicited by our HA mutants. This analysis will allow us to identify antigens that elicit broadly reactive antibodies that target conserved epitopes. Immunology studies will be carried out by Dr. P. Thomas, St. Jude Children’s Research Hospital. On the basis of the data obtained in Aim 2, the top 2 IBV HA immunogens will be used to assess the protective efficacy of influenza B candidate vaccine viruses (Aim 3, R33 phase). Ferrets will be immunized as established in Aim 2 and challenged with IBVs representing both current lineages and an ancestral virus (isolated before the separation of the lineages). Virus titers and immune responses will be compared with those of control animals. We expect that a single immunization with the IBV HA mutants will elicit more broadly protective immunity than a single immunization with wild-type IBV HA. In summary, upon completion of both phases, we expect to have developed a novel strategy for the design of broadly protective IBV vaccines, and to have demonstrated their broadly protective efficacy in ferrets.