Development of broadly-protective vaccines for influenza B viruses

项目摘要 流感B病毒（IBV）引起每年的流行病，具有可观的发病率和死亡率，但已经被广泛应用于临床。 与甲型流感病毒（IAV）相比，目前可用的IBV和IAV疫苗是亚- 由于新的抗原变体的出现，必须经常更新。迄今为止， 开发具有广泛保护性的、潜在的“通用”疫苗几乎完全集中在IAV上。RFA-AI-20- 003因此呼吁“开发和/或表征IBV疫苗组分， 补充现有的IAV候选疫苗。在目标1（R21阶段）中，我们计划开发广泛的反应性 流感B候选疫苗病毒。使用诱变方法，我们已经产生了突变体， IBV血凝素（HA，主要病毒抗原），其抗原特性介于两者之间 IBV的主要血统。因此，这些抗原可引发赋予针对病毒的保护的免疫应答 两种IBV的血统。在这里，我们计划开发具有潜在更高交叉反应性的额外IBV HA突变体 比我们现有的候选人更有能力此外，我们还将建立IBV HA的抗原图谱，以分析IBV HA的抗原性。 IBV HA的抗原特性（抗原图谱现在广泛用于IAV HA，但尚未开发 用于IBV HA）。在目标2（R33阶段）中，我们将评估B型流感候选疫苗的免疫原性 病毒简言之，来自目标1的前5名候选物将用于免疫雪貂。将进行免疫接种 与佐剂化的分泌型IBV HA（sHA）突变体（从而消除了其他IBV蛋白对IBV HA（sHA）突变体的贡献）相比， 免疫应答），或与存在于由自组装的IBV HA组成的纳米颗粒上的佐剂化IBV HA 噬菌体蛋白（由R. Kane，格鲁吉亚理工大学）。将对接种疫苗的雪貂的血清进行检测， 这些数据将被整合到抗原图谱中。使用已建立的 噬菌体展示方法，S. Khurana（联邦药物管理局）将鉴定由该抗体靶向的表位。 我们的HA突变体引发的抗体。这种分析将使我们能够识别出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St. Jude的P.托马斯博士进行 儿童研究医院基于目标2中获得的数据，前2种IBV HA免疫原将是 用于评估B型流感候选疫苗病毒的保护效力（Aim 3，R33阶段）。雪貂 将按照目标2中建立的方法进行免疫，并用代表当前谱系的IBV和 祖先病毒（在谱系分离之前分离）。病毒滴度和免疫应答将被 与对照动物相比。我们期望用IBV HA突变体的单次免疫将引起 比用野生型IBV HA的单次免疫更广泛的保护性免疫。总之，在 完成这两个阶段，我们预计已经制定了一个新的战略，设计广泛的保护 IBV疫苗，并已证明其广泛的保护作用，在雪貂。

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.