Despite diligent vaccination efforts, influenza virus infection remains a major cause for respiratory-related illness across the globe. The less-than-optimal immunity conferred by the currently prescribed seasonal vaccines and protracted production times warrant the development of novel vaccines. Induction of an epitope-focused antibody response targeting known neutralization epitopes is a viable strategy to enhance the breadth of protection against rapidly evolving infectious viruses. We report the development of a design framework to mimic the hemagglutinin (HA) head fragment of H1-subtype viruses by delineating the interaction network of invariant residues lining the receptor binding site (RBS); a site targeted by cross-reactive neutralizing antibodies. The incorporation of multiple sequence alignment information in our algorithm to fix the construct termini and engineer rational mutations facilitates the facile extension of the design to heterologous (subtype-specific) influenza strains. We evaluated our design protocol by generating head fragments from divergent influenza A H1N1 A/Puerto Rico/8/34 and pH1N1 A/California/07/2009 strains that share a sequence identity of only 74.4% within the HA1 subunit. The designed immunogens exhibited characteristics of a well-ordered protein, and bound conformation-specific RBS targeting antibodies with high affinity, a desirable feature for putative vaccine candidates. Additionally, the bacterial expression of these immunogens provides a low-cost, rapidly scalable alternative.

尽管努力接种疫苗，流感病毒感染仍然是全球呼吸道相关疾病的主要原因。当前规定的季节性疫苗所赋予的不太理想的免疫力和延长的生产时间保证了新型疫苗的开发。诱导针对已知中和表位的以表位为重点的抗体反应是一种可行的策略，可增强针对快速进化的传染性病毒的保护范围。我们报告了通过描绘受体结合位点 (RBS) 内的不变残基的相互作用网络来模拟 H1 亚型病毒的血凝素 (HA) 头部片段的设计框架的开发；交叉反应中和抗体靶向的位点。在我们的算法中加入多序列比对信息以固定构建体末端和工程合理突变有助于将设计轻松扩展到异源（亚型特异性）流感毒株。我们通过从不同的 A H1N1 A/Puerto Rico/8/34 和 pH1N1 A/California/07/2009 菌株中生成头部片段来评估我们的设计方案，它们在 HA1 亚基中的序列同一性仅为 74.4%。设计的免疫原表现出有序蛋白质的特征，并结合具有高亲和力的构象特异性 RBS 靶向抗体，这是假定的候选疫苗的理想特征。此外，这些免疫原的细菌表达提供了一种低成本、可快速扩展的替代方案。