Manipulating immunodominance in influenza HA

每一种流感血凝素(HA)都是由保守的毒株特异性表位拼接而成，其中一些表位可被中和抗体识别。优先诱导识别保守表位的中和抗体的流感疫苗将比目前使用的疫苗具有更广泛的保护作用。了解受试者的暴露史、流感疫苗抗原的差异以及佐剂的添加如何使免疫反应偏向不同的HA表位，将使我们能够设计出最佳的疫苗。以下三个假设将得到检验。(1)非复制型流感疫苗和感染疫苗诱导的B细胞谱系在多克隆激活程度和中和广度上存在差异。由以下因素引起的剧目 佐剂疫苗和非佐剂疫苗不同，因为佐剂扩大了识别表位的范围。(2) 广泛反应的抗体，包括那些识别异亚型干细胞表位的抗体，在真正的一次免疫后比二次流感免疫后更少出现，这是因为多次HA刺激扩大了反应。(3)有效地诱导针对所需表位的抗体需要：(A)良好的生殖系抗体的增殖和(B)达到所需最终特异性的亲和力成熟途径。确实有 针对特定表位的抗体的首选种系前体和成熟途径。 假设1和2将通过绘制具有不同流感感染和/或佐剂或非佐剂疫苗免疫史的受试者的识别表位来进行测试。我们将寻找广泛的中和抗体(那些我们想要诱导的抗体)，以了解它们的生殖系前体和成熟途径。我们还将绘制与HA结合的各种抗体的表位图，以确定体液免疫系统“看到”了什么。从这一图谱中获得的见解将被用于合理设计优良的HA免疫原，这些免疫原将通过抗原工程、小鼠免疫、谱系分析和抗原重新设计的迭代周期进行优化。抗原设计技术将会 包括选择性表位呈递、表位掩蔽和种系抗体靶向，然后引导亲和成熟。这项工作揭示的抗原设计原理可以应用于需要疫苗的多种病原体的保护性决定簇。

Each influenza hemagglutinin (HA) is a mosaic of conserved and strain-specific epitopes, some of which are recognized by neutralizing antibodies. An influenza vaccine that preferentially elicits neutralizing antibodies that recognize conserved epitopes will be more broadly protective than those now in use. Understanding how the exposure history of subjects, differences in influenza vaccine antigens, and the addition of adjuvants bias the immune response towards different HA epitopes will enable us to design optimal vaccines. The following three hypotheses will be tested. (1] The B-cell repertoires elicited by non-replicating influenza vaccines and by infection differ in degree of polyclonal activation and breadth of neutralization. The repertoires elicited by adjuvanted and non-adjuvanted vaccines differ because adjuvant broadens the range of recognized epitopes. (2] Broadly reactive antibodies, including those recognizing the heterosubtypic stem epitope, are less frequent after true primary than after secondary influenza immunization due to broadening of the response by multiple HA stimulations. (3) Efficient induction of antibodies against a desired epitope requires: (a] proliferation of a favorable germline antibody and (b) an affinity maturation pathway to a desired final specificity. There are preferred germline precursors and maturation pathways for antibodies targeting particular epitopes. Hypotheses 1 and 2 will be tested by mapping the epitopes recognized by the repertoires of human subjects with different exposure histories to influenza infection and/or immunization with adjuvanted or un-adjuvanted vaccines. We will seek broadly neutralizing antibodies (those we want to elicit) to understand their germline precursors and maturation pathways. We will also map the epitopes of the full range of antibodies that bind HA to determine what the humoral immune system "sees." The insights obtained from this mapping will be used to rationally design superior HA immunogens that will be optimized through an iterative cycle of antigen engineering, mouse immunization, repertoire analysis, and antigen redesign. Antigen design techniques will include selective epitope presentation, epitope masking, and germ-line antibody targetting followed by guided affinity maturation. The principles of antigen design revealed by this work could be applied to protective determinants of multiple pathogens for which vaccines are needed.