Maximizing germinal centers and somatic hypermutation to HIV Env immunogens

摘要 我们认为，生殖中心的生物学特征对于将高亲和力的B细胞发育为非常适合人类的细胞是重要的。 困难的表位，如HIV Env三聚体上的第2层nAb表位，与充分表征的表位非常不同。 常规抗原如半抗原的GC生物学特征。我们已经证明， 免疫改变了免疫反应的基本方面，这可能导致严重的免疫缺陷。 nAb反应的改善（Cell 2019）。常规免疫策略可能不足以 由于所造成的免疫障碍，开发针对HIV或其他困难病原体的bnAb疫苗， 包括B细胞免疫优势和GC的数量和质量。我们发现两种独立的方法 RM的缓慢递送免疫导致更稳健的Tfh细胞和更多的具有Env结合的GC B细胞， 通过纵向淋巴结（LN）细针抽吸物（FNA）追踪1。GC改善与 产生> 20倍更高滴度的自体2级中和Ab（nAb）。BCR测序和Ab 图谱显示，通过常规推注可靶向免疫显性非中和（nnAb）表位 免疫动物，而缓慢递送免疫动物靶向更多样化的表位组，包括 多个第2层nAb表位。我们将继续这些开创性的研究，使用新的缓释 探索与针对困难的HIV三聚体的亲和力成熟相关的生发中心生物学的技术 免疫原在非人灵长类动物（NHP，恒河猴）。

Abstract We propose that the features of germinal center biology important for developing high affinity B cells to a very difficult epitope, such as a tier 2 nAb epitope on HIV Env trimer, are very different than the well characterized features of GC biology for conventional antigens, such as haptens. We have demonstrated that slow delivery immunization changes fundamental aspects of the immune response, which can result in dramatic improvements in nAb responses (Cell 2019). Conventional immunization strategies will likely be insufficient for the development of a bnAb vaccine to HIV or other difficult pathogens due to the immunological hurdles posed, including B cell immunodominance and GC quantity and quality. We found that two independent methods of slow delivery immunization of RMs resulted in more robust Tfh cells and more GC B cells with Env-binding, tracked by longitudinal lymph node (LN) fine needle aspirates (FNA) 1. Improved GCs correlated with the development of > 20-fold higher titers of autologous tier 2 neutralizing Abs (nAbs). BCR sequencing and Ab mapping demonstrated targeting of immunodominant non-neutralizing (nnAb) epitopes by conventional bolus immunized animals, while slow delivery immunized animals targeted a more diverse set of epitopes, including multiple tier 2 nAb epitopes. We will continue these groundbreaking studies to use novel slow release technologies to probe the biology of germinal centers relevant to affinity maturation against a difficult HIV trimer immunogen in non-human primates (NHP, rhesus macaques).