Synthetic bacterial analogs of mammalian oligomannose for eliciting neutralizing antibodies to the high-mannose patch on HIV Env

哺乳动物寡甘露糖的合成细菌类似物，用于引发针对 HIV 包膜上高甘露糖斑块的中和抗体

• 批准号: 9410721
• 负责人: Ralph Alphonso Pantophlet
• 金额: $ 33.05万
• 依托单位: SIMON FRASER UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-09-01 至 2021-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9410721
• 关键词: Address; Adjuvant; Affinity; Animal Model; Animals; Antibodies; Antibody Formation; Antibody Response; Antigens; Avidity; B-Cell Development; B-Lymphocytes; Binding; Biological Assay; Carrier Proteins; Collaborations; Data; Development; Engineering; Epitopes; Exhibits; Family; Frequencies; Genes; Genetic Engineering; Glycoconjugates; Goals; HIV; HIV Envelope Protein gp120; HIV vaccine; HIV-1; Human; Immune Sera; Immune Tolerance; Immune system; Immunization; Immunize; In Vitro; Investigation; Laboratories; Lead; Macaca; Mannose; Measures; Molecular Mimicry; Oligosaccharides; Polysaccharides; Rattus; Recombinants; Reporting; Serum; Site; Somatic Mutation; Specificity; Sum; System; Testing; Transgenic Animals; Transgenic Organisms; Vaccine Design; Vaccines; Viral Antibodies; Viral Physiology; Virus; Work; Yeasts; analog; arm; clinically relevant; cross reacting material 197; cross reactivity; deep sequencing; design; immunogenicity; man; member; mimetics; mimicry; neutralizing antibody; nonhuman primate; novel vaccines; receptor; response; simian human immunodeficiency virus; sugar; tool; vaccine candidate

In recent years there have been an increasing number of reports on broadly cross-reactive neutralizing antibodies (nAbs) with specificity for oligomannose-type glycans on the HIV envelope spike (Env). Immunization strategies that could yield such nAbs would therefore be desirable. One of the challenges faced by efforts to elicit oligomannose-specific nAbs is the host origin of the glycans, with immune tolerance mechanisms possibly limiting the frequency or development of B cells capable of producing Abs with specificity for mammalian oligomannose. For example, Abs elicited in typical experimental animals by glycoconjugate immunogens presenting oligomannosides are generally unable to bind oligomannose on Env and even when Env-binding Abs have been obtained, such as with recombinant yeast, they appear to bind insufficiently avid to the virus and fail to exert meaningful neutralizing activity. Here, we propose to utilize bacterially derived oligosaccharide analogs of oligomannose to overcome these challenges. We focus in this application on a fairly conserved patch of high-mannose glycans at and surrounding Asn301 and Asn332 on HIV gp120. Prototypic for Abs targeting these oligomannose-type glycans is the PGT128 family of Abs, which exhibit potent neutralizing activity. A vaccine component capable of eliciting similar nAbs could thus offer protection at even modest serum Ab titers. We not long ago discovered a bacterial oligosaccharide that closely resembles the D1 arm of mammalian oligomannose and subsequently made synthetic analogs of it with a D3 arm-like extension. One of these analogs, in the form of a neoglycoconjugate, is bound avidly by members of the PGT128 Ab family and their predicted germline predecessor. More crucially, preliminary data show that immunization of transgenic animals expressing an unarranged human Ab repertoire with this conjugate results in glycan- specific Abs with HIV tier 2 cross-neutralizing activity. Here, we propose to expand on these encouraging first results. Specifically, we seek to elaborate on our conjugate design and utilize transgenic animals to identify an optimal adjuvant+conjugate combination to maximize nAb responses. We also seek to dissect Ab responses at the serum and repertoire levels to compare similarities between the elicited and existing nAbs, which may inform boosting strategies. Finally, we propose to test our strategy in macaques to assess the extent to which it may work in outbred systems. In sum, this project will investigate whether glycan mimicry can serve to readily trigger the development of cross-reactive nAbs to the highly vulnerable oligomannose patch on HIV Env. If so, this work could inform strategies for targeting other glyco-epitopes on HIV-1.

近年来，关于广泛交叉反应的报道越来越多。 对 HIV 包膜上的寡甘露糖型聚糖具有特异性的中和抗体 (nAb) 尖峰（环境）。因此，能够产生此类 nAb 的免疫策略将是可取的。中的一个 引发寡甘露糖特异性 nAb 的努力所面临的挑战是聚糖的宿主来源， 免疫耐受机制可能限制 B 细胞的频率或发育 产生对哺乳动物寡甘露糖具有特异性的抗体。例如，Abs 在典型的 实验动物通过呈递寡甘露糖苷的糖缀合物免疫原通常无法 结合 Env 上的寡甘露糖，甚至在获得 Env 结合抗体时，例如使用 重组酵母，它们似乎与病毒的结合不够充分，并且无法发挥作用 有意义的中和活动。在这里，我们建议利用细菌来源的寡糖 寡甘露糖类似物可以克服这些挑战。 我们在此应用中重点关注位于及其周围的相当保守的高甘露糖聚糖片段 HIV gp120 上的 Asn301 和 Asn332。靶向这些寡甘露糖型聚糖的 Abs 的原型是 PGT128 抗体家族，具有有效的中和活性。疫苗成分能够 因此，即使血清抗体滴度适中，引发类似的 nAb 也能提供保护。 不久前我们发现了一种细菌寡糖，它与细菌的 D1 臂非常相似。 哺乳动物寡甘露糖，随后合成了具有 D3 臂状延伸的类似物。 这些类似物之一以新糖缀合物的形式与 PGT128 的成员紧密结合 Ab 家族及其预测的种系前身。更重要的是，初步数据显示 使用该缀合物对表达未排列的人类抗体库的转基因动物进行免疫 产生具有 HIV 2 级交叉中和活性的聚糖特异性抗体。在此，我们建议 扩展这些令人鼓舞的初步结果。具体来说，我们试图详细说明我们的共轭 设计并利用转基因动物来确定最佳的佐剂+结合物组合 最大化 nAb 反应。我们还试图剖析血清和库水平的抗体反应，以 比较引发的和现有的 nAb 之间的相似性，这可能会为加强策略提供信息。 最后，我们建议在猕猴身上测试我们的策略，以评估它在多大程度上发挥作用。 远交系统。 总之，该项目将研究聚糖拟态是否可以轻松触发 开发针对 HIV Env 上高度脆弱的寡甘露糖补丁的交叉反应性 nAb。如果是这样， 这项工作可以为针对 HIV-1 上其他糖表位的策略提供信息。