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

近年来，关于广泛交叉反应的报道越来越多。 对HIV包膜上的寡聚糖链具有特异性的中和抗体 尖峰(环境)。因此，能够产生这种nabs的免疫战略将是可取的。其中一个 诱导低聚甘露糖特异性NAB所面临的挑战是多糖的宿主来源， 免疫耐受机制可能限制B细胞的频率或发育 生产具有哺乳动物寡聚糖体特异性的抗体。例如，Abs在典型的 实验动物通过糖结合免疫原递呈低聚甘露糖苷，一般不能 在Env上结合寡核苷酸，甚至在获得Env结合抗体时也是如此，例如使用 重组酵母，它们似乎与病毒结合不够亲和力，无法发挥作用 有意义的中和活性。在这里，我们建议使用细菌衍生的低聚糖 寡头注释的类似物来克服这些挑战。 我们将重点放在一块相当保守的高甘露糖聚糖及其周围。 HIV gp120上的Asn301和Asn332。靶向这些低聚糖链类型的抗体的原型是 PGT128家族的抗体，具有很强的中和活性。一种能够 因此，诱导类似的nabs可以在适度的血清抗体效价下提供保护。 不久前，我们发现了一种细菌低聚糖，它与猪细小病毒的d1臂非常相似。 哺乳动物的寡核苷酸，随后用D3臂状延伸合成了它的类似物。 其中一个类似物，以新糖共轭形式，被PGT128的成员贪婪地结合 AB家族及其预测的生殖系前身。更关键的是，初步数据显示 用该结合物免疫表达未排列人源抗体谱系的转基因动物 结果产生具有HIV第2层交叉中和活性的糖特异性抗体。在此，我们建议 在这些令人鼓舞的初步结果的基础上进行扩展。具体地说，我们试图详细说明我们的共轭 设计和利用转基因动物来确定最佳佐剂+结合物组合以 最大限度地提高NAB反应。我们还试图在血清和谱系水平上剖析抗体反应 比较引出的NAB和现有的NAB之间的相似性，这可能会为促进战略提供参考。 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可能起作用。 繁衍的系统。 总而言之，这个项目将调查模拟多糖是否可以很容易地触发 开发对HIV环境高度脆弱的寡核苷酸补丁的交叉反应NaB。如果是的话， 这项工作可以为针对HIV-1上其他糖基表位的策略提供参考。

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.