基于抗体恒定区CH2域骨架的新型抗人免疫缺陷病毒I型纳米抗体的筛选与鉴定

Selection of broadly neutralizing monoclonal antibodies (bnmAbs) against human immunodeficiency virus type 1 (HIV-1) is one of the hottest directions in the field of antibody-based therapeutics. However, because of the large molecular weight (about 150 kD), it is difficult for them to access sterically restricted epitopes which are crucial for viral entry. Therefore, decrease of the size of full-length antibodies is one of the important strategies for development of bnmAbs against HIV-1. This plan is to select and characterize novel nanoantibodies (nAbs, M.W.: about 12-15 kD) against HIV-1 which is based on scaffold derived from antibody constant CH2 domain. Sequential antigen panning (SAP) of yeast-displayed library with membrane proximal external region (MPER) on envelope glycoprotein (Env) from different HIV-1 clades is to be used to get candidate clones. After expression and purification of these clones, the affinity of them to HIV-1 Envs are to be measured to get candidates with increased affinity for further optimization and analysis.

筛选抗人免疫缺陷病毒I型（HIV-1）广谱高效的单克隆抗体是当前研究的一大热门方向。然而全长抗体过大的分子量（约150 kD）阻碍它们结合到HIV-1囊膜糖蛋白上那些存在位阻效应并对病毒进入细胞起关键作用的位点。因此将全长抗体小型化是目前开发抗HIV-1抗体的一个重要策略。本研究以抗体恒定区CH2域为骨架，筛选并鉴定针对HIV-1的新型纳米抗体（分子量：约12-15 kD）。通过构建酵母展示库，以不同型的HIV-1囊膜糖蛋白近膜端外部区为靶点，运用次序抗原筛选的方法，得到与该区域上保守位点相结合的候选纳米抗体。经表达纯化后，测定它们与HIV-1囊膜糖蛋白的亲和力，得到亲和力提高的若干候选者，为进一步优化、分析做准备。

我们以一个改造后的抗体恒定区CH2结构域（m01sm1）为骨架，构建了噬菌体展示库（库容为10的10次方），以人免疫缺陷病毒I型（HIV-1）的囊膜蛋白、来源于囊膜蛋白近膜端外部区的肽为抗原进行了筛选，得到了如若干候选纳米抗体克隆。相比我们以前所得到的纳米抗体m2a1，它们的活性有所增强。这些候选克隆将被进一步分析，评估其成为抗HIV-1候选新型抑制剂的潜力。