新型广谱强效双特异性 HIV-1 中和抗体 iMabm36 的合理设计与鉴定。
Rational design and characterization of the novel, broad and potent bispecific HIV-1 neutralizing antibody iMabm36.
机构信息
*Aaron Diamond AIDS Research Center, The Rockefeller University, New York, NY; †Institute of Medical Biology, Chinese Academy of Medical Science and Peking Union Medical College, Kunming, China; and ‡Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA.
出版信息
J Acquir Immune Defic Syndr. 2014 Aug 15;66(5):473-83. doi: 10.1097/QAI.0000000000000218.
BACKGROUND
Although broadly neutralizing monoclonal antibodies (bNAbs) have always been considered to be a potential therapeutic option for the prophylaxis and treatment of HIV infection, their lack of breadth against all HIV variants has been one of the limiting factors. To provide sufficient neutralization breadth and potency against diverse viruses, including neutralization escape mutants, strategies to combine different bNAbs have been explored recently.
METHODS
We rationally designed and engineered a novel bispecific HIV-1-neutralizing antibody (bibNAb), iMabm36. The potency and breadth of iMabm36 against HIV were extensively characterized in vitro.
RESULTS
iMabm36 comprises the anti-CD4 Ab ibalizumab (iMab) linked to 2 copies of the single-domain Ab m36, which targets a highly conserved CD4-induced epitope. iMabm36 neutralizes a majority of a large, multiclade panel of pseudoviruses (96%, n = 118) at an IC50 concentration of less than 10 µg/mL, with 83% neutralized at an IC50 concentration of less than 0.1 µg/mL. In addition, iMabm36 neutralizes a small panel of replication-competent transmitted-founder viruses to 100% inhibition at a concentration of less than 0.1 µg/mL in a peripheral blood mononuclear cell-based neutralizing assay. Mechanistically, the improved antiviral activity of iMabm36 is dependent on both the CD4-binding activity of the iMab component and the CD4i-binding activity of the m36 component. After characterizing that viral resistance to iMabm36 neutralization was due to mutations residing in the bridging sheet of gp120, an optimized m36 variant was engineered that, when fused to iMab, improved antiviral activity significantly.
CONCLUSIONS
The interdependency of this dual mechanism of action enables iMabm36 to potently inhibit HIV-1 entry. These results demonstrate that mechanistic-based design of bibNAbs can generate potential preventive and therapeutic candidates for HIV/AIDS.
背景
尽管广泛中和的单克隆抗体（bNAb）一直被认为是预防和治疗 HIV 感染的潜在治疗选择，但它们对所有 HIV 变体的缺乏广度一直是限制因素之一。为了提供针对多种病毒的足够中和广度和效力，包括中和逃逸突变体，最近已经探索了结合不同 bNAb 的策略。
方法
我们合理设计并构建了一种新型双特异性 HIV-1 中和抗体（bibNAb）iMabm36。在体外广泛表征了 iMabm36 对 HIV 的效力和广度。
结果
iMabm36 由抗 CD4 Ab ibalizumab（iMab）与 2 个单域 Ab m36 连接组成，该抗体针对高度保守的 CD4 诱导表位。iMabm36 在 IC50 浓度低于 10μg/ml 时，可中和大多数大型、多克隆的假病毒（96%，n=118），其中 83%在 IC50 浓度低于 0.1μg/ml 时被中和。此外，iMabm36 在基于外周血单核细胞的中和测定中，以浓度低于 0.1μg/ml 时可中和小部分复制能力的传播起始病毒，达到 100%抑制。从机制上讲，iMabm36 抗病毒活性的提高依赖于 iMab 成分的 CD4 结合活性和 m36 成分的 CD4i 结合活性。在表征到对 iMabm36 中和的病毒耐药性是由于 gp120 的桥接片上的突变引起的之后，构建了一个优化的 m36 变体，当与 iMab 融合时，显著提高了抗病毒活性。
结论
这种双重作用机制的相互依存关系使 iMabm36 能够有效抑制 HIV-1 进入。这些结果表明，基于机制的 bibNAb 设计可以为 HIV/AIDS 生成潜在的预防和治疗候选物。
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