HIV remains one of the most important health issues worldwide, with almost 40 million people living with HIV. Although patients develop antibodies against the virus, its high mutation rate allows evasion of immune responses. Some patients, however, produce antibodies that are able to bind to, and neutralise different strains of HIV. One such ‘broadly neutralising’ antibody is ‘N6’. Identified in 2016, N6 can neutralise 98% of HIV-1 isolates with a median IC50 of 0.066 µg/mL. This neutralisation breadth makes N6 a very promising therapeutic candidate. N6 was expressed in a glycoengineered line of N. benthamiana plants (pN6) and compared to the mammalian cell-expressed equivalent (mN6). Expression at 49 mg/kg (fresh leaf tissue) was achieved in plants, although extraction and purification are more challenging than for most plant-expressed antibodies. N-glycoanalysis demonstrated the absence of xylosylation and a reduction in α(1,3)-fucosylation that are typically found in plant glycoproteins. The N6 light chain contains a potential N-glycosylation site, which was modified and displayed more α(1,3)-fucose than the heavy chain. The binding kinetics of pN6 and mN6, measured by surface plasmon resonance, were similar for HIV gp120. pN6 had a tenfold higher affinity for FcγRIIIa, which was reflected in an antibody-dependent cellular cytotoxicity assay, where pN6 induced a more potent response from effector cells than that of mN6. pN6 demonstrated the same potency and breadth of neutralisation as mN6, against a panel of HIV strains. The successful expression of N6 in tobacco supports the prospect of developing a low-cost, low-tech production platform for a monoclonal antibody cocktail to control HIV in low-to middle income countries.

中文翻译：

---

烟草植物中表达的高效且近泛中和的抗 HIV 单克隆抗体的表征


艾滋病毒仍然是全世界最重要的健康问题之一，有近 4000 万人感染艾滋病毒。尽管患者会产生针对该病毒的抗体，但其高突变率可以逃避免疫反应。然而，一些患者会产生能够结合并中和不同病毒株的抗体。一种这样的“广泛中和”抗体是“N6”。 2016 年发现，N6 可以中和 98% 的 HIV-1 分离株，中值 IC50 为 0.066 µg/mL。这种中和广度使 N6 成为非常有前途的治疗候选者。 N6 在本塞姆氏烟草植物的糖工程系 (pN6) 中表达，并与哺乳动物细胞表达的等效物 (mN6) 进行比较。尽管提取和纯化比大多数植物表达的抗体更具挑战性，但在植物中实现了 49 mg/kg（新鲜叶组织）的表达。 N-糖分析表明，植物糖蛋白中常见的木糖基化不存在，且 α(1,3)-岩藻糖基化减少。 N6 轻链包含一个潜在的 N-糖基化位点，该位点经过修饰并比重链显示出更多的 α(1,3)-岩藻糖。通过表面等离子体共振测量，pN6 和 mN6 的结合动力学与 HIV gp120 相似。 pN6 对 FcγRIIIa 的亲和力高出十倍，这反映在抗体依赖性细胞毒性测定中，其中 pN6 诱导效应细胞的反应比 mN6 更有效。 pN6 对一组 HIV 毒株表现出与 mN6 相同的中和效力和广度。 N6 在烟草中的成功表达支持了开发低成本、低技术含量的单克隆抗体混合物生产平台的前景，以在中低收入国家控制艾滋病毒。