Development of highly neutralizing nanobodies against HIV-1, SARS-CoV-2 and other pathogens

HIV-1和2是导致人类获得性免疫缺陷综合征（艾滋病）的慢病毒。迄今为止，还没有开发出有效的疫苗，根据世界卫生组织的数据，全世界有近4000万人感染了艾滋病毒。由于预防措施和治疗不能广泛获得，艾滋病是撒哈拉以南非洲等地区的主要死亡原因。因此，迫切需要开发有效的方法，包括疫苗和免疫疗法，以防止易感人群感染艾滋病毒。一种接近天然的三聚体模拟物BG505 DS-SOSIP在各种动物模型中已被证明是一种很好的HIV-1疫苗免疫原。在这里，我们将这种免疫原注射到羊驼体内，以开发仅重链抗体，旨在产生广泛而有效的中和纳米体（bnnab）来对抗HIV-1。我们通过噬菌体筛选鉴定出两种纳米体，mT36和R27，当以三聚体形式进行工程设计时，可以中和来自不同分支的20个HIV-1毒株。我们正在一个208张力的面板上测试他们的活动。表位定位和结构分析将揭示其中和机制，为指导免疫原的优化提供重要信息。纳米体的独特特性，如低成本、高产和高稳定性，将使bNNbs成为控制长期艾滋病大流行的理想治疗方法。

HIV-1 and -2 are lentiviruses that cause acquired immunodeficiency syndrome (AIDS) in humans. To date, no effective vaccine has been developed and according to the World Health Organization nearly 40 million people are infected with HIV across the world. Because preventive measures and treatments are not widely available, AIDS is the leading cause of death in areas such as Sub-Saharan Africa. There is therefore an urgent need to develop efficient methods, including vaccines and immunotherapies, to prevent HIV infection in susceptible populations. A near-native trimer mimic, BG505 DS-SOSIP, has been shown to be a nice immunogen for HIV-1 vaccination in various animal models. Here we injected this immunogen in llama to develop heavy chain-only antibodies, aiming to generate broad and potent neutralizing nanobodies (bNNABs) against HIV-1. Two nanobodies that we identified through phage screening, mT36 and R27, when engineered in trimeric form, can neutralize a panel of 20 HIV-1 strains from various clades. We are currently testing their activity on a 208-strain panel. Epitope mapping and structural analysis will reveal their neutralization mechanism and provide essential information that can guide the optimization of the immunogen. Nanobodys unique properties such as low-cost, high-yield production and great stability will make bNNbs ideal therapeutics for controlling the long-lasting AIDS pandemic. The HMPV surface glycoprotein F mediates the fusion of viral and cellular membrane and is an attractive target for hMPV vaccine and neutralizing antibodies development. This fiscal year, we immunized llama with the third generation prefusion stabilized F protein developed at VRC/NIH, and isolated dozens of nanobodies targeting different epitopes on F protein. The neutralization activity of these nanobodies is currently under investigation. Structural analysis of both neutralizing and non-neutralizing nanobodies will likely assist the further refinement of F immunogen. And we expect that engineering such as Fc conjugation and multimerization can lead to a potent nanobody/antibody therapeutic for hMPV infection.