Development of highly neutralizing nanobodies against HIV-1

HIV-1和HIV-2是导致人类获得性免疫缺陷综合征(AIDS)的慢病毒。到目前为止，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。由于没有广泛的预防措施和治疗方法，艾滋病是撒哈拉以南非洲等地区的主要死亡原因。因此，迫切需要开发包括疫苗在内的有效方法，以防止易感人群感染艾滋病毒。在过去的十年中，几种药物被测试为局部杀微生物剂，以防止艾滋病毒进入，结果喜忧参半。然而，这些方法需要通过阴道环、凝胶、薄膜或灌肠给药，这在世界贫困地区并不实用。一种有趣的替代方法是使用胃肠道和生殖道细菌作为体内抗病毒多肽的递送载体。例如，乳杆菌输送的HIV-1进入抑制剂显著降低了恒河猴SIV感染的发生率。一种类似的策略也被用来通过仅骆驼重链抗体来阻断艰难梭菌毒素。这些抗体的V(D)J结构域，也被称为纳米体，特别适合于杀微生物剂的开发，因为它们很容易由共生细菌分泌，在不同的pH条件下抵抗变性，并且很容易穿透宫颈阴道粘膜。此外，由于其尺寸较小，可以开发出针对抗原缝隙的纳米体，例如HIV糖蛋白屏蔽的尖峰，这是较大的传统抗体的挑战性靶点。纳米抗体也可以相对容易地人性化，这是一种在临床试验中降低其免疫原性的策略。该项目建议开发高度中和的抗艾滋病毒纳米抗体，作为杀微生物剂或体内治疗的潜在用途。此外，我们还展示了一种在小鼠身上生产纳米体的方法，目的是开发基于纳米体的疗法来对抗HIV-1和其他人类病原体。

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, to prevent HIV infection in susceptible populations. With mixed results, several drugs have been tested in the past decade for use as topical microbicides to prevent HIV entry. However, these approaches require drug delivery through vaginal rings, gels, films or enemas, which are not practical treatments in poor areas of the world. An intriguing alternative is the use of gastrointestinal and genital tract bacteria as in vivo delivery vectors for anti-viral peptides. For instance, Lactobacillus delivery of HIV-1 entry inhibitors markedly reduced the incidence of SIV infection in rhesus monkeys. A similar strategy was used to block Clostridium difficile toxins by means of camelid heavy chain only antibodies. V(D)J domains from these antibodies, also known as nanobodies, are particularly suited for the development of microbicides because they are readily secreted by commensal bacteria, are resistant to denaturation under varied pH conditions, and can easily penetrate the cervicovaginal mucosa. In addition, because of their small size, nanobodies can be developed against antigen crevices such as HIV glycan-shielded spikes, which are challenging targets for bulkier conventional antibodies. Nanobodies can also be humanized with relative ease, a strategy that reduces their immunogenicity in clinical trials. This project proposes the development of highly neutralizing anti-HIV nanobodies for potential use as microbicides or in in vivo therapies. Furthermore, we lay out an approach to produce nanobodies in mice with the goal of developing nanobody-based therapies against HIV-1 and other human pathogens.