A potent bispecific nanobody protects hACE2 mice against SARS-CoV-2 infection via intranasal administration

Xilin Wu; Lin Cheng; Ming Fu; Bilian Huang; Linjing Zhu; Shijie Xu; Haixia Shi; Doudou Zhang; Huanyun Yuan; Waqas Nawaz; Ping Yang; Qinxue Hu; Yalan Liu; Zhiwei Wu

doi:10.1101/2021.02.08.429275

Abstract

The dramatically expanding COVID-19 needs multiple effective countermeasures. Neutralizing antibodies are a potential therapeutic strategy for treating COVID-19. A number of neutralizing nanobodies (Nbs) were reported for their in vitro activities. However, in vivo protection of these nanobodies was not reported in animal models. In the current report, we characterized several RBD-specific Nbs isolated from a screen of an Nb library derived from an alpaca immunized with SARS-CoV-2 spike glycoprotein (S); among them, three Nbs exhibited picomolar potency against SARS-CoV-2 live virus, pseudotyped viruses, and 15 circulating SARS-CoV-2 variants. To improve the efficacy, various configurations of Nbs were engineered. Nb₁₅-Nb_H-Nb₁₅, a novel trimer constituted of three Nbs, was constructed to be bispecific for human serum albumin (HSA) and RBD of SARS-CoV-2. Nb₁₅-Nb_H-Nb₁₅ exhibited sub-ng/ml neutralization potency against the wild-type and currently circulating variants of SARS-CoV-2 with a long half-life in vivo. In addition, we showed that intranasal administration of Nb₁₅-Nb_H-Nb₁₅ provided 100% protection for both prophylactic and therapeutic purposes against SARS-CoV-2 infection in transgenic hACE2 mice. Nb₁₅-Nb_H-Nb₁₅ is a potential candidate for both prevention and treatment of SARS-CoV-2 through respiratory administration.

One sentence summary Nb₁₅-Nb_H-Nb₁₅, with a novel heterotrimeric bispecific configuration, exhibited potent and broad neutralization potency against SARS-CoV-2 in vitro and provided in vivo protection against SARS-CoV-2 infection in hACE2 transgenic mice via intranasal delivery.

Graphical abstract:

Highlights

We described a novel heterotrimeric configuration of Nb-Nb_H-Nb (Nb₁₅-Nb_H-Nb₁₅) that exhibited improved viral inhibition and stability.
Nb₁₅-Nb_H-Nb₁₅ provides ultrahigh neutralization potency against SARS-CoV-2 wild type and 18 mutant variants, including the current circulating variants of D614G and N501Y predominantly in the UK and South Africa.
It is the first to demonstrate the Nbs efficacy in preventing and treating SARS-CoV-2 infection in hACE2 transgenic mice via intranasal delivery.

Competing Interest Statement

The authors have declared no competing interest.

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