Nanobody-Functionalized Cellulose for Capturing and Containing SARS-CoV-2

Sun, Xin; Yang, Shaobo; Al-Dossary, Amal A.; Broitman, Shana; Ni, Yun; Yang, Mengdi; Li, Jiahe

The highly transmissible severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has infected more than 217 million people, claiming ~ 4.5 million lives to date. Although mandatory quarantines, lockdowns, and vaccinations help curb viral transmission, safe and effective preventative measures remain urgently needed. Here, we present a generic strategy for containing SARS-CoV-2 by cellulose materials. Specifically, we developed a bifunctional fusion protein consisting of a cellulose-binding domain and a nanobody (Nb) targeting the receptor-binding domain of SARS-CoV-2. The immobilization of the fusion proteins on cellulose substrates enhanced the capture efficiency of Nbs against SARS-CoV-2 pseudoviruses of the wildtype and the D614G variant, the latter of which has been shown to confer higher infectivity. Furthermore, the fusion protein was integrated into a customizable chromatography with highly porous cellulose for neutralizing virus from contaminated fluids in a continuous and cost-effective fashion. Taken together, our work leverages low-cost cellulose materials and recently developed Nbs to provide a complementary approach to addressing the pandemic. IMPORTANCE The ongoing efforts to address the COVID-19 pandemic center around the development of point-of-care diagnostics, preventative measures, and therapeutic strategies against COVID-19. In contrast to existing work, we have provided a complementary approach to target and contain SARS-CoV-2 from contaminated fluids and surfaces. Specifically, we present a generic strategy for the capture and containing of SARS-CoV-2 by cellulose-based substrates. This was archived by developing a bifunctional fusion protein consisting of both a cellulose-binding domain and a nanobody specific for the receptor-binding domain of SARS-CoV-2. As a proof-of-concept, our fusion protein-coated cellulose substrates exhibited enhanced capture efficiency against SARS-CoV-2 pseudovirus of both wildtype and the D614G mutant variants, the latter of which has been shown to confer higher infectivity. Furthermore, the fusion protein was integrated into a customizable chromatography with highly porous cellulose for neutralizing the virus from contaminated fluids in a highly continuous and cost-effective fashion.