High Affinity Nanobodies Block SARS-CoV-2 Spike Receptor Binding Domain Interaction with Human Angiotensin Converting Enzyme

Abstract

There are currently no approved effective treatments for SARS-CoV-2, the virus responsible for the COVID-19 pandemic. Nanobodies are 12-15 kDa single-domain antibody fragments that are more stable and amenable to large-scale production compared to conventional antibodies. Nanobodies can also be administered in an inhaled form directly to the lungs. We have isolated several nanobodies that bind to the SARS-CoV-2 spike protein receptor binding domain and block spike protein interaction with the angiotensin converting enzyme 2 (ACE2) receptor. The SARS-CoV-2 spike protein is responsible for viral entry into human cells via interaction with ACE2 on the cell surface. The lead therapeutic candidate, NIH-CoVnb-112, binds to the SARS-CoV-2 spike protein receptor binding domain at approximately 5 nM affinity, and blocks spike protein interaction with the human ACE2 receptor at approximately 0.02 micrograms/mL EC50 (1.1 nM). The affinity and blocking potency of NIH-CoVnb-112 are substantially better than previously reported candidate nanobody therapeutics for SARS-CoV-2, and bind to a distinct site. Furthermore, NIH-CoVnb-112 blocks interaction between ACE2 and several high affinity variant forms of the spike protein. When multimerized or combined with other nanobodies, the effective affinity and blocking interactions may be even more potent, as has been well described for other nanobody therapeutics. These resulting nanobodies have therapeutic, preventative, and diagnostic potential.

NeutrobodyPlex - Nanobodies to monitor a SARS-CoV-2 neutralizing immune response

“…Nbs can be efficiently selected against different epitopes on the same antigen and can be easily converted into multivalent formats 9 . The potential of Nbs to address SARS-CoV-2 has been impressively demonstrated by the recent identification of several RBD specific Nbs from naïve/ synthetic libraries [10][11][12] or immunized animals [12][13][14][15][16] .…”

Perspective on therapeutic and diagnostic potential of camel nanobodies for coronavirus disease-19 (COVID-19)

“…These Nbs, named 2F2, 3F11 and 5F8 could be very advantageous to find new specific drugs to prevent SARS-CoV-2 infection by inhibiting membrane fusion between RBDs of the viral Spike and their host cell receptors and then blocks the entry of SARS-CoV-2 into cells (Fig. 3; adapted from Esparza et al 2020). Another illustration of a VHH against SARS-CoV-2 is VHHs against prefusion-stabilized MERS-CoV and SARS-CoV-1 spikes of Betacoronaviruses.…”

“…The major therapeutic goal is to develop inhibitory agents that disrupt the interaction between the receptor-binding domain of SARS-CoV-2 (green color) with its host cell receptor (angiotensin-converting enzyme 2: ACE2). Nanobodies bound directly to the receptor-binding domain (RBD) and competed with the ACE2 receptor from the surface of human cells (adapted from Esparza et al 2020) needs to be monitored. In a similar study, the identification and characterization of two other high-affinity Nbs (H11-D4 and H11-H4) have been reported (Huo et al 2020).…”

“…In another study, several Nbs that bind to the SARS-CoV-2 RBD have been isolated (Esparza and Brody 2020). Among those, the lead therapeutic candidate named NIH-CoVnb-112 showed high affinity in monomeric form and blocked interaction between ACE2 and several variant forms of the spike protein.…”

Application of a Method for Engineering Multivalent Antibodies to Substantially Enhance Functional affinity of Clinical Trial Anti-SARS-CoV-2 Antibodies

“…The severity of the SARS-CoV-2 pandemic has initiated a major international effort to develop antibodies that bind to the SARS-CoV-2 spike protein in the ACE2 receptor binding domain (RBD). These have been derived as monoclonal antibodies (mAbs) from infected people [5][6][7][8][9][10][11][12] , by animal immunizations with SARS-CoV-2 spike glycoprotein [13][14][15][16][17] or phage screening methods [18][19][20][21] . At present more than a dozen anti-SARS-CoV-2 mAbs are in clinical development 22 of which bamlanivimab (LV-CoV555, Lilly) and a cocktail antibody containing casirivimab (REGN10933, Regeneron) and imdevimab (REGN10987, Regeneron) have received Emergency Use Approval (EUA) from the Food and Drug Administration.…”