Camelid Nanobodies as a Novel Prophylactic for SARS-CoV-2

WILLIAM B. STONE; VIVIANA PARRENO; FLORENCIA PAVAN; MARINA BOK; JUAN PABLO MALITO; ITATÍ IBAÑEZ; DANIELLE PORIER; KRISANGEL LÓPEZ; JOHN A. MULLER; ALBERT J. AUGUSTE; LIJUAN YUAN

Wisconsin

Congreso; 41th Annual Meeting American Society for Virology; 2022

ASV

Nanobodies are a promising pre-exposure prophylactic approach forprotecting individuals against SARS-CoV-2 infection. Nanobodies areshelf-stable, highly heat tolerant, and chemically resistant. Considering theirlow cost, relative ease of production, and strong binding affinity forpathogens, nanobodies represent a therapeutic option with immense potential foruse against SARS-CoV-2. SARS-CoV-2 spike and receptor binding domain (RBD)proteins were administered subcutaneously to a llama (Lama glama) at 0, 14, 28,and 50 days, and immune response was monitored via ELISA. Four days after thefinal dose was administered, lymphocytes were harvested and nanobodies wereisolated via biopanning and phage display was used to create a gene library ofnanobody candidates. Isolated nanobodies were then introduced into an E. coliprotein expression system and purified via metal affinity and size exclusionchromatography for further testing. Nanobody candidates were screened usingplaque reduction neutralization tests with a 50% cut-off, resulting indown-selection to four lead candidates for in vivo efficacy studies. Nanobodies were administered intranasally to K18-hACE2 mice four hours before alethal SARS-CoV-2 challenge. Mice were monitored daily for weight and survivalfor 10 days. Our results indicate the nanobodies were effective at protectingthe mice from disease, even at doses as low as 10 micrograms. We are currentlyassessing combinatorial synergies between nanobodies with the intention ofdeveloping a more potent cocktail for higher order animal study and looking atthe efficacy of the nanobody candidates against new and emerging variants ofSARS-CoV-2. These nanobodies have a high potential to serve as a supplementalprophylactic measure, and as such will continue to be the subject of intenseapplied research.