Neutralizing single domain antibodies against SARS-CoV-2 virus for therapeutic use

PAVAN MARÍA FLORENCIA; BOK MARINA; MALITO JUAN PABLO; MARCOPPIDO GISELA ARIANA; FRANCO DIEGO RAFAEL; SCHAMMAS JUAN MANUEL; BAUMEISTER ELSA; AUGUSTE ALBERT J; YUAN LIJUAN; WIGDOROVITZ ANDRES; PARREÑO VIVIANA; IBAÑEZ LORENA ITATÍ

Bruselas

Conferencia; Nanobodies (Hybrid 2nd edition); 2021

VIB - Vlaams Instituut voor Biotechnologie

The emergence of the disease caused by the SARS-CoV-2 virus is the third major coronavirus outbreak in the past 20 years. Despite the recent approval of different vaccines, the development of anti-infectious agents is still essential as a way to mitigate the effects of the disease. The SARS-CoV-2 spike protein (S), containing the receptor-binding domain (RBD), is a potential therapeutic target. For this reason, we propose the development of single domain antibodies (sdAbs) to neutralize the SARS-CoV-2 infection.In order to obtain sdAbs, a llama was immunized with the pre-fusion and locked S, and RBD proteins expressed in the HEK-293T cell line. A sdAb library was generated by cloning sdAbs encoding sequences in the phagemid vector pMECS-GG. More than 80 sdAbs against S and RBD proteins were selected by phage display. From these clones, 52 unique sdAbs were expressed in Escherichia coli WK6 and purified by immobilized metal chelate chromatography (IMAC) followed by size exclusion chromatography (SEC). Ten sdAbs were able to block transduction at a nanomolar level in a pseudovirus neutralization assay, as well as infection of Vero cells with the wild-type SARS-CoV-2 virus circulating in Argentina and the United States of America. The neutralization potency of SARS-CoV-2 variants will be determined in the near future. We are currently modifying some sdAbs to enhance their avidity, and their ability to inhibit the infection in vivo will be assessed in animal models. In conclusion, we have developed sdAbs capable of neutralizing the SARS-CoV-2 virus in vitro. These promising results make Argentina one of the few countries in Latin America capable of applying this kind of technology and turning sdAbs into therapeutic products. The strong neutralizing activity of some of these molecules highlights their potential to develop an intranasal treatment for COVID-19.