Isolation and characterization of antibodies against SARS-Cov-2 RBD

Coronavirus disease 2019 (COVID-19) is a highly contagious respiratory disease that emerged in December 2019 in Wuhan, China, and was declared by the World Health Organization (WHO) as a global pandemic. With over 6 million deaths worldwide, COVID-19 is considered one of the deadliest pandemics in history.

The virus responsible for COVID-19 is the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a novel virus with high infectivity and transmissibility, that spreads between human hosts by aerosols and respiratory droplets. Infection of host cells by SARS-CoV-2 is initiated by binding of the viral spike protein to angiotensin-converting enzyme 2 (ACE2), a membranal enzyme that can be found in several human tissues. The receptor binding is possible due to a receptor binding domain (RBD) located on the top of the spike protein of the virus.

The rapid spread of SARS-CoV-2 around the world resulted in high mutation rate, causing the emergence of variants that have gained the ability to escape immunity and reinfect recoverees and vaccinees, lost their susceptibility to treatments and detection methods and caused more severe illness, declared as variants of concern (VOCs).

This research was aimed to isolate SARS-CoV-2 RBD-specific neutralizing monoclonal antibodies (mAbs) from immunized mice using single B cell sorting. The three mAbs we isolated were produced as recombinant human IgGs and their binding and neutralizing abilities were evaluated. The three antibodies showed high affinity binding and neutralizing capabilities against Wuhan SARS-CoV-2 RBD. In addition, we found that these mAbs bound several VOCs RBDs with high affinity.