Immunogenic Potential of Selected Peptides from SARS-CoV-2 Proteins and Their Ability to Block S1/ACE-2 Binding

The first infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes the coronavirus disease 2019 (COVID-19), occurred in December 2019. Within a single month, the disease reached other countries, spreading in a rapid and generalized manner worldwide to cause the COVID-19 pandemic. In Brazil, the number of COVID-19 cases surpassed 38 million. This study was conducted to produce antibodies against SARS-CoV-2 and investigate the immunogenic potential of synthetic peptides containing partial sequences of the main proteins (spike, membrane, and nucleocapsid proteins). In addition, we evaluated the ability of the antibodies to impair the interaction between the spike S1 protein and human ACE-2 protein, which is the main route of entry of the virus into host cells. By immunizing horses with synthetic peptides, we obtained hyperimmune sera with specific anti-SARS-CoV-2 antibodies, which were fragmented to release the F(ab')2 portion that binds to the different SARS-CoV-2 proteins as a recombinant S1-protein and proteins from a viral lysate. The other F(ab')2 samples also impaired the interaction between S1 protein and ACE-2 proteins, showing high potential to prevent viral spreading.