High neutralizing potency of swine glyco-humanized polyclonal antibodies against SARS-CoV-2

• Published in: bioRxiv
• Main Authors: Vanhove, Bernard, Duvaux, Odile, Rousse, Juliette, Royer, Pierre-Joseph, Evanno, Gwénaëlle, Ciron, Carine, Lheriteau, Elsa, Vacher, Laurent, Gervois, Nadine, Oger, Romain, Jacques, Yannick, Conchon, Sophie, Salama, Apolline, Duchi, Roberto, Lagutina, Irina, Perota, Andrea, Delahaut, Philippe, Ledure, Matthieu, Paulus, Melody, So, Ray T, Mok, Chris Ka-Pun, Bruzzone, Roberto, Bouillet, Marc, Brouard, Sophie, Cozzi, Emanuele, Galli, Cesare, Blanchard, Dominique, Bach, Jean-Marie, Soulillou, Jean-Paul
• Format: Journal Article Paper
• Language: English
• Published: United States Cold Spring Harbor Laboratory Press 28.10.2020
• Subjects: ACE2; Allergies; Angiotensin; Angiotensin-converting enzyme 2; Antigen-antibody complexes; COVID-19; Epitopes; Fc receptors; Galactose; Hogs; Hydroxylase; Immunoglobulin G; Inflammation; Macrophages; N-Acetylneuraminic acid; Peptidyl-dipeptidase A; Perfusion; Polyclonal antibodies; Serum sickness; Severe acute respiratory syndrome coronavirus 2; Standardization
• DOI: 10.1101/2020.07.25.217158

Perfusion of convalescent plasma (CP) has demonstrated a potential to improve the pneumonia induced by SARS-CoV-2, but procurement and standardization of CP are barriers to its wide usage. Many monoclonal antibodies (mAbs) have been developed but appear insufficient to neutralize SARS-CoV-2 unless two or three of them are being combined. Therefore, heterologous polyclonal antibodies of animal origin, that have been used for decades to fight against infectious agents might represent a highly efficient alternative to the use of CP or mAbs in COVID-19 by targeting multiple antigen epitopes. However, conventional heterologous polyclonal antibodies trigger human natural xenogeneic antibody responses particularly directed against animal-type carbohydrate epitopes, mainly the N-glycolyl form of the neuraminic acid (Neu5Gc) and the Gal α1,3-galactose (αGal), ultimately forming immune complexes and potentially leading to serum sickness or allergy. To circumvent these drawbacks, we engineered animals lacking the genes coding for the cytidine monophosphate-N-acetylneuraminic acid hydroxylase (CMAH) and α1,3-galactosyl-transferase (GGTA1) enzymes to produce glyco-humanized polyclonal antibodies (GH-pAb) lacking Neu5Gc and α-Gal epitopes. We found that pig IgG Fc domains fail to interact with human Fc receptors and thereby should confer the safety advantage to avoiding macrophage dependent exacerbated inflammatory responses, a drawback possibly associated with antibody responses against SARS-CoV-2 or to avoiding a possible antibody-dependent enhancement (ADE). Therefore, we immunized CMAH/GGTA1 double knockout (DKO) pigs with the SARS-CoV-2 spike receptor-binding domain (RBD) to elicit neutralizing antibodies. Animals rapidly developed a hyperimmune response with anti-SARS-CoV-2 end-titers binding dilutions over one to a million and end-titers neutralizing dilutions of 1:10,000. The IgG fraction purified and formulated following clinical Good Manufacturing Practices, named XAV-19, neutralized Spike/angiotensin converting enzyme-2 (ACE-2) interaction at a concentration < 1μg/mL and inhibited infection of human cells by SARS-CoV-2 in cytopathic assays. These data and the accumulating safety advantages of using glyco-humanized swine antibodies in humans warranted clinical assessment of XAV-19 to fight against COVID-19.