摘要：SummaryWe used the recombinant trimeric spike (S) glycoprotein in the prefusion conformation to immunize horses for the production of hyperimmune globulins against SARS-CoV-2. Serum antibody titers measured by ELISA were above 1:106, and the neutralizing antibody titer against authentic virus (WT) was 1:14,604 (average PRNT90). Plasma from immunized animals was pepsin digested to remove the Fc portion and purified, yielding an F(ab’)2preparation with PRNT90titers 150-fold higher than the neutralizing titers in human convalescent plasma. Challenge studies were carried out in hamsters and showed thein vivoability of equine F(ab’)2to reduce viral load in the pulmonary tissues and significant clinical improvement determined by weight gain. The neutralization curve by F(ab’)2was similar against the WT and P.2 variants, but displaced to higher concentrations by 0.39 log units against the P.1 (Gamma) variant. These results support the possibility of using equine F(ab’)2preparation for the clinical treatment of COVID patients.Graphical abstractDisplay OmittedHighlights•Trimeric spike glycoprotein induces high level of horse neutralizing antibodies•The F(ab’)2Ab has neutralizing titer 150-fold higher than human convalescent plasma•The neutralizing activity of F(ab’)2was high against the P.1 (Gamma) and P.2 variants•Anti-spike F(ab’)2protected hamsters against SARS-CoV-2 challengeImmunology; Equine immunology; Biological sciences
