Generation and Effect Testing of a SARS-CoV-2 RBD-Targeted Polyclonal Therapeutic Antibody Based on a 2-D Airway Organoid Screening System

Abstract

Coronavirus disease 2019 (COVID-19) is an acute respiratory infectious disease caused by infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The US FDA has approved several therapeutics and vaccines worldwide through the emergency use authorization in response to the rapid spread of COVID-19. Nevertheless, the efficacies of these treatments are being challenged by viral escape mutations. There is an urgent need to develop effective treatments protecting against SARS-CoV-2 infection and to establish a stable effect-screening model to test potential drugs. Polyclonal antibodies (pAbs) have an intrinsic advantage in such developments because they can target rapidly mutating viral strains as a result of the complexity of their binding epitopes. In this study, we generated anti–receptor-binding domain (anti-RBD) pAbs from rabbit serum and tested their safety and efficacy in response to SARS-CoV-2 infection both in vivo and ex vivo. Primary human bronchial epithelial two-dimensional (2-D) organoids were cultured and differentiated to a mature morphology and subsequently employed for SARS-CoV-2 infection and drug screening. The pAbs protected the airway organoids from viral infection and tissue damage. Potential side effects were tested in mouse models for both inhalation and vein injection. The pAbs displayed effective viral neutralization effects without significant side effects. Thus, the use of animal immune serum–derived pAbs might be a potential therapy for protection against SARS-CoV-2 infection, with the strategy developed to produce these pAbs providing new insight into the treatment of respiratory tract infections, especially for infections with viruses undergoing rapid mutation.

Development of Equine Polyclonal Antibodies as a Broad-Spectrum Therapy Against SARS-CoV-2 Variants

“…As shown in Figure 3a , immunofluorescent staining revealed the apical cells containing both goblet cells (labeled with MUC5AC in red) and ciliated cells (labeled with Ac-α-tubulin in green), indicating the nasal progenitor cells were well differentiated to form a nasal epithelium. Together with the H&E staining ( Figure 3b ) which showed well-organized structures and high similarities compared with nasal biopsy reported in the literatures(20-22), the nasal organoids were confirmed as successfully constructed. The 2-D airway organoids were then applied in the infection model as a testing platform for the neutralization effect of the antibodies.…”

“…Together with the H&E staining (Figure 3b) which showed well-organized structures and high similarities compared with nasal biopsy reported in the literatures (20)(21)(22), the nasal organoids were confirmed as successfully constructed. The 2-D airway organoids were then applied in the infection model as a testing platform for the neutralization effect of the antibodies.…”

Evaluating Bacterial Pathogenesis Using a Model of Human Airway Organoids Infected with Pseudomonas aeruginosa Biofilms

“…The HAOs were cultured as described previously ( 76 , 77 ). Briefly, the biopsy samples were rinsed with precooled Dulbecco’s phosphate-buffered saline (DPBS; pH 7.4) (Thermo Fisher Scientific, USA) and disassociated overnight at 4°C in Dispase I (10 mg · mL −1 ; Sigma-Aldrich, USA) supplied with penicillin (100 U), streptomycin (0.1 mg · mL −1 ), and fluconazole (50 μg · mL −1 ).…”

“…The HAO cultures were fixed overnight in aqueous 4% paraformaldehyde (PFA; Beyotime, PRC), washed with PBS, embedded in paraffin, sectioned, and mounted on slides. H&E staining was performed following a standard protocol used in our previous studies ( 76 , 77 ).…”

Revisiting potential value of antitumor drugs in the treatment of COVID-19

“…Thus, the screened repurposed drugs, although exhibiting high efficacy in cell lines and animal models, may fail to achieve the expected treatment response in patients with COVID-19. To overcome the limitations of cell lines, various organoid culture systems which can simulate the process of SARS-CoV-2 infecting different human organs have been, or are being, developed and used to test potential therapies for COVID-19 [ 140 – 142 ]. In addition, more accurate screening models for drug repurposing screen are still needed to be developed and refined.…”