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Full-Length Recombinant hSP-D Binds and Inhibits SARS-CoV-2

Division of Neonatology and Pulmonary Biology, Cincinnati Children’s Hospital, Cincinnati, OH 45229, USA
Airway Therapeutics Inc., Cincinnati, OH 45249, USA
NanoBio laboratory, Department of Biotechnology and Bioscience, University of Milano-Bicocca, 20126 Milano, Italy
Istituti Clinici Scientifici Maugeri IRCCS, via Maugeri 4, 27100 Pavia, Italy
Division of Anesthesiology and Intensive Care Medicine, ASST Fatebenefratelli Sacco, Luigi Sacco Hospital, University of Milan, 20157 Milano, Italy
Institute for Antiviral Research, Utah State University, Logan, UT 84322, USA
Department of Pediatrics, University of Cincinnati, Cincinnati, OH 45229, USA
Author to whom correspondence should be addressed.
Academic Editor: Jesús Pérez-Gil
Biomolecules 2021, 11(8), 1114;
Received: 24 May 2021 / Revised: 21 July 2021 / Accepted: 23 July 2021 / Published: 28 July 2021
SARS-CoV-2 infection of host cells is driven by binding of the SARS-CoV-2 spike-(S)-protein to lung type II pneumocytes, followed by virus replication. Surfactant protein SP-D, member of the front-line immune defense of the lungs, binds glycosylated structures on invading pathogens such as viruses to induce their clearance from the lungs. The objective of this study is to measure the pulmonary SP-D levels in COVID-19 patients and demonstrate the activity of SP-D against SARS-CoV-2, opening the possibility of using SP-D as potential therapy for COVID-19 patients. Pulmonary SP-D concentrations were measured in bronchoalveolar lavage samples from patients with corona virus disease 2019 (COVID-19) by anti-SP-D ELISA. Binding assays were performed by ELISAs. Protein bridge and aggregation assays were performed by gel electrophoresis followed by silver staining and band densitometry. Viral replication was evaluated in vitro using epithelial Caco-2 cells. Results indicate that COVID-19 patients (n = 12) show decreased pulmonary levels of SP-D (median = 68.9 ng/mL) when compared to levels reported for healthy controls in literature. Binding assays demonstrate that SP-D binds the SARS-CoV-2 glycosylated spike-(S)-protein of different emerging clinical variants. Binding induces the formation of protein bridges, the critical step of viral aggregation to facilitate its clearance. SP-D inhibits SARS-CoV-2 replication in Caco-2 cells (EC90 = 3.7 μg/mL). Therefore, SP-D recognizes and binds to the spike-(S)-protein of SARS-CoV-2 in vitro, initiates the aggregation, and inhibits viral replication in cells. Combined with the low levels of SP-D observed in COVID-19 patients, these results suggest that SP-D is important in the immune response to SARS-CoV-2 and that rhSP-D supplementation has the potential to be a novel class of anti-viral that will target SARS-CoV-2 infection. View Full-Text
Keywords: SP-D; COVID-19; spike-protein; ACE2; anti-inflammatory SP-D; COVID-19; spike-protein; ACE2; anti-inflammatory
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MDPI and ACS Style

Arroyo, R.; Grant, S.N.; Colombo, M.; Salvioni, L.; Corsi, F.; Truffi, M.; Ottolina, D.; Hurst, B.; Salzberg, M.; Prosperi, D.; Kingma, P.S. Full-Length Recombinant hSP-D Binds and Inhibits SARS-CoV-2. Biomolecules 2021, 11, 1114.

AMA Style

Arroyo R, Grant SN, Colombo M, Salvioni L, Corsi F, Truffi M, Ottolina D, Hurst B, Salzberg M, Prosperi D, Kingma PS. Full-Length Recombinant hSP-D Binds and Inhibits SARS-CoV-2. Biomolecules. 2021; 11(8):1114.

Chicago/Turabian Style

Arroyo, Raquel, Shawn N. Grant, Miriam Colombo, Lucia Salvioni, Fabio Corsi, Marta Truffi, Davide Ottolina, Brett Hurst, Marc Salzberg, Davide Prosperi, and Paul S. Kingma. 2021. "Full-Length Recombinant hSP-D Binds and Inhibits SARS-CoV-2" Biomolecules 11, no. 8: 1114.

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