Activity of a Carbohydrate-Binding Module Therapy, Neumifil, against SARS-CoV-2 Disease in a Hamster Model of Infection

Abstract

The rapid global spread of severe acute respiratory coronavirus 2 (SARS-CoV-2) has resulted in an urgent effort to find efficacious therapeutics. Broad-spectrum therapies which could be used for other respiratory pathogens confer advantages, as do those based on targeting host cells that are not prone to the development of resistance by the pathogen. We tested an intranasally delivered carbohydrate-binding module (CBM) therapy, termed Neumifil, which is based on a CBM that has previously been shown to offer protection against the influenza virus through the binding of sialic acid receptors. Using the recognised hamster model of SARS-CoV-2 infection, we demonstrate that Neumifil significantly reduces clinical disease severity and pathological changes in the nasal cavity. Furthermore, we demonstrate Neumifil binding to the human angiotensin-converting enzyme 2 (ACE2) receptor and spike protein of SARS-CoV-2. This is the first report describing the testing of this type of broad-spectrum antiviral therapy in vivo and provides evidence for the advancement of Neumifil in further preclinical and clinical studies.

Keywords: COVID-19; SARS-CoV-2; host targeted; therapy.

Figure 1

Schematic diagram of CBM domain arrangement and trimerisation in the Neumifil compound. Bound 2,3 sialyllactose molecules (shown as spheres) indicate the ligand-binding sites. The image was produced with PyMOL Molecular Graphics System (Version 2.0., Schrödinger, LLC). PDB accession codes: 4c1w and 2w38.

Figure 2

Clinical disease progression of Neumifil-treated compared with mock-treated hamsters after challenge with SARS-CoV-2: (a) schematic overview of the study, with hamsters receiving Neumifil three times prior to challenge; (b) changes in weight compared with the day of challenge; (c) clinical scores. Data show mean values with error bars denoting standard error of the mean. *, p < 0.05 for comparison between vehicle-treated and Neumifil-treated groups (Mann–Whitney test). n = 6 hamsters per group.

Figure 3

Viral RNA levels in (a) nasal washes, (b) throat swabs, and (c) lung tissue samples taken from Neumifil- and mock-treated hamsters 7 days after SARS-CoV-2 challenge. Samples were tested in an N1-based PCR assay. LLOQ, lower limit of quantification; LLOD, lower limit of detection. *, p < 0.05 (Mann–Whitney test). n = 6 hamsters per group.

Figure 4

Quantitative analysis of histological specimens from Neumifil-treated and vehicle-treated animals after SARS-CoV-2 challenge: (a) percentage of area of pneumonia in the lung; (b) percentage of area positively stained for viral RNA in the lung using in situ hybridisation; (c) cumulative scores of nasal cavity lesions (presence of exudates and necrosis of epithelium); (d) subjective scores of viral RNA presence in the nasal cavity using in situ hybridisation. Bars show mean values with error bars denoting standard error of the mean. * p < 0.05 (Mann–Whitney test). n = 6 hamsters per group.

Figure 5

Representative images of lung histopathology (H&E) and presence of viral RNA (in situ hybridisation) in respiratory samples. (a–c) Lung histolopathology. Areas of bronchopneumonia (*) were observed in the lungs from both vehicle-treated and Neumifil-treated animals, with a lower severity in the Neumifil-treated group. (d–f) Presence of viral RNA in the lung. A small amount of virus RNA was detected in the airway epithelium and inflammatory infiltrates within the lung and olfactory/respiratory epithelium (arrows). (g–i) Presence of viral RNA in the nasal cavity. Inflammatory infiltrates and exudates were detected within the nasal cavity (arrows). Scale bars on lung images represent 100 μm and on nasal cavity images represent 50 μm.

Figure 6

Detection of Neumifil binding to SARS-CoV-2 Spike proteins tested by ELISA technique: (a) spike S1 and (b) spike RBD. The dotted lines represent 4PL curve fits of the data. Inset: EC50 values for each variant.

Figure 7

Detection of Neumifil binding to recombinant human ACE2 tested by ELISA technique. The dotted line represents a 4PL curve fitting of the data. Inset: EC50 value.