Pulmonary Surfactant Phospholipids as Novel Anti-Virals Against SARS-CoV-2 Infection

Background: A novel coronavirus (SARS-CoV-2) has led to the worldwide spread of pandemic proportions and currently no effective therapy is available. The minor pulmonary surfactant lipids, palmitoyl-oleoyl-phosphatidylglycerol (POPG), and phosphatidylinositol (PI), are potent regulators of inflammatory processes, and are effective as anti-viral agents for multiple respiratory viruses including Respiratory syncytial virus (RSV), Influenza A virus (IAV) and Rhinoviruses (RVs). Objective: The primary objectives of this study are to determine whether POPG or PI are potent against SARS-CoV-2 in vitro, using human airway epithelial cells, and examine the potency of PI against SARS-CoV-2 in vivo, in a hamster model. Methods: We examined efficacies of POPG or PI against SARS-CoV-2 (USA WA/2020) in human bronchial epithelial cells, and nasal epithelial cells from healthy control subjects differentiated by ALI cultures. We quantified SARS-CoV-2 replication by quantitative plaque assays and qRT-PCR. We determined the potency of PI against SARS-CoV- 2 in golden Syrian hamster as in vivo model for SARS-CoV-2 infection. Results: We examined the efficacies of POPG and PI using primary human tracheal and nasal epithelial cells, differentiated in ALI culture. Cells were treated with POPG (10mg/ml) and PI (4mg/ml) added to apical media alone for 16hrs. Subsequently, cells were infected with SARS-CoV-2 at m.o.i = 0.02, for 48hrs, harvested for RNA extraction and qRT-PCR. SARS-CoV-2 replicated in tracheal cells with a 106-fold increase in mRNA. POPG and PI reduced viral mRNA expression by 70% and 85%, respectively (subject numbers n=3). In nasal epithelia, SARS-CoV-2 mRNA expression increased 105 -fold compared to sham infected cultures. Both POPG and PI attenuated the increase in viral mRNA expression by 70% - 82% (subject numbers n=6). We determined the PI effect in an in vivo study in hamsters. Hamsters were challenged with 103 pfu of SARS-CoV-2, either with, or without PI (2mg/hamster) administered intranasally. Hamsters were harvested at Day 3, and lungs were processed for histopathology. Pharyngeal swabs were used to examine viral burden by plaque assays. PI reduced plaque numbers compared to viral infection alone groups at day1 (Virus alone: 2.4±2.7(X104pfu/ml), Virus+PI: 0.9±2.1(X106pfu/ml), p<0.05). PI reduced lung histopathology score at day 3 (Virus alone: 28.0±15.6, Virus+PI: 6.7±7.0, p<0.05). Conclusions: POPG and PI significantly reduced SARS-CoV2 replication in human differentiated airway epithelial cells. PI inhibited SARS-CoV-2 infection in vivo in hamsters. These findings suggest that inhalation of POPG, or PI might be effective as novel anti-viral compounds for treating and preventing SARSCoV- 2 infection.