In Silico Target Analysis of Treatment for COVID-19 Using Huang-Lian-Shang-Qing-Wan, a Traditional Chinese Medicine Formula

Due to the significantly negative impact of the coronavirus (CoV) disease (COVID-19) pandemic on the health of the community and the economy, it remains urgent and necessary to develop a safe and effective treatment method for COVID-19. Huang-Lian-Shang-Qing-Wan (HLSQW) is a herbal formula of traditional Chinese medicine (TCM) that has been applied extensively for treating ?wind-heat-associated? symptoms in the upper parts of the body. The objective of the present in silico study was to investigate the potential effects of HLSQW in the context of severe acute respiratory syndrome (SARS)-CoV-2 infection. We analyzed the possible interactions between bioactive compounds within HLSQW on targets that may confer antiviral activity using network pharmacology and pharmacophore-based screening. HLSQW was found to potentially target a number of pathways and the expression of various genes to regulate cell physiology and, consequently, the anti-viral effects against SARS-CoV-2. Bioactive compounds contained within HLSQW may exert combined effects to reduce the production of proinflammatory factors, which may trigger the ?cytokine storm? in patients with severe COVID-19. Results from molecular modeling suggested that the bioactive HLSQW components puerarin, baicalin, and daidzin exhibit high binding affinity to the active site of 3-chymotrypsin-like cysteine protease (3CLpro) to form stable ligand-protein complexes, thereby suppressing SARS-CoV-2 replication. In addition, our results also demonstrated protective effects of the HLSQW extract against cell injury induced by the proinflammatory cytokines tumor necrosis factor-α, interleukin (IL)-1?, and IL-6, against reactive oxygen species production and nuclear factor-?B activity in normal human lung cells in vitro. To conclude, HLSQW is a potential TCM remedy that warrants further study with the aim of developing an effective treatment for COVID-19 in the future.

Structural insight into SARS-CoV-2 neutralizing antibodies and modulation of syncytia.

Infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is initiated by binding of the viral Spike protein to host receptor angiotensin-converting enzyme 2 (ACE2), followed by fusion of viral and host membranes. Although antibodies that block this interaction are in emergency use as early coronavirus disease 2019 (COVID-19) therapies, the precise determinants of neutralization potency remain unknown. We discovered a series of antibodies that potently block ACE2 binding but exhibit divergent neutralization efficacy against the live virus. Strikingly, these neutralizing antibodies can inhibit or enhance Spike-mediated membrane fusion and formation of syncytia, which are associated with chronic tissue damage in individuals with COVID-19. As revealed by cryoelectron microscopy, multiple structures of Spike-antibody complexes have distinct binding modes that not only block ACE2 binding but also alter the Spike protein conformational cycle triggered by ACE2 binding. We show that stabilization of different Spike conformations leads to modulation of Spike-mediated membrane fusion with profound implications for COVID-19 pathology and immunity.

Bivalent binding of a fully human IgG to the SARS-CoV-2 spike proteins reveals mechanisms of potent neutralization.

In vitro antibody selection against pathogens from naïve combinatorial libraries can yield various classes of antigen-specific binders that are distinct from those evolved from natural infection 1-4 . Also, rapid neutralizing antibody discovery can be made possible by a strategy that selects for those interfering with pathogen and host interaction 5 . Here we report the discovery of antibodies that neutralize SARS-CoV-2, the virus responsible for the COVID-19 pandemic, from a highly diverse naïve human Fab library. Lead antibody 5A6 blocks the receptor binding domain (RBD) of the viral spike from binding to the host receptor angiotensin converting enzyme 2 (ACE2), neutralizes SARS-CoV-2 infection of Vero E6 cells, and reduces viral replication in reconstituted human nasal and bronchial epithelium models. 5A6 has a high occupancy on the viral surface and exerts its neutralization activity via a bivalent binding mode to the tip of two neighbouring RBDs at the ACE2 interaction interface, one in the "up" and the other in the "down" position, explaining its superior neutralization capacity. Furthermore, 5A6 is insensitive to several spike mutations identified in clinical isolates, including the D614G mutant that has become dominant worldwide. Our results suggest that 5A6 could be an effective prophylactic and therapeutic treatment of COVID-19.