Conversion of Host Cell Receptor into Virus Destructor by Immunodisc to Neutralize Diverse SARS-CoV-2 Variants.

The decreasing efficacy of antiviral drugs due to viral mutations highlights the challenge of developing a single agent targeting multiple strains. Using host cell viral receptors as competitive inhibitors is promising, but their low potency and membrane-bound nature have limited this strategy. In this study, the authors show that angiotensin-converting enzyme 2 (ACE2) in a planar membrane patch can effectively neutralize all tested severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants that emerged during the COVID-19 pandemic. The ACE2-incorporated membrane patch implemented using nanodiscs replicated the spike-mediated membrane fusion process outside the host cell, resulting in virus lysis, extracellular RNA release, and potent antiviral activity. While neutralizing antibodies became ineffective as the SARS-CoV-2 evolved to better penetrate host cells the ACE2-incorporated nanodiscs became more potent, highlighting the advantages of using receptor-incorporated nanodiscs for antiviral purposes. ACE2-incorporated immunodisc, an Fc fusion nanodisc developed in this study, completely protected humanized mice infected with SARS-CoV-2 after prolonged retention in the airways. This study demonstrates that the incorporation of viral receptors into immunodisc transforms the entry gate into a potent virucide for all current and future variants, a concept that can be extended to different viruses.

Korean Red Ginseng Relieves Inflammation and Modulates Immune Response Induced by Pseudo-Type SARS-CoV-2.

Few studies have reported the therapeutic effects of Korean red ginseng (KRG) against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, the positive effects of KRG on other viruses have been reported and the effects of KRG on pulmonary inflammatory diseases have also been studied. Therefore, this study investigated the therapeutic effects of KRG-water extract (KRG-WE) in a pseudo-type SARS-CoV-2 (PSV)-induced lung injury model. Constructing the pseudovirus, human angiotensin-converting enzyme 2 (hACE2) transgenic mice were infected via intranasal injection that had been orally administered with KRG-WE for six weeks. After 7-days post infection (dpi), the antiviral effects of KRG-WE were confirmed, followed by real-time polymerase chain reaction (PCR), western blot analysis, flow cytometric analysis, and an enzyme-linked immunoassay (ELISA). KRG-WE significantly inhibited an increase in immunoglobulin caused by PSV. Furthermore, KRG-WE effectively suppressed alveolar macrophages (AMs) inside the lungs and helped normalize the population of other immune cells. In addition, virus-induced gene expression and inflammatory signals such as nuclear factor-kappa B and other upstream molecules were downregulated. Moreover, KRG-WE also normalized gene expression and protein activity in the spleen. In conclusion, KRG-WE reduced AMs, normalized the immune response, and decreased the expression of inflammatory genes and activation of signaling pathway phosphorylation, thereby exhibiting anti-inflammatory effects and attenuating lung damage.

Production and characterization of lentivirus vector-based SARS-CoV-2 pseudoviruses with dual reporters: Evaluation of anti-SARS-CoV-2 viral effect of Korean Red Ginseng.

Background: Pseudotyped virus systems that incorporate viral proteins have been widely employed for the rapid determination of the effectiveness and neutralizing activity of drug and vaccine candidates in biosafety level 2 facilities. We report an efficient method for producing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pseudovirus with dual luciferase and fluorescent protein reporters. Moreover, using the established method, we also aimed to investigate whether Korean Red Ginseng (KRG), a valuable Korean herbal medicine, can attenuate infectivity of the pseudotyped virus. Methods: A pseudovirus of SARS-CoV-2 (SARS-2pv) was constructed and efficiently produced using lentivirus vector systems available in the public domain by the introduction of critical mutations in the cytoplasmic tail of the spike protein. KRG extract was dose-dependently treated to Calu-3 cells during SARS2-pv treatment to evaluate the protective activity against SARS-CoV-2. Results: The use of Calu-3 cells or the expression of angiotensin-converting enzyme 2 (ACE2) in HEK293T cells enabled SARS-2pv infection of host cells. Coexpression of transmembrane protease serine subtype 2 (TMPRSS2), which is the activator of spike protein, with ACE2 dramatically elevated luciferase activity, confirming the importance of the TMPRSS2-mediated pathway during SARS-CoV-2 entry. Our pseudovirus assay also revealed that KRG elicited resistance to SARS-CoV-2 infection in lung cells, suggesting its beneficial health effect. Conclusion: The method demonstrated the production of SARS-2pv for the analysis of vaccine or drug candidates. When KRG was assessed by the method, it protected host cells from coronavirus infection. Further studies will be followed for demonstrating this potential benefit.

Nanodisc-Mediated Conversion of Virustatic Antiviral Antibody to Disrupt Virus Envelope in Infected Cells.

Many antibody-based antivirals, including broadly neutralizing antibodies (bnAbs) against various influenza virus strains, suffer from limited potency. A booster of the antiviral activity of an antibody is expected to facilitate development of antiviral therapeutics. In this study, a nanodisc (ND), a discoidal lipid bilayer encircled by membrane scaffold proteins, is engineered to provide virucidal properties to antibodies, thereby augmenting their antiviral activity. NDs carrying the Fc-binding peptide sequence form an antibody-ND complex (ANC), which can co-endocytose into cells infected with influenza virus. ANC efficiently inhibits endosome escape of viral RNA by dual complimentary mode of action. While the antibody moiety in an ANC inhibits hemagglutinin-mediated membrane fusion, its ND moiety destroys the viral envelope using free hemagglutinins that are not captured by antibodies. Providing virus-infected host cells with the ability to self-eliminate by the synergistic effect of ANC components dramatically amplifies the antiviral efficacy of a bnAb against influenza virus. When the efficacy of ANC is assessed in mouse models, administration of ANCs dramatically reduces morbidity and mortality compared to bnAb alone. This study is the first to demonstrate the novel nanoparticle ANC and its role in combating viral infections, suggesting that ANC is a versatile platform applicable to various viruses.

Tannic acid-functionalized HEPA filter materials for influenza virus capture.

Influenza, one of the most contagious and infectious diseases, is predominantly transmitted through aerosols, leading to the development of filter-based protective equipment. Though the currently available filters are effective at removing submicron-sized particulates, filter materials with enhanced virus-capture efficiency are still in demand. Coating or chemically modifying filters with molecules capable of binding influenza viruses has received attention as a promising approach for the production of virus-capturing filters. For this purpose, tannic acid (TA), a plant-derived polyphenol, is a promising molecule for filter functionalization because of its antiviral activities and ability to serve as a cost-efficient adhesive for various materials. This study demonstrates the facile preparation of TA-functionalized high-efficiency particulate air (HEPA) filter materials and their efficiency in influenza virus capture. Polypropylene HEPA filter fabrics were coated with TA via a dipping/washing process. The TA-functionalized HEPA filter (TA-HF) exhibits a high in-solution virus capture efficiency of up to 2,723 pfu/mm2 within 10 min, which is almost two orders of magnitude higher than that of non-functionalized filters. This result suggests that the TA-HF is a potent anti-influenza filter that can be used in protective equipment to prevent the spread of pathogenic viruses.