Polyanionic Amphiphilic Dendritic Polyglycerols as Broad-Spectrum Viral Inhibitors with a Virucidal Mechanism

Supramolecular Architectures of Dendritic Polymers Provide Irreversible Inhibitor to Block Viral Infection

In Nature, most known objects can perform their functions only when in supramolecular self-assembled from, e.g. protein complexes and cell membranes. Here, a dendritic polymer is presented that inhibits severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) with an irreversible (virucidal) mechanism only when self-assembled into a Two-dimmensional supramolecular polymer (2D-SupraPol). Monomeric analogs of the dendritic polymer can only inhibit SARS-CoV-2 reversibly, thus allowing for the virus to regain infectivity after dilution. Upon assembly, 2D-SupraPol shows a remarkable half-inhibitory concentration (IC50 30 nM) in vitro and in vivo in a Syrian Hamster model has a good efficacy. Using cryo-TEM, it is shown that the 2D-SupraPol has a controllable lateral size that can be tuned by adjusting the pH and use small angle X-ray and neutron scattering to unveil the architecture of the supramolecular assembly. This functional 2D-SupraPol, and its supramolecular architecture are proposed, as a prophylaxis nasal spray to inhibit the virus interaction with the respiratory tract.

High-Throughput Synthesis and Evaluation of Antiviral Copolymers for Enveloped Respiratory Viruses

COVID-19 made apparent the devastating impact viral pandemics have had on global health and order. Development of broad-spectrum antivirals to provide early protection upon the inevitable emergence of new viral pandemics is critical. In this work, antiviral polymers are discovered using a combination of high-throughput polymer synthesis and antiviral screening, enabling diverse polymer compositions to be explored. Amphipathic polymers, with ionizable tertiary amine groups, are the most potent antivirals, effective against influenza virus and SARS-CoV-2, with minimal cytotoxicity. It is hypothesized that these polymers interact with the viral membrane as they showed no activity against a nonenveloped virus (rhinovirus). The switchable chemistry of the polymers during endosomal acidification was evaluated using lipid monolayers, indicating that a complex synergy between hydrophobicity and ionization drives polymer-membrane interactions. This new high-throughput methodology can be adapted to continue to engineer the potency of the lead candidates or develop antiviral polymers against other emerging viral classes.

Antiviral activity of a polysaccharide from Sargassum fusiforme against respiratory syncytial virus

This experiment examined the antiviral activity of polysaccharides from Sargassum fusiforme against respiratory syncytial virus (RSV) in vitro, including their mechanism of action and preliminary structural analysis. Four polysaccharides (SFP1, SFP2, SFP3, and SFP4) were purified from Sargassum fusiforme using a DEAE-52 cellulose column and an NW Super 150 gel column. CCK-8 and western blot were utilized to study the antiviral activities and mechanisms of the polysaccharides. Preliminary structural analysis was conducted using HPLC and NMR techniques. The findings suggest that SFP4 (120 kD) is an acidic chemical compound composed of 88.8 % total sugars, 0.13 % proteins, 10.8 % glucuronidic acids, and 21.1 % sulfates. It contains at least ten monosaccharides, primarily mannuronic acid and fucose. Among the four polysaccharides, SFP4 had the highest anti-RSV activity, with a therapeutic index (TI) exceeding 139. SFP4 exhibited noteworthy antiviral efficacy in both upper and lower respiratory cells that were infected, especially when administered as a prophylactic treatment 2 h in advance. Furthermore, SFP4 showed a dose-dependent antiviral effect, with the highest therapeutic index (TI > 320) observed at a concentration of 7.81 μg·mL-1 during the prophylactic phase. It was speculated that SFP4's antiviral effect is due to its ability to inhibit the attachment of G-proteins to cells.

Pathogen-binding nanoparticles to inhibit host cell infection by heparan sulfate and sialic acid dependent viruses and protozoan parasites

Global health faces an immense burden from infectious diseases caused by viruses and intracellular protozoan parasites such as the coronavirus disease (COVID-19) and malaria, respectively. These pathogens propagate through the infection of human host cells. The first stage of this host cell infection mechanism is cell attachment, which typically involves interactions between the infectious agent and surface components on the host cell membranes, specifically heparan sulfate (HS) and/or sialic acid (SA). Hence, nanoparticles (NPs) which contain or mimic HS/SA that can directly bind to the pathogen surface and inhibit cell infection are emerging as potential candidates for an alternative anti-infection therapeutic strategy. These NPs can be prepared from metals, soft matter (lipid, polymer, and dendrimer), DNA, and carbon-based materials among others and can be designed to include aspects of multivalency, broad-spectrum activity, biocidal mechanisms, and multifunctionality. This review provides an overview of such anti-pathogen nanomedicines beyond drug delivery. Nanoscale inhibitors acting against viruses and obligate intracellular protozoan parasites are discussed. In the future, the availability of broadly applicable nanotherapeutics would allow early tackling of existing and upcoming viral diseases. Invasion inhibitory NPs could also provide urgently needed effective treatments for protozoan parasitic infections.

Benzene with Alkyl Chains Is a Universal Scaffold for Multivalent Virucidal Antivirals

Most viruses start their invasion by binding to glycoproteins' moieties on the cell surface (heparan sulfate proteoglycans [HSPG] or sialic acid [SA]). Antivirals mimicking these moieties multivalently are known as broad-spectrum multivalent entry inhibitors (MEI). Due to their reversible mechanism, efficacy is lost when concentrations fall below an inhibitory threshold. To overcome this limitation, we modify MEIs with hydrophobic arms rendering the inhibitory mechanism irreversible, i.e., preventing the efficacy loss upon dilution. However, all our HSPG-mimicking MEIs only showed reversible inhibition against HSPG-binding SARS-CoV-2. Here, we present a systematic investigation of a series of small molecules, all containing a core and multiple hydrophobic arms terminated with HSPG-mimicking moieties. We identify the ones that have irreversible inhibition against all viruses including SARS-CoV-2 and discuss their design principles. We show efficacy in vivo against SARS-CoV-2 in a Syrian hamster model through both intranasal instillation and aerosol inhalation in a therapeutic setting (12 h postinfection). We also show the utility of the presented design rules in producing SA-mimicking MEIs with irreversible inhibition against SA-binding influenza viruses.

Ligand concentration determines antiviral efficacy of silica multivalent nanoparticles

We have learned from the recent COVID-19 pandemic that the emergence of a new virus can quickly become a global health burden and kill millions of lives. Antiviral drugs are essential in our fight against viral diseases, but most of them are virus-specific and are prone to viral mutations. We have developed broad-spectrum antivirals based on multivalent nanoparticles grafted with ligands that mimic the target of viral attachment ligands (VALs). We have shown that when the ligand has a sufficiently long hydrophobic tail, the inhibition mechanism switches from reversible (virustatic) to irreversible (virucidal). Here, we investigate further how ligand density and particle size affect antiviral efficacy, both in terms of half-inhibitory concentration (IC50) and of reversible vs irreversible mechanism. We designed antiviral silica nanoparticles modified with 11-mercaptoundecane-1-sulfonic acid (MUS), a ligand that mimics heparan sulfate proteoglycans (HSPG) and we showed that these nanoparticles can be synthesized with different sizes (4-200 nm) and ligand grafting densities (0.59-10.70 /nm2). By testing these particles against herpes simplex virus type 2 (HSV-2), we show that within the size and density ranges studied, the antiviral IC50 is determined solely by equivalent ligand concentration. The nanoparticles are found to be virucidal at all sizes and densities studied.