Viral pathogens continue to constitute a heavy burden on healthcare and socioeconomic systems. Efforts to create antiviral drugs repeatedly lag behind the advent of pathogens and growing understanding is that broad-spectrum antiviral agents will make strongest impact in future antiviral efforts. This work performs selection of synthetic polymers as novel broadly active agents and demonstrates activity of these polymers against Zika, Ebola, Lassa, Lyssa, Rabies, Marburg, Ebola, influenza, herpes simplex, and human immunodeficiency viruses. Results presented herein offer structure-activity relationships for these pathogens in terms of their susceptibility to inhibition by polymers, and for polymers in terms of their anionic charge and hydrophobicity that make up broad-spectrum antiviral agents. The identified leads cannot be predicted based on prior data on polymer-based antivirals and represent promising candidates for further development as preventive microbicides.

We present three classes of chemical zymogens established around the protein cysteinome. In each case, the cysteine thiol group was converted into a mixed disulfide: with a small molecule, a non-degradable polymer, or with a fast-depolymerizing fuse polymer (ZLA). The latter was a polydisulfide based on naturally occurring molecule, lipoic acid. Zymogen designs were applied to cysteine proteases and a kinase. In each case, enzymatic activity was successfully masked in full and reactivated by small molecule reducing agents. However, only ZLA could be reactivated by protein activators, demonstrating that the macromolecular fuse escapes the steric bulk created by the protein globule, collects activation signal in solution, and relays it to the active site of the enzyme. This afforded first-in-class chemical zymogens that are activated via protein-protein interactions. We also document zymogen exchange reactions whereby the polydisulfide is transferred between the interacting proteins via the “chain transfer” bioconjugation mechanism.

Inhibitorsof viral cell entry based on poly(styrene sulfonate) and its core-shell nanoformulations based on gold nanoparticles are investigated against a panel of viruses, including clinical isolates of SARS-CoV-2. Macromolecular inhibitors are shown to exhibit the highly sought-after broad-spectrum antiviral activity, which covers most analyzed enveloped viruses and all of the variants of concern for SARS-CoV-2 tested. The inhibitory activity is quantified in vitro in appropriate cell culture models and for respiratory viral pathogens (respiratory syncytial virus and SARS-CoV-2) in mice. Results of this study comprise a significant step along the translational path of macromolecular inhibitors of virus cell entry, specifically against enveloped respiratory viruses.

Macromolecular (pro)drugs hold much promise as broad-spectrum antiviral agents as either microbicides or carriers for intracellular delivery of antiviral drugs. Intriguing opportunity exists in combining the two modes of antiviral activity in the same polymer structure such that the same polymer acts as a microbicide and also serves to deliver the conjugated drug (ribavirin) into the cells. We explore this opportunity in detail and focus on the polymer backbone as a decisive constituent of such formulations. Fourteen polyanions (polycarboxylates, polyphosphates and polyphosphonates, and polysulfonates) were analyzed for blood pro/anti coagulation effects, albumin binding and albumin aggregation, inhibitory activity on polymerases, cytotoxicity, and anti-inflammatory activity in stimulated macrophages. Ribavirin containing monomers were designed to accommodate the synthesis of macromolecular prodrugs with disulfide-exchange triggered drug release. Kinetics of drug release was fast in all cases however enhanced hydrophobicity of the polymer significantly slowed release of ribavirin. Results of this study present a comprehensive view on polyanions as backbone for macromolecular prodrugs of ribavirin as broad-spectrum antiviral agents.

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