Development of targeted nanoparticles loaded with antiviral drugs for SARS-CoV-2 inhibition

Recently, a novel coronavirus, known as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has raised global concerns, being the etiological agent of the current pandemic infectious coronavirus disease 2019 (COVID-19). Specific prophylactic treatments like vaccines, have been authorized for use by regulatory bodies in multiple countries, however there is an urgent need to identify new, safe, and targeted therapeutics as post-exposure therapy for COVID-19. Among a plethora of potential pharmacological targets, the angiotensin-converting enzyme 2 (ACE2) membrane receptor, which plays a crucial role in viral entry, is representing an attractive intervention opportunity for SARS-CoV-2 antiviral discovery process. In this scenario, we envisioned that binding to ACE2 by multivalent attachment of ligands to nanocarriers incorporating antiviral therapeutics, it would increase receptor avidity and impart specificity to these nanovectors for host cells, particularly in the pulmonary tract, which is the primary entry route for SARS-CoV-2. Herein, we report the design and development of novel polymeric nanoparticles (NP), densely grafted with various ligands to selectively bind to ACE2, as innovative nanovectors for targeted drug delivery. We first evaluated the impact of these biocompatible targeted NP (TNP) on ligand binding toward ACE2 and measured their competition ability vs a model of spike protein (Lipo-S1). Next, we tested the effectiveness of the most performing nanoprotopype, TNP-1, loaded with a model anti-SARS-CoV-2 drug such as remdesivir (RDV), on antiviral activity against SARS-CoV-2 infected Vero E6 cells. The RDV-TNP-1 exhibited a significantly improved antiviral effect compared to RDV at the same concentration. Interestingly, unloaded TNP (TNP-1E) also exhibited a basal antiviral activity, potentially due to a direct competitive mechanism with viral particles for the ACE2 binding site. We also measured the anti-exopeptidase activity of TNP-1E against ACE2 protein. Collectively, these insights warrant in-depth preclinical development for our nanoprototypes, for example as potential inhalable drug carriers, with the perspective of a clinical translation.