Long-chain polyphosphates impair SARS-CoV-2 infection and replication.

Area of Science:

• Biochemistry
• Virology
• Molecular Biology

Background:

• Inorganic polyphosphates (polyPs) are biopolymers with known cytoprotective and antiviral activities.
• Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) utilizes angiotensin-converting enzyme 2 (ACE2) for host cell entry.
• Understanding host-pathogen interactions is crucial for developing antiviral strategies.

Purpose of the Study:

• To investigate the antiviral potential of long-chain polyphosphates against SARS-CoV-2.
• To elucidate the molecular mechanisms underlying polyP antiviral activity.
• To evaluate the efficacy of polyP120 in cellular models of SARS-CoV-2 infection.

Main Methods:

• Molecular docking simulations to predict polyP interactions with ACE2 and viral RNA-dependent RNA polymerase (RdRp).
• ELISA, limited proteolysis, and nano-LC-MS/MS assays to confirm polyP120 binding to ACE2.
• Site-directed mutagenesis to identify specific amino acid residues involved in ACE2-RdRp interactions.
• In vitro assays using SARS-CoV-2-infected cell lines (Vero E6, Caco2) and primary human nasal epithelial cells.

Main Results:

• Polyphosphates (polyPs) docked to conserved residues in ACE2 and SARS-CoV-2 RdRp.
• PolyP120 was confirmed to bind ACE2, and specific residues mediating ACE2-RdRp interaction were identified.
• PolyP120 promoted the proteasomal degradation of both ACE2 and RdRp, inhibiting the B.1.1.7 variant.
• Nebulized polyP120 reduced viral RNA, proinflammatory cytokine transcripts, and viral structural proteins in infected cells.

Conclusions:

• Long-chain polyphosphates, specifically polyP120, exhibit significant antiviral activity against SARS-CoV-2.
• PolyP120 functions by enhancing the degradation of ACE2 and viral RdRp, thereby disrupting viral replication.
• Nebulized polyP120 demonstrates potential as a therapeutic agent for respiratory viral infections.