Pharmacologically stabilizing RNA G-quadruplexes in coronavirus genome reduces infectivity

Area of Science:

• Molecular Biology
• Virology
• Drug Discovery

Background:

• RNA G-quadruplexes (rG4s) are non-canonical RNA structures.
• Single-stranded RNA (ssRNA) viruses are thought to have fewer rG4-forming sequences.
• Non-canonical rG4 motifs are found in ssRNA viruses at high frequencies.

Purpose of the Study:

• Investigate rG4-forming potential in ssRNA viruses.
• Determine if non-canonical rG4s can be leveraged to block viral replication.
• Explore therapeutic applications of rG4-targeting compounds against ssRNA viruses.

Main Methods:

• In silico analysis of rG4-forming potential in ssRNA viruses.
• d-rG4-seq profiling of OC43 RNA genome.
• Treatment of OC43-infected cells with rG4 ligands.

Main Results:

• Canonical rG4 motifs are depleted in ssRNA viruses, but non-canonical motifs are abundant.
• OC43 RNA genome shows a lack of folded rG4 during natural infection.
• rG4 ligands induce non-canonical rG4 structures, inhibit OC43 replication, and reduce infectivity.
• rG4 ligands disrupt OC43 discontinuous transcription.

Conclusions:

• Non-canonical rG4s are prevalent in ssRNA viruses and can be targeted therapeutically.
• rG4-targeting compounds show potential for treating ssRNA viral infections, including coronaviruses.
• Disruption of viral discontinuous transcription by rG4 ligands is a key mechanism of action.