Targeting the Conserved Stem Loop 2 Motif in the SARS-CoV-2 Genome

Area of Science:

• Virology
• Molecular Biology
• Antiviral Drug Discovery

Background:

• Many single-stranded positive-sense RNA viruses utilize conserved RNA structural elements.
• The stem-loop 2 motif (s2m) is highly conserved across diverse viral families, including coronaviruses like SARS-CoV-2, and is present in all viral subgenomic transcripts.
• Its conserved nature suggests a critical role in the viral infection cycle.

Purpose of the Study:

• To investigate the potential of targeting the conserved s2m motif in RNA viruses.
• To evaluate the efficacy of antisense oligonucleotides (ASOs) in targeting and inhibiting viral replication through the s2m element.

Main Methods:

• Reporter assays to assess sequence-specific RNA cleavage induced by ASOs targeting the s2m motif.
• Astrovirus replicon model system to evaluate ASO-mediated inhibition of viral replication.
• Cell culture experiments to assess ASO efficacy against SARS-CoV-2 replication.

Main Results:

• The s2m element, despite its stable fold, can be invaded and remodeled by ASOs, leading to efficient sequence-specific RNA cleavage.
• ASOs demonstrated sequence-specific, dose-dependent inhibition of viral replication in an astrovirus replicon model.
• ASOs effectively inhibited SARS-CoV-2 replication in cell culture.

Conclusions:

• The s2m motif is a readily targetable element in various RNA viruses.
• ASOs targeting the s2m element show significant promise as potent antiviral agents.
• Targeting conserved RNA structures like s2m represents a viable strategy for developing broad-spectrum antiviral therapies.