An inhaled therapeutic targeting a conserved RNA structure in SARS-CoV-2

The Covid-19 pandemic is exacting an increasing toll worldwide, with new SARS-CoV-2 variants emerging that exhibit higher infectivity rates and which may partially evade vaccine and antibody immunity. Rapid deployment of non-invasive therapeutic avenues capable of preventing infection by all SARS-CoV-2 variants could complement current vaccination efforts and help turn the tide on the Covid-19 pandemic. Here, we describe a novel therapeutic strategy targeting the SARS-CoV-2 RNA using locked nucleic acid antisense oligonucleotides (LNA ASOs). We identified an LNA ASO binding to the 5' leader sequence of SARS-CoV-2 ORF1a/b and which disrupts a highly conserved stem-loop structure, with nanomolar efficacy in preventing viral replication in human cells. Daily intranasal administration of this LNA ASO in the K18-hACE2 humanized Covid-19 mouse model potently (98-99%) suppressed viral replication in the lungs of infected mice, revealing strong prophylactic and treatment effects. We found that the LNA ASO is highly efficacious in countering all SARS-CoV-2 variants of concern (VOC) tested in vitro and in vivo, including B.1.427 (CA), B.1.1.7 (UK), and B.1.351 (SA) variants. LNA ASOs are chemically stable and can be flexibly modified to target different viral RNA sequences. Hence, virus-targeting LNA ASOs represent a promising therapeutic approach to reduce the transmission of SARS-CoV-2, especially in areas where vaccine distribution is a challenge, and it may be stockpiled for future coronavirus pandemics. Overall design: Evaluate the viral repressive effect of LNA ASO in SARS-CoV-2-infected K18-hACE2 mice at day 4 post-infection Evaluate the immune-stimulatory effect of LNA ASO in lung of wild-type mice