Efficient Targeted Delivery of Bifunctional Circular Aptamer ASO Chimera to Suppress the SARS-CoV-2 Proliferation and Inflammation

Inhibition of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and excessive inflammation is the current task in the prevention and treatment of COVID-19. Here, we designed a dual-function circular aptamerASO chimera (circSApt-NASO) to suppress SARS-CoV-2 replication and inflammation. The chemically unmodified circSApt-NASO exhibited high serum stability by artificial cyclization, significantly enhancing the utility of oligonucleotides. It presents great efficiency in knocking down, demonstrating the superiority of the circular ASO as a novel tool for sequence-specific silencing of gene expression. Furthermore, we propose and demonstrate that the SApt binding to spike protein enables the chimera to be efficiently delivered into the susceptible host cells expressing ACE2 along with the infection of SARS-CoV-2. At high concentrations of SARS-CoV-2, the efficiency of targeted delivery of circSApt-NASO can even be compared to transfection. Among them, the anti-spike aptamer (SApt) that blocks the Spike-TLR4 interaction potently inhibits spike-induced inflammation. The NASO targeting to silence N genes not only display robust anti-N-induced inflammatory activity, but also achieve efficient inhibition of SARS-CoV-2 replication. Therefore, benefiting from the high stability of the cyclization, anti-spike aptamer-dependent and viral infection-mediate targeted delivery, the circSApt-NASO displays robust potential against authentic SARS-CoV-2 and Omicron (B.1.1.529), providing a promising specific anti-inflammatory and anti-proliferative reagent for therapeutic COVID-19 based on the oligonucleotide therapeutics strategy.