Broad-spectrum antiviral activity of antisense oligonucleotides targeting GBF1 against SARS-CoV-2 and influenza viruses

Influenza viruses and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are respiratory pathogens that continue to challenge global health due to their efficient transmission and ability to circumvent virus-specific treatments. Targeting host factors that are essential for viral replication may enable the development of broad-spectrum antivirals with reduced resistance potential. Here, we used small interfering RNA (siRNA) to screen 91 host factors previously implicated in influenza virus replication and identified seven that were also required for SARS-CoV-2 replication. Of these, Golgi-specific brefeldin A-resistance factor 1 (GBF1), a guanine nucleotide exchange factor involved in coat protein complex I (COPI) vesicle trafficking, was also involved in human coronavirus 229E replication. We found that GBF1 relocated to sites of viral replication in SARS-CoV-2-infected cells. Using a computational design pipeline, we generated antisense oligonucleotides (ASOs) targeting GBF1. The lead candidate, GBF1-ASO#1502, potently inhibited influenza viruses and SARS-CoV-2 <i>in vitro</i>, with nanomolar half-maximal inhibitory concentration (IC₅₀) values and favorable selectivity indices. GBF1-targeting ASOs thus represent a promising host-directed antiviral approach for controlling respiratory RNA viruses.