Aerosolized delivery of a virus-inspired A20FMDV2-siRNA conjugate targeting ST6GAL1 for influenza prophylaxis

The continued evolution of influenza viruses can reduce vaccine effectiveness and promote resistance to direct-acting antivirals. ST6GAL1 is required for the formation of α2,6-linked sialylated glycans on respiratory epithelial cells, which serve as major attachment structures for human-adapted influenza A viruses. Here, we prepared a chemically modified siSt6gal1 conjugated with A20FMDV2 and delivered it to the lung by nebulization. The conjugate resisted enzymatic degradation and maintained pulmonary St6gal1 silencing for at least 14 days after a single dose. Following viral challenge, the A20FMDV2-conjugated siSt6gal1 delayed the accumulation of viral nucleoprotein RNA and protein in the lung and reduced neuraminidase activity, infectious viral titers, and inflammatory markers. No obvious acute histopathological, serum biochemical, or hematological abnormalities were detected after a single nebulized dose. Local and sustained silencing of a host susceptibility factor may therefore provide a pre-exposure approach to limiting early influenza A virus replication.