A new strategy to reduce human influenza infection: creating pigs with partial resistance to influenza A virus infection by targeting ST6GAL1 and ST3GAL4 genes

A major threat to the global human population is zoonosis, which refers to viral infections transmitted from animals. Pigs are crucial to the transmission of the influenza A virus (IAV) because they express both human-type (α-2,6-linked) and avian-type (α-2,3-linked) sialic acid (SA) receptors, making them a direct source of zoonosis and providing essential "mixing vessels" for avian and swine viruses. We aimed to mitigate the IAV threat by disrupting pig influenza infection through gene targeting of the viral receptors in pigs. We utilized CRISPR/Cas9 to knock out the ST6GAL1 and ST3GAL4 genes, which encode enzymes responsible for synthesizing both the human and avian SA receptors in pigs. We observed a significant reduction in these SA receptors in the respiratory tract of the genetically modified pigs. The deletion of these genes conferred partial resistance to IAV infection in vitro, substantially decreasing viral susceptibility. Post-infection transcriptomic analysis revealed distinct expression profiles in ST6GAL1^-/-/ST3GAL4^-/- pigs compared with those of wild-type pig cells. Creating ST6GAL1^-/-/ST3GAL4^-/- pigs provides a large-animal model for studying cross-species transmission of IAV, offering a novel strategy to reduce pandemic risks by disrupting influenza transmission between pigs and humans. This approach suggests a new method for controlling pandemics by targeting animals rather than humans, making it potentially safer than many current alternatives.