Porcine Genome-Wide CRISPR Screen Identifies the Golgi Apparatus Complex Protein COG8 as a Pivotal Regulator of Influenza Virus Infection.

Avian and human influenza viruses bind to porcine sialic acid receptors to generate novel viruses that pose a potential pandemic threat to public health. Evidence suggests that the host factors regulating the influenza virus life cycle and viral reassortment are potential broad-spectrum antiviral drug targets, compared to the ineffective seasonal vaccines against highly pathogenic viruses, leading to drug resistance. After performing a genome-wide CRISPR-Cas9 screen targeting 13,735 genes in porcine cell lines, we identified several host factors critical for influenza virus infection-notably, a conserved oligomeric Golgi complex protein, COG8, which regulates viral protein transport and immune factor expression. Viral titers indicated that the loss of COG8 significantly enhanced cellular resistance to influenza (p < 0.005). Moreover, COG8 knockout reduced the colocalization between viral particles and early endosome marker (EEA1), indicating COG8's role in the early endosome trafficking events of the virus. COG8 deletion inhibited the retrograde transport from the endosome to the trans-Golgi network, thereby accumulating the influenza protein M2 in early endosomes. COG8 silencing enhanced the expression of immune-related genes, indicating COG8-mediated host immune responses affect virus replication. Our experiments have revealed COG8 as an essential factor in influenza virus infection.