NS1-mediated inhibition of c-Abl results in acute lung injury and priming for bacterial co-infections; insights into 1918 H1N1 pandemic

NS1 proteins from avian influenza viruses like the 1918 pandemic NS1 are capable of inhibiting the key signaling integrator c-Abl (Abl1), resulting in massive cytopathic cell alterations. In the current study, we addressed the consequences of NS1-mediated alteration of c-Abl on acute lung injury and pathogenicity. Comparing isogenic strains that differ only in their ability to inhibit c-Abl, we observed elevated pathogenicity for the c-Abl-inhibiting virus. NS1-mediated block of c-Abl resulted in severe lung pathology and massive edema formation and facilitated secondary bacterial pneumonia. This phenotype was independent of differences in replication and immune responses, defining it as an NS1 virulence mechanism distinct from its canonical functions. Microarray analysis revealed extensive down-regulation of genes involved in cell integrity and vascular endothelial regulation. In conclusion, NS1 protein-mediated blockade of c-Abl signaling drives acute lung injury and primes for bacterial co-infections revealing potential insights into the pathogenicity of the 1918 pandemic virus.

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Hrincius ER, Liedmann S, Finkelstein D, Vogel P, Gansebom S, Ehrhardt C, Ludwig S, Hains DS, Webby R, McCullers JA