Indeed, approximately ~20% of the virus-infected cells are expressing IFNβ. Moreover, the induction of Interferon Stimulated Genes (ISGs) after acute viral infections has also been found to be highly heterogeneous at the single-cell level (99), with only a fraction of cells inducing an antiviral gene expression program at physiological concentrations of IFNs. This evidence concerns the gene IFNB1 and viral infectious disease.