To determine the role of each of the three genes in YFV replication and induction of inflammatory cytokine response, parental HEK293 and each of the three knockout cell lines were infected with YFV and infected cells were harvested at the indicated time points post infection for qRT-PCR quantification of intracellular viral RNA and IFN-β mRNA (S6 Fig). This evidence concerns the gene IFNB1 and infection.