IFNB1 and infection: At 36 hpi, both viruses still blocked activation of the IFN-β promoter, and no sensitization was observed, but only the parental virus showed an increased blockade at the later time, while that resulting from infection with rNigeria/75/1_ΔC was essentially unchanged (Fig 11C), despite the higher level of viral protein in the cells at 36 hpi compared to 16 hpi (Fig 11D).