OAS1 and infection: To investigate whether the increased resistance of AHR−/− THP-1 cells to HSV-1 infection is dependent on IFN-β, we first quantified the percentage of virally infected cells (GFP+) and the expression of the IFN-inducible genes IFIT1 and OAS1 6 h and 24 h after infection in the presence or absence of a neutralizing antibody to human IFN-β.