Consistent with this observation, we also found that hMPV infection inhibited IFN-β-dependent ISRE transactivation, as cells treated with both hMPV and IFN-β did not have ISRE promoter activity equivalent to additive levels of ISRE promoter activity induced by respective treatment of hMPV and IFN-β (Fig. 2). Here, IFNB1 is linked to infection.