However, we did not observe activation of the IFNβ promoter in MDCK IFNβ-GFP/IFNβ-FFluc cells infected with HPhTX, HPhTX NSs, or HPhTX NSs-Nluc with comparable levels of infection, as determined by nucleoprotein (NP) staining (Figures 2A and 2B). The gene discussed is IFNB1; the disease is infection.