IFNA1 and infection: Different multiplicities of infection (MOI) of HSV-1 generated a strong IFN-β response in a dose-dependent manner, ∼160- to 2,000-fold greater than that in noninfected (NI) cells or THP-1 cells infected with heat-inactivated (HI) virus, but failed to induce potent induction of IFN-α expression (Fig. 1A).