IFITM3 and infection: Notably, ZIKV was potently inhibited in the same cells engineered to express IFITM3 when they were treated with IFNβ, with drastic reductions in viral replication for both strains (1.6 × 103–5.1 × 103-fold) when compared to infection of untreated control cells (Figure 4a; p = 0.007 for MR 766, p = 0.01 for PRVABC59).