IL6 and infection: To address whether MERS-CoV accessory genes 3, 4a, 4b or 5 interfere with the innate immune response during infection, we infected Huh-7 cells with previously engineered MERS-CoV deletion mutants (Δ3, Δ4ab, Δ5) [8] and analyzed the expression of interferon β (IFN-β) and the pro-inflammatory cytokines IL-6, IL-8, and TNF-α.