IFN-α-induced restriction factors in SM and RM macrophages. MDMs from SMs and RMs were stimulated with IFN-α, and the fold change in mRNA levels was quantified via real-time PCR relative to unstimulated controls for APOBEC3G, APOBEC3H, TRIM5α, SAMHD1, tetherin, TRIM22, MX1, MX2, and OAS2. All genes were normalized to the housekeeping gene GAPDH.