RSAD2 and viral infectious disease: Finally, to control for the specificity of the viperin shRNA effects and confirm that viperin is involved in lipogenesis in the context of viral infection, we infected cells with a recombinant HCMV (HCMV.mVIP) in which the loci US7–US16, nonessential for in vitro replication, were replaced by mouse viperin-GFP under an inducible promoter such that expression could be enhanced by the addition of doxycycline, although some breakthrough transcription occurred in the absence of doxycycline [24].