In this issue of Cell Host & Microbe, Courtney et al. (2019a) Courtney D.G. Tsai K. Bogerd H.P. Kennedy E.M. Law B.A. Emery A. Swanstrom R. Holley C.L. Cullen B.R. Epitranscriptomic Addition of m5C to HIV-1 Transcripts Regulates Viral Gene Expression. Cell Host Microbe. 2019; 26 ( ) : 217-227 find that HIV-1 genomic RNA has much more m 5C than cellular mRNA. Deleting the m5C “writer” NSUN2 decreases HIV-1 m 5C levels, promotes translation of the HIV-1 5′ gag gene, and alters splicing at the A2 site.