S100B and infection: To test our hypothesis that Vpr alters the cellular epigenetic landscape, we infected cells with Vpr-proficient (VprWT) or -deficient (mCh) HIVNL4–3 reporter viruses (CMV-driven mCherry in place of nef) and profiled roughly two-dozen histone PTMs 48 hours post-infection (Figures 1A and 1B).