It was found that the HIV-1 Integrase binds the Viral RNA genome and is essential during Virion Morphogenesis. The L50 Peptide: Cyclo-(-Arg-Val-Arg-Thr-Arg-Gly-LysArg-Arg-Ile-Arg-Arg-DPro-Pro-) was synthesized by LifeTein and used for the inhibition assays. The L50 is a Tat-derived peptide sequence, which selectively engages both the loop and 3-nt bulge
but not the double-stranded stem of the transactivation response. The TAT-derived peptide is a well-defined cell penetration peptide.