PCMV-DR8.91 plasmid (2 µg) is a third-generation lentiviral packaging construct derived from HIV-1, designed for high-efficiency pseudotyped viral particle production in transient transfection systems. It encodes the essential gag, pol, tat, and rev genes under the control of the human CMV immediate-early promoter (PCMV), ensuring robust transcription in mammalian cells, particularly HEK293T. This plasmid excludes accessory HIV-1 genes (vif, vpr, vpu, nef) to enhance biosafety, making it replication-incompetent in target cells. DR8.91 provides structural and enzymatic components required for lentiviral assembly, reverse transcription, and integration but does not contain the viral packaging signal (Ψ), which is instead supplied by a co-transfected transfer vector. Typically used with envelope plasmids such as VSV-G (e.g., pMD2.G), PCMV-DR8.91 supports the generation of high-titer, self-inactivating lentiviral vectors for stable transgene delivery in dividing and non-dividing mammalian cells.