Schematic representation of luciferase vectors used for recruitment into retroviral particles. psi: MLV packaging signal. PBS: retroviral primer binding site. PPT: polypurine tract, priming + strand synthesis following the fist jump during reverse transcription. pA: Bovine Growth Hormone polyadenylation signal. The last two constructs (pMNGag-Pol and pCMV-Env-Ampho) were used for transcomplementation in order to drive particles formations.