The pLKO.1 vector and its derivatives are lentiviral (HIV)-based plasmids. Lentivirus is regarded as a biosafety level 2 material and safe to use due to its modified features (deletion of a number of accessory virulence genes, minimal genome of the viral particles, non-replicating and self-inactivation features), making it incapable of producing virus once infected into the host cell. Please consult with your institution’s biosafety officer on specific requirements.