Lentivirus production refers to the process of generating lentiviral particles for research or therapeutic applications. This involves co-transfection of plasmids (packaging, envelope, and transfer plasmids) into a host cell line (usually HEK293T cells) to produce the viral particles. The process includes transfection, harvesting of viral supernatants, and purification to obtain high-titer, functional lentivirus. Lentivirus production is a critical step in applications such as stable gene expression, gene knockdown using shRNA, and preclinical gene therapy studies.