Monitoring Lentivirus Vector Stocks for Replication-Competent Viruses.

The potential emergence of replication-competent lentiviruses (RCLs) during vector production and the significant biosafety risk that this represents has led to the development of lentivirus vector production systems to minimize the risk of generating RCLs. Second- and third-generation lentivirus vector production systems appear to be safe, because there are no reports of RCL generation in either system. Screening of lentivirus vector stocks for RCLs involves serial passaging of transduced cells for 30 d with weekly monitoring of p24 levels in supernatants using an ELISA Kit.