Classification of transgenic laboratory animals produced using third-generation lentiviral vectors

Lentiviral vectors based on the third-generation packaging system are often used as an effective gene transfer system in animals. In this system the viral genes necessary for the gene transfer and for the transgene to be inserted, are distributed over four different plasmids to prevent the occurrence of replication-competent viruses. COGEM has been asked to advise on the use and safety of third-generation lentiviral vectors for the production of transgenic mice and rats. COGEM is of the opinion that the safety of third-generation lentiviral vectors for use in mice and rats has been sufficiently demonstrated. Therefore, under certain conditions, newborn transgenic animals can be placed in a level 1 animal accommodation immediately, without this affecting the safety of humans and the environment. The conditions are that the vector batch used is free of replication-competent virus, the vector is a ‘self-inactivating’ vector from the third-generation packaging system, in which the accessory genes are absent, and that the transgene is not harmful and does not affect the replication or distribution characteristics of the vector.