A new vector system with inducible E2a cell line for production of higher titer and safer adenoviral vectors

Adenovirar vectors have been used in gene therapy and for vaccination. The major concerns with using adenoviral vectors are the pathogenic potential o f the virus backbone and the generation of replication-competent adenovirus that may replicate in an uncontrolled manner, especially in immunocompromi sed patients. It is important to develop new vectors that are safer for cli nical trials while maintaining high titer and efficient transduction. A new adenovirus vector production system was developed, which includes several vector backbone plasmids deleted for E2a and a new cell line expressing bot h Fl and E2a. The new cell line with the tTA-inducible E2a expression casse tte can significantly increase the titer of E1/E2a-deleted vectors by four to five orders of magnitude upon withdrawal of tetracycline. Furthermore, t here is no sequence overlap between the vector and the cellular DNA within the E2a open reading frame and downstream, making the generation of virus w ith wild-type E2a through homologous recombination substantially less likel y. The new vector system may improve the safety of vectors for vaccination and cancer therapy and may also provide safer backbones for further vector development, such as helper-dependent and hybrid vectors. (C) 2000 Academic Press.