Adenovirus, vector propagation

Mitani K, Graham EL, Caskey CT, Kochanek S (1995) Rescue, propagation, and partial purification of a helper virus-dependent adenovirus vector. Proc Natl Acad Sci USA 92 3854-3858. 

Another form of gene therapy to treat cancer involves oncolytic virotherapy. This involves the use of oncolytic vectors, which are virus-designed to home and kill the tumor cells without harming the normal cells in the body. The cancer cells are killed by cell lysis as a result of the production of cytotoxic proteins or due to the propagation of the virus itself. The viruses that have been used to produce oncolytic vectors include adenovirus, vaccinia, reovirus, HSV-1 and Newcastle disease virus. 

Adeno-associated virus (AAV) is a non-pathogenic member of the parvovirus family. Its single-stranded DNA viral genome requires co-infection with either adenovirus or HSV for its own replication/propagation. Wild-type AAV encodes two viral gene products, Rep and Cap, which function in rep-lication/integration and structural stability, respectively. Vectors... 

The presence of replication- competent virus in the vector preparation is problematic, since it could be associated with increased toxicity and may lacilitate the spread of the recombinant in vivo (18-20). Replication-competent adenovirus occurs by either cross contamination of the initial plaque with replication-competent vims from an adj acent plaque or reversion of the E1 deletion during the propagation of the recombinant by homologous recombination between sequences in the vector flanking the El deletion and the transfected El sequences in 293 cells. 

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