Replication-defective adenovirus vectors are deficient in early viral gene E1 and are generally grown in cell lines such as HEK-293, which contain and express an integrated copy of E1 for the purpose of complementing the defective adenoviral genome. Although the host cell E1 gene is required for complementation, its presence can also be problematic because recombination between vector and host cell genomes may lead to the reacquisition of E1 by the vector and the formation of replication-competent adenoviruses (RCAs).
QVirus Platform has developed several methods to determine RCA levels in purified adenovirus batches, including direct PCR analysis for the presence of El sequences and analysis of cytopathic effect (CPE) caused by RCA and infectivity-linked PCR for infectious RCA.
