NOVEL COMPLEMENTATION CELL-LINES DERIVED FROM HUMAN LUNG-CARCINOMA A549 CELLS SUPPORT THE GROWTH OF E1-DELETED ADENOVIRUS VECTORS

Replication-defective E1-deleted adenoviruses are attractive vectors f or gene therapy or live vaccines. However, manufacturing methods requi red for their pharmaceutical development are not optimized. For exampl e, the generation of E1-deleted adenovirus vectors relies on the compl ementation functions present in 293 cells. However, 293 cells are pron e to the generation of replication competent particles as a result of recombination events between the viral DNA and the integrated adenovir us sequences present in the cell line. We report here that human lung A549 cells transformed with constitutive or inducible E1-expression ve ctors support the replication of E1-deficient adenoviruses. E1A transc ription was elevated in most of the cell lines, and E1A proteins were expressed at levels similar to those of 293 cells. However, the levels of expression of E1A did not correlate with the efficiencies of compl ementation of E1-deleted viruses in A549 clones, since some clones com plemented replication in the absence of induction of E1A expression. I n addition, complementation of E1-deficient adenoviruses did not requi re expression of the E1B 55-kDa protein. Although these cell lines con tain the coding and cis-acting regulatory sequences of the structural protein IX gene, they are not able to complement viruses in which this gene has been deleted. In contrast to 293 cells, such new complementa tion cell lines do not contain the left end of the adenoviral genome a nd thus represent a significant improvement over the currently used 29 3 cells, in which a single recombination event is sufficient to yield replication competent adenovirus.