COMPLEMENTATION OF HELPER-DEPENDENT ADENOVIRAL VECTORS - SIZE EFFECTSAND TITER FLUCTUATIONS

The complementation of adenoviral vectors with large deletions in the viral genome was studied. The helper adenovirus used to complement the se vectors contains a partial deletion of the packaging signal and the El region substituted by the lacZ gene. The effect of vector size on packaging efficiency was analysed in 293 cells using decreasingly shor ter vectors expressing GFP from a CMV enhancer-beta-actin promoter. Ve ctors with longer genomes propagated more efficiently than shorter one s. Vectors containing only the packaging signal and the ITRs of Ad5, h aving all the viral genes replaced with unrelated sequences packaged a s efficiently as vectors of the same size containing adenoviral DNA in stead of exogenous DNA. The amounts of helper and vector produced in c oinfected 293 cells exhibited the typical cycling fluctuation observed during serial propagation of a virus with defective interfering parti cles. (C) 1997 Elsevier Science B.V.