Novel rAd vector systems. (A) Genomic organization of replication-competent, wild-type Ad26. (B) Genomic organization of replication-incompetent rAd26 vector system with E1/E3 deleted, consisting of an adaptor plasmid (pAdApt26) and a cosmid (pWE.Ad26.ΔE3.5orf6). The E1 region was replaced by a TG cassette in the adaptor plasmid. The E3 region was deleted and the E4orf6 region was replaced by the corresponding region from Ad5 (5orf6) in the cosmid. The numbers indicate Ad26 nucleotide positions, and the region of homology that facilitates recombination between the adaptor plasmid and the cosmid is depicted. The genomic organizations and vector systems for rAd48 and rAd50 are analogous. ψ, packaging signal; E1 to E4, early genes; L1 to L5, late genes.