FIG. 1.

Schematic of vectors. (A) Ad5. The gray bar indicates the DNA genome of 36 kbp. The open arrow indicates the immediate-early E1A transcription unit, and the black arrows are the delayed-early E1B, E2, E3, and E4 transcription units. The upper shaded arrows indicate the five families of major late mRNAs and also the ADP mRNA, which is synthesized as part of the major late transcription unit. Each major late mRNA has a tripartite leader (leaders 1, 2, and 3) spliced to its 5′ terminus. (B) dl309. dl309 is identical to Ad5, except that it has the E3-RID and E3-14.7K genes deleted. dl309 expresses ADP at levels similar to those of Ad5. (C) KD1. KD1 has two small deletions (indicated by “X” marks) in the E1A gene that abolish binding of the E1A proteins to pRB or p300/CBP. It lacks all E3 genes except adp. ADP is expressed earlier in infection and in greater abundance than is ADP from Ad5 or dl309 (8). (D) KD1-SPB. KD1-SPB is identical to KD1, except that it has the E4 promoter replaced by the promoter for SPB (SPB-P).