Characterization of the early region 3 and fiber genes of Ad7.

The nucleotide sequence and the predicted amino acid sequences for open reading frames (ORFs) encoded in the Bam-Hl D fragment of Ad7 (Gomen) DNA show an organization and conservation of potential polypeptides between Ad3 and Ad7. Five ORFs encoded within early region 3 (E3) and shared with the corresponding region of Ad3 can be identified; four of these potential coding regions also share homology to ORFs found in E3 of Ad2 and Ad5. The fiber gene of late region 5 (L5) is also apparent within this region; S1 mapping experiments show that the 5' and 3' boundaries of the main exon in fiber mRNA lie at each end of the proposed fiber ORF. The predicted amino acid sequence for Ad7 fiber shares 60% amino acid homology to Ad3 fiber, but only 20% to Ad2 fiber. Surprisingly, there are three regions of partial amino acid homology near the N- and C-termini of the predicted fiber gene sequences from Ad2, Ad3, Ad5, and Ad7; these conserved regions may be important for interaction with penton base, for proper folding of the shaft of the molecule, or for recognition of the cellular receptor to which adenovirus attaches during infection.