Characterization of adenovirus type 40 E1 region

The left-most 3.9 kb of adenovirus type 40 (Ad40) DNA has been sequenced using cloned viral DNA fragments. The Ad40 E1 region is deduced to code for at least four polypeptides, 221 and 249 amino acids as E1A products in addition to 166 and 475 amino acids as E1B products. E1B polypeptides share about 50% homology with well-defined adenovirus types, 2/5, 7, and 12, throughout the E1B sequences. E1A homology of Ad40 to these types is relatively lower than that of E1B, while highly conserved regions of E1A are retained to a certain level in Ad40 as well. Activity for morphological transformation of Ad40 E1A on 3Y1 cells is considerably lower when compared to that of Ad5 and Ad12 E1A genes. Transient chloramphenicol acetyltransferase (CAT) expression assay shows that Ad40 E1A has a trans-acting function, though lower than that of other E1A genes, on adenovirus early promoter. The Ad40 E1A promoter also holds only a little cis-acting activity in 3Y1 cells. Lower activities of both Ad40 E1A promoter and certain E1A functions may explain in part the difficulty in propagation of Ad40.