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.     

Transcriptional activation by the E1A regions of adenovirus types 40 and 41

In order to establish whether the poor growth of the two fastidious adenoviruses types 40 and 41 (Ad40 and Ad41) in HeLa cells is due to a reduced trans-activation by the early region 1A (E1A), we have determined the trans-activating effect of this region on the expression of the chloramphenicol acetyltransferase (CAT) gene controlled by the Ad2 E4 promoter. Cotransfection of HeLa cells with plasmids containing the E1A regions of Ad5, Ad40, and Ad41, respectively, and the CAT gene controlled by the Ad2 E4 promoter showed that activation of the E4 promoter by the E1A regions of Ad40 and Ad41 depends on the same sequence elements of the E4 promoter as activation by the Ad5 E1A gene products. The level of activation, however, is significantly lower. This might partly explain the reduced growth in HeLa cells of the two viruses.