SEQUENCE, TRANSCRIPTIONAL ANALYSIS, AND DELETION OF THE BOVINE ADENOVIRUS TYPE-1 E3 REGION

The early 3 (E3) transcriptional unit of human adenoviruses (HAV) enco des proteins that modulate host antiviral immune defenses. HAV E3 sequ ences are highly variable; different HAV groups encode phylogeneticall y unrelated proteins. The role of the E3 region of many human and anim al adenoviruses is unknown because the sequences are unrelated to prev iously characterized viruses and the functions of proteins encoded by these regions have not been studied. We sequenced a portion of the bov ine adenovirus serotype 1 (BAV-1) genome corresponding to the putative E3 region. This sequence was substantially different from other adeno viral E3 sequences, including those of two other bovine adenoviruses. However, two regions of putative sequence conservation were identified . BAV-1 E3 sequences were identified in early and late transcripts, bu t, unlike HAV, introns were not detected in the E3 region transcripts. Like HAV E3, a majority of the BAV-1 E3 region was not essential for growth in cell culture, as demonstrated by the construction of a recom binant BAV-1 lacking 60% of the putative E3 region. (C) 1998 Academic Press.