A heteroploid permanent cell line originating from embryonic calf thyroid supporting the replication of all known bovine adenovirus serotypes

Transcription map and expression of bovine herpesvirus-1 glycoprotein D in early region 4 of bovine adenovirus-3

Early region 4 (E4) of bovine adenovirus type 3 (BAV-3) was analyzed by Northern blotting, RT-PCR analysis, cDNA sequencing, and S1 nuclease protection assays. The transcriptional map of the E4 region of BAV-3 has marked dissimilarities from those of mouse adenovirus-1, ovine adenovirus-287, and human adenovirus-2, for which the transcriptional maps have been constructed. The E4 region of BAV-3, located between 98.6 and 89.8 MU transcribes seven distinct classes of bovine adenovirus type 3 mRNA. The seven mRNA species formed by the removal of one to three introns share both the 3' end and a short 5' leader (25 nucleotides). The E4 mRNAs can encode at least five unique polypeptides, namely, 143R1, 69R, 143R2, 268R, and 219R. Isolation of a replication-competent recombinant "BAV404" containing 1.9-kb insertion [glycoprotein (gD) of bovine herpesvirus 1, under the control of a SV40 early promoter and poly(A)] in the region between E4 and the right ITR suggested that this region is nonessential for BAV-3 replication. Expression of gD by BAV404 recombinant virus was confirmed by immunoprecipitation with gD-specific monoclonal antibodies. Analysis of the kinetics of protein expression indicated that gD is expressed at both early and late times postinfection. These results suggest that: (a) E4 produces seven 5'-3' coterminal mRNAs and (b) the right terminal region of BAV-3 can be used for the expression of vaccine antigens.

Cloning and sequencing of the bovine adenovirus type 2 early region 4

Bovine adenovirus type 2 (BAV2) is a medium size double-stranded DNA virus which infects both bovine and ovine species, resulting in mild respiratory and gastrointestinal disorders. To better understand the virus and its growth characteristics in Madin-Darby bovine kidney (MDBK) cells, we have cloned and sequenced the extreme right-end segment of the BAV2 genome (90.5-100 map units). Analysis of the nucleotide sequence revealed 40 potential open reading frames (ORFs) with coding capacity for polypeptides that are 25 or more amino acid (aa) residues long. Six of these ORFs encode polypeptides that show homology to well-characterized early region 4 (E4) proteins of human adenovirus type 2 (Ad2) and Ad12. ORF1 has the potential to encode a 114 aa long polypeptide that is 54% homologous to the E4 14kDa protein of Ad2. ORF2 encodes a 78 aa long polypeptide that exhibits 40% homology to the E4 13 kDa protein of Ad2. ORFs 3-6 encode polypeptides that have homology to the E4 34 kDa protein encoded by ORF6 of Ad2 and Ad12. ORFs 3, 4 and 5 encode 128, 96 and 31 aa long polypeptides, respectively. The 128-aa polypeptide exhibits 59% homology, while the 96 and 31 aa long polypeptides exhibit 61% and 70% homology to the E4 34 kDa protein, respectively. ORF6 has the potential to encode a 57 aa long polypeptide that has 67% homology to the E4 34 kDa protein of Ad2 and 50% homology to the E4 34 kDa protein of Ad12.