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

Early region 4 (E4) of bovine adenovirus type 3 (BAV-3) was analyzed by Nor thern blotting, RT-PCR analysis, cDNA sequencing, and S1 nuclease protectio n assays. The transcriptional map of the E4 region of BAV-3 has marked diss imilarities from those of mouse adenovirus-1, ovine adenovirus-287, and hum an 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 f ormed by the removal of one to three introns share both the 3' end and a sh ort 5' leader (25 nucleotides). The E4 mRNAs can encode at least five uniqu e polypeptides, namely, 143R1, 69R, 143R2, 268R, and 219R. Isolation of a r eplication-competent recombinant "BAV404" containing 1.9-kb insertion [glyc oprotein (gD) of bovine herpesvirus 1, under the control of a SV40 early pr omoter and poly(A)] in the region between E4 and the right ITR suggested th at this region is nonessential for BAV-3 replication. Expression of go by B AV404 recombinant virus was confirmed by immunoprecipitation with go-specif ic monoclonal antibodies. Analysis of the kinetics of protein expression in dicated that go is expressed at both early and late limes postinfection, Th ese results suggest that: (a) 54 produces seven 5'-3' coterminal mRNAs and (b) the right terminal region of BAV-3 can be used for the expression of va ccine antigens. (C) 1999 Academic Press.