IDENTIFICATION OF SIGNAL SEQUENCES THAT CONTROL TRANSCRIPTION OF BORNA-DISEASE VIRUS, A NONSEGMENTED, NEGATIVE-STRAND RNA VIRUS

Borna disease virus (BDV) is a nonsegmented, negative-strand RNA virus that causes neurologic disorders in a wide range of animal species. A lthough the virus is unclassified, sequence analysis of the 8.9-kb vir al genome has shown that it is related to rhabdoviruses and paramyxovi ruses. We have mapped subgenomic RNAs of BDV strain He80-1 to the vira l genome by determining the precise sequences at their 5' and 3' termi ni. This analysis showed that the genome contains three transcription initiation sites and four termination sites. A 14- to 16-nucleotide se miconserved sequence was present at the gene start sites and partially copied into the subgenomic RNAs. The termination sites contained a U- rich motif reminiscent of termination signals in rhabdoviruses and par amyxoviruses. In contrast to the genomes of other nonsegmented, negati ve-strand RNA viruses, the BDV genome lacked the typical configuration of termination signal, intergenic region, and initiation signal at th e gene boundaries. Instead, transcription units and transcription sign als frequently overlapped. These differences have implications for our understanding of the control of viral transcription and may relate to the low-level replication and persistence of BDV.