Borna disease virus (BDV), a nonsegmented, negative-strand RNA virus, infects a 
wide variety of mammalian species and readily establishes a long-lasting, 
persistent infection in brain cells. Therefore, this virus could be a promising 
candidate as a novel RNA virus vector enabling stable gene expression in the 
central nervous system (CNS). Previous studies demonstrated that the 5' 
untranslated region of the genome is the only site for insertion and expression 
of a foreign gene. In this study, we established a novel BDV vector in which an 
additional transcription cassette has been inserted into an intercistronic 
noncoding region between the viral phosphoprotein (P) and matrix (M) genes. The 
recombinant BDV (rBDV) carrying green fluorescent protein (GFP) between the P 
and M genes, rBDV P/M-GFP, expressed GFP efficiently in cultured cells and 
rodent brains for a long period of time without attenuation. Furthermore, we 
generated a nonpropagating rBDV, ΔGLLP/M, which lacks the envelope glycoprotein 
(G) and a splicing intron within the polymerase gene (L), by the 
transcomplementation system with either transient or stable expression of the G 
gene. Interestingly, rBDV ΔGLLP/M established a persistent infection in cultured 
cells with stable expression of GFP in the absence of the expression of G. Using 
persistently infected rBDV ΔGLLP/M-infected cells, we determined the amino acid 
region in the cytoplasmic tail (CT) of BDV G important for the release of 
infectious rBDV particles and also demonstrated that the CT region may be 
critical for the generation of pseudotyped rBDV having vesicular stomatitis 
virus G protein. Our results revealed that the newly established BDV vector 
constitutes an alternative tool not only for stable expression of foreign genes 
in the CNS but also for understanding the mechanism of the release of enveloped 
virions.