Jc. Paterna et al., Influence of promoter and WHV post-transcriptional regulatory element on AAV-mediated transgene expression in the rat brain, GENE THER, 7(15), 2000, pp. 1304-1311
Recombinant adeno-associated viruses (rAAVs) can transduce several tissues,
including the brain. However, in brain the duration of gene expression in
different areas is variable, which has been ascribed to viral (CMV) promote
r silencing in some regions over time. We have compared expression of enhan
ced green fluorescent protein (EGFP) in the nigrostriatal pathway of rats m
ediated by rAAVs containing the CMV or platelet-derived growth factor-beta
chain (PDGF-beta) promoter. In addition, we studied the effects of the wood
chuck hepatitis virus post-transcriptional regulatory element (WPRE) on tra
nsgene expression in vivo. The rAAV vectors containing the neuron-specific
PDGF-beta chain promoter transduced significantly more dopaminergic neurons
than titer-matched vectors carrying the CMV promoter. Moreover, the WPRE f
urther increased EGFP expression, and a rAAV vector incorporating both the
PDGF-beta chain promoter and the WPRE resulted in efficient EGFP expression
in dopaminergic neurons and their projections in the striatum for at least
41 weeks after virus injection. Our results emphasize the importance of a
strong tissue-specific promoter in achieving optimal transgene expression,
not only in longterm but also in short-term studies where viral titers may
be limiting. Furthermore, they suggest that incorporation of the WPRE into
rAAVs, and possibly other types of vectors, is useful to enhance transgene
expression in vivo.