Kr. Clark et al., Gene transfer into the CNS using recombinant adeno-associated virus: Analysis of vector DNA forms resulting in sustained expression, J DRUG TAR, 7(4), 1999, pp. 269
Recombinant adeno-associated virus (rAAV) vectors have shown significant pr
omise as vehicles for in vivo gene transfer, particularly for transduction
of organs composed primarily of non-dividing cells (i.e., muscle, CNS, and
liver), However, the mechanistic basis for this desirable property remains
unclear. To investigate the fate of rAAV genomes in mouse brain, we stereot
actically injected an rAAV vector carrying the E. coli lacZ gene into the c
audate of BALB/c mice and demonstrate efficient transduction of mouse brain
cells that possess cellular morphology consistent with post-mitotic neuron
s. We observed a significant increase in beta-galactosidase expression from
5 to 56 days after injection that paralleled the disappearance of single-s
tranded DNA input genomes, Analysis of in vivo viral DNA forms over time ou
t to 5 months after inoculation revealed that rAAV genomes associated with
high molecular weight mouse chromosomal DNA by 14 days after injection and
persisted for the length of this study, The pattern of Southern hybridizati
on was consistent with random viral integration in predominantly head-to-ta
il concatameric arrays. Importantly, we also documented an additional DNA s
pecies that appears to be a monomeric episomal circular form based on nucle
ase sensitivity assays, These data are the first to document the existence
of multiple vector DNA forms present within the adult murine brain followin
g direct rAAV inoculation and therefore, provide insight into the molecular
events that ultimately result in long-term rAAV mediated transgene express
ion.