Adeno-associated viral (AAV) vectors have become the primary delivery agent for somatic gene transfer into the central nervous system (CNS). To date, AAV-mediated gene delivery to the CNS is based on serotypes 1-9, with efficient gene transfer to neurons only-selective and widespread transduction of glial cells have not been observed. Recently, additional endogenous AAVs have been isolated from nonhuman primate tissues. In this study, transduction obtained with AAV serotypes bb2, cy5, rh20, rh39, and rh43 was compared to that obtained with AAV8, another nonhuman primate isolate previously shown to perform well in mammalian brain. Titer-matched vectors encoding the enhanced green fluorescent protein (EGFP) reporter, driven by the constitutive CAG promoter, were injected into the hippocampus, striatum, or substantia nigra (SN) of adult rats. More widespread neuronal transduction was observed following infusion of cy5, rh20, and rh39 than observed with AAV8. Of interest, preferential transduction of astrocytes was observed with rh43. To optimize glial transduction, vector stocks driven by cell-specific promoters were generated-widespread and targeted transduction of astrocytes and oligodendrocytes was observed using rh43 and AAV8, driven by the glial fibrillary acidic protein (GFAP) and myelin basic protein (MBP) promoters, expanding the utility of AAV for modeling and treating diseases involving glial cell pathology.
cAMP response element-binding protein (CREB) is important for the formation and facilitation of long-term memory in diverse models. However, to our knowledge, involvement of CREB in age-associated memory impairment has not been reported. Here, we use a recombinant adeno-associated virus vector to obtain stable transgenic expression of CREB as well as the inducible cAMP early repressor (ICER) in the hippocampus of adult rats. In a longitudinal study, we show that somatic gene transfer of both CREB and ICER does not alter long-term memory in young (3-month-old) rats. However, at 15 months of age, the same CREBtransduced rats show significantly better long-term memory in spatial-navigation and passive-avoidance tasks compared with their equally aged control littermates, and a threshold effect is evident. In contrast, the aged ICER-transduced rats demonstrate significantly reduced memory in comparison with the same control group. Hippocampal CREB gene transfer prevented the agingrelated decrease in long-term memory found in the control rats. These data suggest that elevation of CREB protein levels in a subset of hippocampal neurons as achieved by somatic cell gene transfer might compensate for general deficits in molecular mechanisms underlying age-related memory loss in rats and, therefore, attenuate long-term-memory impairment during normal aging.adeno-associated virus vector ͉ inducible cAMP early repressor ͉ long-term memory ͉ hippocampus D eficits in hippocampus-dependent long-term memory, which accompany normal aging, have been reported for many mammal species, including rats (1, 2), mice (3), monkeys (4), and humans (5). However, molecular mechanisms underlying such age-related changes are still unknown.Studies by Kandel and colleagues (6) using in vitro cultures of mollusk neurons revealed the involvement of the transcription factor cAMP response element-binding protein (CREB) in the molecular mechanisms underlying long-term facilitation. Further behavioral analysis in Drosophila (7, 8) and mice (9, 10) demonstrated that CREB is necessary for long-term-memory formation both in nonmammalian and mammalian species. Also, pharmacological antagonism and genetic disruption of CREB signaling prevents or attenuates long-term-memory consolidation in these model systems.CREB is constitutively expressed in cells, with the phosphorylation of Ser-133 generally believed to be the main mechanism of regulation of its transcriptional activity (11). However, several studies indicate that the CREB protein concentration might be critical in some aspects of long-term-memory formation. A transgenic fly that overexpresses an active form of CREB shows a lower threshold for the consolidation of long-term memory (8). Also, transiently increasing WT CREB levels in the basolateral amygdala by means of herpes simplex virus vector-mediated gene transfer facilitates long-term-memory formation after massed fear training (12).There is no direct evidence that implicates CREB in agerelated memory impairment. However, electrophysiological stud...
Adeno-associated viral vectors (AAV) have been shown to be safe in the treatment of retinal degenerations in clinical trials. Thus, improving the efficiency of viral gene delivery has become increasingly important to increase the success of clinical trials. In this study, structural domains of different rAAV serotypes isolated from primate brain were combined to create novel hybrid recombinant AAV serotypes, rAAV2/rec2 and rAAV2/rec3. The efficacy of these novel serotypes were assessed in wild type mice and in two models of retinal degeneration (the Abca4−/− mouse which is a model for Stargardt disease and in the Pde6brd1/rd1 mouse) in vivo, in primate tissue ex-vivo, and in the human-derived SH-SY5Y cell line, using an identical AAV2 expression cassette. We show that these novel hybrid serotypes can transduce retinal tissue in mice and primates efficiently, although no more than AAV2/2 and rAAV2/5 serotypes. Transduction efficiency appeared lower in the Abca4−/− mouse compared to wild type with all vectors tested, suggesting an effect of specific retinal diseases on the efficiency of gene delivery. Shuffling of AAV capsid domains may have clinical applications for patients who develop T-cell immune responses following AAV gene therapy, as specific peptide antigen sequences could be substituted using this technique prior to vector re-treatments.
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