Widespread distribution of gene products at clinically relevant levels throughout the CNS has been challenging. Adeno-associated virus type 9 (AAV9) vector has been reported as a good candidate for intravascular gene delivery, but low levels of preexisting antibody titers against AAV in the blood abrogate cellular transduction within the CNS. In the present study we compared the effectiveness of vascular delivery and cerebrospinal fluid (CSF) delivery of AAV9 in transducing CNS tissue in nonhuman primates. Both delivery routes generated similar distribution patterns, although we observed a more robust level of transduction after CSF delivery. Consistent with previous reports administering AAV9, we found greater astrocytic than neuronal tropism via both routes, although we did find a greater magnitude of CNS transduction after CSF delivery compared with intravascular delivery. Last, we have demonstrated that delivery of AAV9 into the CSF does not shield against AAV antibodies. This has obvious implications when developing and/or implementing any clinical trial studies.

Phosphatase and tensin homolog-induced putative kinase 1 gene mutations have been associated with autosomal recessive early-onset Parkinson’s disease. To date, no neuropathological reports have been published from patients with Parkinson’s disease with both phosphatase and tensin homolog-induced putative kinase 1 gene copies mutated. We analysed the coding region of phosphatase and tensin homolog-induced putative kinase 1 gene in a large Spanish family with six members with parkinsonism. The phenotype was characterized by an early-onset (mean: 31.6, standard deviation: 9.6 years, range: 14–45 years), slowly progressive levodopa-responsive parkinsonism, initial gait impairment and psychiatric symptoms. We identified two segregating pathogenic phosphatase and tensin homolog-induced putative kinase 1 mutations that were either in homozygous or heterozygous compound state in all affected family members. We found an exon 7 deletion (g.16089_16383del293; c.1252_1488del) and a novel + 1U1-dependent 5′ splice-site mutation in exon 7 (g.16378G > A; c.1488 + 1G > A). Leukocyte-derived messenger RNA analysis showed that both mutations caused exon 7 skipping and c.1488 + 1G > A also lead to an in-frame transcript with a 33 base-pair deletion (p.L485_R497del) resulting from activation of a 5′ cryptic exon 7 splice site. Single photon emission computed tomography quantification of striatal dopamine transporter binding (¹²³I-Ioflupane) revealed a posterior–anterior gradient similar to that of idiopathic Parkinson’s disease, but there was no correlation between striatal reduced uptake and disease duration. Post-mortem neuropathological examination of an early-onset Parkinson’s disease carrier of two heterozygous compound phosphatase and tensin homolog-induced putative kinase 1 mutations showed neuronal loss in the substantia nigra pars compacta, Lewy bodies and aberrant neurites in the reticular nuclei of the brainstem, substantia nigra pars compacta and Meynert nucleus, but the locus ceruleus and the amygdala were spared. This is the first neuropathological report of the brain from an early-onset phosphatase and tensin homolog-induced putative kinase 1-linked parkinsonism showing that mutated phosphatase and tensin homolog-induced putative kinase 1 protein induces Lewy body pathology. Unbalanced preservation of the locus ceruleus may well play a role in the slow evolution of motor symptoms and, probably, in the psychiatric symptoms often encountered in Parkinson’s disease associated with phosphatase and tensin homolog-induced putative kinase 1 mutation.

We have previously shown that adeno-associated virus type 2 (AAV2) undergoes anterograde axonal transport in rat and non-human primate brain. We screened other AAV serotypes for axonal transport and found that AAV6 is transported almost exclusively in a retrograde direction and, in the same way as AAV2, it is also neuron-specific in rat brain. Our findings show that axonal transport of AAV is serotype dependent and this has implications for gene therapy of neurological diseases such as Huntington's disease.

The present study builds on previous work showing that infusion of adeno-associated virus type 9 (AAV9) into the cisterna magna (CM) of nonhuman primates resulted in widespread transduction throughout cortex and spinal cord. Transduction efficiency was severely limited, however, by the presence of circulating anti-AAV antibodies. Accordingly, we compared AAV9 to a related serotype, AAV7, which has a high capsid homology. CM infusion of either AAV7 or AAV9 directed high level of cell transduction with similar patterns of distribution throughout brain cortex and along the spinal cord. Dorsal root ganglia and corticospinal tracts were also transduced. Both astrocytes and neurons were transduced. Interestingly, little transduction was observed in peripheral organs. Our results indicate that intrathecal delivery of either AAV7 or AAV9 directs a robust and widespread cellular transduction in the central nervous system and other peripheral neural structures. Samaranch and colleagues compare the transduction profiles of AAV9-GFP and AAV7-GFP in nonhuman primates. They show that intrathecal delivery of either vector leads to equally high levels of cell transduction with similar patterns of distribution throughout the brain cortex and spinal cord, including the dorsal root ganglia and corticospinal tracts. Importantly, using this approach, they observe virtually no transduction of peripheral organs.