Transduction of Nonhuman Primate Brain with Adeno-Associated Virus Serotype 1: Vector Trafficking and Immune Response

Abstract

We used convection-enhanced delivery (CED) to characterize gene delivery mediated by adeno-associated virus type 1 (AAV1) by tracking expression of hrGFP (humanized green fluorescent protein from Renilla reniformis) into the striatum, basal forebrain, and corona radiata of monkey brain. Four cynomolgus monkeys received single infusions into corona radiata, putamen, and caudate. The other group (n = 4) received infusions into basal forebrain. Thirty days after infusion animals were killed and their brains were processed for immunohistochemical evaluation. Volumetric analysis of GFP-positive brain areas was performed. AAV1-hrGFP infusions resulted in approximately 550, 700, and 73 mm3 coverage after infusion into corona radiata, striatum, and basal forebrain, respectively. Aside from targeted regions, other brain structures also showed GFP signal (internal and external globus pallidus, subthalamic nucleus), supporting the idea that AAV1 is actively trafficked to regions distal from the infusion site. In addition to neuronal transduction, a significant nonneuronal cell population was transduced by AAV1 vector, for example, oligodendrocytes in corona radiata and astrocytes in the striatum. We observed a strong humoral and cell-mediated response against AAV1-hrGFP in transduced monkeys irrespective of the anatomic location of the infusion, as evidenced by induction of circulating anti-AAV1 and anti-hrGFP antibodies, as well as infiltration of CD4+ lymphocytes and upregulation of MHC-II in regions infused with vector. We conclude that transduction of antigen-presenting cells within the CNS is a likely cause of this response and that caution is warranted when foreign transgenes are used as reporters in gene therapy studies with vectors with broader tropism than AAV2.

Gene therapy for the neurological manifestations in lysosomal storage disorders

“…Evidence of broader therapeutic coverage of brain structures with the enzyme was observed when these sites were included as part of the compendium of intracranial injections. Over the past few years, there have been signifi cant improvements in imaging methodologies that may support the deposition of viral vectors to precise locations of interest thereby imparting greater specifi city and safety for this procedure ( 114,128 ). The number of intracranial injections may also the therapeutic agent to regions that are distal to the sites of the injections ( 33, 34, 39, 96 ).…”

“…For example, in the study using MPS IIIA mice, the utilization of a strong, myeloid-restricted promoter to enhance transgene expression by microglia in the CNS was necessary for robust effi cacy ( 155 ). For LSDs that are primarily characterized by neurological disease, restriction of the expression to the brain using selective promoters may be further minimized by favoring AAV serotypes that demonstrate a higher tropism for neural cells or a propensity to undergo axonal transport (e.g., AAV1, -5, -9, and -rh.10), Finally, these strategies may also be combined with the use of convection-enhanced delivery to further physically disseminate the vectors ( 114,128 ).…”

Adeno-Associated Virus Serotypes 1, 8, and 9 Share Conserved Mechanisms for Anterograde and Retrograde Axonal Transport

“…When compared directly after brain injection, these serotypes demonstrate distinct nervous cell tropism, transduction strength, and distribution of gene expression (Davidson et al, 2000;Burger et al, 2004;Wolfe, 2006, 2007;Li et al, 2006;Taymans et al, 2007;Cearley et al, 2008;Klein et al, 2008). While some serotypes transduce only within a normal range of diffusion, others also transduce cells at a substantial distance from the injection site (Burger et al, 2004;Wolfe, 2006, 2007;Klein et al, 2006Klein et al, , 2008Li et al, 2006;Reimsnider et al, 2007;Sondhi et al, 2007;Taymans et al, 2007;Cearley et al, 2008;Hollis et al, 2008;Hadaczek et al, 2009;Masamizu et al, 2011;Bu et al, 2012). This distal transduction is caused by axonal transport of the intact vector, either via uptake by an axon terminus, retrograde transport to the cell body, and subsequent transduction Wolfe, 2006, 2007;Reimsnider et al, 2007;Sondhi et al, 2007;Taymans et al, 2007;Hollis et al, 2008;Hadaczek et al, 2009;Masamizu et al, 2011;Bu et al, 2012), or via uptake by a projection neuron, anterograde transport along the axonal projection, secretion from the axon terminus, and transduction of a second-order neuron (Cearley and Wolfe, 2007).…”

Efficient transduction of non-human primate motor neurons after intramuscular delivery of recombinant AAV serotype 6

“…These findings are encouraging considering that intraparenchymal injections of therapeutically-relevant doses of rAAV have been shown to induce innate and adaptive immune responses in rodents and non-human primates. [18][19][20] Such immune responses lead to the elimination of transgeneexpressing cells and/or silencing of the transgene, and may account for the poor translation of gene therapy approaches observed in preclinical and clinical studies. 21 Indeed, eradication of rAAV2/2-transduced hepatocytes by cell-mediated immunity has been observed in a Phase I clinical trial for hemophilia.…”