Work

113. Transduction of Neural Cells in Primate Brain Using Adeno-Associated Virus (AAV) Serotypes 2 and 5

Year: 2006

Type: article

Abstract: Top of pageAbstract There are currently eleven identified serotypes of the adenoassociated virus (AAV), a single stranded DNA parvovirus used extensively for gene delivery in animals; yet AAV serotype 2, the first to be characterized, is the most widely used for gene delivery. While homology exists among most serotypes, considerable differences in the viral capsid surface have been described for AAV4, and AAV5, which are believed to have greater tropism for cells in the central nervous system than other serotypes of AAV. To test the relative efficiency with which vectors made from AAV2, and AAV5 can transduce cells of the primate central nervous system, we injected the brains of St. Kitts green monkeys with viral vectors of both serotypes, each expressing the reporter gene green fluorescent protein (GFP). The vectors were all of comparable titer, injected in equal amounts in positive pressure, stereotaxic injections using the same rate of infusion into the substantia nigra. Animals were perfused after a one month survival, and their brains removed and sectioned. One series of sections was stained with the antibody to GFP using a diaminobenzidine (DAB) secondary reaction. These DAB sections were counted under a light microscope using a computer equipped with software for unbiased stereology, and counts for labeled cells were made. Remaining adjacent series of sections were processed for immunohistochemistry for glial fibrillary acidic protein (GFAP), an intermediate filament protein that labels cells of astroglial lineage, or neurofilament (NF), three intermediate filament proteins that are structural components of neurons and their axons. Sections were reacted with fluorescent secondary antibodies, the inherent fluorescence of GFP remaining unreacted, and the sections were examined using confocal laser scanning microscopy. Counts made for numbers of transduced cells using unbiased stereology show that AAV5 transduced a greater number of cells in the central nervous system than did AAV2. Furthermore, AAV5 transduced GFAP positive glial cells with notable preference over NF-positive neurons. This preference presages a role for AAV5 in cell supportive, or cell replacement strategies, as transduced glial cells mat be induced to produce neuron supportive gene products, such as GDNF, in a more physiological and sustainable fashion than can neurons.

Source: Molecular Therapy

DOI: 10.1016/j.ymthe.2006.08.133