Receptor for AAV

IneflScient transduction of WD airway epithelia by luminal application of AAV vectors may also be limiting for CFTR gene transfer. A membrane-associated heparan sulfate proteoglycan has been identified as a receptor for AAV-2,... 

Heparan sulfate proteoglycans and the coreceptors have been localized predominantly to the basolateral surface of WD HAE cells (47), which correlates with preferential transduction of these cells when vector is applied to the basolateral membrane relative to the apical membrane. However, binding studies of radiolabeled AAV-2 have shown only a four- to sevenfold reduction in binding to the cal membrane of WD HAE in culture as compared to the basal membrane. Because gene transfer efficiency was 200- fold greater following basal application than for luminal qiplication, the existence of apical membrane receptors for AAV-2 that are not functional for vector expression have been proposed (47,94). 

Diran et al. have suggested that receptors for AAV-2 tttay exist on the apical membrane of polarized WD HAE cells that can bind and mediate AAV-2 entry. 

There is a wide variety of vectors used to deliver DNA or oligonucleotides into mammalian cells, either in vitro or in vivo. The most common vector systems are based on viral [retroviruses (9, 10), adeno-associated virus (AAV) (11), adenovirus (12, 13), herpes simplex virus (HSV) (14)] andnonviral [cationic liposomes (15,16), polymers and receptor-mediated polylysine-DNA] complexes (17). Other viral vectors that are currently under development are based on lentiviruses (18), human cytomegalovirus (CMV) (19), Epstein-Barr virus (EBV) (20), poxviruses (21), negative-strand RNA viruses (influenza virus), alphaviruses and herpesvirus saimiri (22). Also a hybrid adenoviral/retroviral vector has successfully been used for in vivo gene transduction (23). A simplified schematic representation of basic human gene therapy methods is described in Figure 13.1. 

AAV2 and its helper viruses like HSV, AAY2 interacts with the cell surface via heparin sulfate, and AAV internalization is mediated by aV/ 5 integrin, which is also required by adenovirus for uptake. Serotypes other than AAV2 exhibit different tropisms and interact with different cell surface molecules. Some of the cell surface receptors have been identified for AAV3 (HSPG Rabinowitz et al.,... 

In addition to the work presented here, several alternative viral-vectored approaches have been reported recently. An adeno-associated viral vector (AAV) encoding the soluble VEGF receptor 1, sFlt-1, shows promise for long-term inhibition of two types of ocular neovascularization (Lai et al., 2002). This vector, when injected into the anterior chamber, resulted in expression in both the corneal endothelium and iris pigment epithelium and reduced corneal NV by 36%. Subretinal injection of the same vector reduced choroidal NV subsequent to laser lesions around the optic nerve. These results suggest that a secretable factor expressed in one or more transduced cell populations can be elfective in the control of ocular NV occurring in a disparate cell population. 

The reason(s) observed in our studies for the preferential transduction of the proximal tubule and intercalated cells is not entirely clear. Several possible mechanisms may be implicated. The early steps of AAV infection involve attachment to a variety of cell surface receptors (heparan sulfate proteoglycan, fibroblast growth factor receptor, and av-/ 5 integrin) followed by a clathrin-dependent... 

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