Gangliosides Are Essential for Bovine Adeno-Associated Virus Entry

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Abstract
Recombinant adeno-associated viruses (AAV) are promising gene therapy vectors. We have recently identified a bovine adeno-associated virus (BAAV) that demonstrates unique tropism and transduction activity compared to primate AAVs. To better understand the entry pathway and cell tropism of BAAV, we have characterized the initial cell surface interactions required for transduction with BAAV vectors. Like a number of AAVs, BAAV requires cell surface sialic acid groups for transduction and virus attachment. However, glycosphingolipids (GSLs), not cell surface proteins, were required for vector entry and transduction. Incorporation of gangliosides, ceramide-based glycolipids containing one or more sialic acid groups, into the cytoplasmic cell membranes of GSL-depleted COS cells partially reconstituted BAAV transduction. The dependency of BAAV on gangliosides for transduction was further confirmed by studies with C6 cells, a rat glioma cell line that is deficient in the synthesis of complex gangliosides. C6 cells were resistant to transduction by BAAV. Addition of gangliosides to C6 cells prior to transduction rendered the cells susceptible to transduction by BAAV. Therefore, gangliosides are a likely receptor for BAAV.