Automated Glycan Assembly of Oligo-N-Acetyllactosamine and Keratan Sulfate Probes to Study Virus-Glycan Interactions

Oligo-N-acetyllactosamine (LacNAc) and keratan sulfate (KS) glycans exert crucial functions in disease-relevant processes, including cancer formation, inflammation, and viral infection. To facilitate structure-activity studies with these glycans, we established a universal strategy to synthesize linear and branched LacNAc as well as differentially sulfated KS oligosaccharides by automated glycan assembly. We synthesized oligosaccharides as long as hexamers by combining four monosaccharide building blocks. Key to the strategy was installing three orthogonal protection groups, 9-fluorenylmethoxycarbonyl (Fmoc), levulinoyl (Lev) ester, and 2-naphthylmethyl (Nap) ether, which were selectively removed from a common oligosaccharide precursor for differential sulfation. Microarrays presenting the synthetic oligosaccharides revealed a specific interaction between a disulfated KS tetrasaccharide and the adeno-associated virus AAVrh10 gene-therapy vector, which was further corroborated by surface plasmon resonance studies. Thus, KS represents a novel receptor candidate for AAVrh10. These insights could have implications for cell-type-specific gene-delivery approaches.