Oligosaccharide specificity of influenza H1N1 virus neuraminidases

Abstract
A fluorescent neuraminidase (NA) assay has been developed; 20 samples in five replicates could be analyzed at the same time, allowing us to study the kinetics of the enzyme-substrate interaction. The specificities of six influenza H1N1 virus NAs for BODIPY-labeled 3′SiaLac, 3′SiaLacNAc, SiaLec, SiaLea, 6′SiaLac, and 6′SiaLacNAc were evaluated. The duck virus NA hydrolyzed 6′SiaLac and 6′SiaLacNAc 50 times more slowly than 2–3 isomers. Swine viruses digested SiaLea and 2–6 sialosides 20 times more slowly than 2–3 trisaccharides. For the human viruses, the difference between 2–6 and 2–3 oligosaccharides desialylation efficiency did not exceed five times; notably, the inner core of 2–3 sialosaccharide was discriminated. The results are evidence that influenza virus NAs can distinguish substrate structure at the tri- and tetrasaccharide level.