Abstract
Although avian influenza A viruses (avian IAVs) bind preferentially to terminal sialic acids (Sia) on glycans that possess Siaα2-3Gal, the actual glycan structures found in chicken respiratory tracts have not been reported. Herein, we analyzed N-glycan structures in chicken trachea and lung, the main target tissues of low pathogenic avian IAVs. 2-Aminopyridine (PA)-labeled N-glycans from chicken tissues were analyzed by combined methods using reversed-phase liquid chromatography (LC), electrospray ionization (ESI)-mass spectrometry (MS), MS/MS, and multistage MS (MSn), with or without modifications using exoglycosidases, sialic acid linkage-specific alkylamidation (SALSA), and/or permethylation. The results of SALSA indicated that PA-N-glycans in both chicken trachea and lung harbored slightly more α2,6-Sia than α2,3-Sia. Most α2,3-Sia on N-glycans in chicken trachea was a fucosylated form (sialyl Lewis X, sLex), whereas no sLex was detected in lung. By contrast, small amounts of N-glycans with 6-sulfo sialyl LacNAc were detected in lung but not in trachea. Considering previous reports that hemagglutinins (HAs) of avian IAVs originally isolated from chicken bind preferentially to α2,3-Sia with or without fucosylation and/or 6-sulfation but not to α2,6-Sia, our results imply that avian IAVs do not evolve to possess HAs that bind preferentially to α2,6-Sia, regardless of the abundance of α2,6-Sia.
Highlights
IntroductionAvian influenza A viruses (avian Influenza A viruses (IAVs)) bind preferentially to terminal sialic acids (Sia) on glycans that possess Siaα2-3Gal, the actual glycan structures found in chicken respiratory tracts have not been reported
Avian influenza A viruses bind preferentially to terminal sialic acids (Sia) on glycans that possess Siaα2-3Gal, the actual glycan structures found in chicken respiratory tracts have not been reported
Some chicken-origin Influenza A viruses (IAVs) have stronger affinity for 6-sulfo α2,3-sialyl LacNAc (NeuAcα2-3Galβ1-4(SO3H-6)GlcNAc), sialyl Lewis X ( sLex, NeuAcα2-3Galβ14(Fucα1-3)GlcNAc), and/or 6-sulfo sLex (NeuAcα2-3Galβ1-4(Fucα1-3)(SO3H-6)GlcNAc) than for α2,3-sialyl LacNAc without fucosylation and sulfation, the patterns of viral binding to the synthesized glycans varied significantly among viruses of different subtypes and among different isolates[6,7,8,9,10]
Summary
Avian influenza A viruses (avian IAVs) bind preferentially to terminal sialic acids (Sia) on glycans that possess Siaα2-3Gal, the actual glycan structures found in chicken respiratory tracts have not been reported. Some chicken-origin IAVs have stronger affinity for 6-sulfo α2,3-sialyl LacNAc (NeuAcα2-3Galβ1-4(SO3H-6)GlcNAc), sialyl Lewis X ( sLex, NeuAcα2-3Galβ14(Fucα1-3)GlcNAc), and/or 6-sulfo sLex (NeuAcα2-3Galβ1-4(Fucα1-3)(SO3H-6)GlcNAc) than for α2,3-sialyl LacNAc without fucosylation and sulfation, the patterns of viral binding to the synthesized glycans varied significantly among viruses of different subtypes and among different isolates[6,7,8,9,10]. This fact implies that target glycan structures expressed on host cells may differ depending on the avian species, and induce acquisition of appropriate specificities through selective mutation on HAs
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