FIG 1.

Components of LPS that contribute to poliovirus stabilization. (A) LPS from E. coli O127:B8 was hydrolyzed by acid and analyzed by FACE. Intact LPS cannot be labeled with fluorophore and therefore does not generate a band in the FACE gel. Weak-acid treatment of LPS (2% acetic acid, 100°C) is sufficient to release intact polysaccharide (detoxified LPS), as indicated by the red arrow. Strong-acid treatment of LPS (0.1 M HCl, 100°C) generated multiple degraded fragments of the polysaccharide. Glucose oligomers (Glc4 to Glc7) were used to roughly indicate glycan sizes. (B) FACE analysis of the monosaccharide composition of the detoxified LPS (dLPS) from E. coli O127:B8 following strong-acid hydrolysis. N-Acetylgalactosamine, fucose, and galactose were detected by comparison with monosaccharide standards. (C) Detoxified LPS from E. coli O127:B8 stabilizes poliovirus but at a lower efficiency than intact LPS. Poliovirus (10⁶ PFU) was incubated with compounds at 45°C for 5 h. Remaining titers after incubation were calculated by plaque assays and normalized to the result for the untreated control. (D) Polysaccharide (dLPS) and lipid components of LPS contribute to poliovirus stabilization, but monosaccharides or short oligosaccharides do not. Concentrations of compounds: 1 mg/ml for dimethyl sulfoxide (DMSO), BSA, LPS, dLPS, and lipid A; 20 mg/ml for monosaccharides; 5 mg/ml for oligosaccharides. Poliovirus (10⁶ PFU) was incubated with compounds at 45°C for 5 h. Remaining titers after incubation were calculated by plaque assays and normalized to the result for the untreated control. The saccharides used were d-glucose (Glc), d-galactose (Gal), d-mannose (Man), l-fucose (Fuc), d-glucosamine (GlcN), d-galactosamine (GalN), d-mannosamine (ManN), N-acetyl-d-glucosamine (GlcNAc), N-acetyl-d-galactosamine (GalNAc), N-acetyl-d-mannosamine (ManNAc), maltotriose (Glc3), maltohexaose (Glc6), tri-N-acetylchitotriose (GlcNAc3), and hexa-N-acetylchitohexaose (GlcNAc6). Results represent mean ± standard error of the mean (SEM) (n = 4 to 8). *, P < 0.05 by Kruskal-Wallis test.