Before HPLC analysis, exopolysaccharide polymers were hydrolyzed into monomers by adding 1 mL of TFA 4 M to 1 mL of exopolysaccharide sample. The reaction was carried out for 2 h at 120 °C and TFA was removed by SpeedVac. The final exopolysaccharide sample was resuspended in 1 mL of dH2O. 1D and 2D NMR spectra of the exopolysaccharide in D2O (1 mg in 0.5 mL) were recorded at 70 °C on a Bruker AVANCE III 700 MHz spectrometer and on a Bruker AVANCE 500 MHz spectrometer, both equipped with 5 mm TCI Z-Gradient CryoProbes. 1H chemical shifts were referenced to internal TSP (δH 0.00) and https://www.selleckchem.com/products/AZD6244.html 13C chemical shifts

were referenced to external dioxane in D2O (δC 67.40). The 1D 1H,1H-TOCSY experiments were carried out with five different mixing

times between 10 and 120 ms. The 1H,13C-HMBC CHIR-99021 price experiment was performed with a 65-ms delay for the evolution of long-range couplings. Data processing was performed using vendor-supplied software. Measurement of the translational diffusion coefficient of the exopolysaccharide was carried out as described previously (Eklund et al., 2005). We used 50 mM Tris-HCl pH 7.5 and borate–10%NaCl (in some animals, up to 10% NaCl is necessary for the IgG to precipitate with the Brucella O-chain or NH, and borate buffers often help in the diffusion of polysaccharides). Exopolysaccharide was used at 5 mg mL−1 and tested with a pool of cattle sera that yields good precipitin bands with S Brucella polysaccharides (as a reference, with this pool of sera, B. melitensis lipopolysaccharide precipitates at about 1 mg mL−1, the O-PS down to 100 μg mL−1, and the pure NH down to 5 μg mL−1). Other sera were Dimethyl sulfoxide also tested from rabbits infected with B. melitensis (109 CFU intravenously) bled 3 months later, and from a rabbit infected with B. abortus 544 bled 6 months later. We also tested the exopolysaccharide in double-gel diffusion

with a serum from a rabbit hyperimmunized with B. melitensis 115 (rough) that yields several precipitin lines with soluble proteins. Brucella melitensis were grown for 20 h in 2YT medium at 37 °C. Cultures were then supplemented with 50 μg mL−1 DNaseI (Roche), incubated at 37 °C for different times and examined immediately by an agarose pad at appropriate times. For DIC imaging, cell populations of B. melitensis strains were placed on a microscope slide that was layered with a pad of 1% agarose containing PBS (agarose pads) (Jacobs et al., 1999). Samples were observed on a Nikon E1000 microscope through a differential interference contrast (DIC) × 100 objective with a Hamamatsu Orca-ER LCD camera. Images were taken and processed with Simple PCI (Hamamatsu). Brucella were grown for 20 h in 2YT medium at 37 °C. Cultures were adjusted at the same OD600 nm before centrifugation to separate the supernatants from the cell pellets.