Structure, chain conformation, and immunomodulatory activity of the polysaccharide purified from Bacillus Calmette Guerin formulation

A polysaccharide, coded as BDP, purified from the injection powder of Bacillus Calmette Guerin (BCG) polysaccharide and nucleic acid, was composed mainly of alpha-D-(1 -> 4)-linked glucan with (1 -> 6)-linked branches and trace amounts of fucose and mannose from the results of FT-IR, HPAEC-PAD and NMR spectrum. The 4,, Mz, and < s(2)> z(1/2) were determined to be 1.320 x 10(5) g/mol, 1.012 x 10(5) g/mol, 2.139 x 105 g/mol, and 21.8 +/- 3.2%nm by using HPSEC-MALLS, respectively. The v value from (s(2))z(1/2) KMWv was calculated to be 0.52 +/- 0.01, which firstly clarified that BDP existed as random coils in 0.9% NaCl aqueous solution. AFM and SEM combined with Congo -red test also revealed that the polysaccharide was irregular globular like or curly structure. Furthermore, in vitro tests on RAW264.7 murine macrophages cells revealed that BDP exhibited significant immunomodulatory activity. (C) 2016 Elsevier Ltd. All rights reserved.