To study the effect of degradation with hydrogen peroxide method and high pressure homogenization method on structure and antigenicity of type 6A pneumococcal polysaccharide (PnPS6A).

PnPS6As were degraded by hydrogen peroxide method [adding hydrogen peroxide into polysaccharide (PS) solution and reacting at 50 ℃ for 3 h] or high pressure homogenization method (degrading with high pressure homogenizer at 5×10⁷ Pa ). After the degraded products were treated by ultrafiltration concentration and freeze-drying, the degraded PnPS6As were obtained. The structure and antigenicity of PnPS6A were detected with nuclear magnetic resonance hydrogen spectrum (¹H-NMR) and double immunodiffusion test, respectively. The antigenicity consistency of treated and untreated PnPS6A was analyzed by inhibition ELISA.

Both degradation methods could reduce the relative molecular weight of PnPS6A. The half effective concentrations for antisera inhibition of 2 degraded PnPS6As were in the same order of magnitude as the untreated PnPS6A, indicating no antigenicity change in degraded PnPS6A. ¹H-NMR analysis showed that the structures of 2 degraded PnPS6A were consistent with that of untreaded PnPS6A.

Both degradation methods can reduce the relative molecular weight of PnPS6A, and don’t affect PnPS6A structure and antigenicity.

Streptococcus pneumoniae; Polysaccharides, bacterial; Hydrogen peroxide; High pressure homogenization