9V型肺炎链球菌荚膜多糖降解研究

Research on Degradation of Type 9V Pneumococcal Capsular Polysaccharide

肺炎链球菌荚膜多糖分子质量较大,在制备结合疫苗的过程会有诸多不便,如溶液黏度大、结合过程易过度交联形成凝胶、不易于过滤以及纯化,而荚膜多糖分子片段化是降低其分子质量的有效途径。文章选取了酸水解和超声降解两种方法分别处理9V型肺炎链球菌荚膜多糖。利用不同相对分子质量的葡聚糖在HPLC上的保留时间绘制标准曲线,计算处理后多糖相对分子质量,并通过核磁共振检测结构稳定性,免疫双扩散检测抗原性。实验结果表明,在适宜的条件下,酸水解和超声降解均能有效降低肺炎链球菌荚膜多糖分子质量,减少重复单元,保留重复单元内部结构,保留时间从5.7 min延长到8.25 min,相对分子质量约为580 k。但是酸水解方法破坏了多糖的抗原完整性,而超声降解可以良好保持。

In the process of the preparation of conjugate vaccines, there will be a lot of inconvenience due to the high molecularweight of Streptococcus pneumoniae capsular polysaccharide, for example, the viscosity of the solution is high, the binding process is easy to over cross-link to form a gel and it is difficult to be filtered and purified. The fragmentation of the capsular polysaccharide molecules can effectively reduce its molecular weight. Acid hydrolysis and ultrasonic degradation are selected to reduce the molecular weight of type 9V pneumonia capsular macromolecules polysaccharide. Using different relative molecular weight dextrans and their retention time on HPLC, the standard curve to calculate the relative molecular weight can be drawn. Structural stability can be detected by NMR and antigenicity can be detected by double immunodiffusion. The results showed that the acid hydrolysis and the ultrasonic degradation can effectively decrease the relative molecular weight of pneumonia polysaccharides by reducing duplication units. Retention time increased from 5.7 min to 8.25 min and Mr≈580 ku. Acidic hydrolysis method destroyed the antigenicity of the polysaccharide while ultrasonic degradation could reserve antigenicity.