Study on the antigenicity of Streptococcus pneumonia polysaccharide, its derivatives and conjugates by three immunological assays

Objective To monitor and analyze the antigenicity of Streptococcus pneumonia polysaccharide, its derivatives and conjugates by three immunological assays .Methods Inhibition ELISA and rate nephelometry（RN） were established for this study.Antigenicity of serotype 23F pneumococcal conjugates and their intermediates were analyzed by double immunodiffusion assay , inhibition ELISA and RN .The results derived from three assays were comparatively analyzed to evaluate the changes of antigenicity during the preparing process of serotype 23F conjugate.Results Double immunodiffusion assay, inhibition ELISA and RN were all applicable to antigenicity analysis during the process of conjugate preparation .Inhibition ELISA could quantitatively detect a slight difference of polysaccharide antigenicity during the preparing process . Conclusion The antigenicity of polysaccharide during the preparing process of pneumococcal conjugates could be analytically monitored by using three immunological assays .This study provided evidence for successfully using immunological assays as the quality control means during the preparing process of pneumococcal conjugates . Key words: Streptococcus pneumococcal conjugate ;  Inhibition ELISA ;  Antigenicity ;  Double immunodiffusion;  Rate nephelometry