ABSTRACT
Objective To dynamically analyze the antibodies with regard to in vitro serum bacteri-cidal activity and the quantity of IgG in healthy adults received one dose of immunization with ACYW 135 me-ningococcal polysaccharide vaccine .To investigate the term of protection with polysaccharide vaccine and the correlation between bactericidal titer and IgG concentration .Methods Twenty healthy adults were given one dose of immunization with quadrivalent meningococcal polysaccharide vaccine .Serum samples were col-lected before and after vaccination at specific time points .Test for serum bactericidal activity ( SBA ) and quantitative ELISA were performed to detect bactericidal titers and IgG concentrations in serum samples .Re-sults Certain levels of antibodies against capsular polysaccharides of serogroup A , C, Y and W135 strains had already existed prior to immunization .Moreover, bactericidal titers against serogroup A , Y and W135 strains except serogroup C strain were relatively high .Specific IgG concentrations and bactericidal titers for all serogroup stains were significantly increased on day 15 after vaccination (P0.05).However, a close correla-tion was demonstrated between GMTs and GMCs of serum samples (r>0.7, P<0.05).Conclusion The geometric mean titers ( GMTs) and geometric mean concentrations ( GMCs) of serum samples collected be-fore and after vaccination at different time points were reliable and consistent parameters for the evaluation of vaccine .The term of protection of quadivalent meningococcal polysaccharide vaccine was about 3 years upon a single dose of immunization .
ABSTRACT
Objective To monitor and analyze the antigenicity of Streptococcus pneumonia polysac-charide, 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 re-sults 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 suc-cessfully using immunological assays as the quality control means during the preparing process of pneumococ -cal conjugates .
ABSTRACT
Objective To investigate the molecular size distribution and the structure of group B me-ningococcal capsular polysaccharides for the development of vaccines .Methods The molecular size distribution of group B meningococcal capsular polysaccharides was analyzed by chromatography on a Sepharose CL -4B col-umn.The molecular weight of repeat units were measured by matrix assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF-MS).The structural characteristics of group B meningococcal capsular polysaccharides were analyzed by nuclear magnetic resonance ( NMR) based on the chemical shift of all charac-teristic protons by using group C meningococcal capsular polysaccharides and sialic acid as the controls .Results The KD value of group B meningococcal capsular polysaccharides extracted from 15 strains were ranged from 0.60 to 0.76.The molecular weight of repeat units was 284, which was identical to the theoretical value .The group B meningococcal capsular polysaccharides were 2→8 linked homopolymers of sialic acid lacking O-acetyl groups.Conclusion The group B meningococcal capsular polysaccharides had lower molecular weights , which might result in their poor immunogenicity .The structure of group B meningococcal capsular polysaccharides could be quickly and accurately analyzed by NMR technology .