Determination of meningococcal polysaccharides by capillary zone electrophoresis

Monoclonal Antibodies Against the Capsular Polysaccharides A, C, Y, W, and X of Neisseria meningitidis: A Platform for the Quality Control of Meningococcal Vaccines

Vaccination has reduced morbidity and mortality of many diseases that previously caused devastating epidemics and deaths globally. Vaccines as a biological product may contain microorganisms or their derivatives. This aspect together with the fact that they are administered to healthy individuals (mainly children) means that approximately 70% of vaccines development time is dedicated to quality control. Monoclonal antibodies (MAbs) have become essential analytical tools for application in ELISAs, Western and Dot blotting, immunoprecipitation, and flow cytometric assays that ensure the quality control of vaccines. The aim of this work is to present a review of the methods used to obtain a platform of MAbs against Neisseria meningitidis polysaccharide antigens to use as an analytical tool for quality control of anti-meningococcal polysaccharide (Ps) vaccines. The MAbs obtained are used in five sandwich ELISAs developed for Ps quantification. The assays showed good reproducibility and repeatability, with quantitation and detection limits below 1 ng/mL. Dot Blot, as the Identity test of the Ps vaccine, was carried out to positively identify licensed and experimental vaccines. All assays described are suitable for the screening of multiple vaccine samples and could be useful for monitoring lot-to-lot consistency and stability.

A novel monoclonal antibody to Neisseria meningitidis serogroup X capsular polysaccharide and its potential use in quantitation of meningococcal vaccines

A novel murine hybridoma monoclonal antibody (MAb) was produced against the capsular polysaccharide (CP) of Neisseria meningitidis serogroup X (MenX) in order to develop a sandwich enzyme linked immunosorbent assay (ELISA) for the quantitation of the meningococcal polysaccharide. The MAb only reacted with the CP from MenX and did not react with CPs from N. meningitidis serogroups A, C, Y and W (MenA, MenC, MenY, MenW). The affinity constant (Ka) of the MAb measured by non-competitive ELISA was 7.25 × 10(7) M(-1). The application of this MAb in a sandwich ELISA was demonstrated by its ability to properly quantitate three lots of an experimental meningococcal CP-based vaccine. The MAb obtained in this work could be a valuable reagent for the detection and quantitation of future meningococcal vaccines containing MenX CP.

Bioanalysis of meningococcal vaccines

Meningococcal meningitis is feared because of the rapid onset of severe disease from mild symptoms and, therefore, is an important target for vaccine research. Five serogroups, defined by the structures of their capsular polysaccharides, are responsible for the vast majority of disease. Protection against four of these five serogroups can be obtained with polysaccharide or glycoconjugate vaccines, in which fragments of the capsular polysaccharides attached to a carrier protein generate anticarbohydrate immune responses, whilst protection against group B disease requires protein immunogens, often presented in vesicles containing outer membrane proteins. Glycoconjugate vaccines are now an established technology, but outer-membrane protein vaccines are still under development and present significant challenges. This review discusses physicochemical approaches to the characterization and quality control of these vaccines, as well as highlighting the problems and differences in vaccine design required for protection against different serogroups of the same species of pathogen.

Development and application of a rapid and efficient CZE method coupled with correction factors for determination of monosaccharide composition of acidic hetero-polysaccharides from Ephedra sinica

INTRODUCTION

Ephedrine alkaloids cannot account for all the effects of Ephedra sinica and the polysaccharides are also demonstrated to be one of the main bioactive constituents of E. sinica. However, no work has been reported on the analysis of monosaccharide composition of purified polysaccharides isolated from the stem of E. sinica.

OBJECTIVE

To develop a rapid and efficient capillary zone electrophoresis (CZE) method based on pre-column derivatisation with 1-phenyl-3-methyl-5-pyrazolone for the simultaneous determination of neutral and acidic sugars of purified polysaccharides from E. sinica.

METHODOLOGY

Three polysaccharides (ESP-A3, ESP-A4 and ESP-B4) were isolated and purified by ion exchange and gel-filtration chromatography from the stem of E. sinica. The effects of background electrolyte pH and concentration, applied voltage and temperature on the separation were investigated. Meanwhile, factors affecting the hydrolysis of ESP-B4 with sulphuric acid were investigated by changing the hydrolysis time, acid concentration and hydrolytic temperature to achieve complete hydrolysis. The standard curves coupled with correction factors were used to calculate molar ratios.

RESULTS

The optimal CZE method coupled with correction factors was successfully applied to the determination of molar ratios of three purified polysaccharides and their corresponding partial acid hydrolysis products. ESP-A3, ESP-A4 and ESP-B4 were all typical acidic hetero-polysaccharides and consisted of xylose, arabinose, glucose, rhamnose, mannose, galactose, glucuronic acid and galacturonic acid, and their corresponding molar ratios were 6.8:7.5:1.0:14.0:13.7:22.3:10.2:3.8 for ESP-A3, 1.2:4.1:1.0:5.1:1.6:17.3:3.1:2.2 for ESP-A4, and 1.0:4.5:1.0:2.0:1.0:5.5:1.5:50.0 for ESP-B4.

CONCLUSION

The results provided scientific evidence for the further study of the structure and bioactivity of complex acidic E. sinica polysaccharides.

Development and application of a capillary electrophoretic method for the composition analysis of a typical heteropolysaccharide from Codonopsis pilosula NANNF

A simple capillary electrophoretic method based on 1-phenyl-3-methyl-5-pyrazolon (PMP) derivatization has been developed for simultaneous separation and determination of nine aldoses (xylose, arabinose, glucose, rhamnose, fucose, galactose, mannose, glucuronic acid and galacturonic acid). The separation of PMP-labeled monosaccharide derivatives was carried out in uncoated capillary (48.5 cm x 75 microm i.d.) and under the selected optimum conditions of pH 11.0, 200 mM borate buffer at applied voltage 15 kV and capillary temperature 20 degrees C, the nine PMP-monosaccharides could be perfectly separated from each other within 40 min. Furthermore, the developed method was firstly applied to determine the sugar composition in the polysaccharide isolated from Chinese Codonopsis pilosula. The results showed that C. pilosula polysaccharide was a typically acidic heteropolysaccharide and was composed of arabinose, glucose, rhamnose, galactose, mannose, glucuronic acid and galacturonic acid in the molar contents of 48.1, 103.5, 16.1, 48.5, 7.5, 4.2 and 119.1 microM, respectively. The assay results were satisfactory.

Enantiomeric separation of synthetic 2,3-dihydroxy-3-phenylpropionate compounds by β-cyclodextrin-modified capillary electrophoresis

A new capillary electrophoretic method was developed for enantiomeric separation and optical impurity analysis of three synthetic 2,3-dihydroxy-3-phenylpropionate compounds using native beta-cyclodextrin (beta-CD) as chiral selector and borate as a background electrolyte. The separation was carried out in uncoated capillary (58.5 cm x 75 microm I.D., effective length 48.5 cm). The results showed that beta-CD as the chiral selector exhibited good enantioselectivity and the baseline separation was obtained at pH 9.8, 200 mM borate buffer containing 1.7% beta-CD at applied voltage 15 kV and capillary temperature 20 degrees C within 15 min. The precision of each tested compound was less than 1.0% at migration time and 5.0% in corrected peak area and the accuracy of the method was in the range of 98.7-105%. Furthermore, the developed method was successfully applied to the determination of the undesirable trace (2S,3R)-(+)-form impurity in the synthetic (2R,3S)-(-)-2,3-dihydroxy-3-phenylpropionate samples.

Chiral Separation of Synthetic Vicinal Diol Compounds by Capillary Zone Electrophoresis with Borate Buffer and .BETA.-Cyclodextrin as Buffer Additive

The investigation on capillary electrophoretic enantioseparation of six synthetic compounds containing vicinal diol groups has been undertaken to acquire the optimum conditions using native beta-cyclodextrin (beta-CD) as chiral selector and borate as a background electrolyte. The separation was carried out in an uncoated capillary (58.5 cm x 75 microm i.d., effective length 48.5 cm) and the effects of several important factors were investigated in detail. The results showed that beta-CD as a chiral selector exhibited good enantioselectivity and that the enantioseparation was greatly influenced by the structure of the diols, the borate concentration and the buffer pH. The optimum performance was obtained for the chiral vicinal diols under the conditions of 200 mM borate buffer of pH 9.8 containing 1.7% beta-CD at an applied voltage of 15 kV and a capillary temperature of 20 degrees C. Under the conditions, four diols were baseline separated with fast analysis time and the good theoretical plate numbers (above 10 x 10(4)) and favorable migration-time reproducibilities (RSDs below 3.0%) were obtained. The separation results were satisfactory.