Determination of saccharide content in pneumococcal polysaccharides and conjugate vaccines by GC-MSD

A simple and sensitive gas chromatographic method was designed for quantitative analysis of Streptococcus pneumoniae capsular polysaccharides, activated polysaccharides, and polysaccharide conjugates. Pneumococcal serotypes 1, 3, 4, 5, 6A, 6B, 7F, 9V, 14, 18C, 19A, 19F, and 23F polysaccharide or conjugate were subjected to methanolysis in 3N hydrochloric acid in methanol followed by re-N-acetylation and trimethylsilylation. Derivatized samples were chromatographed and detected using gas chromatography with mass selective detector. Gas chromatographic results were compared with colorimetric values with agreement of 92 to 123% over the range of all samples tested. Monosaccharides released during methanolysis included hexoses, uronic acids, 6-deoxy-hexoses, amino sugars, and alditols. Quantitative recovery of monosaccharides was achieved for all serotypes by the use of a single methanolysis, derivatization, and chromatography procedure. Response factors generated from authentic monosaccharide standards were used for quantitation of pneumococcal polysaccharides and conjugates with confirmation of peak assignments by retention time and mass spectral analysis. This method allows saccharide quantitation in multivalent pneumococcal vaccine intermediates and final drug products with low-level detection (10 pg) and peak purity.     

Use of acid,alkali and enzymes for the extraction of nucleic acids from pollen

Various methods for extracting nucleic acids from pollen were tested to find a suitable procedure for obtaining a pure preparation of nucleic acids uncontaminated by polysaccharides and polyphosphates without the use of ion exchangers. Extraction was carried out with perchloric acid, potassium hydroxide, ribonuclease and deoxyribonuclease, sodium tetraborate, and combinations of these. In all fractions, residues of precipitates and residues of extracted pollen matter, the quantity of RNA, DNA, proteins and concomitants,i.e. Polysaccharides and polyphosphates, was determined. The purity of preparations was checked by means of UV-spectra. The criterion of nucleic acid purity was agreement between the nucleic acid amounts calculated on the basis of measurement of absorption in UV-region, orcinol reaction and content of phosphorus. It was found that in our material only a few methods would be applicable and with great limitation, because many polysaccharides and polyphosphates appeared in nucleic acid fractions.     

Base hydrolysis of phosphodiester bonds in pneumococcal polysaccharides

A comprehensive study of the base hydrolysis of all phosphodiester bond-containing capsular polysaccharides of the 23-valent pneumococcal vaccine is described here. Capsular polysaccharides from serotypes 6B, 10A, 17F, 19A, 19F, and 20 contain a phosphodiester bond that connects the repeating units in these polysaccharides (also referred to as backbone phosphodiester bonds), and polysaccharides from serotypes 11A, 15B, 18C, and 23F contain a phosphodiester bond that links a side chain to their repeating units. Molecular weight measurements of the polysaccharides, using high performance size exclusion chromatography with tandem multiangle laser light scattering and refractive index detection, was used to evaluate the kinetics of hydrolysis. The measurement of molecular weight provides a high degree of sensitivity in the case of small extents of reaction, thus allowing reliable measurements of the kinetics over short times. Pseudo-first-order rate constants for these polysaccharides were estimated using a simple model that accounts for the polydispersity of the starting sample. It was found that the relative order of backbone phosphodiester bond instability due to base hydrolysis was 19A > 10A > 19F > 6B > 17F, 20. Degradation of side-chain phosphodiester bonds was not observed, although the high degree of sensitivity in measurements is lost in this case, due to the low contribution of the side chains to the total polysaccharide molecular weight. In comparison with literature data on pneumococcal polysaccharide 6A, 19A was found to be the more labile, and hence appears to be the most labile pneumococcal polysaccharide studied to date. The rate of hydrolysis increased at higher pH and in the presence of divalent cation, but the extent was lower than expected based on similar data on RNA. Finally, the differences in the phosphodiester bond stabilities were analyzed by considering stereochemical factors in these polysaccharides. These results also provide a framework for evaluation of molecular integrity of phosphodiester-bond-containing polysaccharides in different solution conditions.     

Novel vaccine strategies with protein antigens of Streptococcus pneumoniae

Infections caused by Streptococcus pneumoniae (pneumococcus) are a major cause of mortality throughout the world. This organism is primarily a commensal in the upper respiratory tract of humans, but can cause pneumonia in high-risk persons and disseminate from the lungs by invasion of the bloodstream. Currently, prevention of pneumococcal infections is by immunization with vaccines which contain capsular polysaccharides from the most common serotypes causing invasive disease. However, there are more than 90 antigenically distinct serotypes and there is concern that serotypes not included in the vaccines may become more prevalent in the face of continued use of polysaccharide vaccines. Also, certain high-risk groups have poor immunological responses to some of the polysaccharides in the vaccine formulations. Protein antigens that are conserved across all capsular serotypes would induce more effective and durable humoral immune responses and could potentially protect against all clinically relevant pneumococcal capsular types. This review provides a summary of work on pneumococcal proteins that are being investigated as components for future generations of improved pneumococcal vaccines.     

Effect of vaccination against pneumococcal infection in children with type 1 diabetes mellitus

Vaccination with polysaccharide pneumococcal vaccine "Pneumo 23" (Sanofi Pasteur, France) was performed in 31 children with type 1 diabetes mellitus (DM1) as well as in 19 children with respiratory tract diseases (asthma, chronic pneumonia), which formed comparison group. Fourty-three unvaccinated children with DM1 were included in the control group. Dynamics of IgG levels to mixture of pneumococcal polysaccharides (PS) included in the vaccine as well as to PS of serotypes 3, 6B, 9N, 23F, and to cell wall polysaccharides of Streptococcus pneumoniae were assessed. Using ELISA method, significant increase of IgG levels to mixture of PS and to PS of pneumococcal serotype 3 was detected. Although intensity of immune response to vaccination in children with respiratory diseases was significantly higher compared to children with DM1 (mean geometric titer of antibodies, proportion of patients with high antibody titers, and with 4-fold seroconversion). Development of methods to strengthen immune response in children with DM1 vaccinated against pneumococcal infection is required.     

~1H-NMR用于肺炎链球菌荚膜多糖质量控制的尝试

纯化的6B、18C血清型肺炎链球菌荚膜多糖用生化试验和免疫学试验检测分析后再用一维氢谱核磁共振波谱(1H-NMR)法分析。生化检测其相应多糖的主要化学基团含量是否合格,免疫学检测旨在了解多糖纯化工艺是否影响了多糖的抗原活性,并间接佐证纯化多糖的生化特性是否正确。在此基础上进行1H-NMR分析,可以对纯化多糖的特性有进一步的了解。结果表明,常规的生化检测试验和免疫学检测试验并联合应用1H-NMR分析法后可更好地控制纯化肺炎链球菌荚膜多糖的质量。     

The quantitative immunochemical determination of pneumococcal and meningococcal capsular polysaccharides by light scattering rate nephelometry

A quantitative nephelometric method was used for the measurement of the individual pneumococcal, as well as meningococcal, polysaccharides in the polyvalent vaccine final containers. This method is simple, rapid, inexpensive, and provides both qualitative and quantitative analyses of the polyvalent polysaccharide vaccines. By this method the individual pneumococcal types, 1, 2, 3, 4, 6A, 7F, 8, 9N, 12F, 14, 18C, 19F, 23F and 25 polysaccharides, were found to be present at 90-114% of the manufacturer's indicated concentrations; meningococcal group A, C, Y and W135 polysaccharides were at 90-108% of the manufacturer's listed concentrations. This nephelometric method coupled with gel filtration can also be used for measurement of the molecular sizes or stability of individual polysaccharides in the final container. Pneumococcal polysaccharide types 3, 6A, 9N and 19F, used as representative types, were treated with 0.5 N hydrochloric acid. The molecular sizes for types 3 and 9 N polysaccharides were stable to acid treatment. In contrast, types 6A and 19F polysaccharides were degraded. Heating meningococcal groups A, C, Y and W135 polysaccharides at 37 degrees C for 48 h did not affect their molecular size in the polyvalent vaccine.     

Proteins of Streptococcus pneumoniae: perspectives for development of pneumococcal vaccine

Streptococcus pneumoniae cell wall and cytoplasmic proteins contribute directly to pathogenesis of pneumococcal infection. Protective effect of pneumococcal proteins such as pneumolysin (Ply), muramylamidase (LytA) and pneumococcal surface protein A (PspA). There is discussion in the literature about development of conjugared pneumococcal vaccines, which should include polysaccharides of invasive serotypes of pneumococci as well as protein antigens of this pathogen, for prevention of infections caused by S. pneumoniae. Researches suggest that such hybrid vaccines will be effective, first of all, for children < 2 years of age and elderly > 65 years old because immune response to polysaccharide vaccines either do not form at all or insufficient for prevention of pneumococcal infection.     

An Improved Method for the Isolation of Total RNA from Malva pusilla Tissues Infected with Colletotrichum gloeosporioides

A modified RNA extraction method was developed for fungal and plant tissues that has several advantages compared with existing, published methods for materials with high contents of ribonuclease, phenolics and polysaccharides. The method uses guanidinium isothiocyanate in the homogenization buffer, and then hexadecyltrimethylammonium bromide (CTAB). soluble polyvinylpyrrolidone and insoluble polyvinylpolypyrrolidone in the extraction buffer. The procedure consistently produced a high yield of relatively high purity, undegraded RNA from a variety of biological materials and should be useful for other tissues where RNases, phenolics and sticky polysaccharides are a problem.     

羊肚菌多糖研究进展

羊肚菌多糖是羊肚菌中重要的药用活性成分,对羊肚菌多糖的国内外研究概况、提取分离纯化步骤及其纯度、含量测定、结构鉴定、分析方法和免疫药理作用等作了详细介绍。     

Human memory B lymphocyte subsets fulfill distinct roles in the anti-polysaccharide and anti-protein immune response

There is controversy on the role of IgM memory and switched memory B lymphocytes in the Ab response to T cell-independent and T cell-dependent Ags. We transplanted SCID/SCID mice with human B lymphocyte subsets and immunized them with heat-inactivated Streptococcus pneumoniae or with a pneumococcal vaccine. Inactivated S. pneumoniae and soluble pneumococcal capsular polysaccharides elicited an IgM anti-polysaccharide and anti-protein Ab response from IgM memory B lymphocytes and an IgG anti-polysaccharide and anti-protein response from switched memory B lymphocytes. In addition to the IgM Ab response, IgM memory B cells elicited an IgG anti-polysaccharide and anti-protein Ab response after immunization with inactivated S. pneumoniae or soluble pneumococcal capsular polysaccharides. In conclusion, our findings provide evidence for a versatile role of IgM memory B cells in T-independent and T-dependent immune responses.     

Immobilization of pneumococcal polysaccharide vaccine on silicon oxide wafer for an acoustical biosensor.

One the most important aspects of a biosensor is related to immobilization and maintenance of specific reference compounds on sensing surfaces. A method for the immobilization of polysaccharides to a silicon oxide surface intended for Surface Acoustical Waves (SAW) sensors is described. Silicon oxide is a hydrophobic inorganic support used for the fabrication of many electronic devices. The pneumococcal polysaccharide (PPS) vaccine is immobilized via Protein A after pre-treatment of the surface with hydrochloric acid. The effects of non-specific binding are discussed. The results indicate that the immobilization of PPS via Protein A increases the sensitivity of detecting Streptococcus pneumoniae antibodies in human sera and offers greater reproducibility of response compared with ELISA methods. The principles of this technique are simple and are applicable to the immobilization of many capsular polysaccharides.     

Genetic relatedness of the Streptococcus pneumoniae capsular biosynthetic loci

Streptococcus pneumoniae (the pneumococcus) produces 1 of 91 capsular polysaccharides (CPS) that define the serotype. The cps loci of 88 pneumococcal serotypes whose CPS is synthesized by the Wzy-dependent pathway were compared with each other and with additional streptococcal polysaccharide biosynthetic loci and were clustered according to the proportion of shared homology groups (HGs), weighted for the sequence similarities between the genes encoding the shared HGs. The cps loci of the 88 pneumococcal serotypes were distributed into eight major clusters and 21 subclusters. All serotypes within the same serogroup fell into the same major cluster, but in six cases, serotypes within the same serogroup were in different subclusters and, conversely, nine subclusters included completely different serotypes. The closely related cps loci within a subcluster were compared to the known CPS structures to relate gene content to structure. The Streptococcus oralis and Streptococcus mitis polysaccharide biosynthetic loci clustered within the pneumococcal cps loci and were in a subcluster that also included the cps locus of pneumococcal serotype 21, whereas the Streptococcus agalactiae cps loci formed a single cluster that was not closely related to any of the pneumococcal cps clusters.     

Pneumococcal virulence factors: structure and function.

The overall goal for this review is to summarize the current body of knowledge about the structure and function of major known antigens of Streptococcus pneumoniae, a major gram-positive bacterial pathogen of humans. This information is then related to the role of these proteins in pneumococcal pathogenesis and in the development of new vaccines and/or other antimicrobial agents. S. pneumoniae is the most common cause of fatal community-acquired pneumonia in the elderly and is also one of the most common causes of middle ear infections and meningitis in children. The present vaccine for the pneumococcus consists of a mixture of 23 different capsular polysaccharides. While this vaccine is very effective in young adults, who are normally at low risk of serious disease, it is only about 60% effective in the elderly. In children younger than 2 years the vaccine is ineffective and is not recommended due to the inability of this age group to mount an antibody response to the pneumococcal polysaccharides. Antimicrobial drugs such as penicillin have diminished the risk from pneumococcal disease. Several pneumococcal proteins including pneumococcal surface proteins A and C, hyaluronate lyase, pneumolysin, autolysin, pneumococcal surface antigen A, choline binding protein A, and two neuraminidase enzymes are being investigated as potential vaccine or drug targets. Essentially all of these antigens have been or are being investigated on a structural level in addition to being characterized biochemically. Recently, three-dimensional structures for hyaluronate lyase and pneumococcal surface antigen A became available from X-ray crystallography determinations. Also, modeling studies based on biophysical measurements provided more information about the structures of pneumolysin and pneumococcal surface protein A. Structural and biochemical studies of these pneumococcal virulence factors have facilitated the development of novel antibiotics or protein antigen-based vaccines as an alternative to polysaccharide-based vaccines for the treatment of pneumococcal disease.     

Pneumococcal Virulence Factors: Structure and Function

The overall goal for this review is to summarize the current body of knowledge about the structure and function of major known antigens of Streptococcus pneumoniae, a major gram-positive bacterial pathogen of humans. This information is then related to the role of these proteins in pneumococcal pathogenesis and in the development of new vaccines and/or other antimicrobial agents. S. pneumoniae is the most common cause of fatal community-acquired pneumonia in the elderly and is also one of the most common causes of middle ear infections and meningitis in children. The present vaccine for the pneumococcus consists of a mixture of 23 different capsular polysaccharides. While this vaccine is very effective in young adults, who are normally at low risk of serious disease, it is only about 60% effective in the elderly. In children younger than 2 years the vaccine is ineffective and is not recommended due to the inability of this age group to mount an antibody response to the pneumococcal polysaccharides. Antimicrobial drugs such as penicillin have diminished the risk from pneumococcal disease. Several pneumococcal proteins including pneumococcal surface proteins A and C, hyaluronate lyase, pneumolysin, autolysin, pneumococcal surface antigen A, choline binding protein A, and two neuraminidase enzymes are being investigated as potential vaccine or drug targets. Essentially all of these antigens have been or are being investigated on a structural level in addition to being characterized biochemically. Recently, three-dimensional structures for hyaluronate lyase and pneumococcal surface antigen A became available from X-ray crystallography determinations. Also, modeling studies based on biophysical measurements provided more information about the structures of pneumolysin and pneumococcal surface protein A. Structural and biochemical studies of these pneumococcal virulence factors have facilitated the development of novel antibiotics or protein antigen-based vaccines as an alternative to polysaccharide-based vaccines for the treatment of pneumococcal disease.     

Development and validation of an NMR-based identity assay for bacterial polysaccharides

A method utilizing NMR spectroscopy has been developed to confirm the identity of bacterial polysaccharides used to formulate a polyvalent pneumococcal polysaccharide vaccine. The method is based on 600 MHz proton NMR spectra of individual serotype-specific polysaccharides. A portion of the anomeric region of each spectrum (5.89 to 4.64 ppm) is compared to spectra generated for designated reference samples for each polysaccharide of interest. The selected region offers a spectral window that is unique to a given polysaccharide and is sensitive to any structural alteration of the repeating units. The similarity of any two spectral profiles is evaluated using a correlation coefficient (rho), where rho >/= 0.95 between a sample and reference profile indicates a positive identification of the sample polysaccharide. This method has been shown to be extremely selective in its ability to discriminate between serotype-specific polysaccharides, some of which differ by no more than a single glycosidic linkage. Furthermore, the method is rapid and does not require extensive sample manipulations or pretreatments. The method was validated as a qualitative identity assay and will be incorporated into routine quality control testing of polysaccharide powders to be used in preparation of the polyvalent pneumococcal vaccine PNEUMOVAX 23. The specificity and reproducibility of the NMR-based identity assay is superior to the currently used colorimetric assays and can be readily adapted for use with other bacterial polysaccharide preparations as well.     

Pneumococcal surface protein A and new approaches for pneumococcal vaccine development

The problem of pneumococcal infections is pressing for the whole world. Existing vaccines based only on pneumococci polysaccharide antigens or polysaccharide antigens and diphtherial anatoxin are not capable of protecting from all serotypes of the microorganism. Reasonability of creation of pneumococcal vaccine based on surface proteins of Streptococcus pneumoniae is discussed in the literature. One of such key pneumococcal proteins is pneumococcal surface protein A (PSPA), because it is detected in all the S. pneumoniae strains, has cross activity and switches B-cell immune response to T-cell. Currently the development of conjugated vaccine based on surface proteins and capsule polysaccharides of pneumococcus seems promising.     

Purification and characterization of macrolide 2''-phosphotransferase type II from a strain of Escherichia coli highly resistant to macrolide antibiotics

Hyperimmune and high-titered polyclonal pneumococcal antisera, specific for cross-reactive types within groups, were produced in adult rabbits. Purified capsular polysaccharide was injected intravenously into adult rabbits. One week later, these rabbits were given multiple intravenous injections of formalin-inactivated pneumococci of the cross-reactive type by an established method. Each of the resultant antisera were specific for the cross-reactive type indicating that the previous injection of the polysaccharide had induced epitope-specific tolerance. This method was successful for production of antisera against pneumococcal types 6A, 6B, 9N, 9V, 19F and 19A. Polyclonal rabbit pneumococcal antisera have some advantages over murine monoclonal antibodies for serologic studies and this method should be applicable for producing type-specific antibodies to cross-reactive polysaccharides of clinical interest. Further, this method is simpler and generally produces higher titered monovalent (factor) reagents than absorbed antisera.     

Type-specific enzyme immunoassay for detection of pneumococcal capsular polysaccharide antigens in nasopharyngeal specimens

We developed a new competitive EIA method for the demonstration of pneumococcal capsular polysaccharides from respiratory samples. The pediatric types 4, 6B, 9V, 14, 18C, 19F and 23F were selected for this study, because these capsular polysaccharides were included in the first heptavalent pneumococcal conjugate vaccines, which were used in the Finnish Otitis Media Vaccine Trial. Sensitivity of the EIA tests for purified polysaccharide antigens varied between 5 and 100 ng/ml, depending on the type. The assays performed well in 100 nasopharyngeal samples (NPS) samples processed through an enrichment culture, with an almost 100% sensitivity compared with routine culture. The method appeared type-specific, except that EIA for 6B capsule also detected 6A. The method is applicable for type-specific identification of pneumococcus in carriage studies.     

Experimental human pneumococcal carriage models for vaccine research

Pneumococcal conjugate vaccines have had unprecedented success in controlling vaccine-type invasive pneumococcal disease. As serotype replacement and the complexity of designing vaccines to multiple capsular polysaccharides ultimately pose a threat to these vaccines, the development of alternative protein vaccines is important. Protein vaccines offer the promise of extended serotype coverage, reduced cost, and improved protection against otitis media and pneumococcal pneumonia. As placebo-controlled trials are not currently ethically justifiable, human pneumococcal challenge models using prevention of carriage as a test endpoint offer an attractive link between preclinical studies and clinical efficacy trials. Experimental human pneumococcal carriage studies offer a means of describing mechanisms of protection against carriage and a clinical tool to choose between vaccine candidates.