Harold J. Jennings

Capsular polysaccharides as human vaccines.

Publisher Summary This chapter discusses the use of capsular polysaccharides as human vaccines. Vaccination has proved to be one of the most useful scientific developments in the control and eradication of human disease. Early vaccines were based on whole-organism preparations or on protein toxins isolated from different bacteria. Although these methods are still effective, the discovery of a “specific soluble substance” secreted by pneumococcal organisms during growth, and the immunogenicity of these substances (capsular polysaccharides) opened the door to a new and important development in vaccine technology. Current interest in the capsular polysaccharides has evolved simultaneously with the resurgence of interest in the prophylaxis of human, bacterial disease because of their potential as good immunogens in providing protection against bacterial infections. This chapter outlines the development of bacterial-polysaccharide vaccines and relates the structures of these capsular polysaccharides to their many roles in the immune response to bacterial infection. Because bacterial disease is host-related, the chapter focuses only on the bacterial polysaccharides associated with human disease, particularly those capsular polysaccharides that are currently being used as human vaccines, or those having some immediate potential as human vaccines.

Biochemical Engineering of Surface α2–8 Polysialic Acid for Immunotargeting Tumor Cells

To target tumor cells for immunotherapy, we evaluated the feasibility of altering the epitopes on the surface polysialic acid of tumor cells. A precursor (N-propionylmannosamine), when incubated with leukemic cells, RBL-2H3 and RMA, resulted in substitution of theN-acetyl groups of surface α2–8 polysialic acid withN-propionyl groups. Expression of the altered α2–8N-propionylpolysialic acid on the surface of tumor cells induced their susceptibility to cell death mediated by monoclonal antibody 13D9 (mAb 13D9), which specifically recognizes α2–8N-propionylated polysialic acid. The expression of α2–8 N-propionylated polysialic acid and the lysis of tumor cells by antibody-dependent cytotoxicity depended on the time and dose of incorporation of N-propionylated mannosamine. In vivo, mAb 13D9 effectively controlled metastasis of leukemic cells RMA when mice were administered the precursor N-propionylated mannosamine.

Structural and Immunochemical Characterization of the Type VIII Group B Streptococcus Capsular Polysaccharide

The type VIII capsular polysaccharide has been isolated and purified from a newly described strain of group B Streptococcus which is a leading cause of sepsis and neonatal meningitis in Japan. The polysaccharide contains D-glucose, D-galactose, L-rhamnose, and sialic acid in the molar ratio 1:1:1:1. By means of high resolution 1H nuclear magnetic resonance (1H NMR), C NMR, and homo- and heterocorrelated NMR, the repeating unit structure of the type VIII polysaccharide was delineated as the following, Enzymatic studies established this polysaccharide as the first from which sialic acid, linked to a branched β-D-galactopyranosyl residue, is known to be removed by bacterial neuraminidase.

Vaccination of Small Cell Lung Cancer Patients with Polysialic Acid or N-Propionylated Polysialic Acid Conjugated to Keyhole Limpet Hemocyanin

Purpose: Long chain polysialic acid (polySA) is a side chain on embryonal neural cell adhesion molecules that, in the adult, is largely restricted to small cell lung cancer (SCLC). Long chains of polySA are also expressed on group B meningococcus. In this clinical trial, we aimed to elicit an immune response against polysialic acid to target clinically inapparent residual disease in patients with SCLC who had successfully completed initial therapy. Experimental Design: Patients were vaccinated with either 30 μg unmodified polySA or N-propionylated-polySA (NP-polySA), conjugated to keyhole limpet hemocyanin (KLH) and mixed with 100 μg of immunological adjuvant QS-21 at weeks 1, 2, 3, 4, 8, and 16. Results: Of the 5 evaluable patients vaccinated with unmodified polySA, only 1 mounted an IgM antibody response to polySA. On the other hand, all 6 of the patients vaccinated with NP-polySA produced IgM antibodies to NP-polySA and these cross-reacted with unmodified polySA in all but 1 case. IgG antibodies to NP-polySA were observed in 5 of the patients, but these did not cross-react with polySA. The presence of IgM antibodies reactive with SCLC cell lines was confirmed in this group by flow cytometry. Complement-dependent lysis of tumor cells could not be demonstrated. However, postimmunization sera induced significant bactericidal activity against group B meningococcus when combined with rabbit complement. Conclusions: Vaccination with NP-polySA-KLH, but not polySA-KLH, resulted in a consistent high titer antibody response. We are now conducting a de-escalation dosing study with NP-polySA-KLH to better assess the immunogenicity, toxicities, and optimal dose of this vaccine. We plan to incorporate this vaccine as a component of a polyvalent vaccine with GM2, fucosylated GM1, and Globo H to target SCLC.

A Simplified, One-Pot Preparation of Acetobromosugars from Reducing Sugars

ABSTRACT Acetobromoglycoses continue to be important as glycosyl donors in the synthesis of simple glycosides as well as complex oligosaccharides. From reducing sugars they are usually prepared via their peracetates in two steps. In the first step, sugars are converted to their peracetates using pyridine and acetic anhydride1,2 and the acetates are then converted in a second step to acetobromosugars using a solution of hydrogen bromide in glacial acetic acid(HBr/HOAc).2 Although not in use very often Redemann and Niemann3 as well as Lemieux4 have described one-pot methods for the preparation of acetobromoglucose wherein the reducing sugar is first treated with acetic anhydride in the presence of sulfuric acid3 or perchloric acid4 respectively to afford the peracetate. Direct conversion of the peracetate to its 1-bromo-derivative, in yields ranging from 80-87%, was then achieved by either treating the solution of the peracetate with gaseous HBr3 or with bromine in the presence of red phosphorus.4 In anothe...

Structure, conformation and immunology of sialic acid-containing polysaccharides of human pathogenic bacteria

Capsular polysaccharides of types Ia, Ib, II and IIIGroup B Streptococcus and groups B and C Neisseria meni ngi ti di S contai n termi nal si al i c aci d i n di ffe rent molecular environments. Experimentation has identified sialic acid as an important factor in the virulence of these organisms and in the human antibody response to their capsular polysacchari de anti gens . Al though termi nal si al i c aci d i s not normally immunogenic it controls the determinants which are responsible for the production of protective antibodies. Using immunological and NMR spectroscopic techniques on the native and specifically modified polysaccharides, a number of these si al I c aci d-control 1 ed determi nants have been identified and located. These determinants are only formed in structures which can accommodate long—range interactions between sialic acid and other remote glycosyl residues. The carboxylate group of si ali c acid is essential for these interactions to occur.

Structural determination of the capsular polysaccharide of Streptococcuspneumoniae type-19 (19F)

The structure of the Pneumococcus type 19A (57) capsular polysaccharide has been reinvestigated by using methylation analysis and n.m.r. spectroscopy. It is composed of residues of 2-acetamido-2-deoxy-D-mannose, D-glucose, L-rhamnose, and phosphate in the molar ratios of 1:1:1:1. The polysaccharide is linear, and is composed of these components in a repeating unit of the following structure. ---- 4)-beta-D-ManpNAc-(1 ---- 4)-alpha-D-Glcp-(1 ---- 3)-alpha-L- Rhap-(1-PO4-) ---- The type 19A polysaccharide (Na+ salt) was depolymerized by heating it in water at 100 degrees, conditions that also hydrolyzed the newly formed phosphoric monoesters.

A new, stereoselective synthesis of methyl 1,2-trans-1-thioglycosides

Abstract Per-0-acetylated glycopyranoses were converted by methylthiotrimethylsilane in the presence of boron trifluoride or trimethylsilyl trifluoromethanesulfonate to the corresponding methyl 1,2- trans -1-thioglycopyranosides in a highly stereoselective process.

Conformations of Ammonium 3-Deoxy-D-manno-2-octulosonate (KDO) and Methyl α- and β-Ketopyranosides of KDO: X-Ray Structure and 1H NMR Analyses

Abstract Ammonium 3-deoxy-D-manno-2-octulosonate monohydrate (KDO) crystallizes in the orthorhombic space group P212121, and the cell dimensions are a - 6.9700(4)A, b = 7.7230(4) A, c = 23.4067 (12) A. X-ray intensity data were measured on a diffractometer, and the structure was determined by direct methods. Least-squares refinement, which included all hydrogen atoms, converged at R = 0.034 for 1526 observed reflections. The pyranose ring exists in an almost perfect 5C2 (D) chair conformation. The COO-, 4-OH and 6-CHOHCH2OH groups are In equatorial orientation, while the 2-OH and 5-OH groups are axial. The solution conformations of the ammonium salts of methyl α- and β-ketopyranosides of KDO were determined by high-resolution 1H NMR spectroscopy. The conformation of the ethylene glycol side chain in the α-methyl glycopyranoside of KDO was found to be indistinguishable from that in the solid state. However, the solution conformation of the side chain is different in the β-anomer, possibly indicative of an ...

Structural basis of the Neisseria meningitidis immunotypes including the L4 and L7 immunotypes

The application of high-resolution 1H, 13C and 31P NMR and MS analyses to the oligosaccharide moieties of the L4 and L7 immunotypes of Neisseria meningitidis revealed that they had the following structures: [formula: see text] The fact that the L7 LPS is not sialylated at O-3 of its terminal beta-D-galactopyranosyl residue implies that it is a mutant strain unable to endogenously sialylate its lacto-N-neotetraose antenna. With the structural elucidation of the L4 and L7 LPS immunotypes, a more comprehensive structural profile of the LPS involved in disease isolates can now be assembled. This provides valuable insights into the structural basis of the N. meningitidis immunotyping system which could be of use in formulating an LPS-based vaccine against meningococcal meningitis.