Use of a booster dose of capsular group C meningococcal glycoconjugate vaccine to demonstrate immunologic memory in children primed with one or two vaccine doses in infancy

BackgroundUse of a polysaccharide vaccine challenge to demonstrate immunologic memory after priming with capsular group C meningococcal conjugate vaccines (MenCC) risks induction of immunologic hyporesponsiveness. For this reason, MenCC vaccines are now used as probes of immunologic memory, however, no studies have demonstrated their ability to distinguish primed from unprimed children.MethodsThis study was part of a randomised controlled trial investigating the immunogenicity of a booster dose of the combined Haemophilus influenzae type b and MenC-tetanus toxoid vaccine (Hib-MenC-TT) in infants receiving reduced dose MenCC vaccine priming schedules (one MenC-CRM/MenC-TT or two MenC-CRM vaccine doses) compared with an unprimed group. Antibody kinetics were studied in a subset of 269 children by measuring changes in the MenC serum bactericidal antibody, using rabbit complement, (MenC rSBA) titres and MenC specific IgG memory B-cells before and at 6 and 28 days following the 12 month booster vaccination.ResultsAt 6 days after the 12 month MenCC vaccine, the rise in MenC rSBA titres and MenC specific IgG memory B-cells of the primed groups were significantly higher than the infant MenCC naïve group. Participants primed with one MenC-TT dose had the highest increase in MenC rSBA titres compared with all other groups. The MenC rSBA titres at the 28th compared with the 6th day after boosting was significantly higher in those primed with a single MenC-TT/MenC-CRM vaccine in infancy compared with those who were not primed or who were primed with two doses of the MenC-CRM vaccine.ConclusionImmunologic memory can be demonstrated by a MenCC booster vaccination but is affected by the type and number of MenCC doses used for infant priming. The MenC rSBA responses can be used to demonstrate successful immunologic priming.     

Nitrocellulose-based assays for the detection of glycolipids and other antigens: mechanism of binding to nitrocellulose

A variety of simple and rapid assays for the detection of glycolipids by direct binding to nitrocellulose or binding to antibody-coated nitrocellulose, and probing with monoclonal antibodies are described. These include dot-blotting, charge shift electrophoresis and electroblotting. It is shown that the direct binding of the Leishmania major glycolipid to nitrocellulose is dependent on its lipid moiety, indicating that the mechanism of binding is probably via hydrophobic interactions. However, the L. major glycolipid from which the lipid moiety has been removed can still be detected by blotting onto nitrocellulose precoated with a monoclonal antibody directed to a carbohydrate epitope. The general approach of blotting onto antibody-coated nitrocellulose thus extends the usefulness of these techniques to cases in which the antigen to be detected does not bind directly to nitrocellulose.     

Lectin histochemical study of cholagiocarcinoma arising from stone-bearing intrahepatic bile duct

With the purpose of studying changes in the expression of glycoconjugate structures in cholangiocarcinoma and the nonneoplastic epithelium of stone-bearing intraheptic bile ducts, a panel of 12 biotinylated lectins were used on formalin-fixed, paraffin-embedded tissue sections from 13 patients who had undergone surgical resection of cholangiocarcinoma and on nonneoplastic stone-bearing intrahepatic bile ducts from 10 patients. Of the 13 patients with cholangiocarcinoma 10 had hepatolithiasis and 3 did not. Among the 12 lectins, only wheat germ agglutinin (WGA) stained the cholangiocarcinoma and nonneoplastic epithelium of the stone-bearing intrahepatic bile duct. all nonneoplastic epithelia of stone-bearing intrahepatic bile ducts were stained heavily and homogenously by WGA, the GlcNAC-specific lectin. The high columnar epithelium of both intramural and extramural glands was stained in the supranuclear region, while the low columnar epithelium of serous acini was stained in the whole cytoplasm. In the well-differentiated cholangiocarcinoma, the WGA weakly stained the neoplastic cells in the supranuclear region, while it stained the luminal cytoplasmic membrane heavily. In the poorly-differentiated chollangiocarcinoma, about 50% of cancer cells were stained with WGA. The carcinoma was moderately stained in the cytoplasm. Less reactivity and a lower percentage of cells stained with lectin were found in cholangiocarcinomas when compared to nonneoplastic epithelial. This led us to conclude that there is a dramatic decrease in lectin-binding carbohydrate structures associated with cholangiocarcinoma progression.     

Phase I and pharmacokinetic study of Bay 38-3441, a camptothecin glycoconjugate, administered as a 30-minute infusion daily for five days every 3 weeks in patients with advanced solid malignancies

Bay 38-3441 is a camptothecin glycoconjugate which stabilizes the active lactone form of camptothecin and allows selective uptake into tumor cells. We conducted a phase I study of Bay 38-3441 administered as a 30-minute infusion daily for five consecutive days every 21 days. Thirty-one patients were enrolled at 8 dose levels. Most common nonhematologic side effects were diarrhea (29%), vomiting (19%), nausea (19%), lethargy (13%), and abdominal pain (10%). The main hematologic toxicity was prolonged neutropenia. Nine patients had a best response of stable disease with a median duration of 2.7 months (range: 2.3–20.6 months). The study was closed without reaching the maximum tolerated dose (MTD) due to excessive toxicity in a companion trial resulting in termination of development of this agent. Bay 38-3441 was well tolerated in this study with granulocytopenia as the main hematologic toxicity. This study showed that glycoconjugation is a feasible delivery technique for camptothecin.The study medication, Bay 43-9006 and a partial funding for the study were provided by Bayer Inc.     

Effectiveness of meningococcal serogroup C vaccine programmes

Since the introduction of monovalent meningococcal serogroup C (MenC) glycoconjugate (MCC) vaccines and the implementation of national vaccination programmes, the incidence of MenC disease has declined markedly as a result of effective short-term vaccination and reduction in acquisition of MenC carriage leading to herd protection. Monovalent and quadrivalent conjugate vaccines are commonly used vaccines to provide protection against MenC disease worldwide. Studies have demonstrated that MCC vaccination confers protection in infancy (0–12 months) from the first dose but this is only short-term. NeisVac-C^® has the greatest longevity of the currently licensed MCC vaccines in terms of antibody persistence, however antibody levels have been found to fall rapidly after early infant vaccination with two doses of all MCC vaccines – necessitating a booster at ∼12 months. In toddlers, only one dose of the MCC vaccine is required for routine immunization. If herd protection wanes following catch-up campaigns, many children may become vulnerable to infection. This has led many to question whether an adolescent booster is also required.     

肿瘤糖疫苗的研究进展

肿瘤细胞表面异常表达的糖抗原为肿瘤糖疫苗的研究提供了合适的靶标, 然而由于这些糖抗原的免疫原性较差, 这又给糖疫苗的发展带来了很大的困难。本文概述了近年来科学工作者在提高肿瘤糖疫苗的免疫原性方面所做的努力: 半合成的肿瘤糖疫苗将糖抗原与蛋白共价连接, 已经有很多疫苗进入了临床试验; 随后发展的全合成的肿瘤糖疫苗将糖抗原、T细胞表位和内源性佐剂共价连接, 使疫苗的结构和组成更加确定; 基于细胞代谢糖工程的肿瘤糖疫苗将非天然的糖疫苗与细胞表面代谢糖工程相结合, 得到了强烈的免疫应答; 某些基于天然糖抗原结构修饰的疫苗产生的抗体也可以与天然糖抗原发生交叉反应, 这为肿瘤糖疫苗的发展提供了新的方向。     

Recombinant Clostridium difficile Toxin Fragments as Carrier Protein for PSII Surface Polysaccharide Preserve Their Neutralizing Activity

Clostridium difficile is a Gram-positive bacterium and is the most commonly diagnosed cause of hospital-associated and antimicrobial-associated diarrhea. Despite the emergence of epidemic C. difficile strains having led to an increase in the incidence of the disease, a vaccine against this pathogen is not currently available. C. difficile strains produce two main toxins (TcdA and TcdB) and express three highly complex cell-surface polysaccharides (PSI, PSII and PSIII). PSII is the more abundantly expressed by most C. difficile ribotypes offering the opportunity of the development of a carbohydrate-based vaccine. In this paper, we evaluate the efficacy, in naive mice model, of PSII glycoconjugates where recombinant toxins A and B fragments (TcdA_B2 and TcdB_GT respectively) have been used as carriers. Both glycoconjugates elicited IgG titers anti-PSII although only the TcdB_GT conjugate induced a response comparable to that obtained with CRM₁₉₇. Moreover, TcdA_B2 and TcdB_GT conjugated to PSII retained the ability to elicit IgG with neutralizing activity against the respective toxins. These results are a crucial proof of concept for the development of glycoconjugate vaccines against C. difficile infection (CDI) that combine different C. difficile antigens to potentially prevent bacterial colonization of the gut and neutralize toxin activity.     

Synthesis,characterization, and immunogenicity in mice of Shigella sonnei O-specific oligosaccharide-core-protein conjugates

Shigellosis, an enteric disease, is on the World Health Organization''s priority prevention list. In one study, the Shigella sonnei O-specific polysaccharide (O-SP)-protein conjugate showed 72% protection against disease in Israeli army recruits exposed to high rates (8–14%) of infection. The protection was related to vaccine-induced IgG anti-O-SP levels. Synthetic oligosaccharides of Shigella dysenteriae type 1, bound by their reducing ends to a carrier protein (“sun”-type configuration), induced significantly higher antibody levels than the native O-SP bound to protein by multiple-point attachments (“lattice”-type configuration). Attempts to synthesize the S. sonnei O-SP based oligosaccharides were not successful. Here, we describe the isolation, characterization, and conjugation of low-molecular-mass O-SP-core (O-SPC) fragments. The O-SPC fragments were bound by their reducing ends similar to the preparation of the synthetic S. dysenteriae type 1 conjugates. The O-SPC conjugates used oxime linkages between the terminal Kdo residues at the reducing ends of the S. sonnei saccharides and aminooxy linkers bound to BSA or a recombinant diphtheria toxin. The coupling reaction was carried out at a neutral pH and room temperature. IgG antibody levels induced in young outbred mice by the S. sonnei O-SPC conjugates were significantly higher then those elicited by the O-SP conjugates. Accordingly, we propose to evaluate clinically these conjugates.     

Coatings of Low-Density Lipoprotein and Synthetic Glycoconjugates as Substrata for Hepatocytes

Asialoglycoprotein (ASGP) receptors expressed on rat hepatocytes interact with glycoproteins containing galactose or N-acetylgalactosamine residues at the nonreducing termini of oligosaccharide chains to mediate endocytosis, and cholesterol transport protein with apolipoprotein B (LDL, low-density lipoprotein) in plasma interacts with LDL receptors and heparinoids in the extracellular matrix. We developed novel techniques to prepare galactose- and LDL-immobilized culture plates, using galactose-tagged polystyrene (galactose-carrying polystyrene [GalCPS]: N-p-vinylbenzyl-O-β-D-galactopyranosyl-[1→4]-D-gluconamide) and poly(2-acrylamide-2-methyl-1-propanesulfonate) (PAPS), respectively. Hepatocytes adhered well to plates coated with either GalCPS or LDL, and therefore the GalCPS- and LDL-coated plates were examined as specific substrata for culturing hepatocytes. These cultures promoted the formation of three-dimensional, multicellular aggregates with regulation of excess proliferation of non-parenchymal cells. Furthermore, the LDL coating resulted in higher albumin synthesis and an identical level of lactate dehydrogenase (LDH) compared with cells cultured on collagen- and GalCPS-coated plates. Thus, the two culture systems described here, and especially the LDL-coated plates, have potential for the development of a hybrid artificial liver.