CSDB: Search results

Eleven serotypes of capsular polysaccharide from Staphylococcus aureus have been reported. We have previously cloned a cluster of type 1 capsule (cap1) genes responsible for type 1 capsular polysaccharide biosynthesis in S. aureus M. To clone the type 8 capsule (cap8) genes, a plasmid library of type 8 strain Becker was screened with a labelled DNA fragment containing the cap1 genes under low-stringency conditions. One recombinant plasmid containing a 14-kb insert was chosen for further study and found to complement 14 of the 18 type 8 capsule-negative (Cap8-) mutants used in the study. Additional library screening, subcloning, and complementation experiments showed that all of the 18 Cap8- mutants were complemented by DNA fragments derived from a 20.5-kb contiguous region of the Becker chromosome. The mutants were mapped into six complementation groups, indicating that the cap8 genes are clustered. By Southern hybridization analyses under high-stringency conditions, we found that DNA fragments containing the cap8 gene cluster show extensive homology with all 17 strains tested, including type 1 strains. By further Southern analyses and cloning of the cap8-related homolog from strain M, we show that strain M carries an additional capsule gene cluster different from the cap1 gene cluster. In addition, by using DNA fragments containing different regions of the cap8 gene cluster as probes to hybridize DNA from different strains, we found that the central region of the cap8 gene cluster hybridizes only to DNAs from certain strains tested whereas the flanking regions hybridize to DNAs of all strains tested. Thus, the cap8 gene clusters and its closely related homologs are likely to have organizations similar to those of the encapsulation genes of other bacterial systems.

analysis, capsular polysaccharides, cloning, type, gene cluster, capsule, Staphylococcus aureus

NCBI PubMed ID: 8606192
Journal NLM ID: 2985120R
Publisher: American Society for Microbiology
Correspondence: clee@kumc.edu
Institutions: Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, Kansas City, Kansas 66160
Methods: genetic methods

Staphylococcus aureus is the most common nosocomial pathogen and is responsible for approximately one-third of hospital-acquired bacteremias. The emergence of strains with multidrug resistance, including resistance to vancomycin, the antibiotic of last resort, presents the medical community with a major public health problem. Alternative therapies, including immunotherapy, have been in development for several decades. The discovery of S. aureus capsular polysaccharides from clinical isolates, and their importance to pathogenicity via antiphagocytic activity, opened a new window of opportunity for development of vaccines and immunotherapy against this pathogen. A conjugate vaccine, StaphVAX that includes the two most prevalent capsular polysaccharides, types 5 and 8, coupled to a carrier protein efficient in promoting a Th2 response, was developed. In a recent phase III clinical study in hemodialysis patients, StaphVAX was shown to prevent S. aureus bacteremia for up to 10 months following a single immunization. The history, epidemiology, serology, and development of StaphVAX, including preclinical and clinical studies demonstrating efficacy are described in this review.

polysaccharide, Staphylococcus, conjugate vaccine

NCBI PubMed ID: 15040941
Journal NLM ID: 8406899
Publisher: Elsevier
Correspondence: afattom@nabi.com
Institutions: NABI Biopharmaceuticals, 12280 Wilkins Avenue, Rockville, MD 20852, USA
Methods: ELISA

The O antigen unit of Pseudomonas aeruginosa serotype O5 is a complex trisaccharide containing 2-acetamido-3-acetiminido-2,3-dideoxy- L-D-mannuronic acid, 2-acetimido-3-acetimido-2,3-dideoxy-L-D-mannuronic acid, and 2-acetimido-2,6-deoxy-L-D-galactosamine. Specific knockout mutations in the putative UDP-D-N-acetylglucosamine (UDP-D-GlcNAc) epimerase gene, wbpI, or the putative UDP-D-Nacetylmannosamine dehydrogenase gene, wbpA, resulted in strains that no longer produced B-band lipopolysaccharide, confirming the essential roles of these genes in B-band O antigen synthesis. Despite approximately 50% similarity of wbpI and wbpA to the Escherichia coli genes wecB (rffE) and wecC (rffD) involved in enterobacterial common antigen synthesis, cross-complementation experiments were not successful. These results imply that the P. aeruginosa UDP-D-GlcNAc precursor may be di-N-acetylated prior to further modification, preventing the E. coli enzymes from recognizing it as a substrate.

Lipopolysaccharide, gene, B-band, Escherichia, Escherichia coli, WbpA, WbpI

NCBI PubMed ID: 10930727
Journal NLM ID: 8902526
Publisher: Oxford University Press
Correspondence: jlam@uoguelph.ca
Institutions: Department of Microbiology, University of Guelph, Gueph, Canada
Methods: genetic methods

Antibodies against the cell surface carbohydrates of many microbial pathogens protect against infection. This was initially exploited by the development of purified polysaccharide vaccines, but glycoconjugate vaccines, in which the cell surface carbohydrate of a microbial pathogen is covalently attached to an appropriate carrier protein, are proving the most effective means to generate this protective immunity. Carbohydrate-based vaccines against Haemophilus influenzae Type b, Neisseria meningitidis, Streptococcus pneumoniae and Salmonella enterica serotype Typhi (S. Typhi) are already licensed, and many similar products are in various stages of development. For many of these vaccines, biological assays are not available or are inappropriate and NMR spectroscopy is proving a valuable tool for the characterisation and quality control of existing and novel products. This review highlights some of the areas in which NMR spectroscopy is currently used, and where further developments may be expected.

capsular polysaccharide, O-acetylation, pneumonia, glycoconjugate, meningitis, carbohydrate-based vaccines, identity, typhoid

NCBI PubMed ID: 16087046
Publication DOI: 10.1016/j.jpba.2005.01.044
Journal NLM ID: 8309336
Publisher: London: Elsevier
Institutions: Laboratory for Molecular Structure, National Institute for Biological Standards and Control, South Mimms, UK
Methods: NMR

Capsules are produced by over 90% of Staphylococcus aureus strains, and approximately 25% of clinical isolates express type 5 capsular polysaccharide (CP5). We mutagenized the type 5 strain Reynolds with Tn918 to target genes involved in CP5 expression. From a capsule-deficient mutant, we cloned into a cosmid vector an approximately 26-kb EcoRI fragment containing the transposon insertion. In the absence of tetracycline selection, Tn918 was spontaneously excised, thereby resulting in a plasmid containing 9.4 kb of S. aureus DNA flanking the Tn918 insertion site. The 9.4-kb DNA fragment was used to screen a cosmid library prepared from the wild-type strain. Positive colonies were identified by colony hybridization, and a restriction map of one clone (pJCL19 with an approximately 34-kb insert) carrying the putative capsule gene region was constructed. Fragments of pJCL19 were used to probe genomic DNA digests from S. aureus strains of different capsular serotypes. Fragments on the ends of the cloned DNA hybridized to fragments of similar sizes in most of the strains examined. Blots hybridized to two fragments flanking the central region of the cloned DNA showed restriction fragment length polymorphism. A centrally located DNA fragment hybridized only to DNA from capsular types 2, 4, and 5. DNA from pJCL19 was subcloned to a shuttle vector for complementation studies. A 6.2-kb EcoRI-ClaI fragment complemented CP5 expression in a capsule-negative mutant derived by mutagenesis with ethyl methanesulfonate. These experiments provide the necessary groundwork for identifying genes involved in CP5 expression by S. aureus.

genetic, clinical, expression, gene, genetics, DNA, strain, capsular, polysaccharide, serotype, analysis, capsular polysaccharide, Serotypes, type, mutant, region, insertion, plasmid, capsule, Staphylococcus, Staphylococcus aureus, fragment, site, clone, PDF, capsules, selection, polymorphism

NCBI PubMed ID: 805001
Journal NLM ID: 2985120R
Publisher: American Society for Microbiology
Institutions: Channing Laboratory, Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts.
Methods: serological methods, genetic methods