Sequential One‐pot Three‐enzyme Synthesis of the Tetrasaccha‐ride Repeating Unit of Group B Streptococcus Serotype VIII Capsular Polysaccharide

Group B Streptococcus (GBS) is a common cause of neonatal sepsis and meningitis. A major GBS virulence determinant is its sialic acid (Sia)-capped capsular polysaccharide. Recently, we discovered the presence and genetic basis of capsular Sia O-acetylation in GBS. We now characterize a GBS Sia O-acetylesterase that modulates the degree of GBS surface O-acetylation. The GBS Sia O-acetylesterase operates cooperatively with the GBS CMP-Sia synthetase, both part of a single polypeptide encoded by the neuA gene. NeuA de-O-acetylation of free 9-O-acetyl-N-acetylneuraminic acid (Neu5,9Ac2) was enhanced by CTP and Mg2+, the substrate and co-factor, respectively, of the N-terminal GBS CMP-Sia synthetase domain. In contrast, the homologous bifunctional NeuA esterase from Escherichia coli K1 did not display cofactor dependence. Further analyses showed that in vitro, GBS NeuA can operate via two alternate enzymatic pathways: de-O-acetylation of Neu5,9Ac2 followed by CMP activation of Neu5Ac or activation of Neu5,9Ac2 followed by de-O-acetylation of CMP-Neu5,9Ac2. Consistent with in vitro esterase assays, genetic deletion of GBS neuA led to accumulation of intracellular O-acetylated Sias, and overexpression of GBS NeuA reduced O-acetylation of Sias on the bacterial surface. Site-directed mutagenesis of conserved asparagine residue 301 abolished esterase activity but preserved CMP-Sia synthetase activity, as evidenced by hyper-O-acetylation of capsular polysaccharide Sias on GBS expressing only the N301A NeuA allele. These studies demonstrate a novel mechanism regulating the extent of capsular Sia O-acetylation in intact bacteria and provide a genetic strategy for manipulating GBS O-acetylation in order to explore the role of this modification in GBS pathogenesis and immunogenicity.

Download Full-text

ChemInform Abstract: Synthesis of a Single Repeat Unit of Type VIII Group B Streptococcus Capsular Polysaccharide.

ChemInform ◽

10.1002/chin.199743221 ◽

2010 ◽

Vol 28 (43) ◽

pp. no-no

Author(s):

E. EICHLER ◽

H. J. JENNINGS ◽

D. M. WHITFIELD

Keyword(s):

Capsular Polysaccharide ◽

Repeat Unit ◽

Group B Streptococcus ◽

Type Viii ◽

Group B

Download Full-text

Structural elucidation of the novel type VII group B Streptococcus capsular polysaccharide by high resolution NMR spectroscopy

Carbohydrate Research ◽

10.1016/0008-6215(95)00195-y ◽

1995 ◽

Vol 277 (1) ◽

pp. 1-9 ◽

Cited By ~ 32

Author(s):

Grigorij Kogan ◽

Jean-Robert Brisson ◽

Dennis L. Kasper ◽

Christina von Hunolstein ◽

Graziella Orefici ◽

...

Keyword(s):

Nmr Spectroscopy ◽

High Resolution ◽

Capsular Polysaccharide ◽

Group B Streptococcus ◽

Structural Elucidation ◽

The Novel ◽

High Resolution Nmr ◽

Group B

Download Full-text

Molecular epidemiology of infections caused by group B Streptococcus in pregnant women and newborns, and development of preventive vaccines

Journal of obstetrics and women s diseases ◽

10.17816/jowd67562-73 ◽

2018 ◽

Vol 67 (5) ◽

pp. 62-73

Author(s):

Vasilisa A. Vasilyeva ◽

Elena V. Shipitsyna ◽

Kira V. Shalepo ◽

Alevtina M. Savicheva

Keyword(s):

Capsular Polysaccharide ◽

Vaccine Development ◽

Current Knowledge ◽

Group B Streptococcus ◽

Epidemiological Data ◽

Group B Streptococci ◽

Group B ◽

Sequence Types ◽

Experimental Immunization ◽

Selection Of

Hypothesis/aims of study. The present analysis was undertaken to summarize current knowledge about molecular properties of group B streptococci (GBS), emphasizing potential targets of vaccines against neonatal GBS infection. Study design, materials, and methods. This review is based on articles published mainly in the last ten years. Results. Epidemiological data on serotypes, multilocus sequence types, clonal complexes of GBS and their relationship are presented. Genetic events in GBS populations indicate significant obstacles to vaccine development. We described key properties of major GBS virulence factors, such as capsular polysaccharide, pili, and cell adhesion molecules, as well as results of experimental immunization on their basis. Conclusion. The population of invasive GBS strains is molecularly and genetically heterogeneous, which complicates selection of vaccine targets. Capsular switching, a low level of immunogenicity and variability of population composition are the most important factors that necessitate the accumulation and monitoring of molecular epidemiological data.

Download Full-text

OC 8465 THE DEVELOPMENT OF A CONJUGATE VACCINE AGAINST GROUP B STREPTOCOCCUS: AN AFRICAN PERSPECTIVE

BMJ Global Health ◽

10.1136/bmjgh-2019-edc.18 ◽

2019 ◽

Vol 4 (Suppl 3) ◽

pp. A8.1-A8

Author(s):

Seanette Wilson ◽

Patrick Tippoo

Keyword(s):

South Africa ◽

Clinical Trial ◽

Conjugate Vaccine ◽

Capsular Polysaccharide ◽

Disease Risk ◽

Group B Streptococcus ◽

International Health ◽

Infant Deaths ◽

Young Infants ◽

Group B

BackgroundStreptococcus agalactiae, or group B streptococcus (GBS), is a gram-positive streptococcal bacterium that is well-recognised as one of the leading causes of infant death, particularly in the early neonatal period (the first week of life). An estimated one in five pregnant women around the world carries GBS bacteria in their gastrointestinal or genitourinary tracts and vertical transmission from colonised mothers can lead to invasive disease in their offspring. A recent study conservatively estimated that out of 410,000 GBS cases globally every year, there are at least 1 47 000 stillbirths and infant deaths. Despite being home to only 13% of the world’s population, Africa has the highest GBS disease burden, with 54% of estimated cases and 65% of stillbirths and infant deaths.An effective GBS vaccine, given during pregnancy, is a promising strategy to protect against GBS disease. Currently, no licensed vaccine exists to prevent it, but scientific evaluation of feasibility is favourable. The leading vaccine candidates are capsular polysaccharide-protein conjugate vaccines. Evidence suggests maternal immunisation with a safe and effective GBS vaccine may reduce the disease risk in neonates and young infants.The Biovac Institute was established as a private-public partnership and is the only Southern African vaccine manufacturer. Located in Cape Town, South Africa, Biovac’s mission is to become a leading vaccine developer and producer in South Africa to increase capacity in Africa which only has four other vaccine manufacturers.In collaboration with PATH, an international health organisation, and other partners, Biovac is developing a multivalent conjugate vaccine against GBS. The first stage of the project involves the development of biopharmaceutical manufacturing processes and analytical tests, the preparation of clinical trial product, and execution of a first-in-human clinical trial.This presentation will provide an overview of the project, progress to date, and the path to commercialisation.

Download Full-text