Synthetic avenues towards a tetrasaccharide related to <i>Streptococcus pneumonia</i> of serotype 6A

Chaudhury, Aritra; Mukherjee, M.; Ghosh, Rina

doi:10.3762/bjoc.14.95

Cited by 8 publications

(5 citation statements)

References 40 publications

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“…2B) 41 . Serotype 6 A' CPS, based on tetrasaccharides, includes a rhamnose modification 42 . Streptococcus suis (S. suis) strains were initially classified into 35 serotypes based on CPS antigenicity [43][44][45] , later revised to 33 serotypes 46 .…”

Section: Serotypes and Pathogenicitymentioning

confidence: 99%

Bacterial capsules: Occurrence, mechanism, and function

Gao,

Jin,

Quan

et al. 2024

npj Biofilms Microbiomes

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In environments characterized by extended multi-stress conditions, pathogens develop a variety of immune escape mechanisms to enhance their ability to infect the host. The capsules, polymers that bacteria secrete near their cell wall, participates in numerous bacterial life processes and plays a crucial role in resisting host immune attacks and adapting to their niche. Here, we discuss the relationship between capsules and bacterial virulence, summarizing the molecular mechanisms of capsular regulation and pathogenesis to provide new insights into the research on the pathogenesis of pathogenic bacteria.

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Section: Serotypes and Pathogenicitymentioning

confidence: 99%

Bacterial capsules: Occurrence, mechanism, and function

Gao,

Jin,

Quan

et al. 2024

npj Biofilms Microbiomes

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“…Hence, the orthogonal glycosylation between donor 17 and acceptor 18 62 in the presence of tert-butyldimethylsilyl trifluorosulfonate Given that only a modest selectivity of α/β = 6:1 and lower yields were observed for the synthesis of disaccharide 6 and the surprising outcome of only α/β = 1:4 for a β-selective glycosylation to obtain trisaccharide 20 as an inseparable mixture (Scheme 1), we explored different donors. One of the best reactions turned out to be the coupling between donor 26 65 and acceptor 18 using NIS/TMSOTf to obtain 27 in 71% with lower selectivity (α/β = 2:1) than obtained for disaccharide 6 as an inseparable mixture (Scheme 2). The anomers were separated after the benzylidene cleavage to afford 4,6-diol 28 in 53%.…”

Section: Synthetic Strategymentioning

confidence: 99%

Semisynthetic Glycoconjugate Vaccine Candidates against Escherichia coli O25B Induce Functional IgG Antibodies in Mice

Naini¹,

Bartetzko²,

Sanapala³

et al. 2022

JACS Au

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Extraintestinal pathogenic Escherichia coli (ExPEC) is a major health concern due to emerging antibiotic resistance. Along with O1A, O2, and O6A, E. coli O25B is a major serotype within the ExPEC group, which expresses a unique O -antigen. Clinical studies with a glycoconjugate vaccine of the above-mentioned O -types revealed O25B as the least immunogenic component, inducing relatively weak IgG titers. To evaluate the immunological properties of semisynthetic glycoconjugate vaccine candidates against E. coli O25B, we here report the chemical synthesis of an initial set of five O25B glycan antigens differing in length, from one to three repeat units, and frameshifts of the repeat unit. The oligosaccharide antigens were conjugated to the carrier protein CRM 197 . The resulting semisynthetic glycoconjugates induced functional IgG antibodies in mice with opsonophagocytic activity against E. coli O25B. Three of the oligosaccharide–CRM 197 conjugates elicited functional IgGs in the same order of magnitude as a conventional CRM 197 glycoconjugate prepared with native O25B O -antigen and therefore represent promising vaccine candidates for further investigation. Binding studies with two monoclonal antibodies (mAbs) revealed nanomolar anti-O25B IgG responses with nanomolar K D values and with varying binding epitopes. The immunogenicity and mAb binding data now allow for the rational design of additional synthetic antigens for future preclinical studies, with expected further improvements in the functional antibody responses. Moreover, acetylation of a rhamnose residue was shown to be likely dispensable for immunogenicity, as a deacylated antigen was able to elicit strong functional IgG responses. Our findings strongly support the feasibility of a semisynthetic glycoconjugate vaccine against E. coli O25B.

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“…In continuation of this program, we describe here the preparation of similar pseudotetrasaccharide 2 that represents the repeating unit of the type 6A CP. Although several oligosaccharides related to the type 6A CP have been synthesized ( Slaghek et al, 1991 ; Parameswar et al, 2007 ; Parameswar et al, 2008 ; Parameswar et al, 2009 ; Chaudhury et al, 2018 ), none of them contained both the phosphate bridge and a spacer group that enables further conjugation with labels or protein carriers.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Preliminary Immunological Evaluation of a Pseudotetrasaccharide Related to a Repeating Unit of the Streptococcus pneumoniae Serotype 6A Capsular Polysaccharide

Сухова

Yashunsky

Курбатова

et al. 2021

Front. Mol. Biosci.

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2-Aminoethyl glycoside of the pseudotetrasaccharide α-d-Glcp-(1→3)-α-l-Rhap-(1→3)-d-Rib-ol-(5-P-2)-α-d-Galp corresponding to a repeating unit of the Streptococcus pneumoniae type 6A capsular polysaccharide has been synthesized. A suitably protected pseudotrisaccharide α-d-Glcp-(1→3)-α-l-Rhap-(1→3)-d-Rib-ol with a free 5-OH group in the ribitol moiety and a 2-OH derivative of 2-trifluoroacetamidoethyl α-d-galactopyranoside have been efficiently prepared and then connected via a phosphate bridge using the hydrogen phosphonate procedure. Preliminary immunological evaluation of this pseudotetrasaccharide and the previously synthesized pseudotetrasaccharide corresponding to a repeating unit of the capsular polysaccharide of S. pneumoniae serotype 6B has shown that they contain epitopes specifically recognized by anti-serogroup 6 antibodies and are able to model well the corresponding capsular polysaccharides. Conjugates of the synthetic pseudotetrasaccharides with bovine serum albumin were shown to be immunogenic in mice.

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Synthetic avenues towards a tetrasaccharide related to Streptococcus pneumonia of serotype 6A

Cited by 8 publications

References 40 publications

Bacterial capsules: Occurrence, mechanism, and function

Bacterial capsules: Occurrence, mechanism, and function

Semisynthetic Glycoconjugate Vaccine Candidates against Escherichia coli O25B Induce Functional IgG Antibodies in Mice

Synthesis and Preliminary Immunological Evaluation of a Pseudotetrasaccharide Related to a Repeating Unit of the Streptococcus pneumoniae Serotype 6A Capsular Polysaccharide

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