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

2021 ◽  
Vol 8 ◽  
Author(s):  
Elena V. Sukhova ◽  
Dmitry V. Yashunsky ◽  
Ekaterina A. Kurbatova ◽  
Elina A. Akhmatova ◽  
Yury E. Tsvetkov ◽  
...  

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.

2020 ◽  
Vol 11 ◽  
Author(s):  
Ekaterina A. Kurbatova ◽  
Nelli K. Akhmatova ◽  
Anton E. Zaytsev ◽  
Elina A. Akhmatova ◽  
Nadezhda B. Egorova ◽  
...  

A number of studies have demonstrated the limited efficacy of S. pneumoniae type 3 capsular polysaccharide (CP) in the 13-valent pneumococcal conjugate vaccine against serotype 3 invasive pneumococcal diseases and carriage. Synthetic oligosaccharides (OSs) may provide an alternative to CPs for development of novel conjugated pneumococcal vaccines and diagnostic test systems. A comparative immunological study of di–, tri–, and tetra–bovine serum albumin (BSA) conjugates was performed. All oligosaccharides conjugated with biotin and immobilized on streptavidin-coated plates stimulated production of IL-1α, IL-2, IL-4, IL-5, IL-10, IFNγ, IL-17A, and TNFα, but not IL-6 and GM-CSF in monocultured mice splenocytes. The tetrasaccharide–biotin conjugate stimulated the highest levels of IL-4, IL-5, IL-10, and IFNγ, which regulate expression of specific immunoglobulin isotypes. The tetra–BSA conjugate adjuvanted with aluminum hydroxide elicited high levels of IgM, IgG1, IgG2a, and IgG2b antibodies (Abs). Anti-CP-induced Abs could only be measured using the biotinylated tetrasaccharide. The tetrasaccharide ligand possessed the highest binding capacity for anti-OS and antibacterial IgG Abs in immune sera. Sera to the tetra–BSA conjugate promoted greater phagocytosis of bacteria by neutrophils and monocytes than the CRM197-CP-antisera. Sera of mice immunized with the tetra–BSA conjugate exhibited the highest titer of anti-CP IgG1 Abs compared with sera of mice inoculated with the same doses of di– and tri–BSA conjugates. Upon intraperitoneal challenge with lethal doses of S. pneumoniae type 3, the tri– and tetra–BSA conjugates protected mice more significantly than the di–BSA conjugate. Therefore, it may be concluded that the tetrasaccharide ligand is an optimal candidate for development of a semi-synthetic vaccine against S. pneumoniae type 3 and diagnostic test systems.


Author(s):  
E. A. Kurbatova ◽  
E. A. Akhmatova ◽  
N. K. Akhmatova ◽  
N. B. Egorova ◽  
N. E. Yastrebova ◽  
...  

Aim. Evaluation of the ability of capsule polysaccharides (CP) of Streptococcus pneumoniae serotype 3 and 14 and their synthetic structure analogues, conjugated with bovine serum albumin (BSA), to detect antibodies in post-vaccination sera of mice. Materials and methods. Oligosaccharides corresponding to one, one and a half and two repeating links of serotype 3 and 14 S. pneumoniae CP were synthesized, their conjugates with BSA were produced by squarate method as well. Ligand content per BSA molecule was controlled by MALDI-TOF spectrometry. Immune sera were obtained after 2 intraperi-toneal administrations to mice of glucoconjugates adsorbed on aluminum hydroxide or 13-valent pneumococcal conjugated vaccine. Determination of levels of post-vaccination class G antibodies and their sub-isotypes was carried out in EIA. Results. Immunization of mice with neoglucoconjugates resulted in formation of predominantly IgGl recognizing serotype 3 and 14 S. pneumoniae CP. IgGl in mice immunized with a 13-valent conjugated vaccine recognized serotype 3 S. pneumoniae CP, but detected serotype 14 S. pneumoniae CP weakly. All the conjugated synthetic oligosaccharides were characterized by a high ability to bind antibodies in blood of mice immunized with the polysaccharide conjugated vaccine. BSA-tetrasaccharide of serotype 3 S. pneumoniae and BSA-tetrasaccharide of serotype 14 S. pneumoniae were characterized by the highest ability to detect IgG 1 against CP. Conclusion. Synthetic oligosaccharides, conjugated with BSA protein-carrier, may be used to develop diagnostic test-systems for determination of antibodies in post-vaccination sera.


Author(s):  
G. D. Gagne ◽  
M. F. Miller

We recently described an artificial substrate system which could be used to optimize labeling parameters in EM immunocytochemistry (ICC). The system utilizes blocks of glutaraldehyde polymerized bovine serum albumin (BSA) into which an antigen is incorporated by a soaking procedure. The resulting antigen impregnated blocks can then be fixed and embedded as if they are pieces of tissue and the effects of fixation, embedding and other parameters on the ability of incorporated antigen to be immunocyto-chemically labeled can then be assessed. In developing this system further, we discovered that the BSA substrate can also be dried and then sectioned for immunolabeling with or without prior chemical fixation and without exposing the antigen to embedding reagents. The effects of fixation and embedding protocols can thus be evaluated separately.


1981 ◽  
Vol 46 (03) ◽  
pp. 645-647 ◽  
Author(s):  
M A Orchard ◽  
C Robinson

SummaryThe biological half-life of prostacyclin in Krebs solution, human cell-free plasma or whole blood was measured by bracket assay on ADP-induced platelet aggregation. At 37°C, pH 7.4, plasma and blood reduced the rate of loss of antiaggregatory activity compared with Krebs solution. The protective effect of plasma was greater than that of whole blood. This effect could be partially mimicked by the addition of human or bovine serum albumin to the Krebs solution. The stabilisation afforded by human serum albumin was dependent on the fatty acid content of the albumin, although this was less important for bovine serum albumin.


1974 ◽  
Vol 75 (1) ◽  
pp. 133-140 ◽  
Author(s):  
B. E. Senior

ABSTRACT A radioimmunoassay was developed to measure the levels of oestrone and oestradiol in 0.5–1.0 ml of domestic fowl peripheral plasma. The oestrogens were extracted with diethyl ether, chromatographed on columns of Sephadex LH-20 and assayed with an antiserum prepared against oestradiol-17β-succinyl-bovine serum albumin using a 17 h incubation at 4°C. The specificity, sensitivity, precision and accuracy of the assays were satisfactory. Oestrogen concentrations were determined in the plasma of birds in various reproductive states. In laying hens the ranges of oestrone and oestradiol were 12–190 pg/ml and 29–327 pg/ml respectively. Levels in immature birds, in adult cockerels and in an ovariectomized hen were barely detectable. The mean concentrations of oestrone and oestradiol in the plasma of four non-laying hens (55 pg/ml and 72 pg/ml respectively) and one partially ovariectomized hen (71 pg/ml and 134 pg/ml respectively) were well within the range for laying hens. It is evident that the large, yolk-filled follicles are not the only source of oestrogens in the chicken ovary.


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