Enzymatic depolymerization of streptococcus pneumoniae type 8 polysaccharide

Although there have been decades of research on streptococcus pneumoniae, it is still among the leading cause of infectious disease in the world. As a type of capsular polysaccharide (CPS) of streptococcus pneumoniae, pneumococcal polysaccharides are essential components for colonization and virulence in mammalian hosts. This study aimed to characterize the CPS structure of type 8 streptococcus pneumoniae, which is one of the most fatal serotypes. In this work, heparinase I&III was used to successfully digest pneumococcal type 8 polysaccharide (Pn8P). We characterized the oligosaccharide generated from the enzymatic depolymerization of Pn8P by size exclusion chromatography, mass spectrometry and nuclear magnetic resonance. This is the first study to enzymatically depolymerize and characterize Pn8P.

A randomized, triple-blinded, placebo-controlled clinical trial evaluating immune responses of Typhim Vi and PPSV23 vaccines in healthy adults: The PREP study

Rapid and early identification of emergent infections is essential for delivering prompt clinical care. To advance the development of algorithms for the clinical management of infection identification, we performed a vaccination clinical trial to investigate the potential of using vaccination as a model for studying mild inflammation responses associated with different infections (NCT05346302). We collected data at various time points over 4 weeks from blood samples, wearable devices, and questionnaires. Following a 2-week baseline period, 210 healthy participants, aged 18-40 years, were administered either a Pneumococcal Polysaccharide vaccine (PPSV23), Typhoid Vi Polysaccharide vaccine (Typhim Vi), or placebo. In longitudinal analyses of blood biomarkers, we found that CRP was significantly higher at 2 days post-vaccination, whereas basophils, IL-10, IL-12p40, and MIG were significantly higher at 7 days post-vaccination in the PPSV23 group compared to both other groups (all p < 0.05). MIP-1β was significantly lower in the PPSV23 group than in the placebo group, while monocytes and MPV were significantly lower in the Typhim Vi group than in the placebo group at 7 days post-vaccination (all p < 0.05). The PPSV3 group showed a higher inflammatory profile, suggesting that PPSV23 induces a stronger immune response compared to Typhim Vi. The distinct immune responses induced by the two vaccines indicate the potential for utilizing vaccines as models for studying inflammation responses associated with different infectious pathogens.

Evaluation of GC-MS for identification and characterization of pneumococcal serotype 24A, 24B, and 24F capsular polysaccharide

Analysis of pneumococcal polysaccharides (PnPs) has been an arduous task, especially in similar serotypes. Pneumococci invades the host immune response by modulating capsule structure with small genetic changes making them indistinguishable from similar serotypes by conventional modes of analysis. The new serotype 24F causing invasive pneumococcal-resistant infection is an analytical challenge for its analysis as related serotypes 24A and 24B Ps share a common backbone. The difference in the branched chain which contains arabinitol and ribitol in 24F and 24B respectively are stereoisomers making their identification even more challenging. The composition analysis by GC-MS revealed distinct peaks for arabinitol in 24F and 24A Ps and ribitol in Pn 24B serotype polysaccharide. The mass spectral analysis confirmed their identification along with a heterologous cross-reactivity which confirmed anti-Pn-24F mAb reactive to Pn 24B than Pn 24A. The quantitative analysis of pneumococcal 24A, 24B and 24F using GC-MS showed sensitive analysis over the concentration range 3.125-200 μg/mL with regression coefficient >0.99 making ideal modality for the characterization, identification, and quantitation of pneumococcal 24A, 24B and 24F similar serotypes.

Evaluation of structural modification induced activation of pneumococcal polysaccharide by GC-MS for the conjugate vaccine

Polysaccharide (Ps) activation evaluation is an imperative quality attribute in a conjugate vaccine. Pneumococcal polysaccharide (PnPs) serotypes 5, 6B, 14, 19A and 23F were cyanylated for 3 and 8 min. The cyanylated and non-cyanylated polysaccharides were methanolysed and derivatized to assess the activation of each sugar by GC-MS. The activation of 22 and 27% serotype 6B and 11 and 36% in serotype 23 F Ps at 3 and 8 min respectively showed controlled conjugation kinetics with CRM197 carrier protein estimated by SEC-HPLC and optimal absolute molar mass by SEC-MALS. The Glc and Gal are the most commonly activated sugars of all PnPs serotypes while N-acetyl sugars PneuNAc, GalNAc and Rha in serotypes 5, 14 and 19A respectively showed >50% activation which contributes to conjugate aggregate formation at 8 min compared to 3 min cyanylation. The GC-MS analysis of structural modifications at functional groups entails important information to characterize the activated polysaccharide for consistent conjugate vaccine manufacturing.