Optimization of the Process for Preparing Bivalent Polysaccharide Conjugates to Develop Multivalent Conjugate Vaccines against Streptococcus pneumoniae or Neisseria meningitidis and Comparison with the Corresponding Licensed Vaccines in Animal Models.

OBJECTIVE: This study aimed to describe, optimize and evaluate a method for preparing multivalent conjugate vaccines by simultaneous conjugation of two different bacterial capsular polysaccharides (CPs) with tetanus toxoid (TT) as bivalent conjugates. METHODS: Different molecular weights (MWs) of polysaccharides, activating agents and capsular polysaccharide/protein (CP/Pro) ratio that may influence conjugation and immunogenicity were investigated and optimized to prepare the bivalent conjugate bulk. Using the described method and optimized parameters, a 20-valent pneumococcal conjugate vaccine and a bivalent meningococcal vaccine were developed and their effectiveness was compared to that of corresponding licensed vaccines in rabbit or mouse models. RESULTS: The immunogenicity test revealed that polysaccharides with lower MWs were better for Pn1-TT-Pn3 and MenA-TT-MenC, while higher MWs were superior for Pn4-TT-Pn14, Pn6A-TT-Pn6B, Pn7F-TT-Pn23F and Pn8-TT-Pn11A. For activating polysaccharides, 1-cyano-4-dimethylaminopyridinium tetrafluoroborate (CDAP) was superior to cyanogen bromide (CNBr), but for Pn1, Pn3 and MenC, N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride (EDAC) was the most suitable option. For Pn6A-TT-Pn6B and Pn8-TT-Pn11A, rabbits immunized with bivalent conjugates with lower CP/Pro ratios showed significantly stronger CP-specific antibody responses, while for Pn4-TT-Pn14, higher CP/Pro ratio was better. Instead of interfering with the respective immunological activity, our bivalent conjugates usually induced higher IgG titers than their monovalent counterparts. CONCLUSION: The result indicated that the described conjugation technique was feasible and efficacious to prepare glycoconjugate vaccines, laying a solid foundation for developing extended-valent multivalent or combined conjugate vaccines without potentially decreased immune function.

Acquiring an effective CaO-based CO2 sorbent and achieving selective methanation of CO2.

CO2 capture, utilization, and storage are promising strategies to solving the problems of superfluous CO2 or energy shortage. Here, mechanochemical reduction of CO2 by a MgH2/CaH2 mixture was first performed, by which we achieve selective methanation of CO2 and acquire an effective CaO-based CO2 sorbent, simultaneously. The selectivity of methanation is near 100% and the yield of CH4 reaches 30%. Four MgO and carbon-doped CaO-based CO2 sorbents (MgO/CaO/C, MgO/2CaO/C, MgO/4CaO/C, and MgO/8CaO/C) were formed as solid products in these reactions. Among them, the MgO/4CaO/C sorbent shows high initial adsorption amount of 59.3 wt% and low average activity loss of 1.6% after 30 cycles. This work provides a novel, well-scalable, and sustainable approach to prepare an efficient inert additive-including CaO-based CO2 sorbent and selectively convert CO2 to CH4 at the same time.

Effect of static magnetic field on endospore germination.

This work investigated the effect of static magnetic field (SMF) on Bacillus atrophaeus endospore germination. Germination was triggered by L-alanine in 1.3-T SMF and characterized by ion release, Ca2+ -dipicolinic acid release, and water influx. These events were monitored by electrical conductivity, Tb-DPA fluorescence, and optical density, respectively. Culturability of endospore germinated in SMF exposure was evaluated by CFU enumeration. Results indicated that 1.3-T SMF failed to significantly affect endospore germination and culturability, suggesting that the three aforementioned processes were not sensitive to SMF. Bioelectromagnetics. 38:121-127, 2017. © 2016 Wiley Periodicals, Inc.

Effect of sonic stimulation on Bacillus endospore germination.

This study investigates the effect of sonic stimulation on Bacillus endospore germination. Germinating endospores in a microtiter plate were exposed to audible sound wave generated by an array of piezoelectric transducers. In situ germination kinetics was measured by terbium-dipicolinate fluorescence assay, optical density measurement and phase contrast microscopy. Fluorescence results revealed that sonic stimulation (5 kHz at 90 dB) promoted the germination speed by 43.7% ± 11.3% and final germination level by 61.7% ± 11.9% of Bacillus atrophaeus. This acoustic energy absorbed by endospores is postulated to change membrane permeability and increase enzyme activities; thereby, expediting the germination process. This also raises the likelihood of dormant endospores undergoing germination because of a rapid release of unidentified chemical mediators for quorum sensing. On the other hand, acoustic effect was not observed in B. subtilis endospores. This may be attributed to the different spore aspect ratio, 1.43 ± 0.05 for B. atrophaeus and 2.02 ± 0.08 for B. subtilis, which results in a difference in specific absorption rates towards audible sound waves. Our results demonstrate the modulation of endospore germination by an external field to shed light on germination mechanism and cell-wave interaction.