Retaining the structural integrity of disulfide bonds in diphtheria toxoid carrier protein is crucial for the effectiveness of glycoconjugate vaccine candidates

The introduction of glycoconjugate vaccines marks an important point in the fight against various infectious diseases. The covalent conjugation of relevant polysaccharide antigens to immunogenic carrier proteins enables the induction of a long-lasting and robust IgG antibody response, which is not observed for pure polysaccharide vaccines. Although there has been remarkable progress in the development of glycoconjugate vaccines, many crucial parameters remain poorly understood. In particular, the influence of the conjugation site and strategy on the immunogenic properties of the final glycoconjugate vaccine is the focus of intense research. Here, we present a comparison of two cysteine selective conjugation strategies, elucidating the impact of both modifications on the structural integrity of the carrier protein, as well as on the immunogenic properties of the resulting glycoconjugate vaccine candidates. Our work suggests that conjugation chemistries impairing structurally relevant elements of the protein carrier, such as disulfide bonds, can have a dramatic effect on protein immunogenicity.

The introduction of glycoconjugate vaccines marks an important point in the fight against various infectious diseases.     

Fucose-specific conjugation of hydrazide derivatives to a vascular-targeting monoclonal antibody in IgG format

We describe a method that enables specific and efficient conjugation of hydrazide-moieties to an IgG targeting the tumor neovasculature. The resulting chemically defined, homogeneous hydrazone-linked IgG conjugates remain immunoreactive and have a half-life of approximately 18 hours at physiological pH and temperature suitable for localized delivery of toxic drugs.     

Direct radiolabelling of proteins at cysteine using [18F]-fluorosugars

A strategy for the site-specific attachment of 2-deoxy-2-fluorosugars to cysteine and dehydroalanine tagged proteins is reported. When combined with thionation of fluorosugars, such as the widely available (18)F probe 2-deoxy-2-[(18)F]fluoroglucose ([(18)F]FDG), this methodology allows fast and direct access to site-specific [(18)F]FDG-labelled proteins.     

Synthesis,characterization, and cytotoxicity of glutathione-PEG-iron oxide magnetic nanoparticles

Recently, increasing interest is spent on the synthesis of superparamagnetic iron oxide nanoparticles, followed by their characterization and evaluation of cytotoxicity towards tumorigenic cell lines. In this work, magnetite (Fe₃O₄) nanoparticles were synthesized by the polyol method and coated with polyethylene glycol (PEG) and glutathione (GSH), leading to the formation of PEG-Fe₃O₄ and GSH-PEG-Fe₃O₄ nanoparticles. The nanoparticles were characterized by state-of-the-art techniques: dynamic light scattering (DLS), atomic force microscopy (AFM), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and superconducting quantum interference device (SQUID) magnetic measurements. PEG-Fe₃O₄ and GSH-PEG-Fe₃O₄ nanoparticles have crystallite sizes of 10 and 5 nm, respectively, indicating compression in crystalline lattice upon addition of GSH on the nanoparticle surface. Both nanoparticles presented superparamagnetic behavior at room temperature, and AFM images revealed the regular spherical shape of the nanomaterials and the absence of particle aggregation. The average hydrodynamic sizes of PEG-Fe₃O₄ and GSH-PEG-Fe₃O₄ nanoparticles were 69 ± 37 and 124 nm ± 75 nm, respectively. The cytotoxicity of both nanoparticles was screened towards human prostatic carcinoma cells (PC-3). The results demonstrated a decrease in PC-3 viability upon treatment with PEG-Fe₃O₄ or GSH-PEG-Fe₃O₄ nanoparticles in a concentration-dependent manner. However, the cytotoxicity was not time-dependent. Due to the superparamagnetic behavior of PEG-Fe₃O₄ or GSH-PEG-Fe₃O₄ nanoparticles, upon the application of an external magnetic field, those nanoparticles can be guided to the target site yielding local toxic effects to tumor cells with minimal side effects to normal tissues, highlighting the promising uses of iron oxide nanoparticles in biomedical applications.     

Can males contribute to the genetic improvement of a species?

In the time evolution of finite populations, the accumulation of harmful mutations in further generations might have lead to a temporal decay in the mean fitness of the whole population. This, in turn, would reduce the population size and so lead to its extinction. The production of genetically diverse offspring, through recombination, is a powerful mechanism in order to avoid this catastrophic route. From a selfish point of view, meiotic parthenogenesis can ensure the maintenance of better genomes, while sexual reproduction presents the risk of genome dilution. In this paper, by using Monte Carlo simulations of age-structured populations, through the Penna model, I compare the evolution of populations with different repoductive regimes. It is shown that sexual reproduction with male competition can produce better results than meiotic parthenogenesis. This contradicts results recently published, but agrees with the strong evidence that nature chose sexual reproduction instead of partenogenesis for most of the higher species.     

Stable Pyrrole‐Linked Bioconjugates through Tetrazine‐Triggered Azanorbornadiene Fragmentation

An azanorbornadiene bromovinyl sulfone reagent for cysteine‐selective bioconjugation has been developed. Subsequent reaction with dipyridyl tetrazine leads to bond cleavage and formation of a pyrrole‐linked conjugate. The latter involves ligation of the tetrazine to the azanorbornadiene‐tagged protein through inverse electron demand Diels–Alder cycloaddition with subsequent double retro‐Diels–Alder reactions to form a stable pyrrole linkage. The sequence of site‐selective bioconjugation followed by bioorthogonal bond cleavage was efficiently employed for the labelling of three different proteins. This method benefits from easy preparation of these reagents, selectivity for cysteine, and stability after reaction with a commercial tetrazine, which has potential for the routine preparation of protein conjugates for chemical biology studies.     

DNA vaccine containing the mycobacterial hsp65 gene prevented insulitis in MLD-STZ diabetes

Background  

Our group previously demonstrated that a DNA plasmid encoding the mycobacterial 65-kDa heat shock protein (DNA-HSP65) displayed prophylactic and therapeutic effect in a mice model for tuberculosis. This protection was attributed to induction of a strong cellular immunity against HSP65. As specific immunity to HSP60 family has been detected in arthritis, multiple sclerosis and diabetes, the vaccination procedure with DNA-HSP65 could induce a cross-reactive immune response that could trigger or worsen these autoimmune diseases.     

A convenient synthesis of hexacarbonyldicobalt complexes of chiral (non-racemic) terminal alkoxyacetylenes

The hexacarbonyldicobalt complexes of chiral (non-racemic) unsubstituted terminal alkoxyacetylenes have been synthesized for the first time by a novel procedure that involves one-pot transformation of a chiral alcohol to the corresponding trimethylsilylated alkoxy acetylene, followed by complexation and protodesilylation (also one-pot). The synthesis is efficient and amenable to the preparation of multigram quantities.