Homology modeling and docking of AahII-Nanobody complexes reveal the epitope binding site on AahII scorpion toxin

Scorpion envenoming and its treatment is a public health problem in many parts of the world due to highly toxic venom polypeptides diffusing rapidly within the body of severely envenomed victims. Recently, 38 AahII-specific Nanobody sequences (Nbs) were retrieved from which the performance of NbAahII10 nanobody candidate, to neutralize the most poisonous venom compound namely AahII acting on sodium channels, was established. Herein, structural computational approach is conducted to elucidate the Nb-AahII interactions that support the biological characteristics, using Nb multiple sequence alignment (MSA) followed by modeling and molecular docking investigations (RosettaAntibody, ZDOCK software tools). Sequence and structural analysis showed two dissimilar residues of NbAahII10 CDR1 (Tyr27 and Tyr29) and an inserted polar residue Ser30 that appear to play an important role. Indeed, CDR3 region of NbAahII10 is characterized by a specific Met104 and two negatively chargedresidues Asp115 and Asp117. Complex dockings reveal that NbAahII17 and NbAahII38 share one common binding site on the surface of the AahII toxin divergent from the NbAahII10 one's. At least, a couple of NbAahII10 e AahII residue interactions (Gln38 e Asn44 and Arg62, His64, respectively) are mainly involved in the toxic AahII binding site. Altogether, this study gives valuable insights in the design and development of next generation of antivenom

Securing Africa’s health sovereignty : why investing in science and innovation matters

This paper aims at provoking broad-based dialogues and debates on ways and means of securing Africa’s health sovereignty. It argues that health sovereignty is about the realization of specific national constitutional and policy objectives on citizens’ access to and enjoyment of good health, resilient to COVID-19 and related disease pandemics. The paper also emphasizes the urgency of African countries fulfilling their commitments under global and regional declarations on health research. Investing in research, knowledge and innovation is critical to fight and win the war against COVID-19 and other diseases that undermine economic productivity and competitiveness of African countries. There is also a need for venture capitalists to demonstrate bankable ideas emanating from the science academies and funded by National Science Foundations. The base teachings at school level need to significantly invest in the “African philosophy” to create a shift in mind-set from the “grab and own without use mentality that is currently predominant on the continent. The paper recommends that executive, political and science leadership are needed to strengthen national health research and innovation systems through improved evidence-based policy implementation. With these thrusts working effectively together, rather than in silos, will afford the African continent to emerge victoriously in the combat against COVID-19 and other disease burdens

Development of an Immunosensor Based on Layered Double Hydroxides for MMR Cancer Biomarker Detection.

As a potential biomarker for the investigation of cancer inflammatory profiles, macrophage mannose receptor (MMR, CD206) is herein selected to develop an immunosensor based on layered double hydroxide (LDH). Like an endocyte C-type lectin receptor, MMR plays an important role in immune homeostasis by scavenging unwanted mannose glycoproteins. It attracts a progressive attention thanks to its particularly high expression within the tumor microenvironment. There is a great of interest to develop an immunosensor based on an antibody specific to MMR for detection of stroma versus tumor cells. In this work, we studied the feasibility of high sensitive MMR cancer Screen Printed Electrode (SPE) immunosensor. Working electrode of commercialized SPE was modified by immobilization of specific antibody (anti-MMR) into thin layer of LDH nanomaterials. Structural, morphological, and surface properties of LDHs were studied by X-Ray diffraction, atomic force microscopy and Infrared spectroscopy in ATR. Cyclic Voltammetry technique was used to study interaction between the human recombinant MMR protein (rHu-MMR, NSO derived) and an immobilized antibody into developed immunosensor. High specific response of -11.72 μA/ng.mL(-1) (with a correlation coefficient of R(2)=0.994 ) were obtained in linear range of 0.05 ng/mL to 10.0 ng/mL of specific recombinant antigen. The limit of detection (LOD) was less than 15.0 pg/mL. From these attractive results, the feasibility of an electrochemical immunosensor for cancer was proved. Additional experiments to study stability and reproducibility the immunosensor should be completed in perspective to use these anti-MMR based immunosensors for sensing human MMR in patient biopsies and sera

Xenopus oocyte’s conductance for bioactive compounds screening and characterization

Background: Astaxanthin (ATX) is a lipophilic compound found in many marine organisms. Studies have shown that ATX has many strong biological properties, including antioxidant, antiviral, anticancer, cardiovascular, anti-inflammatory, neuro-protective and anti-diabetic activities. However, no research has elucidated the effect of ATX on ionic channels. ATX can be extracted from shrimp by-products. Our work aims to characterize ATX cell targets to lend value to marine by-products. Methods: We used the Xenopus oocytes cell model to characterize the pharmacological target of ATX among endogenous Xenopus oocytes’ ionic channels and to analyze the effects of all carotenoid-extract samples prepared from shrimp by-products using a supercritical fluid extraction (SFE) method. Results: ATX inhibits amiloride-sensitive sodium conductance, xINa, in a dose-dependent manner with an IC50 of 0.14 µg, a maximum inhibition of 75% and a Hill coefficient of 0.68. It does not affect the potential of half activation, but significantly changes the kinetics, according to the slope factor values. The marine extract prepared from shrimp waste at 10 µg inhibits xINa in the same way as ATX 0.1 µg does. When ATX was added to the entire extract at 10 µg, inhibition reached that induced with ATX 1 µg. Conclusions: ATX and the shrimp Extract inhibit amiloride-sensitive sodium channels in Xenopus oocytes and the TEVC method makes it possible to measure the ATX inhibitory effect in bioactive SFE-Extract samples

Heterotrophic bacteria associated with the green alga <i>Ulva rigida</i>: identification and antimicrobial potential

Heterotrophic bacteria associated with the green alga <i>Ulva rigida</i>, collected from the coast of Tunisia, were isolated andsubsequently identified by their 16S rRNA gene sequences and by phylogenetic analysis. The 71 isolates belong to four phyla:Proteobacteria (Alpha-and Gamma- subclasses), Bacteroidetes, Firmicutes, and Actinobacteria. Most of the isolates belong toProteobacteria. The Gram-positive Firmicutes and especially the genus Bacillus were well-represented at the surface of <i>U. rigida</i>,collected from the coast as well as from the lagoon, while Actinobacteria were represented only at the surface of algae collectedfrom the coast of Cap Zebib. Bacteroidetes were more represented at the surface of algae collected from the Ghar El Melh lagoon.The bacterial community of the water surrounding the algae was different from that associated with the surface of the algae.Moreover, the abundance of bacteria in the surrounding water was much lower compared to the density of bacteria associatedwith the surface of the algae. Bacteria isolated from the algal surface were tested for their antimicrobial potential. The resultsshow that ~ 36%of the algae-associated bacterial isolates possess antibacterial activity whereas free-living bacteria, isolated fromthe surrounding water, did not show such activity. The surface of <i>U. rigida</i> was colonized by a high diversity of culturable andpossibly novel epiphytic bacteria that may be an important source of antimicrobial compounds and are therefore ofbiotechnological interest

Two-Dimensional Isoelectric Focusing OFFGEL, Micro-Fluidic Lab-on-Chip Electrophoresis and FTIR for Assessment of Long-Term Stability of rhG-CSF Formulation

Recombinant human granulocyte colony-stimulating factor (rhG-CSF) has been increasingly recognized from among one of the most abundant families of biosimilars. Upon long-term storage, the rhG-CSF is subject to subtle chemical modifications that rapidly occur and, in particular, produce deaminated variants with divergent charge. Indeed, changes in charge from glutamine deamination may alter the way rhG-SCF will refold and the structure of resulting molecule. To assess this charge heterogeneity, 2-D gel electrophoresis has limited application. Recent micro-fluidic-based technical advances offer a great alternative method to better control liquid volumes on a minute scale. Here, we used IEF OFFGEL-lab-on-chip electrophoresis for 2-D separation of the rhG-CSF peptides according to their isoelectric point (pI) and molecular weight (kDa). We used an rhG-CSF commercial therapeutic formulation, kept refrigerated 24 months after expiry. The samples were analyzed for particulate matter and charge variants. Subsequently, the secondary structure was assessed by FTIR spectroscopy and residual biological activity was recorded. Interestingly, we showed an additional band in the acidic gel area above and below the most intense protein band (fractions 10, 11, and 12 at 22.84s). This observation reveals the presence of the rhG-CSF variant charges without any additional high molecular weight impurity or biological activity decrease. We conclude that after two years of storage, the rhG-CSF solution maintained its native secondary structure with little beta-sheet deviation, as reflected in the 1622 cm(-1) and 1695 cm(-1). These data demonstrated that a combined strategy is a more suitable and accurate analytical assessment of the rhG-CSF and recombinant protein-based biosimilars

A recombinant insect-specific alpha-toxin of Buthus occitanus tunetanus scorpion confers protection against homologous mammal toxins.

International audienceWe have constructed a cDNA library from venom glands of the scorpion Buthus occitanus tunetanus and cloned a DNA sequence that encodes an alpha-toxin. This clone was efficiently expressed in Escherichia coli as a fusion protein with two Ig-binding (Z) domains of protein A from Staphylococcus aureus. After CNBr treatment of the fusion protein and HPLC purification, we obtained approximately 1 mg recombinant apha-toxin/l bacterial culture. The toxin, called Bot XIV, displays no toxicity towards mammals but is active towards insects as shown by its paralytic activity against Blatella germanica cockroach and by electrophysiological studies on Periplaneta americana cockroaches. The Bot XIV protein fused to two Z domains is highly immunogenic in mice and induces production of antisera that specifically recognize and neutralize highly toxic components that had been injected into mice. This fusion protein could be very useful for development of potent protective antisera against scorpion venoms