Safety and immunogenicity of radiation-attenuated PfSPZ vaccine in equatoguinean infants, children, and adults

The radiation-attenuated Plasmodium falciparum sporozoites (PfSPZ) Vaccine has demonstrated safety and immunogenicity in 5-month-old to 50-year-old Africans in multiple trials. Except for one, each trial has restricted enrollment to either infants and children or adults /= 0.17). There were no significant differences between vaccinees and controls with respect to the rates or severity of unsolicited AEs or laboratory abnormalities. Development of antibodies to P. falciparum circumsporozoite protein occurred in 67/69 vaccinees (97%) and 0/15 controls. Median antibody levels were highest in infants and 1-5-year-olds and declined progressively with age. Antibody responses in children were greater than in adults protected against controlled human malaria infection. Robust immunogenicity, combined with a benign AE profile, indicates children are an ideal target for immunization with PfSPZ Vaccine

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

Arsenite and chromate sequestration onto ferrihydrite, siderite and goethite nanostructured minerals: Isotherms from flow-through reactor experiments and XAS measurements

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Nickel accelerates pyrite nucleation at ambient temperature

Chemical and isotopic compositions of pyrites are used as biogeochemical tracers in Archean to modern sediments. Moreover, pyrite formation from monosulphide precursors has been proposed to be involved in prebiotic chemistry. However, the factors controlling pyrite formation and distribution in the sedimentary record are incompletely understood. Here, we show that Ni2+ ions accelerate similar to 5 times the nucleation of pyrite at ambient temperature. Using Fe and Ni K-edge EXAFS and TEM-EDXS we demonstrate that Ni(II) is directly involved in the nucleation of pyrite synthesised by reacting Fe(III) with Na2S in the presence of aqueous Ni(II) impurity. Initial formation of a Ni-enriched pyrite core is followed by overgrowth of a Ni-depleted pyrite shell, leading to compositional zoning of the Fe1-xNixS2 nanocrystals (x = 0.05 to 0.0004). The molar Ni/Fe ratio in the final aqueous solution was then 2000 times lower than the starting ratio of 0.01. This enhanced and accelerated trapping of Ni by pyrite could be of prime importance in controlling Ni concentration in the ocean during early diagenesis of marine sediments, and could thus have important implications for interpreting abundances of Ni and pyrite in the sedimentary record. In addition, acceleration of pyrite nucleation in the presence of nickel could help understanding the role of Fe-Ni sulphides in catalysing potential prebiotic reactions

Chélation de l'Uranium (VI) par les phosphates de fer amorphes précipités sur les filaments de Sphaerotilus natans

International audienceU(VI) sorption to iron oxyhydroxides, precipitation of phosphate minerals, as well as biosorption on bacterial biomass are among the most reported processes able to scavenge U(VI) under oxidizing conditions. Although phosphates significantly influence bacterially mediated as well as iron. oxyhydroxide mediated scavenging of uranium, the sorption or coprecipitation of U(VI) with poorly crystalline nanosized iron phosphates has been scarcely documented, especially in the presence of microorganisms. Here we show that dissolved U(VI) can be bound to amorphous iron phosphate during their deposition on Sphaerotilus natans filamentous bacteria. Uranium LIII -edge EXAFS analysis reveals that uranyl ions share equatorial atoms with phosphate tetrahedron from the amorphous iron phosphate, with a characteristic U− P distance of 3.6 Å. In addition, the uranyl ions are bound to FeO6 octahedra, with U− Fe distances at ∼ 3.4 Å and at ∼ 4.0 Å. The first distance corresponds to bidentate edge-sharing complex while the latter one can be interpreted as bidentate corner-sharing complexes in which two adjacent equatorial oxygen atoms are shared with the vertices of a FeO6 octahedron and that of a phosphate tetrahedron. Furthermore, based on these sorption reactions, we demonstrate the ability of an attached S. natans biofilm to remove uranium from solution without any filtration step.La sorption de l’Uranium (VI) sur les oxyhydroxydes de fer, les phosphates minéraux, ainsi que sa biosorption sur la biomasse bactérienne, sont parmi les procédés les plus à même de piéger cet élément dans des conditions oxydantes. Les phosphates ainsi que le fer, influencent significativement l’action des bactéries. La sorption de l’Uranium par l’intermédiaire des oxyhydroxydes, ainsi que la sorption ou coprécipitation de Uranium (VI) par les phosphates de fer nanométrique faiblement cristallins, en particulier en présence de micro-organismes, est peu documenté. Nous montrons que l’Uranium (VI) dissous peut être lié au phosphate de fer amorphe lors de son dépôt sur les bactéries filamenteuses Sphaerotilus natans. L’analyse en EXAFS de l’Uranium révèle que les ions uranyle partagent des atomes équatoriaux avec le phosphate tétraédrique du phosphate de fer amorphe, avec une distance U-P caractéristique de 3,6 Å. En outre, les ions uranyle sont liés au FeO6 octaédrique, avec une distances U-Fe de ~ 3,4 Å et de ~ 4,0 Å. La première distance correspond au complexe de bord alors que ce dernier peut être interprété comme un complexe de sommet dans lequel deux atomes d'oxygène équatoriaux adjacents sont partagés avec les sommets d'un octaèdre FeO6 et ceux d'un tétraèdre de phosphate. En outre, sur la base de ces réactions de sorption, nous démontrons la capacité de biofilms de S. natans pour éliminer l'uranium de la solution sans aucune étape de filtration

Arsenic cavenging by aluminum-substituted ferrihydrites in a circumneutral ph river impacted by acid mine drainage

Ferrihydrite (Fh) is a nanocrystalline ferric oxyhydroxide involved in the retention of pollutants in natural systems and in water-treatment processes. The status and properties of major chemical impurities in natural Fh is however still scarcely documented. Here we investigated the structure of aluminum-rich Fh, and their role in arsenic scavenging in river-bed sediments from a circumneutral river (pH 6-7) impacted by an arsenic-rich acid mine drainage (AMD). Extended X-ray absorption fine structure (EXAFS) spectroscopy at the Fe K-edge shows that Fh is the predominant mineral phase forming after neutralization of the AMD, in association with minor amount of schwertmannite transported from the AMD. TEM-EDXS elemental mapping and SEM-EDXS analyses combined with EXAFS analysis indicates that Al3+ substitutes for Fe3+ ions into the Fh structure in the natural sediment samples, with local aluminum concentration within the 25-30 +/- 10 mol %Al range. Synthetic aluminous Fh prepared in the present study are found to be less Al-substituted (14-20 +/- 5 mol %Al). Finally, EXAFS analysis at the arsenic K-edge indicates that As(V) form similar inner-sphere surface complexes on the natural and synthetic Al-substituted Fh studied. Our results provide direct evidence for the scavenging of arsenic by natural Al-Fh, which emphasize the possible implication of such material for scavenging pollutants in natural or engineered systems

A methodological framework to study the behavior and kinetic influence of V, Mn, Co, Ni, Cu, Zn, As, Se and Mo during pyrite formation via the polysulfide pathway at ambient temperature

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Synchrotron X-ray studies of heavy metal mineral-microbe interactions

International audienceTHE availability of analytical methods that utilize the very intense and bright X-rays from synchro- tron radiation sources has fundamentally changed the way in which geoscientists, environmental scientists and soil scientists study complex environmental samples and decipher the chemical and biological processes that impact the specia- tion, transport and potential bioavailability of environmental toxins (Brown et al., 2006). Such samples are often mixtures of crystalline and amorphous phases in particle-sizes ranging from cm to nm, adsorbed metal ions and organic molecules, natural organic matter, microbial organisms, algae, plant materials and aqueous solutions. The processes that affect the chemical forms and environmental fate of contaminants in such mixtures range from surface adsorption, desorption, precipitation and dissolution reac- tions, often involving a combination of hydro- lysis, ligand exchange and electron transfer, to biological interactions in which microbial organ- isms, algae or plants interact with mineral surfaces and environmental contaminantform such contaminants into more (or less) toxic forms; and (3) mineral dissolution reactions, which can release heavy metal and metalloid contaminants. Determining the effects of these processes on environmental contaminant

Characterization of ESBL-producing enterobacteria from fruit bats in an unprotected area of Makokou, Gabon [+ Correction in : Microorganisms, 2020, vol.8, no 9, art. 1384]

In Gabon, terrestrial mammals of protected areas have been identified as a possible source of antibiotic-resistant bacteria. Some studies on antibiotic resistance in bats have already been carried out. The main goal of our study was to detect extended-spectrum beta-lactamases (ESBLs) that are produced by enterobacteria from bats in the Makokou region in Gabon. Sixty-eight fecal samples were obtained from 68 bats caught in the forests located 1 km from the little town of Makokou. After culture and isolation, 66 Gram-negative bacterial colonies were obtained. The double-disk diffusion test confirmed the presence of ESBLs in six (20.69%) Escherichia coli isolates, four (13.79%) Klebsiella pneumoniae isolates, and one (3.45%) Enterobacter cloacae isolate. The analysis based on the nucleotide sequences of the ESBL resistance genes showed that all cefotaximase-Munichs (CTX-Ms) were CTX-M-15 and that all sulfhydryl variables (SHVs) were SHV-11: 41.67% CTX-M-15-producing E. coli, 16.67% CTX-M-15+SHV-11-producing E. coli, 8.33% CTX-M-15-producing K. pneumoniae, 25% CTX-M-15+SHV-11-producing K. pneumoniae, and 8.33% CTX-M-15-produced E. cloacae. This study shows for the first time the presence of multiresistant ESBL-producing enterobacteria in fruit bats in Makokou