Based on previous findings supporting HLA-F as a ligand for KIR3DL2 and KIR2DS4, we investigated the potential for MHC-I open conformers (OCs) as ligands for KIR3DS1 and KIR3DL1 through interactions ...measured by surface plasmon resonance. These measurements showed physical binding of KIR3DS1 but not KIR3DL1 with HLA-F and other MHC-I OC while also confirming the allotype specific binding of KIR3DL1 with MHC-I peptide complex. Concordant results were obtained with biochemical pull-down from cell lines and biochemical heterodimerization experiments with recombinant proteins. In addition, surface binding of HLA-F and KIR3DS1 to native and activated NK and T cells was coincident with specific expression of the putative ligand or receptor. A functional response of KIR3DS1 was indicated by increased granule exocytosis in activated cells incubated with HLA-F bound to surfaces. The data extend a model for interaction between MHC-I open conformers and activating KIR receptors expressed during an inflammatory response, potentially contributing to communication between the innate and adaptive immune response.
Vaccines prevent infectious disease largely by inducing protective neutralizing antibodies against vulnerable epitopes. Several major pathogens have resisted traditional vaccine development, although ...vulnerable epitopes targeted by neutralizing antibodies have been identified for several such cases. Hence, new vaccine design methods to induce epitope-specific neutralizing antibodies are needed. Here we show, with a neutralization epitope from respiratory syncytial virus, that computational protein design can generate small, thermally and conformationally stable protein scaffolds that accurately mimic the viral epitope structure and induce potent neutralizing antibodies. These scaffolds represent promising leads for the research and development of a human respiratory syncytial virus vaccine needed to protect infants, young children and the elderly. More generally, the results provide proof of principle for epitope-focused and scaffold-based vaccine design, and encourage the evaluation and further development of these strategies for a variety of other vaccine targets, including antigenically highly variable pathogens such as human immunodeficiency virus and influenza.
Bacteria use tight-binding, ferric-specific chelators called siderophores to acquire iron from the environment and from the host during infection; animals use proteins such as transferrin and ...ferritin to transport and store iron. Recently, candidate compounds that could serve endogenously as mammalian siderophore equivalents have been identified and characterized through associations with siderocalin, the only mammalian siderophore-binding protein currently known. Siderocalin, an antibacterial protein, acts by sequestering iron away from infecting bacteria as siderophore complexes. Candidate endogenous siderophores include compounds that only effectively transport iron as ternary complexes with siderocalin, explaining pleiotropic activities in normal cellular processes and specific disease states.
Sharp rises in the atmospheric abundance of ethane (C2H6) have been detected from 2009 onwards in the Northern Hemisphere as a result of the unprecedented growth in the exploitation of shale gas and ...tight oil reservoirs in North America. Using time series of C2H6 total columns derived from ground-based Fourier transform infrared (FTIR) observations made at five selected Network for the Detection of Atmospheric Composition Change sites, we characterize the recent C2H6 evolution and determine growth rates of ∼5% yr−1 at mid-latitudes and of ∼3% yr−1 at remote sites. Results from CAM-chem simulations with the Hemispheric Transport of Air Pollutants, Phase II bottom-up inventory for anthropogenic emissions are found to greatly underestimate the current C2H6 abundances. Doubling global emissions is required to reconcile the simulations and the observations prior to 2009. We further estimate that North American anthropogenic C2H6 emissions have increased from 1.6 Tg yr−1 in 2008 to 2.8 Tg yr−1 in 2014, i.e. by 75% over these six years. We also completed a second simulation with new top-down emissions of C2H6 from North American oil and gas activities, biofuel consumption and biomass burning, inferred from space-borne observations of methane (CH4) from Greenhouse Gases Observing SATellite. In this simulation, GEOS-Chem is able to reproduce FTIR measurements at the mid-latitudinal sites, underscoring the impact of the North American oil and gas development on the current C2H6 abundance. Finally we estimate that the North American oil and gas emissions of CH4, a major greenhouse gas, grew from 20 to 35 Tg yr−1 over the period 2008-2014, in association with the recent C2H6 rise.
Determinants of protective immunity against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection require the development of well-standardized, reproducible antibody assays. This ...need has led to the emergence of a variety of neutralization assays. Head-to-head evaluation of different SARS-CoV-2 neutralization platforms could facilitate comparisons across studies and laboratories. Five neutralization assays were compared using 40 plasma samples from convalescent individuals with mild to moderate coronavirus disease 2019 (COVID-19): four cell-based systems using either live recombinant SARS-CoV-2 or pseudotyped viral particles created with lentivirus (LV) or vesicular stomatitis virus (VSV) packaging and one surrogate enzyme-linked immunosorbent assay (ELISA)-based test that measures inhibition of the spike protein receptor binding domain (RBD) binding its receptor human angiotensin converting enzyme 2 (hACE2). Vero cells, Vero E6 cells, HEK293T cells expressing hACE2, and TZM-bl cells expressing hACE2 and transmembrane serine protease 2 were tested. All cell-based assays showed 50% neutralizing dilution (ND
) geometric mean titers (GMTs) that were highly correlated (Pearson
= 0.81 to 0.89) and ranged within 3.4-fold. The live virus assay and LV pseudovirus assays with HEK293T/hACE2 cells showed very similar mean titers, 141 and 178, respectively. ND
titers positively correlated with plasma IgG targeting SARS-CoV-2 spike protein and RBD (
= 0.63 to 0.89), but moderately correlated with nucleoprotein IgG (
= 0.46 to 0.73). ND
GMTs mirrored ND
data and showed similar correlation between assays and with IgG concentrations. The VSV pseudovirus assay and LV pseudovirus assay with HEK293T/hACE2 cells in low- and high-throughput versions were calibrated against the WHO SARS-CoV-2 IgG standard. High concordance between the outcomes of cell-based assays with live and pseudotyped virions enables valid cross-study comparison using these platforms.
We report the first long‐term measurements of ammonia (NH3) in the high Arctic. Enhancements of the total columns of NH3, carbon monoxide (CO), hydrogen cyanide (HCN), and ethane (C2H6) were detected ...in July and August 2014 at Eureka, Nunavut, and Toronto, Ontario. Enhancements were attributed to fires in the Northwest Territories using the FLEXPART Lagrangian dispersion model and the Moderate Resolution Imaging Spectroradiometer Fire Hot Spot data set. Emission estimates are reported as average emission factors for HCN (0.62 ± 0.34 g kg−1), C2H6 (1.50 ± 0.75 g kg−1), and NH3 (1.40 ± 0.72 g kg−1). Observations of NH3 at both sites demonstrate long‐range transport of NH3, with an estimated NH3 lifetime of 48 h. We also conclude that boreal fires may be an important source of NH3 in the summertime Arctic.
Key Points
First long‐term time series of NH3 concentrations in the high Arctic
Boreal wildfire emissions of NH3 detected in Canadian Arctic and Southern Canada
2014 Northwest Territories fires were a considerable source of NH3 in the summertime Arctic
Antimicrobial proteins comprise a significant component of the acute innate immune response to infection. They are induced by pattern recognition receptors as well as by cytokines of the innate and ...adaptive immune pathways and play important roles in infection control and immunomodulatory homeostasis. Lipocalin 2 (siderocalin, NGAL, 24p3), a siderophore-binding antimicrobial protein, is critical for control of systemic infection with Escherichia coli; however, its role in mucosal immunity in the respiratory tract is unknown. In this study, we found that lipocalin 2 is rapidly and robustly induced by Klebsiella pneumoniae infection and is TLR4 dependent. IL-1beta and IL-17 also individually induce lipocalin 2. Mucosal administration of IL-1beta alone could reconstitute the lipocalin 2 deficiency in TLR4 knockout animals and rescue them from infection. Lipocalin 2-deficient animals have impaired lung bacterial clearance in this model and mucosal reconstitution of lipocalin 2 protein in these animals resulted in rescue of this phenotype. We conclude that lipocalin 2 is a crucial component of mucosal immune defense against pulmonary infection with K. pneumoniae.
VRC01-class broadly neutralizing HIV-1 antibodies protect animals from experimental infection and could contribute to an effective vaccine response. Their predicted germline forms (gl) bind Env ...inefficiently, which may explain why they are not elicited by HIV-1 Env-immunization. Here we show that an optimized Env immunogen can engage multiple glVRC01-class antibodies. Furthermore, this immunogen activates naive B cells expressing the human germline heavy chain of 3BNC60, paired with endogenous mouse light chains in vivo. To address whether it activates B cells expressing the fully humanized gl3BNC60 B-cell receptor (BCR), we immunized mice carrying both the heavy and light chains of gl3BNC60. B cells expressing this BCR display an autoreactive phenotype and fail to respond efficiently to soluble forms of the optimized immunogen, unless it is highly multimerized. Thus, specifically designed Env immunogens can activate naive B cells expressing human BCRs corresponding to precursors of broadly neutralizing HIV-1 antibodies even when the B cells display an autoreactive phenotype.
Several varieties of vapor-grown carbon nanofiber with diameters under 200
nm and conically shaped graphene planes canted with respect to the longitudinal fiber axis are available. Because of the ...strong inter-fiber bonding, compounding these fibers with polymeric resins demands some care. Therefore, fabrication of nanofiber composites has led to variable and occasionally disappointing electrical conductivity and tensile strength. In the following paper we review the published data for vapor-grown carbon nanofiber (VGCNF) composites and show that the best results, achieved with satisfactory dispersion, are consistent with each other and with calculation. With careful preparation techniques, composite tensile strength and modulus of more than triple that of the neat resin can be achieved with 15
vol% fibers. Electrical conductivity can be achieved with less than 1/2
vol% fiber loading, while above 15
vol% loading resistivities near 0.1
Ω
cm are possible. Excellent compressive strength and thermal conductivity can also be achieved.
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