There are currently few approved effective treatments for SARS-CoV-2, the virus responsible for the COVID-19 pandemic. Nanobodies are 12-15 kDa single-domain antibody fragments that can be delivered ...by inhalation and are amenable to relatively inexpensive large scale production compared to other biologicals. We have isolated nanobodies that bind to the SARS-CoV-2 spike protein receptor binding domain and block spike protein interaction with the angiotensin converting enzyme 2 (ACE2) with 1-5 nM affinity. The lead nanobody candidate, NIH-CoVnb-112, blocks SARS-CoV-2 spike pseudotyped lentivirus infection of HEK293 cells expressing human ACE2 with an EC
of 0.3 µg/mL. NIH-CoVnb-112 retains structural integrity and potency after nebulization. Furthermore, NIH-CoVnb-112 blocks interaction between ACE2 and several high affinity variant forms of the spike protein. These nanobodies and their derivatives have therapeutic, preventative, and diagnostic potential.
Rotavirus is the most common cause of severe diarrhea in infants and children worldwide and is responsible for about 215,000 deaths annually. Over 85% of these deaths originate in ...low-income/developing countries in Asia and Africa. Therefore, it is necessary to explore the development of vaccines that avoid the use of "living" viruses and furthermore, vaccines that have viral antigens capable of generating powerful heterotypic responses. Our strategy is based on the expression of the fusion of the anti-DEC205 single-chain variable fragment (scFv) coupled by an OLLAS tag to a viral protein (VP6) of Rotavirus in
Nicotiana
plants. It was possible to express transiently in
N. benthamiana
and
N. sylvestris
a recombinant protein consisting of the single chain variable fragment linked by an OLLAS tag to the VP6 protein. The presence of the recombinant protein, which had a molecular weight of approximately 75 kDa, was confirmed by immunodetection, in both plant species and in both cellular compartments (cytoplasm and apoplast) where it was expressed. In addition, the recombinant protein was modeled, and it was observed that some epitopes of interest are exposed on the surface, which could favor their immunogenic response.
Objective:
Although amyloid‐beta (Aβ) peptide deposition into insoluble plaques is a pathological hallmark of Alzheimer disease; soluble oligomeric Aβ has been hypothesized to more directly underlie ...impaired learning and memory in dementia of the Alzheimer type. However, the lack of a sensitive, specific, and quantitative assay for Aβ oligomers has hampered rigorous tests of this hypothesis.
Methods:
We developed a plate‐based single molecule counting fluorescence immunoassay for oligomeric Aβ sensitive to low pg/ml concentrations of synthetic Aβ dimers using the same Aβ‐specific monoclonal antibody to both capture and detect Aβ. The Aβ oligomer assay does not recognize monomeric Aβ, amyloid precursor protein, or other non‐Aβ peptide oligomers.
Results:
Aβ oligomers were detected in aqueous cortical lysates from patients with dementia of the Alzheimer type and nondemented patients with Aβ plaque pathology. However, Aβ oligomer concentrations in demented patients' lysates were tightly correlated with Aβ plaque coverage (r = 0.88), but this relationship was weaker in those from nondemented patients (r = 0.30) despite equivalent Aβ plaque pathology. The ratio of Aβ oligomer levels to plaque density fully distinguished demented from nondemented patients, with no overlap between groups in this derived variable. Other Aβ and plaque measures did not distinguish demented from nondemented patients. Aβ oligomers were not detected in cerebrospinal fluid with this assay.
Interpretation:
The results raise the intriguing hypothesis that the linkage between plaques and oligomers may be a key pathophysiological event underlying dementia of the Alzheimer type. This Aβ oligomer assay may be useful for many tests of the oligomer hypothesis. ANN NEUROL 2013
The blood-brain barrier (BBB) presents a major obstacle in developing specific diagnostic imaging agents for many neurological disorders. In this study we aimed to generate single domain anti-mouse ...transferrin receptor antibodies (anti-mTfR VHHs) to mediate BBB transcytosis as components of novel MRI molecular contrast imaging agents. Anti-mTfR VHHs were produced by immunizing a llama with mTfR, generation of a VHH phage display library, immunopanning, and in vitro characterization of candidates. Site directed mutagenesis was used to generate additional variants. VHH fusions with neurotensin (NT) allowed rapid, hypothermia-based screening for VHH-mediated BBB transcytosis in wild-type mice. One anti-mTfR VHH variant was fused with an anti-amyloid-beta (Abeta) VHH dimer and labeled with fluorescent dye for direct assessment of in vivo target engagement in a mouse model of AD-related Abeta plaque pathology. An anti-mTfR VHH called M1 and variants had binding affinities to mTfR of <1nM to 1.52nM. The affinity of the VHH binding to mTfR correlated with the efficiency of the VHH-NT induced hypothermia effects after intravenous injection of 600 nmol/kg body weight, ranging from undetectable for nonbinding mutants to -6°C for the best mutants. The anti-mTfR VHH variant M1.sub.P96H with the strongest hypothermia effect was fused to the anti-Abeta VHH dimer and labeled with Alexa647; the dye-labeled VHH fusion construct still bound both mTfR and Abeta plaques at concentrations as low as 0.22 nM. However, after intravenous injection at 600 nmol/kg body weight into APP/PS1 transgenic mice, there was no detectible labeling of plaques above control levels. Thus, NT-induced hypothermia did not correlate with direct target engagement in cortex, likely because the concentration required for NT-induced hypothermia was lower than the concentration required to produce in situ labeling. These findings reveal an important dissociation between NT-induced hypothermia, presumably mediated by hypothalamus, and direct engagement with Abeta-plaques in cortex. Additional methods to assess anti-mTfR VHH BBB transcytosis will need to be developed for anti-mTfR VHH screening and the development of novel MRI molecular contrast agents.
Soluble amyloid-beta (Aβ) aggregates likely contribute substantially to the dementia that characterizes Alzheimer's disease. However, despite intensive study of in vitro preparations and animal ...models, little is known about the characteristics of soluble Aβ aggregates in the human Alzheimer's disease brain. Here we present a new method for extracting soluble Aβ aggregates from human brains, separating them from insoluble aggregates and Aβ monomers using differential ultracentrifugation, and purifying them >6000 fold by dual antibody immunoprecipitation. The method resulted in <40% loss of starting material, no detectible ex vivo aggregation of monomeric Aβ, and no apparent ex vivo alterations in soluble aggregate sizes. By immunoelectron microscopy, soluble Aβ aggregates typically appear as clusters of 10-20 nanometer diameter ovoid structures with 2-3 amino-terminal Aβ antibody binding sites, distinct from previously characterized structures. This approach may facilitate investigation into the characteristics of native soluble Aβ aggregates, and deepen our understanding of Alzheimer's dementia.
Real-time surveillance of airborne SARS-CoV-2 virus is a technological gap that has eluded the scientific community since the beginning of the COVID-19 pandemic. Offline air sampling techniques for ...SARS-CoV-2 detection suffer from longer turnaround times and require skilled labor. Here, we present a proof-of-concept pathogen Air Quality (pAQ) monitor for real-time (5 min time resolution) direct detection of SARS-CoV-2 aerosols. The system synergistically integrates a high flow (~1000 lpm) wet cyclone air sampler and a nanobody-based ultrasensitive micro-immunoelectrode biosensor. The wet cyclone showed comparable or better virus sampling performance than commercially available samplers. Laboratory experiments demonstrate a device sensitivity of 77-83% and a limit of detection of 7-35 viral RNA copies/m
of air. Our pAQ monitor is suited for point-of-need surveillance of SARS-CoV-2 variants in indoor environments and can be adapted for multiplexed detection of other respiratory pathogens of interest. Widespread adoption of such technology could assist public health officials with implementing rapid disease control measures.
Stream interaction regions (SIRs) dominate the large‐scale solar wind dynamics during the minimum of the solar cycle. The interaction of SIRs with the magnetosphere causes most of geomagnetic storms ...during this epoch. We used in‐situ solar wind observations at 1 AU to study 62 SIRs detected in the interval 2007–2008 (minimum of cycle 23) and 61 SIRs in the interval 2018–2019 (minimum of cycle 24). We compared distinct characteristics of SIRs, such as the solar wind streams velocities, the presence of forward and/or reverse shocks (RS), SIR radial widths, the relative position of the stream interface within the SIRs, SIR latitudinal orientation, and the geoeffectiveness. There were more geomagnetic storms driven by SIRs in cycle 23 than in cycle 24. The pattern of fast solar wind streams in cycle 23 tended to be faster than in cycle 24. We found more SIRs with RS in cycle 23 than in cycle 24. For the geoeffective SIRs, the momentum flows from the fast solar wind to the slow solar wind, as well as their stream interface is closer to the SIR front. Coronal holes associated with SIRs registered in cycle 23 tended to be wider in longitude near the solar equator and/or at midlatitudes. We did not find a clear relation between the geoeffectiveness of the SIRs and their latitudinal inclinations.
Key Points
Stream interaction regions at 1 AU had different characteristics in solar cycle minimum 23 and 24
We found differences in their patterns of solar wind streams, the presence of shock waves, and the relative position of their stream interface
Stream interaction regions were more geoeffective in the minimum of solar cycle 23 than in the minimum of cycle 24
ABSTRACT
Using numerical simulations, we study the effects of thermal conduction and radiative cooling on the formation and evolution of solar jets with some macrospicules features. We initially ...assume that the solar atmosphere is rarely in equilibrium through energy imbalance. Therefore, we test whether the background flows resulting from an imbalance between thermal conduction and radiative cooling influence the jets’ behaviour. In this particular scenario, we trigger the formation of the jets by launching a vertical velocity pulse localized at the upper chromosphere for the following test cases: (i) adiabatic case; (ii) thermal conduction case; (iii) radiative cooling case; and (iv) thermal conduction + radiative cooling case. According to the test results, the addition of the thermal conduction results in smaller and hotter jets than in the adiabatic case. On the other hand, the radiative cooling dissipates the jet after reaching the maximum height (≈5.5 Mm), making it shorter and colder than in the adiabatic and thermal conduction cases. Besides, the flow generated by the radiative cooling is more substantial than that caused by the thermal conduction. Despite the energy imbalance of the solar atmosphere background, the simulated jet shows morphological features of macrospicules. Furthermore, the velocity pulse steepens into a shock that propagates upward into a solar corona that maintains its initial temperature. The shocks generate the jets with a quasi-periodical behaviour that follows a parabolic path on time–distance plots consistent with macrospicule jets’ observed dynamics.
This work assessed the effect of soil amended with tannery sludge (0, 500, 1000, 2000, 4000 and 8000
mg
Cr
kg
−1
soil), Cr
3+ as CrCl
3·6H
2O (0, 100, 250, 500, 1000 and 2000
mg
Cr
kg
−1
soil), and ...Cr
6+ as K
2Cr
2O
7 (0, 25, 50, 100, 200 and 500
mg
Cr
kg
−1
soil) on wheat, oat and sorghum plants.
Seed germination, seedling growth (root and shoot) and Cr accumulation in dry tissue were measured. Toxicological parameters; medium effective concentration, no observed adverse effect concentration and low observed adverse effect concentration were determined. Root growth was the most sensitive assessment of Cr toxicity (
P
<
0.05). There was a significant correlation (
P
<
0.0001) between Cr accumulation in dry tissue and toxic effects on seedling growth. The three Cr sources had different accumulation and mobility patterns; tannery sludge was less toxic for all three plant species, followed by CrCl
3·6H
2O and K
2Cr
2O
7.
Highlights ► We perform a case–case comparison as an improvement of the test-negative design. ► We report IVE estimates with a low probability of bias. ► Influenza vaccination halved the risk of ...confirmed influenza hospitalization. ► This effect was consistent regardless of age over 60. ► The measured effect was specific for confirmed influenza hospitalizations.
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