No abstract

The outbreak of COVID-19 and its continued spread have seriously threatened public health. Antibody testing is essential for infection diagnosis, seroepidemiological analysis, and vaccine evaluation. However, convenient, fast, and accurate antibody detection remains a challenge in this protracted battle. Here, we report an ultrafast, lowcost, label-free, and portable SARS-CoV-2 immunoglobulin G (IgG) detection platform based on organic electrochemical transistors (OECTs), which can be remotely controlled by a mobile phone. To enable faster detection, voltage pulses are applied on the gate electrode of the OECT to accelerate binding between the antibody and antigen. By optimizing ion concentrations and pH values of test solutions, we realize specific detection of SARS-CoV-2 IgG in several minutes with a detectable region from 10 fM to 100 nM, which encompasses the range of serum SARS-CoV-2 IgG levels in humans. These portable sensors show promise for use in diagnosis and prognosis of COVID-19.

The emergence of severe acute respiratory syndrome coronavirus (SARS-CoV) in 2002 and Middle East respiratory syndrome coronavirus (MERS-CoV) in 2012 has generated enormous interest in the biodiversity, genomics and cross-species transmission potential of coronaviruses, especially those from bats, the second most speciose order of mammals. Herein, we identified a novel coronavirus, provisionally designated Rousettus bat coronavirus GCCDC1 (Ro-BatCoV GCCDC1), in the rectal swab samples of Rousettus leschenaulti bats by using pan-coronavirus RT-PCR and next-generation sequencing. Although the virus is similar to Rousettus bat coronavirus HKU9 (Ro-BatCoV HKU9) in genome characteristics, it is sufficiently distinct to be classified as a new species according to the criteria defined by the International Committee of Taxonomy of Viruses (ICTV). More striking was that Ro-BatCoV GCCDC1 contained a unique gene integrated into the 3’-end of the genome that has no homologs in any known coronavirus, but which sequence and phylogeny analyses indicated most likely originated from the p10 gene of a bat orthoreovirus. Subgenomic mRNA and cellular-level observations demonstrated that the p10 gene is functional and induces the formation of cell syncytia. Therefore, here we report a putative heterologous inter-family recombination event between a single-stranded, positive-sense RNA virus and a double-stranded segmented RNA virus, providing insights into the fundamental mechanisms of viral evolution.

BackgroundAn increasing number of studies have implicated the microbiome in certain diseases, especially chronic diseases. In this study, the bacterial communities in the sputum of pulmonary tuberculosis patients were explored. Total DNA was extracted from sputum samples from 31 pulmonary tuberculosis patients and respiratory secretions of 24 healthy participants. The 16S rRNA V3 hyper-variable regions were amplified using bar-coded primers and pyro-sequenced using Roche 454 FLX.ResultsThe results showed that the microbiota in the sputum of pulmonary tuberculosis patients were more diverse than those of healthy participants (p<0.05). The sequences were classified into 24 phyla, all of which were found in pulmonary tuberculosis patients and 17 of which were found in healthy participants. Furthermore, many foreign bacteria, such as Stenotrophomonas, Cupriavidus, Pseudomonas, Thermus, Sphingomonas, Methylobacterium, Diaphorobacter, Comamonas, and Mobilicoccus, were unique to pulmonary tuberculosis patients.ConclusionsThis study concluded that the microbial composition of the respiratory tract of pulmonary tuberculosis patients is more complicated than that of healthy participants, and many foreign bacteria were found in the sputum of pulmonary tuberculosis patients. The roles of these foreign bacteria in the onset or development of pulmonary tuberculosis shoud be considered by clinicians.

Mechanistic studies of ATP-dependent proteolysis demonstrate that substrate unfolding is a prerequisite for processive peptide bond hydrolysis. We show that mitochondrial Lon also degrades folded proteins and initiates substrate cleavage non-processively. Two mitochondrial substrates with known or homology-derived three-dimensional structures were used: the mitochondrial processing peptidase ␣-subunit (MPP␣) and the steroidogenic acute regulatory protein (StAR). Peptides generated during a time course of Lon-mediated proteolysis were identified and mapped within the primary, secondary, and tertiary structure of the substrate. Initiating cleavages occurred preferentially between hydrophobic amino acids located within highly charged environments at the surface of the folded protein. Subsequent cleavages proceeded sequentially along the primary polypeptide sequence. We propose that Lon recognizes specific surface determinants or folds, initiates proteolysis at solvent-accessible sites, and generates unfolded polypeptides that are then processively degraded.

Malignant catarrhal fever (MCF) is an often lethal infection of many species in the order Artiodactyla. It is caused by members of the MCF virus group within Gammaherpesvirinae. MCF is a worldwide problem and has a significant economic impact on highly disease-susceptible hosts, such as cattle, bison, and deer. Several epidemiologic forms of MCF, defined by the reservoir ruminant species from which the causative virus arises, are recognized. Wildebeest-associated MCF (WA-MCF) and sheep-associated MCF (SA-MCF) are the most prevalent and well-studied forms of the disease. Historical understanding of MCF is largely based on WA-MCF, in which the causative virus can be propagated in vitro. Characterization of SA-MCF has been constrained because the causative agent has never been successfully propagated in vitro. Development of molecular tools has enabled more definitive studies on SA-MCF. The current understanding of MCF, including its etiological agents, epidemiology, pathogenesis, and prevention, is the subject of the present review.

Tooth bleaching agents may weaken the tooth structure. Therefore, it is important to minimize any risks of tooth hard tissue damage caused by bleaching agents. The aim of this study was to evaluate the effects of applying 45S5 bioglass (BG) before, after, and during 35% hydrogen peroxide (HP) bleaching on whitening efficacy, physicochemical properties and microstructures of bovine enamel. Seventy-two bovine enamel blocks were prepared and randomly divided into six groups: distilled deionized water (DDW), BG, HP, BG before HP, BG after HP and BG during HP. Colorimetric and microhardness tests were performed before and after the treatment procedure. Representative specimens from each group were selected for morphology investigation after the final tests. A significant color change was observed in group HP, BG before HP, BG after HP and BG during HP. The microhardness loss was in the following order: group HP>BG before HP, BG after HP>BG during HP>DDW, BG. The most obvious morphological alteration of was observed on enamel surfaces in group HP, and a slight morphological alteration was also detected in group BG before HP and BG after HP. Our findings suggest that the combination use of BG and HP could not impede the tooth whitening efficacy. Using BG during HP brought better protective effect than pre/post-bleaching use of BG, as it could more effectively reduce the mineral loss as well as retain the surface integrity of enamel. BG may serve as a promising biomimetic adjunct for bleaching therapy to prevent/restore the enamel damage induced by bleaching agents.

S-Nitrosylation is a reversible PTM for regulating protein function. Thioredoxin-1 (Trx1) catalyzes either transnitrosylation or denitrosylation of specific proteins, depending on the redox status of the cysteines within its conserved oxidoreductase CXXC motif. With a disulfide bond formed between the two catalytic cysteines, Trx1 is not only inactive as a denitrosylase, but it may also be nitrosylated at Cys73 and serve as a transnitrosylating agent. Identification of Trx1-mediated transnitrosylation or denitrosylation targets will contribute to a better understanding of Trx1’s function. Previous experimental approaches based on the attenuation of CXXC oxidoreductase activity cannot readily distinguish Trx1 transnitrosylation targets from denitrosylation targets. In this study, we used the ICAT method in conjunction with the biotin switch technique to differentiate Trx1 transnitrosylation targets from denitrosylation target proteins from neuroblastoma cells. We demonstrate that the ICAT approach is effective for quantitative identification of putative Trx1 transnitrosylation and denitrosylation target peptides. From these analyses, we confirmed reports that peroxiredoxin 1 is a Trx1 transnitrosylation, but not a denitrosylation target, and we found several other proteins, including cyclophilin A to be modulated in this manner. Unexpectedly, we found that many nitrosylation sites are reversibly regulated by Trx1, suggesting a more prominent role for Trx1 in regulating S-nitrosylation.