Dysbiosis of oropharyngeal microbiome and antibiotic resistance in hospitalized COVID-19 patients.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic is ongoing and multiple studies have elucidated its pathogenesis, however, the related- microbiome imbalance caused by SARS-CoV-2 is still not clear. In this study, we have comprehensively compared the microbiome composition and associated function alterations in the oropharyngeal swabs of healthy controls and coronavirus disease 2019 (COVID-19) patients with moderate or severe symptoms by metatranscriptomic sequencing. We did observe a reduced microbiome alpha-diversity but significant enrichment of opportunistic microorganisms in patients with COVID-19 compared with healthy controls, and the microbial homeostasis was rebuilt following the recovery of COVID-19 patients. Correspondingly, less functional genes in multiple biological processes and weakened metabolic pathways such as carbohydrate metabolism, energy metabolism were also observed in COVID-19 patients. We only found higher relative abundance of limited genera such as Lachnoanaerobaculum between severe patients and moderate patients while no worthy-noting microbiome diversity and function alteration were observed. Finally, we noticed that the co-occurrence of antibiotic resistance and virulence was closely related to the microbiome alteration caused by SRAS-CoV-2. Overall, our findings demonstrate that microbial dysbiosis may enhance the pathogenesis of SARS-CoV-2 and the antibiotics treatment should be critically considered.

Effect of Nanobubbles on the Flotation Performance of Oxidized Coal.

In this study, the effects of air bubbles and nanobubbles on flotation performance and kinetics of oxidized coal were investigated. The surface properties of the coal sample before and after oxidation were characterized by a scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). The nanobubbles on highly oriented pyrolytic graphite (HOPG) were observed by an atomic force microscope (AFM). The interaction between coal and conventional bubbles in the absence and presence of nanobubbles was explained by induction time. Flotation results showed that oxidized coal flotation in the presence of nanobubbles resulted in 10% higher combustible matter recovery than conventional air bubble flotation. Moreover, it was found that the flotation of oxidized coal in the absence and presence of nanobubbles can be best described using the first-order model with the rectangular model. AFM images analysis showed that a large number of nanobubbles were produced and attached to the oxidized coal surface. The induction times of the oxidized coal in the absence and presence of nanobubbles were 1000 and 39 ms, respectively, indicating that the existence of nanobubbles effectively promotes the interaction between oxidized coal and macroair bubbles. In addition, the agglomeration between oxidized coal particles also occurred spontaneously in the presence of nanobubbles, which was helpful in improving the combustible matter recovery and flotation rate of oxidized coal.

Development and Evaluation of a Rapid and Sensitive EBOV-RPA Test for Rapid Diagnosis of Ebola Virus Disease.

Confirming Ebola virus disease (EVD), a deadly infectious disease, requires real-time RT-PCR, which takes up to a few hours to yield results. Therefore, a rapid diagnostic assay is imperative for EVD diagnosis. A rapid nucleic acid test based on recombinase polymerase amplification (EBOV-RPA) was developed to specifically detect the 2014 outbreak strains. The EBOV-RPA assay was evaluated by testing samples from suspected EVD patients in parallel with RT-PCR. An EBOV-RPA, which could be completed in 20 min, was successfully developed. Of 271 patients who tested positive for Ebola virus by RT-PCR, 264 (sensitivity: 97%, 95% CI: 95.5-99.3%) were positive by EBOV-RPA; 101 of 104 patients (specificity: 97%, 95% CI: 93.9-100%) who tested negative by RT-PCR were also negative by EBOV-RPA. The sensitivity values for samples with a Ct value of <34, which accounted for 95.59% of the samples, was 100%. Discordant samples positive by RT-PCR but negative by EBOV-RPA had significantly high Ct values. Results of external quality assessment samples with EBOV-RPA were 100%, consistent with those of RT-PCR. The EBOV-RPA assay showed 97% sensitivity and 97% specificity for all EVD samples tested, making it a rapid and sensitive test for EVD diagnosis.

[Western area surge for controlling Ebola hemorrhagic fever outbreak in Sierra Leone and evaluation of its effect].

OBJECTIVE: To investigate the Western Area Surge (WAS) program in the Ebola outbreak of Sierra Leone, and to analyze its implementing effect. METHODS: The subject of this study was 3,813 laboratory confirmed Ebola hemorrhagic fever (EHF) cases reported in Sierra Leone from November 19, 2014 through January 27, 2015, a period before and after the implementation of the WAS program. To analyze and make conclusions according to the working experience of China Mobile Laboratory Reponses Team in the fight of Ebola outbreak, using WHO published EHF case definition to make diagnosis and compare the number of bed numbers, confirmed EHF cases, samples tested, and positive rates before and after implementation of WAS program. RESULTS: From the implementation of WAS program on 17th December 2014 to half a month later, the total numbers of Ebola holding and treatment centers increased from 640 to 960, six additional laboratories were established. On January, 2015, another two laboratories from America and The Netherlands were established. The numbers of samples tested one month before and after WAS program were 7,891 and 9,783, respectively, with an increase of 24.0 percent, while the positive rate of Ebola virus decreased from 22.2% (1,752/7,891) to 11.0% (1,077/9,783). The positive rate of blood samples decreased from 39.6% (248/626) in the month before WAS program to 27.4% (131/478) (χ2=17.93, P<0.001) in the mother after WAS program, the positive rate of blood samples 22.7% (103/454) to 10% (62/609) (χ2=31.03, P<0.001), accordingly. After 3 weeks of WAS program, in addition to Western Area, another four hotspots in Sierra Leone had also reported a significant decrease of the numbers of confirmed EVD cases. Forty-two days after implementation of WAS program, the daily number of laboratory confirmed EHF cases decreased from 63 to 10. CONCLUSION: WAS program played a vital role in controlling the EHF outbreak rapidly in Sierra Leone. It could also provide guidance for the control similar large infectious diseases outbreak in the future.

Synthesis of Pt nanoparticles decorated 1,5-diaminoanthraquinone nanofibers and their application toward catalytic reduction of 4-nitrophenol.

The present communication reports on the rapid preparation of 1,5-diaminoanthraquinone nanofibers (DAAQNFs) on a large scale by a reprecipitation method and their subsequent decoration with small platinum nanoparticles (PtNPs) using tannic acid (TA) as a reducing agent. It suggests the resultant PtNP/DAAQNF composites exhibit a good catalytic activity toward reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) by NaBH4. It also suggests that the composites exhibit higher catalytic activity than the PtNPs due to that the DAAQNF support may play an active part in the catalysis, yielding a synergistic effect. The possible mechanism involved has also been discussed.

Carbon nanocapsules as an effective sensing platform for fluorescence-enhanced nucleic acid detection.

In this communication, we demonstrate the proof of concept that carbon nanocapsules (CNCs) can be used as an effective fluorescent sensing platform for nucleic acid detection with selectivity down to single-base mismatch. The detection is accomplished by two steps: (1) CNC adsorbs and quenches the fluorescence of the dye-labeled single-stranded DNA (ssDNA) probe; (2) in the presence of the target, a hybridization event occurs, which produces a double-stranded DNA (dsDNA) that detaches from the CNC surface, leading to recovery of the dye fluorescence.

Anchoring gold nanoparticles on graphene nanosheets functionalized with cationic polyelectrolyte: a novel catalyst for 4-nitrophenol reduction.

In this paper, a stable aqueous dispersion of graphene nanosheets (GNs) has been prepared by chemical reduction of graphene oxide (GO) with hydrazine hydrate in the presence of poly [(2-ethyldimethylammonioethyl methacrylate ethyl sulfate)-co-(1-vinylpyrrolidone)] (PQ11). Taking advantages of the fact that PQ11 is a positively charged polymer exhibiting reducing ability, we further demonstrated the subsequent decoration of GN with gold nanoparticals (AuNPs) by in-situ chemical reduction of HAuCl4. It was found that such nanocomposites exhibit good catalytic activity toward 4-nitrophenol (4-NP) reduction and the GN supports also enhance the catalytic activity via a synergistic effect.

2,4,6-Tris (2-pyridyl)-1,3,5-triazine nanobelts as an effective fluorescent sensing platform for DNA detection.

In the present study, we report on the use of 2,4,6-tris (2-pyridyl)-1,3,5-triazine nanobelts (TPTNBs) as an effective fluorescent sensing platform for DNA detection for the first time. The general concept used in this approach is based on adsorption of fluorescently labeled single-stranded DNA (ssDNA) probe by TPTNB, due to the strong pi-pi stacking between unpaired DNA bases and TPTNB. As a result, the fluorophor is brought into close proximity of TPTNB, leading to fluorescence quenching. Upon presence of the target ssDNA, specific hybridization with the target takes place to form a double-stranded DNA (dsDNA). The resultant dsDNA cannot be adsorbed by TPTNB due to its rigid conformation and the absence of unpaired DNA bases. Thus, the fluorophor is seperated from TPTNB accompanied by fluorescence recovery. The present system shows a detection limit as low as 3 nM and has a high selectivity down to single-base mismatch.

Complete genomic characterization of two tick-borne encephalitis viruses isolated from China.

Tick-borne encephalitis (TBEV) is prevalent over a wide area of the Eurasian continent. TBE viruses cause severe encephalitis in humans, with serious sequelae, and have a significant impact on public health in these endemic regions. To gain insight into genetic evolution of tick-borne encephalitis virus (TBEV) in China, the complete genomic sequences of two TBEV strains Senzhang and MDJ01, which were isolated in 1953 and 2001 respectively, were characterized. The complete genome sequences of two strains were all consist 10,784 nucleotides and there are 364 nucleotides deletion in the 3' nontranslated region. Compared with other TBEV strains, homology range from 85.2% (Zausaev) to 99.6% (MDJ02 and MDJ03) on the level of nucleotide. Phylogenetic trees based on the complete genome, open reading frame and E gene nucleotide sequences all showed that the strains Senzhang and MDJ01 belong to Far-Eastern subtype and cluster with other Chinese TBEV strains. All these implied that TBEVs prevalent in China were highly conservative, other measurement should be taken to improve protective efficacy of present vaccine.

Economical, green synthesis of fluorescent carbon nanoparticles and their use as probes for sensitive and selective detection of mercury(II) ions.

The present article reports on a simple, economical, and green preparative strategy toward water-soluble, fluorescent carbon nanoparticles (CPs) with a quantum yield of approximately 6.9% by hydrothermal process using low cost wastes of pomelo peel as a carbon source for the first time. We further explore the use of such CPs as probes for a fluorescent Hg(2+) detection application, which is based on Hg(2+)-induced fluorescence quenching of CPs. This sensing system exhibits excellent sensitivity and selectivity toward Hg(2+), and a detection limit as low as 0.23 nM is achieved. The practical use of this system for Hg(2+) determination in lake water samples is also demonstrated successfully.

Reverse genetics of SARS-related coronavirus using vaccinia virus-based recombination.

Severe acute respiratory syndrome (SARS) is a zoonotic disease caused by SARS-related coronavirus (SARS-CoV) that emerged in 2002 to become a global health concern. Although the original outbreak was controlled by classical public health measures, there is a real risk that another SARS-CoV could re-emerge from its natural reservoir, either in its original form or as a more virulent or pathogenic strain; in which case, the virus would be difficult to control in the absence of any effective antiviral drugs or vaccines. Using the well-studied SARS-CoV isolate HKU-39849, we developed a vaccinia virus-based SARS-CoV reverse genetic system that is both robust and biosafe. The SARS-CoV genome was cloned in separate vaccinia virus vectors, (vSARS-CoV-5prime and vSARS-CoV-3prime) as two cDNAs that were subsequently ligated to create a genome-length SARS-CoV cDNA template for in vitro transcription of SARS-CoV infectious RNA transcripts. Transfection of the RNA transcripts into permissive cells led to the recovery of infectious virus (recSARS-CoV). Characterization of the plaques produced by recSARS-CoV showed that they were similar in size to the parental SARS-CoV isolate HKU-39849 but smaller than the SARS-CoV isolate Frankfurt-1. Comparative analysis of replication kinetics showed that the kinetics of recSARS-CoV replication are similar to those of SARS-CoV Frankfurt-1, although the titers of virus released into the culture supernatant are approximately 10-fold less. The reverse genetic system was finally used to generate a recSARS-CoV reporter virus expressing Renilla luciferase in order to facilitate the analysis of SARS-CoV gene expression in human dendritic cells (hDCs). In parallel, a Renilla luciferase gene was also inserted into the genome of human coronavirus 229E (HCoV-229E). Using this approach, we demonstrate that, in contrast to HCoV-229E, SARS-CoV is not able to mediate efficient heterologous gene expression in hDCs.

Novel application of CoFe layered double hydroxide nanoplates for colorimetric detection of H(2)O(2) and glucose.

The present communication demonstrates the proof of concept of using CoFe layered double hydroxide (CoFe-LDHs) nanoplates as an effective peroxidase mimetic to catalyze the oxidation of peroxidase substrate 3,3',5,5'-tetramethylbenzidine in the presence of H(2)O(2) to produce a blue solution. We further demonstrate successfully CoFe-LDHs nanoplate-based colorimetric assay to detect H(2)O(2) and glucose.

Development of an ELISA-array for simultaneous detection of five encephalitis viruses.

Japanese encephalitis virus(JEV), tick-borne encephalitis virus(TBEV), and eastern equine encephalitis virus (EEEV) can cause symptoms of encephalitis. Establishment of accurate and easy methods by which to detect these viruses is essential for the prevention and treatment of associated infectious diseases. Currently, there are still no multiple antigen detection methods available clinically. An ELISA-array, which detects multiple antigens, is easy to handle, and inexpensive, has enormous potential in pathogen detection. An ELISA-array method for the simultaneous detection of five encephalitis viruses was developed in this study. Seven monoclonal antibodies against five encephalitis-associated viruses were prepared and used for development of the ELISA-array. The ELISA-array assay is based on a "sandwich" ELISA format and consists of viral antibodies printed directly on 96-well microtiter plates, allowing for direct detection of 5 viruses. The developed ELISA-array proved to have similar specificity and higher sensitivity compared with the conventional ELISAs. This method was validated by different viral cultures and three chicken eggs inoculated with infected patient serum. The results demonstrated that the developed ELISA-array is sensitive and easy to use, which would have potential for clinical use.

Synthesis of Ag nanoparticle-decorated 2,4,6-tris(2-pyridyl)-1,3,5-triazine nanobelts and their application for H2O2 and glucose detection.

The present paper reports on the first preparation of 2,4,6-tris(2-pyridyl)-1,3,5-triazine nanobelts (TPTNBs) by adjusting the pH value of the solution and the subsequent synthesis of Ag nanoparticle (AgNP)-decorated TPTNBs (AgNP-TPTNBs) by mixing an aqueous AgNO(3) solution with preformed TPTNBs without use of any external reducing agent. It is found that the resultant AgNP-TPTNBs exhibit notable catalytic performance for H(2)O(2) reduction. A glucose biosensor was fabricated by immobilizing glucose oxidase (GOD) onto a AgNP-TPTNBs-modified glassy carbon electrode (GCE) for glucose detection. The constructed glucose sensor has a wide linear response range from 3 mM to 20 mM (r: 0.999) with a detection limit of 190 µM. It is further shown that this glucose biosensor can be used for glucose detection in human blood serum.

Synthesis of Au nanoparticles decorated graphene oxide nanosheets: noncovalent functionalization by TWEEN 20 in situ reduction of aqueous chloroaurate ions for hydrazine detection and catalytic reduction of 4-nitrophenol.

In this paper, we develop a cost-effective and simple route for the synthesis of Au nanoparticles (AuNPs) decorated graphene oxide (GO) nanosheets using polyoxyethylene sorbitol anhydride monolaurate (TWEEN 20) as a stabilizing agent for GO as well as a reducing and immobilizing agent for AuNPs. The AuNPs assemble on the surface of TWEEN-functionalized GO by the in situ reduction of HAuCl(4) aqueous solution. The morphologies of these composites were characterized by atomic force microscopy (AFM) and transmission electron microscopy (TEM). It is found that the resultant AuNPs decorated GO nanosheets (AuNPs/TWEEN/GO) exhibit remarkable catalytic performance for hydrazine oxidation. This hydrazine sensor has a fast amperometric response time of less than 3s. The linear range is estimated to be from 5 µM to 3 mM (r=0.999), and the detection limit is estimated to be 78 nM at a signal-to-noise ratio of 3. The AuNPs/TWEEN/GO composites also exhibit good catalytic activity toward 4-nitrophenol (4-NP) reduction and the GO supports also enhance the catalytic activity via a synergistic effect.

Iron-substituted SBA-15 microparticles: a peroxidase-like catalyst for H2O2 detection.

In this communication, we demonstrate our recent finding that iron-substituted SBA-15 (Fe-SBA-15) microparticles possess intrinsic peroxidase-like activity and can catalyze the oxidation of peroxidase substrate 3,3',5,5'-tetramethylbenzidine (TMB) by H(2)O(2) to develop a blue color in aqueous solution, leading to a simple approach towards colorimetric detection of H(2)O(2) with a linear detection range from 0.4 µM to 15 µM (r = 0.997) and a detection limit of 0.2 µM.

A new preparation of Au nanoplates and their application for glucose sensing.

The present communication demonstrates a relatively green preparative route toward Au nanoplates in aqueous solution at room temperature with the use of tannic acid (TA), which is an environmentally friendly, soluble polyphenol, as a reducing agent. Such Au nanoplates exhibit notable catalytic performance toward the oxidation and reduction of H(2)O(2). A glucose biosensor was further fabricated by immobilizing glucose oxidase (GOD) into chitosan-Au nanoplate composites film on the surface of glassy carbon electrode (GCE). This sensor exhibits good response to glucose, and the linear response range is estimated to be from 2 to 20 mM (R=0.999) at 0.65 V and from 2 to 10 mM (R=0.993) at -0.2 V, respectively. The sensitivity of the sensor determined from the slopes is 49.5 µA mM(-1)cm(-2) at 0.65 V.

Synthesis of functional SiO2-coated graphene oxide nanosheets decorated with Ag nanoparticles for H2O2 and glucose detection.

In this paper, we report on the first preparation of well-defined SiO(2)-coated graphene oxide (GO) nanosheets (SiO(2)/GO) without prior GO functionalization by combining sonication with sol-gel technique. The functional SiO(2)/GO nanocomposites (F-SiO(2)/GO) obtained by surface functionalization with NH(2) group were subsequently employed as a support for loading Ag nanoparticles (AgNPs) to synthesize AgNP-decorated F-SiO(2)/GO nanosheets (AgNP/F-SiO(2)/GO) by two different routes: (1) direct adsorption of preformed, negatively charged AgNPs; (2) in situ chemical reduction of silver salts. The morphologies of these nanocomposites were characterized by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). It is found that the resultant AgNP/F-SiO(2)/GO exhibits remarkable catalytic performance for H(2)O(2) reduction. This H(2)O(2) sensor has a fast amperometric response time of less than 2s. The linear range is estimated to be from 1×10(-4) M to 0.26 M (r=0.998) and the detection limit is estimated to be 4 × 10(-6) M at a signal-to-noise ratio of 3, respectively. We also fabricated a glucose biosensor by immobilizing glucose oxidase (GOD) into AgNP/F-SiO(2)/GO nanocomposite-modified glassy carbon electrode (GCE) for glucose detection. Our study demonstrates that the resultant glucose biosensor can be used for the glucose detection in human blood serum.

Virulence of H5N1 virus in mice attenuates after in vitro serial passages.

The virulence of A/Vietnam/1194/2004 (VN1194) in mice attenuated after serial passages in MDCK cells and chicken embryos, because the enriched large-plaque variants of the virus had significantly reduced virulence. In contrast, the small-plaque variants of the virus and the variants isolated from the brain of mice that were infected with the parental virus VN1194 had much higher virulence in mice. The virulence attenuation of serially propagated virus may be caused by the reduced neurotropism in mice. Our whole genome sequence analysis revealed substitutions of a total of two amino acids in PB1, three in PB2, two in PA common for virulence attenuated variants, all or part of which may be correlated with the virulence attenuation and reduced neurotropism of the serially propagated VN1194 in mice. Our study indicates that serial passages of VN1194 in vitro lead to adaptation and selection of variants that have markedly decreased virulence and neurotropism, which emphasizes the importance of direct analysis of original or less propagated virus samples.