Cryo-EM reveals a previously unrecognized structural protein of a dsRNA virus implicated in its extracellular transmission.

Mosquito viruses cause unpredictable outbreaks of disease. Recently, several unassigned viruses isolated from mosquitoes, including the Omono River virus (OmRV), were identified as totivirus-like viruses, with features similar to those of the Totiviridae family. Most reported members of this family infect fungi or protozoans and lack an extracellular life cycle stage. Here, we identified a new strain of OmRV and determined high-resolution structures for this virus using single-particle cryo-electron microscopy. The structures feature an unexpected protrusion at the five-fold vertex of the capsid. Disassociation of the protrusion could result in several conformational changes in the major capsid. All these structures, together with some biological results, suggest the protrusions' associations with the extracellular transmission of OmRV.

Precast Assembled Road Paving Technology: Progress and Prospects.

This article presents a systematic review of the most cutting-edge research on precast pavement technology for the first time. Firstly, precast pavement is divided into two categories, precast cement concrete pavement and precast carpeted flexible pavement, according to the application of precast technology in pavement engineering. Subsequently, the structural characteristics, advantages, and disadvantages of various precast pavement systems are compared and analyzed; technical problems in precast pavement systems are explained; and future development directions are identified. In addition, the text specifically mentions the great contribution of precast carpeted flexible pavement technology in reducing the harmful effects of asphalt fumes on humans and the environment. This work will promote the application of prefabrication in road engineering and provide suggestions and references for subsequent research.

Changes in soil micronutrients along a temperature gradient in northern China.

How climate warming affected terrestrial ecosystems received considerable attention. Soil micronutrients play a vital role in regulating the growth of all living organisms and thus make a significant contribution to plant production. However, the responses of soil micronutrients to climate warming still remained unclear. While soil sampling along a temperature gradient could reveal the long-term influence of climate warming on soil nutrient dynamics, the variations of soil micronutrients with temperature might be interfered by the effect of precipitation due to the collinearity between temperature and precipitation. Moreover, changes in soil micronutrients over broad geographical scale could be affected by soil texture. Hence, this study conducted a soil investigation across a temperature transect along the 400 mm isohyet in northern China to examine the responses of soil micronutrients to changing temperature and soil texture when the effect of precipitation was minimized. We observed that soil copper (Cu), manganese (Mn) and zinc (Zn) contents all decreased along the temperature gradient. Soil Cu, Mn and Zn contents were positively correlated with soil clay and silt contents and negatively correlated with soil sand content. Temperature and soil texture together accounted for 72.0 % of the variations in soil micronutrient contents. Temperature and soil texture individually explained 10.4 % and 48.0 %, and their shared variation explained 13.6 % of the variations in soil micronutrient contents. Moreover, soil parent material also exerted an effect on soil micronutrient contents. Our results suggested that climate warming might cause a decrease in soil micronutrient contents.

Dynamics of soil metallic nutrients across a 6000-km temperature transect in China.

Global warming has exerted profound effects on terrestrial ecosystems. Soil metallic nutrients, an integrated part of soil nutrient fertility, play a significant role in the maintenance of ecosystem functions. However, how soil metallic nutrients respond to global warming remains poorly understood. Spatial observations across a temperature gradient provide a solid evidence in clarifying the long-term responses of soil metallic nutrients to global warming. But due to the collinearity between temperature and precipitation in the geographical patterns, the influence of temperature on soil metallic nutrients might be interfered by the precipitation effect. To minimize the precipitation effect, this study conducted a soil sampling over broad geographical scale along the 400 mm isohyet in China, which extends about 6000 km. Variations in soil potassium (K), calcium (Ca), magnesium (Mg) and iron (Fe) concentrations across the temperature transect were investigated. These four elements all increased until mean annual temperature (MAT) increased to about 2 °C and then decreased with increasing MAT. Temperature, soil property and vegetation type were responsible for the changes of soil metallic nutrients at MAT below 2 °C; altitude, soil property, vegetation type and soil parent material were dominant influential factors of soil metallic nutrients at MAT above 2 °C. Temperature exerted an indirect influence on soil metallic nutrients through its effects on soil property, vegetation type, rock weathering, microbial decomposition and plant growth. It could be expected based on our results that the effects of global warming on soil K, Ca, Mg and Fe might depend on local MAT. Different regions with different climates should adopt different strategies to cope with the effect of global warming on soil metallic nutrients so that ecosystems maintain stable.

Dengue Fever Outbreaks Caused by Varied Serotype Dengue Virus - Guangdong Province, China, 2019.

What is already known about this topic? Dengue fever (DF) outbreaks affect hundreds of millions of people worldwide and have increased significantly in Guangdong Province in 2019. What is added by this report? This paper described briefly DF outbreaks were attributed to several types of dengue virus (DENV) including DENV-1, DENV-2, and DENV-3 in 2019 in Guangdong, tracked the sources of viruses through phylogenetic analysis and epidemiological investigation, and primarily revealed the epidemiological links among the outbreaks. What are the implications for public health practice? The introduction of DENV from DF endemic areas increased pressure on the prevention and control of DF in Guangdong. Early detection of suspected cases and typing and genotyping of circulating viruses should be prioritized and enhanced to promptly assess the likelihood of local transmission, of introduction, and of subsequent sustained local transmission of the virus to implement optimal prevention and control strategies and measures.

Genomic and biological features of a novel orbivirus isolated from mosquitoes, in China.

A novel orbivirus had been identified as a member of the Orbivirus genus, which was isolated from pooled Culex fatigans mosquitoes in Guangdong of China, named as the Fengkai virus (FKOV). The cytopathic effects (CPEs) on both Aedes albopictus cells (C6/36) and mammalian cell lines (Vero and BHK-21) emerged in the cell cultures inoculated above virus in. Experimental confirmation as the Orbivirus genus was conducted by the Real-time PCR and based on Ion Torrent Next-Generation in sequencing. The Identities of VP1, VP2 and VP3 in amino acid sequences between the Tibet orbivirus (TIBOV) and this strain were 98.6%, 42.9%, and 99.9%, respectively, which indicated that this strain shares the same genus (VP1, Pol) and species (VP3, T2) with TIBOV but was greatly different in VP2 and VP5 (10.3%) of TIBOV. The VP2 and VP5 diversities of both TIBOV and FKOV strains suggested both serotypes are distinct with each other. As natural evolution and circulation, this strain might expand its host ranges and infect human beings as a potential and severe pathogen.

Genomic epidemiological characteristics of dengue fever in Guangdong province, China from 2013 to 2017.

Dengue fever, a mosquito-borne viral disease in humans, has been endemic in many Southeast Asian countries. Since its first outbreak in 1978 in Foshan, Guangdong province, China, dengue has been continually epidemic in recent years in Guangdong, which raised the concern whether dengue infection is endemic in Guangdong. In this study, we performed phylogenetic, recombinant, and nucleotide variation analyses of 114 complete genome sequences of dengue virus serotypes 1-4 (DENV1-4) collected from 2013 to 2017 in 18 of 21 cities of Guangdong. Phylogenetic analyses revealed that DENV sequences did not form a single cluster, indicating that dengue fever was not endemic in Guangdong, although DENV1-4 co-circulated in Guangdong. Twenty intra-serotype recombinant isolates involving DENV1-4 were detected, but no inter-serotype recombinant events were identified in this study. Additionally, the most recombinant events were detected simultaneously in the gene NS3 of DENV1-4. Nucleotide variation analyses showed that no significant intra-serotype differences were observed, whereas more significant inter-subtype differences were discovered in non-structural genes than in structural genes. Our investigation will facilitate the understanding of the current prevalent status of dengue fever in Guangdong and contribute to designing more effective preventive and control strategies for dengue infection.

Disease severity of respiratory syncytial virus (RSV) infection correlate to a novel set of five amino acid substitutions in the RSV attachment glycoprotein (G) in China.

Human respiratory syncytial virus (RSV) is one of the major viruses of acute respiratory tract disease among infants and young children. We performed molecular epidemiology analysis of RSV among inpatient children in Guangzhou, China. Phylogenetic and Bayesian analysis showed that genotype ON1 was the only subgroup A virus in this study. Interestingly, the majority of Guangzhou ON1 strains formed a well-supported cluster, and these strains shared a novel set of five amino acid substitutions that never illustrated before. Furthermore, the degree of disease severity was assessed using a severity scoring system. The patients carrying the novel RSV A strain were associated with milder respiratory symptoms compared to other RSV A positives. In conclusion, a specific set of five amino acid substitutions was found in China and further analysis showed that disease severity was associated with these alterations. These findings will provide valuable information for the pathogenic mechanism and vaccine development of RSV.

Fabrication of macroporous microspheres with core-shell structure for negative chromatography purification of virus.

The macroporous microspheres with core-shell structure, based on a copolymer of 4-Vinylbenzyl chloride, glycidyl methacrylate, and ethylene glycol dimethacrylate, were fabricated through atom transfer radical polymerization suspension polymerization. The microspheres showed 100-200 nm pores in shell and 500-900 nm pores in core. The shell was hydrophilic modified through grafting of poly(N-hydroxyethyl acrylamide) onto the shell surface for reducing adsorption of proteins. The core was coupled with a ligand of poly(ethylene imine) that could bind the proteins. Feedstock of avian influenza virus could be purified on these modified microspheres through negative chromatography. Avian influenza virus cannot enter the core and was recovered from the flow-through, while other proteins with negative charges were able to penetrate into the core and bind to the poly(ethylene imine) ligands. The dynamic binding capacity of proteins was higher on this medium (61 mg/mL) than the commercially available resin (12 mg/mL, Capto Core 700).

Structure-based virtual screening of influenza virus RNA polymerase inhibitors from natural compounds: Molecular dynamics simulation and MM-GBSA calculation.

The resistances of matrix protein 2 (M2) protein inhibitors and neuraminidase inhibitors for influenza virus have attracted much attention and there is an urgent need for new drug. The antiviral drugs that selectively act on RNA polymerase are less prone to resistance and possess fewer side effects on the patient. Therefore, there is increased interest in screening compounds that can inhibit influenza virus RNA polymerase. Three natural compounds were found by using molecular docking-based virtual screening, which could bind tightly within the polymerase acidic protein-polymerase basic protein 1 (PA-PB1) subunit of influenza virus polymerase. Firstly, their drug likeness properties were evaluated, which showed that the hepatotoxicity values of all the three compounds indicating they had less or no hepatotoxicity, and did not have the plasma protein biding (PPB) ability, the three compounds needed to be modified in some aspects, like bulky molecular size. The stability of the complexes of PA-hits was validated through molecular dynamics (MD) simulation, revealing compound 2 could form more stable complex with PA subunit. The torsional conformations of each rotatable bond of the ligands in PA subunit were also monitored, to investigate variation in the ligand properties during the simulation, compound 3 had fewer rotatable bonds, indicating that the molecule had stronger rigidity. The bar charts of protein-ligand contacts and contacts over the course of trajectory showed that four key residues (Glu623, Lys643, Asn703 and Trp706) of PA subunit that participated in hydrogen-bond, water bridge and hydrophobic interactions with the hit compounds. Finally, the binding free energy and contributed energies were calculated by using MM-GBSA method. Out of the three compounds, compound 1 showed the lowest total binding free energy. Among all the interactions, the contribution of the covalent binding and the van der Waals energy were more than other items, compound 1 formed more stable hydrogen bonds with the residues of PA subunit binding pocket. This study smoothed the path for the development of novel lead compounds with improved binding properties, high drug likeness, and low toxicity to humans for the treatment of influenza, which provided a good basis for further research on novel and effective influenza virus PA-PB1 interaction inhibitors.

Clarifying the influence of temperature on variances in plant metallic nutrients through minimizing the effect of precipitation.

Understanding the responses of plant nutrients to climate warming is important in the research of global change. However, the responses of plant metallic nutrients to climate warming have been rarely addressed. Furthermore, in previous field investigations, the influence of temperature on plant metallic nutrients has been not effectively separated from that of precipitation; hence, there exists some uncertainties in the relationships between plant metallic nutrients and temperature. To minimize the effect of precipitation, this study collected plant samples over broad geographical scale along the 400 mm isohyet in China with a temperature span of 14.8 °C. The temperature effects on variations in leaf potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), manganese (Mn) and zinc (Zn) were assessed. For all species pooled together, leaf Ca and Mg kept relatively stable, whereas leaf K, Fe, Mn and Zn decreased with increasing temperature. The responses of leaf Ca, Mg and Mn to changing temperature were almost similar at functional group, genus and species levels and independent of vegetation and soil type. It suggested that the relationships between leaf Ca, Mg and Mn and temperature should be general results. However, the patterns of leaf K, Fe and Zn vs. temperature varied across functional groups, genera and species and were affected by vegetation and soil type, which indicated that the observed patterns were local phenomena. Our results suggested that global warming might have no effect on leaf Ca and Mg, but could decrease leaf K, Fe, Mn and Zn.

Fabrication of poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate) macroporous microspheres through activators regenerated by electron transfer atom transfer radical polymerization for rapid separation of proteins.

Activators regenerated by electron transfer atom transfer radical polymerization (AGET ATRP) were firstly used in suspension polymerization to prepare macroporous microspheres based on a copolymer of glycidyl methacrylate and ethylene glycol dimethacrylate. Compared to conventional radical polymerization (CRP), the microspheres by AGET ATRP showed more homogeneous structure, larger pores, and higher protein binding capacity. The body of microspheres are formed by the large clusters resulted from the aggregated little particles. The size of the particles in microspheres by AGET ATRP was 10-300 nm which was smaller than that (400-800 nm) of the microspheres by CRP. AGET ATRP gave larger pore size (275 ±â€¯5 nm) and surface area (59.3 ±â€¯1 m2/g) than CRP (234 ±â€¯5 nm, 37.5 ±â€¯1 m2/g). The microspheres were modified with polyethylene imine for anion resins that were evaluated in term of its protein binding capacity. The results indicated that the static (69 ±â€¯0.5 mg/mL) and dynamic binding capacity (61 ±â€¯0.5 mg/mL) of proteins on modified microspheres by AGET ATRP were higher than that (34 ±â€¯0.5 mg/mL and 19 ±â€¯0.5 mg/mL) by CRP. Meanwhile, the proteins binding capacity on the microspheres by AGET ATRP decreased only less than 10% when the flow rate increased 10 times. These macroporous media show a large potential in rapid separation of proteins.

Responses of soil organic carbon turnover to nitrogen deposition are associated with nitrogen input rates: Derived from soil 14C evidences.

Elevated atmospheric nitrogen (N) deposition has exerted profound influences on ecosystems. Understanding the effects of N deposition on the dynamics of soil organic carbon (SOC) is important in the studies of global carbon cycle. Although many studies have examined the effects of N deposition on SOC turnover using N addition experiments, the effects were reported to be different across studies. Thus, we lack a predictive understanding of how SOC turnover respond to atmospheric N deposition. The inconsistent results could be associated with ecosystem types and N addition rates. This study mainly wants to confirm the argument that the response of SOC turnover to N deposition is related with N input rates. We conducted a field experiment with multiple N addition levels (0, 3, 6, 12, and 24 g N m-2·yr-1) in Inner Mongolia Grassland, China. To better reveal the responses of SOC turnover to N enrichment, this study measured the soil 14C contents, because it can indicate SOC turnover directly. Compared with the control treatment (0 g N m-2·yr-1), N addition inhibits SOC turnover at the addition rate of 3 g N m-2·yr-1, whereas SOC turnover is not affected when N addition rate was 6, 12, and 24 g N m-2·yr-1. Our results suggest that N input rates affect the responses of SOC turnover to N enrichment. Thus, this study can confirm the argument mentioned above. Based on this study, it should be considered in the climate prediction model that varied atmospheric N deposition levels across regions may have different impacts on local SOC turnover. In addition, we also carried out a soil incubation to compare between the results obtained in incubation and that in 14C measurements. Two results are found to be inconsistent with each other. This indicates that soil respiration from incubation experiments could not comprehensively assess the effects of N deposition on SOC turnover.

Minimizing the effect of precipitation in clarifying the responses of leaf N and P stoichiometry to temperature.

How terrestrial ecosystem responds to global warming has received wide attention. Plant stoichiometry has the potential to reflect ecosystem responses to climate change, thus, investigating the variations in plant stoichiometry with temperature is important and necessary for revealing the responses of terrestrial ecosystem to global warming. Although many studies had explored the relationships between plant N, P stoichiometry and temperature, previous field investigations did not eliminate the interference of precipitation effect with these observed relationships. To minimize the effect of precipitation on leaf N, P stoichiometry, this investigation was conducted across a temperature gradient over broad geographical scale along the 400 mm isohyet, which extends about 6000 km in China. This study showed that leaf N did not vary, whereas leaf P decreased and leaf N:P ratio increased with increasing mean annual temperature (MAT). The responses of leaf N and P stoichiometry to MAT observed in this study might be general patterns; because they were almost ubiquitous across functional groups, genera and species examined, and moreover, they were independent of vegetation and soil type. It could be inferred from this study that global warming in future will have no effect on leaf N, but reduce leaf P and increase leaf N:P ratio. Stable leaf N and varied leaf P with changing MAT suggested that leaf N and P decoupled with changing temperature.

The epidemiological characteristics and molecular phylogeny of the dengue virus in Guangdong, China, 2015.

In 2015, an unexpected multiple outbreak of dengue occurred in Guangdong, China. In total, 1,699 cases were reported, of which 1,627 cases were verified to have DENV infections by nucleic acid or NS1 protein, including 44 DENV-1, 1126 DENV-2, 18 DENV-3 and 6 DENV-4, and the other cases were confirmed by NS1 ELISA. Phylogenetic analyses of DENV-1 isolates identified two genotypes (I and V). The predominant DENV-2 outbreak isolates were the Cosmopolitan genotypes, which likely originated from Malaysia. The DENV-3 isolates were assigned into genotype I and genotype III. All 6 DENV-4 isolates from imported cases were likely originally from Cambodia, Thailand and the Philippines. The entomological surveillance showed a moderate risk for the BI index in Chaozhou and Foshan and a low risk in Guangzhou. The imported cases were mostly detected in Guangzhou and Foshan. Surprisingly, the most serious outbreak occurred in Chaozhou, but not in Guangzhou or Foshan. A combined analyses demonstrated the multiple geographical origins of this outbreak, and highlight the detection of suspected cases after the alerting of imported cases, early implementation of control policies and reinforce the vector surveillance strategies were the key points in the chain of prevention and control of dengue epidemics.

Identification and genetic characterization of Zika virus isolated from an imported case in China.

Zika virus (ZIKV) is a reemerging flavivirus that stroke Brazil in 2015 and appeared in China for the first time in 2016. Sequencing and genomic analysis are essential for Zika virus study. However, the complete genome length of Zika virus is still a disputable issue. In this study, we reported the complete genomic sequence of Zika virus strain ZKC2/2016 from an imported case in China, in February 2016. The virus was isolated and virus characteristics were identified by cytopathic effect, quantitative real time-PCR, immunofluorescence assay and electronic microscopy. Next generation sequencing (NGS) technique and 5' and 3' Rapid Amplification cDNA Ends (RACE) PCR were used to sequence the complete genome. The genome length of this newly obtained Zika virus strain is 10,807base pairs (bp). Genetic analysis showed that ZKC2/2016, along with other Chinese Zika virus strains in 2016, formed three clusters within Asian linage. Multiple sequence alignment and prediction of RNA secondary structure of untranslated regions (UTRs) of ZKC2/2016 and several other ZIKV strains indicated that the difference of ZIKV genome length mainly laid in UTRs. Besides, those genomes shorter than 10,790bp were probably incomplete due to lacking conserved secondary RNA structures in untranslated regions which were playing important roles in flavivirus replication. Our findings benefited the disease control of Zika fever in China and the study of Zika virus genome.

Returning ex-patriot Chinese to Guangdong, China, increase the risk for local transmission of Zika virus.

OBJECTIVES: Fast expansion and linkage to microcephaly and Guillain Barre syndrome have made Zika virus (ZIKV) track attention of global health authority concerns. The epidemiology, virological characteristics and genetic evolution of introduced ZIKV to Guangdong, China, were investigated. METHODS: Analyses of the epidemiological characteristics and genetic diversity of ZIKV isolates were performed. RESULTS: A total of twenty-eight confirmed ZIKV infection cases were imported into China in 2016, of which 19 were imported into Guangdong, China from Venezuela (16), the Samoa Islands (1), Suriname (1) and Guatemala (1). Serial sampling studies of the cases indicated longer shedding times of ZIKV particles from urine and saliva samples than from serum and conjunctiva swab samples. Seven ZIKV strains were successfully isolated from serum, urine and conjunctiva swab samples using cell culture and neonatal mouse injection methods. Genomic analysis indicated that all viruses belonged to the Asian lineage but had different evolutionary transmission routes with different geographic origins. The molecular clock phylogenetic analysis of the ZIKV genomes indicated independent local transmission that appeared to have been previously established in Venezuela and Samoa. Additionally, we found 7 unique non-synonymous mutations in the genomes of ZIKV that were imported to China. The mutations may indicate that ZIKV has undergone independent evolutionary history not caused by sudden adaptation to Chinese hosts. CONCLUSION: The increasing number of ex-patriot Chinese returning from ZIKV hyper-endemic areas to Guangdong combined with the presence of a variety of Aedes species indicate the potential for autochthonous transmission of ZIKV in Guangdong.

Decoupling of nutrient element cycles in soil and plants across an altitude gradient.

Previous studies have examined the decoupling of C, N, and P under rapid changes in climate. While this may occur in different environment types, such climactic changes have been reported over short distances in mountainous terrain. We hypothesized that the decoupling of C, N, and P could also occur in response to increases in altitude. We sampled soil and plants from Mount Gongga, Sichuan Province, China. Soil C and N were not related to altitude, whereas soil P increased with altitude. Soil N did not change with mean annual temperature (MAT), mean annual precipitation (MAP), vegetation and soil types, whereas soil P varied with MAT and vegetation type. Plant C remained constant with increasing altitude; plant N exhibited a quadratic change trend along the altitude gradient, with a turning point at 2350 m above average sea level; and plant P decreased with altitude. MAP mostly accounted for the variation in plant P. MAT was responsible for the variation of plant N at elevations below 2350 m, whereas MAT and vegetation type were the dominant influential factors of plants growing above 2350 m. Thus, the decoupling of C, N, and P in both soil and plants was significantly affected by altitude.