Activity-Based Protein Profiling Identifies ATG4B as a Key Host Factor for Enterovirus 71 Proliferation.

Virus-encoded proteases play diverse roles in the efficient replication of enterovirus 71 (EV71), which is the causative agent of human hand, foot, and mouth disease (HFMD). However, it is unclear how host proteases affect viral proliferation. Here, we designed activity-based probes (ABPs) based on an inhibitor of the main EV71 protease (3Cpro), which is responsible for the hydrolysis of the EV71 polyprotein, and successfully identified host candidates that bind to the ABPs. Among the candidates, the host cysteine protease autophagy-related protein 4 homolog B (ATG4B), a key component of the autophagy machinery, was demonstrated to hydrolytically process the substrate of EV71 3Cpro and had activity comparable to that of the viral protease. Genetic disruption of ATG4B confirmed that the enzyme is indispensable for viral proliferation in vivo Our results not only further the understanding of host-virus interactions in EV71 biology but also provide a sample for the usage of activity-based proteomics to reveal host-pathogen interactions.IMPORTANCE Enterovirus 71 (EV71), one of the major pathogens of human HFMD, has caused outbreaks worldwide. How EV71 efficiently assesses its life cycle with elaborate interactions with multiple host factors remains to be elucidated. In this work, we deconvoluted that the host ATG4B protein processes the viral polyprotein with its cysteine protease activity and helps EV71 replicate through a chemical biology strategy. Our results not only further the understanding of the EV71 life cycle but also provide a sample for the usage of activity-based proteomics to reveal host-pathogen interactions.

Thickness-Dependent NIR LSPR of Curved Ag/TiS2 Bilayer Film.

We demonstrated that the localized surface plasmon resonance (LSPR) features of Ag/TiS2 nanostructures were dependent on the sublayer thickness. The Ag/TiS2 bilayer film was obtained by the self-assembly method and magnetron sputtering. The thickness was controlled by changing the sputtering time when the sputtering powers were the same. When the Ag thickness decreased from 50 nm to 5 nm, the LSPR was tuned from the visible region to the Near Infrared (NIR) region. When the TiS2 thickness decreased from 60 nm to 2 nm, the LSPR shifted from the IR to NIR region. Analysis showed the thickness changes of Ag and TiS2 resulted in the changed carrier density, which led to the thickness-dependent shift of the LSPR.

Structure of the Enterovirus 71 3C Protease in Complex with NK-1.8k and Indications for the Development of Antienterovirus Protease Inhibitor.

Hand-foot-and-mouth disease (HFMD), caused by enterovirus, is a threat to public health worldwide. To date, enterovirus 71 (EV71) has been one of the major causative agents of HFMD in the Pacific-Asia region, and outbreaks with EV71 cause millions of infections. However, no drug is currently available for clinical therapeutics. In our previous works, we developed a set of protease inhibitors (PIs) targeting the EV71 3C protease (3Cpro). Among these are NK-1.8k and NK-1.9k, which have various active groups and high potencies and selectivities. In the study described here, we determined the structures of the PI NK-1.8k in complex with wild-type (WT) and drug-resistant EV71 3Cpro Comparison of these structures with the structure of unliganded EV71 3Cpro and its complex with AG7088 indicated that the mutation of N69 to a serine residue destabilized the S2 pocket. Thus, the mutation influenced the cleavage activity of EV71 3Cpro and the inhibitory activity of NK-1.8k in an in vitro protease assay and highlighted that site 69 is an additional key site for PI design. More information for the optimization of the P1' to P4 groups of PIs was also obtained from these structures. Together with the results of our previous works, these in-depth results elucidate the inhibitory mechanism of PIs and shed light to develop PIs for the clinical treatment of infections caused by EV71 and other enteroviruses.

A Conserved Inhibitory Mechanism of a Lycorine Derivative against Enterovirus and Hepatitis C Virus.

Enterovirus 71 (EV71) (Picornaviridae family) and hepatitis C virus (HCV) (Flaviviridae family) are the causative agents of human hand, foot, and mouth disease (HFMD) and hepatitis C, resulting in a severe pandemic involving millions of infections in the Asia-Pacific region and worldwide. The great impact of EV71 and HCV on public health highlights the need to further our understanding of the biology of these two viruses and develop effective therapeutic antivirals. Here, we evaluated a total of 32 lycorine derivatives and demonstrated that 1-acetyllycorine suppressed the proliferation of multiple strains of EV71 in various cells. The results of the drug resistance analysis revealed that 1-acetyllycorine targeted a phenylalanine (F76) in EV71 2A protease (2A(pro)) to stabilize the conformation of a unique zinc finger. Most interestingly, the zinc binding site in EV71 2A(pro) is the exclusive homolog of HCV NS3 among all viruses. Further analysis revealed that 1-acetyllycorine also inhibits HCV with high efficacy, and the mutation on R118 in HCV NS3, which corresponds to F76 in EV71 2A(pro), confers the resistance of HCV to 1-acetyllycorine. These results revealed a conserved mechanism of 1-acetyllycorine against EV71 and HCV through targeting viral proteases. We also documented the significant synergistic anti-EV71 and anti-HCV effects of 1-acetyllycorine with reported inhibitors, supporting potential combination therapy for the treatment of EV71 and HCV infections.

Peptidyl aldehyde NK-1.8k suppresses enterovirus 71 and enterovirus 68 infection by targeting protease 3C.

Enterovirus (EV) is one of the major causative agents of hand, foot, and mouth disease in the Pacific-Asia region. In particular, EV71 causes severe central nervous system infections, and the fatality rates from EV71 infection are high. Moreover, an outbreak of respiratory illnesses caused by an emerging EV, EV68, recently occurred among over 1,000 young children in the United States and was also associated with neurological infections. Although enterovirus has emerged as a considerable global public health threat, no antiviral drug for clinical use is available. In the present work, we screened our compound library for agents targeting viral protease and identified a peptidyl aldehyde, NK-1.8k, that inhibits the proliferation of different EV71 strains and one EV68 strain and that had a 50% effective concentration of 90 nM. Low cytotoxicity (50% cytotoxic concentration, >200 µM) indicated a high selective index of over 2,000. We further characterized a single amino acid substitution inside protease 3C (3C(pro)), N69S, which conferred EV71 resistance to NK-1.8k, possibly by increasing the flexibility of the substrate binding pocket of 3C(pro). The combination of NK-1.8k and an EV71 RNA-dependent RNA polymerase inhibitor or entry inhibitor exhibited a strong synergistic anti-EV71 effect. Our findings suggest that NK-1.8k could potentially be developed for anti-EV therapy.

Toxic effects on ciliates under nano-/micro-plastics coexist with silver nanoparticles.

Owing to the degradation of plastics, microplastics (MPs) and nanoplastics (NPs) have remained the focus of global attention. Silver nanoparticles (AgNPs) could adversely affect marine organisms due to their broad application. So far, the combined effects of MPs/NPs (strong adsorbents) with AgNPs on marine organisms are scant. Thus, four sizes polystyrene beads (80 nm, 220 nm, 1.07 µm, and 2.14 µm) combined with AgNPs (30 nm) were assessed using ciliated protozoa Uronema marinum. Results showed that MPs/NPs dramatically decrease the abundance, biovolume, and carbon biomass of U. marinum. And, exposure could cause changes of antioxidant enzyme activity and antioxidant content on U. marinum. The combined toxicity of MPs/NPs with AgNPs to ciliates showed an enhanced effect compared to exposure alone. Additionally, the negative effects under exposure of NPs plus AgNPs were more significant than those of MPs plus AgNPs. Transcriptome sequencing showed that co-exposure could affect the energy metabolism and lipid metabolism of ciliates, even cause DNA and protein damage. Our study provided a novel insight and first-hand basic data for the understanding of combined toxicity of MPs /NPs with AgNPs on the basic trophic level ciliated protozoa in marine ecosystems.

Migration and transformation modes of microplastics in reclaimed wastewater treatment plant and sludge treatment center with thermal hydrolysis and anaerobic digestion.

Microplastics in wastewater have been investigated globally, but less research on the migration and transformation of microplastics throughout wastewater and sludge treatment. This study investigated the fate of microplastics in a reclaimed wastewater treatment plant and a centralized sludge treatment center with thermal hydrolysis and anaerobic digestion. The results exhibited that the effluent microplastics of this reclaimed wastewater treatment plant were 0.75 ± 0.26 items/L. Approximately 98 % of microplastics were adsorbed and precipitated into sludge. After thermal hydrolysis, anaerobic digestion and plate and frame dewatering, the removal rate of microplastics was 41 %. Thermal hydrolysis was the most effective method for removing microplastics. Polypropylene, polyamide and polyethylene were widely detected in wastewater and sludge. 30 million microplastics were released into the downstream river and 51.80 billion microplastics entered soil through sludge cake daily. Therefore, substantial microplastics still entered the natural environment despite the high microplastics removal rate of reclaimed wastewater and sludge treatment.

Physiological and transcriptomic responses of seawater halobios to micro/nano-scale polystyrene-cadmium exposure in a marine food web.

Micro/nano-plastics (MPs/NPs) represent an emerging contaminant, posing a significant threat to oceanic halobios. While the adverse effects of joint pollutants on marine organisms are well-documented, the potential biological impacts on the food chain transmission resulting from combinations of MPs/NPs and heavy metals (HMs) remain largely unexplored. This study exposed the microbial loop to combined contaminants (MPs/NPs + HMs) for 48h, bacteria and contaminants are washed away before feeding to the traditional food chain, employing microscopic observation, biochemical detection, and transcriptome analysis to elucidate the toxicological mechanisms of the top predator. The findings revealed that MPs/NPs combined with Cd2+ could traverse both the microbial loop and classical food chain. Acute exposure significantly affected the carbon biomass of the top predator Tigriopus japonicus (75.8% lower). Elevated antioxidant enzyme activity led to lipid peroxidation, manifesting in increased malondialdehyde levels. Transcriptome sequencing showed substantial differential gene expression levels in T. japonicus under various treatments. The upregulation of genes associated with apoptosis and inflammatory responses, highlighting the impact of co-exposure on oxidative damage and necroptosis within cells. Notably, NPs-Cd exhibited stronger toxicity than MPs-Cd. NPs-Cd led to a greater decrease in the biomass of top predators, accompanied by lower activities of GSH, SOD, CAT, and GSH-PX, resulting in increased production of lipid peroxidation product MDA and higher oxidative stress levels. This investigation provides novel insights into the potential threats of MPs/NPs combined with Cd2+ on the microbial loop across traditional food chain, contributing to a more comprehensive assessment of the ecological risks associated with micro/nano-plastics and heavy metals.

Mechanisms of interaction between polystyrene nanoplastics and extracellular polymeric substances in the activated sludge cultivated by different carbon sources.

Nanoplastics (NPs) are ubiquitously present in wastewater treatment plants, which would be removed by the flocculation of extracellular polymeric substances (EPS) from activated sludge. However, the interaction mechanisms between NPs and EPS of activated sludge remain largely unexplored. This study investigated the interaction mechanisms between polystyrene nanoplastics (PS-NPs) and EPS with sodium acetate (NaAc), methanol (MeOH) and glucose (GLC) as carbon sources. The results showed that the functional group involved in the interactions between PS-NPs and EPS was the carbonyl of protein amide I region. The interaction between PS-NPs and EPS increased the ß-sheets content, decreased the ratio of α-helix to (ß-sheet + random coil), and changed the protein secondary structures to strong rigidity. This enhanced the flocculation of activated sludge cultivated by these three carbon sources. The flocculation between PS-NPs and EPS in activated sludge using NaAc as the carbon source was the strongest among these three carbon sources. Therefore, the degree of flocculation between NPs and EPS of activated sludge in wastewater treatment plants varies with carbon sources. This work provides a reference for the NPs removal mechanisms from wastewater, which will help to understand the migration behavior of MPs and NPs in wastewater treatment processes.

Computational and experimental studies of salvianolic acid A targets 3C protease to inhibit enterovirus 71 infection.

Hand, foot, and mouth disease (HFMD) is a common childhood infectious disease caused by enterovirus (EV) infection. EV71 is one of the major pathogens causing hand, foot, and mouth disease and is more likely to cause exacerbation and death than other enteroviruses. Although a monovalent vaccine for EV71 has been developed, there are no clinically available anti-EV71 specific drugs. Here, we performed virtual screening and biological experiments based on the traditional Chinese medicine monomer library. We identified a traditional Chinese medicine monomer, Salvianolic acid A (SA), a polyphenolic compound isolated from Salvia miltiorrhiza. Salvianolic acid A inhibits EV71 virus infection in a concentration-dependent manner, and its antiviral activity is higher than that of other reported natural polyphenols and has a high biosafety. Furthermore, molecular dynamics simulations showed that salvianolic acid A can anchor to E71, a member of the enzyme catalytic triad, and cause H40 to move away from the catalytic center. Meanwhile, molecular mechanics generalized born surface area (MMGBSA) and steered molecular dynamics (SMD) results showed that the P1 group of SA was most easily unbound to the S1 pocket of 3Cpro, which provided theoretical support to further improve the affinity of salvianolic acid A with 3Cpro. These findings suggest that salvianolic acid A is a novel EV71 3Cpro inhibitor with excellent antiviral activity and is a promising candidate for clinical studies.

Microplastics shift macrobenthic community structures near a coastal nuclear power plant under construction in North East China.

Coastal sediments are considered to be a potential sink for microplastics, which mainly derived from the land-based sources. This study investigated microplastic pollution in the sediments of 20 stations near a nuclear power plant under construction in North East China and analyzed its impacts on macrobenthic communities. The average abundance of microplastics in three stations close to the nuclear power plant was 0.33 items/g, which was approximately 10 times higher than those in the distant stations. The clustering of microplastic characteristics (sizes, shapes, and colors) showed that the three stations near the plant were in one group, and the distant stations were in another group. A total of 105 macroinvertebrate species belonging to 7 phyla were identified in all stations, and the dominant phyla were Annelida and Arthropoda. Spearman rank correlation showed that rare taxa (83 species with a contribution <1 %) were positively correlated with microplastics and As, and redundancy analysis demonstrated that the distribution patterns of macrobenthic communities were similar to those of microplastics. Moreover, co-occurrence networks showed that the rare taxa were positively correlated with microplastics. Therefore, microplastics released from the nuclear power plant under construction might shift the structure of macrobenthic communities, especially the rare taxa.

[Microplastics in the stomach and intestine of pelagic squid: A case study of Dosidicus gigas in open sea of Peru]. / å¤§æ´‹æ€§å¤´è¶³ç±»èƒƒå’Œè‚ é“ä¸­çš„å¾®å¡‘æ–™­­ä»¥ç§˜é²å¤–海茎柔鱼为例.

Microplastic (MP) ingestion by marine animals has been well documented, but less being known about pelagic squid. Jumbo squid Dosidicus gigas supports the world's largest cephalopod fishery and plays an important ecological role in the Eastern Pacific Ocean. In this study, D. gigas taken from the open sea of the Peruvian Exclusive Economic Zone were selected as research objects. We estimated the abundance and characteristics of MPs in the stomach and intestine of D. gigas and investigated the differences between tissues and sexes. Similar abundance and characteristics of MPs were observed in the same tissue of females and males. However, the stomach had a higher abundance of MPs with larger size than the intestine, while the MP abundance by stomach wet weight was lower than that of the intestine. The MPs were predominantly fiber-shaped, with blue or black color. The most frequent polymers were high-density cellophane and polyacrylic acid. These polymers could sink into deeper sea layers and were available for D. gigas living there during the daytime. Our findings revealed the distribution pattern of MPs in the waters of the Peruvian fishing ground. This study could improve our understanding of the MP contamination level in pelagic squid, and have implications for evaluating the ecological effects of MP on cephalopods.

Comparison of the efficiency and microbial mechanisms of chemical- and bio-surfactants in remediation of petroleum hydrocarbon.

Surfactant-enhanced remediation (SER) is one of the most effective methods for petroleum hydrocarbon-contaminated sites compared to single physical and chemical methods. However, biosurfactants are not as commonly used as chemical surfactants, and the actual remediation effects and related mechanisms remain undefined. Therefore, to comprehensively compare the remediation effects and biological mechanisms of biosurfactants and chemical surfactants, soil column leaching experiments including two biosurfactants (rhamnolipids and lipopeptide) and three commercially used chemical surfactants (Tween 80, Triton X-100, and Berol 226SA) were conducted. After seven days of leaching, rhamnolipids exhibited the highest petroleum hydrocarbon removal rate of 61.01%, which was superior to that of chemical surfactants (11.73-18.75%) in n-alkanes C10-C30. Meanwhile, rhamnolipids exhibited a great degradation advantage of n-alkanes C13-C28, which was 1.22-30.55 times that of chemical surfactants. Compared to chemical surfactants, biosurfactants significantly upregulated the soil's biological functions, including soil conductivity (80.90-155.56%), and soil enzyme activities of lipase (90.31-497.10%), dehydrogenase (325.00-655.56%), core enzyme activities of petroleum hydrocarbon degradation, and quorum sensing between species. Biosurfactants significantly changed the composition of Pseudomonas, Citrobacter, Acidobacteriota, and Enterobacter at the genus level. Meanwhile, chemical surfactants had less influence on the bacterial community and interactions between species. Moreover, the biosurfactants enhanced the microbial interactions and centrality of petroleum hydrocarbon degraders in the community based on the network. Overall, this work provides a systematic comparison and understanding of the chemical- and bio-surfactants used in bioremediation. In the future, we intend to apply biosurfactants to practical petroleum hydrocarbon-contaminated fields to observe realistic remediation effects and compare their functional mechanisms.

Air pollutant emission and reduction potentials from the sintering process of the iron and steel industry in China in 2017.

The iron and steel industry (ISI) is one of the most energy-intensive industries in China, which makes a substantial contribution to the emissions of air pollutants. Among the various manufacturing processes, sintering is the major emitting process, which shares over half of the emissions of sulfur dioxide (SO2), nitrogen oxide (NOx) and particulate matter (PM) for the entire industry. In this study we made a comprehensive evaluation of the air pollutant emissions from the sintering process of China's ISI in 2017 based on the Continuous Emission Monitoring System (CEMS) database and estimated the future reduction potentials. We found that there was a general decreasing trend of emission concentrations in the sintering flue gas in response to the strengthened emission control policies, but the mild increase of the oxygen content in the second half of the year flattened the decreasing trend, indicating the necessity for simultaneous control of the oxygen content in the flue gas. Despite the relative high standard-reaching rates of 90% to the emission concentration limits in GB 28662-2012, the standard-reaching rates to the ultra-low emission standards were only 12%, 40% and 27% for NOx, SO2 and PM respectively, with the lowest value mostly occurred in the western provinces. In 2017, the NOx, SO2 and PM emissions from the sintering process were 378.6 kt, 169.0 kt and 51.9 kt, respectively. If the ultra-low emission standards were met, the corresponding NOx, SO2 and PM emissions would decrease by 69.9%, 52.9%, and 56.4% respectively, illustrating large emission reducing potentials by achieving the ultra-low emission standards.

The combined effects of microplastics and the heavy metal cadmium on the marine periphytic ciliate Euplotes vannus.

Microplastics could be grazed by marine organisms and possibly transferred to higher trophic levels along the microbial loop. Due to their size and capacity to concentrate heavy metals that trigger joint toxic effects, microplastics (MPs) have already become a severe threat to marine organisms. The detrimental effects of MPs on large marine organisms have been studied, but the combined toxicity of MPs and cadmium (Cd) on protozoan ciliates remains unclear. In the present study, we selected different diameters and concentrations of polystyrene microspheres (PS-MPs) and Cd2+ as model MPs and heavy metals to evaluate their single and combined effects on the periphytic marine ciliate Euplotes vannus in relation to carbon biomass and oxidative stress. The MPs were indeed ingested by Euplotes vannus and significantly reduced the abundance and carbon biomass of ciliate populations. Combined exposure to MPs and Cd2+ not only increased the bioaccumulation of Cd2+ in ciliates but also exacerbated the decrease in ciliate biomass by increasing oxidative stress and membrane damage. In comparison, the effects of nano-sized plastics (0.22 µm) were more harmful than those of micro-sized plastics (1.07 µm, 2.14 µm and 5.00 µm). A smaller size represents a higher potential for penetrating biological members and a stronger adsorption capacity for cadmium. These results provide new insight into the combined toxicity of microplastics and heavy metals on ciliated protozoa and lay a foundation for higher trophic levels and ecosystems.

Trends in air pollutant emissions from the sintering process of the iron and steel industry in the Fenwei Plain and surrounding regions in China, 2014-2017.

China is the largest iron and steel producer and consumer in the world. The iron and steel manufacture, especially the sintering process, is energy-intensive, and contributes substantially to air pollutant emissions in China. Compared with other regions, the Fenwei Plain, a coal base, has a heavy industry concentration, and high pollutant emission total amount. In addition, urban air pollution has rebounded, and the pollutants concentrations in many cities have increased rather than decreased. In this study, we investigated the inter-annual trends of particulate matter (PM), sulfur dioxide (SO2) and nitrogen oxide (NOx) from the sintering process of iron and steel industry (ISI) in the Fenwei Plain and the surrounding regions in China from 2014 to 2017 based on the Continuous Emission Monitoring System (CEMS). We found that the oxygen content of the flue gas is the key to judge whether the sintering flue gas air pollutant emission concentration can meet the standard. Therefore, we adopted the converted concentration by the reference oxygen content in the final analysis. Overall, the SO2 and PM emission concentrations exhibit a downward trend from 2014 to 2017, in response to the strengthening of the emission control policies and standards in the ISI, whereas the NOx emission concentration did not change significantly during the same period The emission factors (EFs) of PM, NOx and SO2 obtained in this study are lower than previous estimates. In 2017, the SO2 and PM emissions were 27% and 32% lower than the levels in 2014.While NOx was 22% higher than the level in 2014. Our study confirmed the effectiveness of current emission control policies and standards in the iron and steel sector. However, the levels of NOx emissions were still high until 2017, illustrating the urgent need for more advanced emission control technologies to further reduce NOx emissions from the sintering flue gas in China.

Microplastics in different tissues of a pelagic squid (Dosidicus gigas) in the northern Humboldt Current ecosystem.

Microplastics (MPs) found in marine invertebrates have aroused great concern, but MP ingestion by cephalopods is rare. To evaluate MP contamination in commercially important pelagic squids, we examined the abundance and characteristics of MPs in the gill, intestine, and stomach of jumbo squid Dosidicus gigas (30.9 to 65.0 cm mantle length), collected from the northern Humboldt Current. The average abundance ranged from 4.0 to 7.4 items/individual and 0.2 to 0.7 items/g wet weight for the three tissues. The MPs were sized 80.75 to 4632.27 µm, with larger MPs generally found in the stomach. The majority of MPs were fibrous in shape, blue or black-gray in color, and cellophane in composition. These results revealed the MP distribution in D. gigas and could be driven by its movement pattern and habitat use. Furthermore, this study provides evidence that adherence to gills is probably an alternative means by which pelagic squid accumulate MPs.

Reversible covalent inhibitors suppress enterovirus 71 infection by targeting the 3C protease.

As one of the principal etiological agents of hand, foot, and mouth disease (HFMD), enterovirus 71 (EV71) is associated with severe neurological complications or fatal diseases, while without effective medications thus far. Here we applied dually activated Michael acceptor to develop a series of reversible covalent compounds for EV71 3C protease (3Cpro), a promising antiviral drug target that plays an essential role during viral replication by cleaving the precursor polyprotein, inhibiting host protein synthesis, and evading innate immunity. Among them, cyanoacrylate and Boc-protected cyanoarylamide derivatives (SLQ-4 and SLQ-5) showed effective antiviral activity against EV71. The two inhibitors exhibited broad antiviral effects, acting on RD, 293T, and Vero cell lines, as well as on EV71 A, B, C, CVA16, and CVB3 viral strains. We further determined the binding pockets between the two inhibitors and 3Cpro based on docking studies. These results, together with our previous studies, provide evidence to elucidate the mechanism of action of these two reversible covalent inhibitors and contribute to the development of clinically effective medicines to treat EV71 infections.

4-Iminooxazolidin-2-One as a Bioisostere of Cyanohydrin Suppresses EV71 Proliferation by Targeting 3Cpro.

The fatal pathogen enterovirus 71 (EV71) is a major cause of hand-foot-and-mouth disease (HFMD), which leads to serious neurological syndromes. While there are no effective clinical agents available for EV71 treatment thus far, EV71 3C protease (3Cpro), a cysteine protease encoded by the virus, has become a promising drug target for discovery of antiviral drugs, given that it plays a crucial role in virus proliferation and interferes with host cell function. Here, we report two inhibitors of EV71 3Cpro, FOPMC and FIOMC, that were developed from previously reported cyanohydrin derivative (R)-1 by replacing the acyl cyanohydrin group with 4-iminooxazolidin-2-one. FOPMC and FIOMC have potent antiviral activity and dramatically improved metabolic stability. These two inhibitors demonstrated broad anti-EV effects on various cell lines and five epidemic viral strains. We further illuminated the binding models between 3Cpro and FOPMC/FIOMC through molecular docking and molecular dynamics simulations. The substitution of an acyl cyanohydrin group with 4-iminooxazolidin-2-one does make FOPMC and FIOMC potent anti-EV71 drug candidates as universal nonclassical bioisosteres with a cyanohydrin moiety. IMPORTANCE EV71 is one of the most epidemic agents of HFMD. Thus far, there are no antiviral drugs available for clinical usage. The conserved EV71 3Cpro plays pivotal roles in virus proliferation and defense host immunity, as well as having no homology in host cells, making it a most promising antiviral target. In this work, we identified that propyl- and isopropyl-substituted 4-iminooxazolidin-2-one moieties (FOPMC and FIOMC) effectively inhibited five epidemic viral strains in rhabdomyosarcoma (RD), HEK-293T, and VeroE6 cell lines. The inhibition mechanism was also illustrated with molecular docking and molecular dynamics (MD) simulations. The successful replacement of the labile cyanohydrin greatly improved the stability and pharmacokinetic properties of (R)-1, making 4-iminooxazolidin-2-one a nonclassical bioisosteric moiety of cyanohydrin. This discovery addressed a critical issue of the primitive structural scaffold of these promising anti-EV71 inhibitors and could lead to their development as broad-spectrum anti-EV agents.

Short- and medium-chain chlorinated paraffins in plastic animal feed packaging and factors affect their migration into animal feed.

Chlorinated paraffins (CPs) are used as plasticizers and flame retardants in plastics. Plastic packaging containing CPs is widely used for storage of animal feed, which can become contaminated by CPs that migrate into the feed. In the present study, 31 commercial animal feed packaging samples made of polypropylene (PP) or polyethylene (PE) were collected from animal feed manufacturers in China. The mean concentrations of short-chain chlorinated paraffins (SCCPs) in the PP and PE samples were 60.0 and 54.5 µg/g, respectively. The medium-chain chlorinated paraffin (MCCP) mean concentrations in the PP and PE samples were 62.7 and 9.23 µg/g, respectively. The carbon congener group profiles of SCCPs and MCCPs in the samples were different. The dominant SCCP and MCCP chlorine congener groups in all the samples were Cl6-7 and Cl6-8, respectively. Time and temperature influenced the migration of CPs from packaging into animal feed. As the time or temperature increased, the CP concentrations in the animal feed increased but the congener group profiles of the SCCPs and MCCPs in the animal feed did not change. To reduce contamination of animal feed by CPs, it is necessary to restrict the use of CPs in animal feed packaging.