Mated-Atom Nanozymes with Efficient Assisted NAD+ Replenishment for Skin Regeneration.

Excessive accumulation of reduced nicotinamide adenine dinucleotide (NADH) within biological organisms is closely associated with many diseases. It remains a challenge to efficiently convert superfluous and detrimental NADH to NAD+. NADH oxidase (NOX) is a crucial oxidoreductase that catalyzes the oxidation of NADH to NAD+. Herein, M1M2 (Mi=V/Mn/Fe/Co/Cu/Mo/Rh/Ru/Pd, i = 1 or 2) mated-atom nanozymes (MANs) are designed by mimicking natural enzymes with polymetallic active centers. Excitingly, RhCo MAN possesses excellent and sustainable NOX-like activity, with Km-NADH (16.11 µM) being lower than that of NOX-mimics reported so far. Thus, RhCo MAN can significantly promote the regeneration of NAD+ and regulate macrophage polarization toward the M2 phenotype through down-regulation of TLR4 expression, which may help to recover skin regeneration. However, RhRu MAN with peroxidase-like activity and RhMn MAN with superoxide dismutase-like activity exhibit little modulating effects on eczema. This work provides a new strategy to inhibit skin inflammation and promote skin regeneration.

RBM14 inhibits the replication of porcine epidemic diarrhea virus by recruiting p62 to degrade nucleocapsid protein through the activation of autophagy and interferon pathway.

Porcine epidemic diarrhea virus (PEDV) results in PED, which is an infectious intestinal disease with the representative features of diarrhea, vomiting, and dehydration. PEDV infects neonatal piglets, causing high mortality rates. Therefore, elucidating the interaction between the virus and host in preventing and controlling PEDV infection is of immense significance. We found a new antiviral function of the host protein, RNA-binding motif protein 14 (RBM14), which can inhibit PEDV replication via the activation of autophagy and interferon (IFN) signal pathways. We found that RBM14 can recruit cargo receptor p62 to degrade PEDV nucleocapsid (N) protein through the RBM14-p62-autophagosome pathway. Furthermore, RBM14 can also improve the antiviral ability of the hosts through interacting with mitochondrial antiviral signaling protein to induce IFN expression. These results highlight the novel mechanism underlying RBM14-induced viral restriction. This mechanism leads to the degradation of viral N protein via the autophagy pathway and upregulates IFN for inhibiting PEDV replication; thus, offering new ways for preventing and controlling PED.IMPORTANCEPorcine epidemic diarrhea virus (PEDV) is a vital reason for diarrhea in neonatal piglets, which causes high morbidity and mortality rates. There is currently no effective vaccine or drug to treat and prevent infection with the PEDV. During virus infection, the host inhibits virus replication through various antiviral factors, and at the same time, the virus antagonizes the host's antiviral reaction through its own encoded protein, thus completing the process of virus replication. Our study has revealed that the expression of RNA-binding motif protein 14 (RBM14) was downregulated in PEDV infection. We found that RBM14 can recruit cargo receptor p62 to degrade PEDV N protein via the RBM14-p62-autophagosome pathway and interacted with mitochondrial antiviral signaling protein and TRAF3 to activate the interferon signal pathway, resulting in the inhibition of PEDV replication.

An Expeditious Neutralization Assay for Porcine Reproductive and Respiratory Syndrome Virus Based on a Recombinant Virus Expressing Green Fluorescent Protein.

Due to the extensive genetic and antigenic variation in Porcine Reproductive and Respiratory Syndrome Virus (PRRSV), as well as its rapid mutability and evolution, PRRS prevention and control can be challenging. An expeditious and sensitive neutralization assay for PRRSV is presented to monitor neutralizing antibodies (NAbs) in serum during vaccine research. Here, a PRRSV expressing eGFP was successfully rescued with reverse genetics based on the infectious clone HuN4-F112-eGFP which we constructed. The fluorescent protein expressions of the reporter viruses remained stable for at least five passages. Based on this reporter virus, the neutralization assay can be easily used to evaluate the level of NAbs by counting cells with green fluorescence. Compared with the classical CPE assay, the newly developed assay increases sensitivity by one- to four-fold at the early antibody response stage, thus saving 2 days of assay waiting time. By using this assay to unveil the dynamics of neutralizing antibodies against PRRSV, priming immunity through either a single virulent challenge or only vaccination could produce limited NAbs, but re-infection with PRRSV would induce a faster and stronger NAb response. Overall, the novel HuN4-F112-eGFP-based neutralization assay holds the potential to provide a highly efficient platform for evaluating the next generation of PRRS vaccines.

The CD2v protein of African swine fever virus inhibits macrophage migration and inflammatory cytokines expression by downregulating EGR1 expression through dampening ERK1/2 activity.

African swine fever virus (ASFV) is a highly contagious and deadly virus that leads to high mortality rates in domestic swine populations. Although the envelope protein CD2v of ASFV has been implicated in immunomodulation, the molecular mechanisms underlying CD2v-mediated immunoregulation remain unclear. In this study, we generated a stable CD2v-expressing porcine macrophage (PAM-CD2v) line and investigated the CD2v-dependent transcriptomic landscape using RNA-seq. GO terms enrichment analysis and gene set enrichment analysis revealed that CD2v predominantly affected the organization and assembly process of the extracellular matrix. Wound healing and Transwell assays showed that CD2v inhibited swine macrophage migration. Further investigation revealed a significant decrease in the expression of transcription factor early growth response 1 (EGR1) through inhibiting the activity of extracellular signal-regulated kinase 1 and 2 (ERK1/2). Notably, EGR1 knockout in swine macrophages restricted cell migration, whereas EGR1 overexpression in PAM-CD2v restored the ability of macrophage migration, suggesting that CD2v inhibits swine macrophage motility by downregulating EGR1 expression. Furthermore, we performed chromatin immunoprecipitation and sequencing for EGR1 and the histone mark H3K27 acetylation (H3K27ac), and we found that EGR1 co-localized with the activated histone modification H3K27ac neighboring the transcriptional start sites. Further analysis indicated that EGR1 and H3K27ac co-occupy the promoter regions of cell locomotion-related genes. Finally, by treating various derivatives of swine macrophages with lipopolysaccharides, we showed that depletion of EGR1 decreased the expression of inflammatory cytokines including TNFα, IL1α, IL1ß, IL6, and IL8, which play essential roles in inflammation and host immune response. Collectively, our results provide new insights into the immunomodulatory mechanism of ASFV CD2v.

PGAM5 degrades PDCoV N protein and activates type I interferon to antagonize viral replication.

IMPORTANCE: As a member of the δ-coronavirus family, porcine deltacoronavirus (PDCoV) is a vital reason for diarrhea in piglets, which can contribute to high morbidity and mortality rates. Initially identified in Hong Kong in 2012, the virus has rapidly spread worldwide. During PDCoV infection, the virus employs evasion mechanisms to evade host surveillance, while the host mounts corresponding responses to impede viral replication. Our research has revealed that PDCoV infection down-regulates the expression of PGAM5 to promote virus replication. In contrast, PGAM5 degrades PDCoV N through autophagy by interacting with the cargo receptor P62 and the E3 ubiquitination ligase STUB1. Additionally, PGAM5 interacts with MyD88 and TRAF3 to activate the IFN signal pathway, resulting in the inhibition of viral replication.

Establishment of Replication Deficient Vesicular Stomatitis Virus for Studies of PEDV Spike-Mediated Cell Entry and Its Inhibition.

The porcine epidemic diarrhea virus (PEDV) is a highly contagious and virulent enteric coronavirus that causes severe enteric disease in pigs worldwide. PEDV infection causes profound diarrhea, vomiting, and dehydration in pigs of all ages, resulting in high mortality rates, particularly among neonatal piglets. The spike glycoprotein (S) of PEDV plays a crucial role in binding to the host cell receptor and facilitating fusion between the viral and host membranes. Pseudotyped viral particles featuring the PEDV S protein are valuable tools for investigating virus entry, identifying neutralizing antibodies, and developing small molecules to impede virus replication. In this study, we used a codon-optimized PEDV S protein to generate recombinant pseudotyped vesicular stomatitis virus (VSV) particles (rVSV-ΔG-EGFP-S). The full-length S protein was efficiently incorporated into VSV particles. The S protein pseudotyped VSV exhibited infectivity towards permissive cell lines of PEDV. Moreover, we identified a new permissive cell line, JHH7, which showed robust support for PEDV replication. In contrast to the SARS-CoV-2 spike protein, the removal of amino acids from the cytoplasmic tail resulted in reduced efficiency of viral pseudotyping. Furthermore, we demonstrated that 25-hydroxycholesterol inhibited rVSV-ΔG-EGFP-S entry, while human APN facilitated rVSV-ΔG-EGFP-S entry through the use of ANPEP knockout Huh7 cells. Finally, by transducing swine intestinal organoids with the rVSV-ΔG-EGFP-S virus, we observed efficient infection of the swine intestinal organoids by the PEDV spike-pseudotyped VSV. Our work offers valuable tools for studying the cellular entry of PEDV and developing interventions to curb its transmission.

Bioactive NIR-II gold clusters for three-dimensional imaging and acute inflammation inhibition.

Strong fluorescence and high catalytic activities cannot be achieved simultaneously due to conflicts in free electron utilization, resulting in a lack of bioactivity of most near-infrared-II (NIR-II) fluorophores. To circumvent this challenge, we developed atomically precise Au22 clusters with strong NIR-II fluorescence ranging from 950 to 1300 nm exhibiting potent enzyme-mimetic activities through atomic engineering to create active Cu single-atom sites. The developed Au21Cu1 clusters show 18-fold higher antioxidant, 90-fold higher catalase-like, and 3-fold higher superoxide dismutase-like activities than Au22 clusters, with negligible fluorescence loss. Doping with single Cu atoms decreases the bandgap from 1.33 to 1.28 eV by predominant contributions from Cu d states, and Cu with lost electron states effectuates high catalytic activities. The renal clearable clusters can monitor cisplatin-induced renal injury in the 20- to 120-minute window and visualize it in three dimensions using NIR-II light-sheet microscopy. Furthermore, the clusters inhibit oxidative stress and inflammation in the cisplatin-treated mouse model, particularly in the kidneys and brain.

PEDV N protein capture protein translation element PABPC1 and eIF4F to promote viral replication.

Porcine epidemic diarrhea (PED) is an acute, highly infectious intestinal disease caused by the porcine epidemic diarrhea virus (PEDV), which seriously endangers the healthy development of the pig industry. PEDV N protein is the most abundant viral structural protein, which can be combined with viral genomic RNA to form ribonucleoprotein complexes, thereby participating in the transcription and replication of the virus. However, how PEDV hijacks the host transcription translation system to promote viral proliferation remains unclear. In this study, we found that there is an interaction between PEDV N, polyadenylate-binding protein cytoplasmic 1 (PABPC1) and eukaryotic initiation factor 4F (eIF4F) proteins through coimmunoprecipitation, GST pulldown and fluorescence microscopy experiments. PABPC1 could bind to the poly(A) tail of the mRNA, and eIF4F could bind to the 5' end cap structure of the mRNA, so the interaction of PABPC1 and eIF4F could facilitate mRNA forming a circular shape to promote translation to the proteins. To further explore the effect of N protein capture protein translation element PABPC1 and eIF4F on PEDV replication, we overexpressed PABPC1, eIF4F (containing eIF4A, eIF4E and eIF4G) separately on Vero cells and LLC-PK1 cells, and we found that the PABPC1 and eIF4F protein could promote PEDV replication. Taken together, our data suggested that PEDV N protein promoted cyclization of viral mRNA carried by N protein through binding with PABPC1 and eIF4F proteins, thus promoting viral transcription and facilitating viral replication.

Expression of ASFV p17 in CHO cells and identification of one novel epitope using a monoclonal antibody.

As a highly pathogenic large DNA virus, African swine fever virus (ASFV) has huge particles and numerous encoded proteins. At present, few of the existing studies on ASFV proteins have investigated the function of p17. Specific antibodies against p17 to promote the development of prevention techniques against African swine fever (ASF) are urgently needed. Herein, we successfully expressed ASFV p17 in CHO cells using a suspension culture system and generated a monoclonal antibody (mAb) against p17. The mAb recognized a novel linear epitope (8LLSHNLSTREGIK20) and exhibited specific reactivity, which was conducive to the identification of ectopically expressed p17, the recombinant porcine reproductive and respiratory syndrome virus expressing p17, and the ASFV-SY18. The epitope was conservative among genotype I and genotype II ASFV strains. Overall, the mAb against p17 revealed efficient detection and promising application prospects, making it a useful tool for future vaccine research on ASF. Determination of the conserved linear epitope of p17 would contribute to the in-depth exploration of the biological function of ASFV antigen protein.

PTBP1 suppresses porcine epidemic diarrhea virus replication via inducing protein degradation and IFN production.

Porcine epidemic diarrhea virus (PEDV) causes severe morbidity and mortality among newborn piglets. It significantly threatens the porcine industry in China and around the globe. To accelerate the developmental pace of drugs or vaccines against PEDV, a deeper understanding of the interaction between viral proteins and host factors is crucial. The RNA-binding protein, polypyrimidine tract-binding protein 1 (PTBP1), is crucial for controlling RNA metabolism and biological processes. The present work focused on exploring the effect of PTBP1 on PEDV replication. PTBP1 was upregulated during PEDV infection. The PEDV nucleocapsid (N) protein was degraded through the autophagic and proteasomal degradation pathways. Moreover, PTBP1 recruits MARCH8 (an E3 ubiquitin ligase) and NDP52 (a cargo receptor) for N protein catalysis and degradation through selective autophagy. Furthermore, PTBP1 induces the host innate antiviral response via upregulating the expression of MyD88, which then regulates TNF receptor-associated factor 3/ TNF receptor-associated factor 6 expression and induces the phosphorylation of TBK1 and IFN regulatory factor 3. These processes activate the type Ⅰ IFN signaling pathway to antagonize PEDV replication. Collectively, this work illustrates a new mechanism related to PTBP1-induced viral restriction, where PTBP1 degrades the viral N protein and induces type Ⅰ IFN production to suppress PEDV replication.

Single Atom-Engineered NIR-II Gold Clusters with Ultrahigh Brightness and Stability for Acute Kidney Injury.

Near-infrared-II (NIR-II) imaging has shown great potential for monitoring the pathological progression and deep tissue imaging but is limited to present unmet NIR-II agent. Present fluorophores show a promising prospect for NIR-II imaging, but brightness and photostability are still highly challenging during real-time monitoring. In this work, atom-engineered NIR-II Au24 Cd1  clusters with ultrahigh brightness, stability, and photostability are developed via single atomic Cd doping. Single atom Cd substitutions contribute to Cd 4d state in HOMO and redistribution of energy level near the gap, exhibiting 56-fold fluorescence enhancement of Au24 Cd1  clusters. Meanwhile, single atomic Cd reinforces CdAu bond energy, formation energy, and stabilized cluster structure, leading to persistent stability for up to 1 month without decay, as well as excellent photostability of 1 h without photobleaching, much longer than clinically approved indocyanine green (<5 min). In vivo imaging shows gold clusters can monitor acute kidney injury (AKI) even after 72 h of injury, enabling evaluating progression at a very long window. Meanwhile, the bioactive gold clusters can alleviate AKI-induced oxidative stress damage and acute neuroinflammation. Single atom-engineered gold clusters exhibit molecular tracking and diagnostic prospect in kidney-related diseases.

N protein of PEDV plays chess game with host proteins by selective autophagy.

Macroautophagy/autophagy is a cellular degradation and recycling process that maintains the homeostasis of organisms. The protein degradation role of autophagy has been widely used to control viral infection at multiple levels. In the ongoing evolutionary arms race, viruses have developed various ways to hijack and subvert autophagy in favor of its replication. It is still unclear exactly how autophagy affects or inhibits viruses. In this study, we have found a novel host restriction factor, HNRNPA1, that could inhibit PEDV replication by degrading viral nucleocapsid (N) protein. The restriction factor activates the HNRNPA1-MARCHF8/MARCH8-CALCOCO2/NDP52-autophagosome pathway with the help of transcription factor EGR1 targeting the HNRNPA1 promoter. HNRNPA1 could also promote the expression of IFN to facilitate the host antiviral defense response for antagonizing PEDV infection through RIGI protein interaction. During viral replication, we found that PEDV can, in contrast, degrade the host antiviral proteins HNRNPA1 and others (FUBP3, HNRNPK, PTBP1, and TARDBP) through its N protein through the autophagy pathway. These results reveal the dual function of selective autophagy in PEDV N and host proteins, which could promote the ubiquitination of viral particles and host antiviral proteins and degradation both of the proteins to regulate the relationship between virus infection and host innate immunity.Abbreviations: 3-MA: 3-methyladenine; ATG: autophagy related; Baf A1: bafilomycin A1; CALCOCO2/NDP52: calcium binding and coiled-coil domain 2; ChIP: chromatin immunoprecipitation; Co-IP: co-immunoprecipitation; CQ: chloroquine; DAPI: 4',6-diamidino-2-phenylindole; GPI: glycosyl-phosphatidylinositol; hpi: hours post infection; MARCHF8/MARCH8: membrane-associated ring-CH-type finger 8; MOI: multiplicity of infection; N protein: nucleocapsid protein; PEDV: porcine epidemic diarrhea virus; siRNA: small interfering RNA; TCID50: 50% tissue culture infectious doses.

The rPRRSV-E2 strain exhibited a low level of potential risk for virulence reversion.

Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) and Classical Swine Fever Virus (CSFV) are two important pathogens, which cause serious impact on swine industry worldwide. In our previous research, rPRRSV-E2, the recombinant PRRSV expressing CSFV E2 protein, could provide sufficient protection against the lethal challenge of highly pathogenic PRRSV and CSFV, and could maintained genetically stable in vitro. Here, to evaluate the virulence reversion potential risk, rPRRSV-E2 had been continuously passaged in vivo, the stability of E2 expression and virulence of the passage viruses were analyzed. The results showed that no clinical symptoms or pathological changes could be found in the inoculated groups, and there were no significant differences of viraemia among the test groups. Sequencing and IFA analysis showed that the coding gene of exogenous CSFV E2 protein existed in the passaged viruses without any sequence mutations, deletions or insertions, and could expressed steadily. It could be concluded that the foreign CSFV E2 gene in the genome of rPRRSV-E2 could be maintained genetically stable in vivo, and rPRRSV-E2 strain had relatively low level of potential risk for virulence reversion.

Selective Enhancement of Photoresponse with Ferroelectric-Controlled BP/In2 Se3 vdW Heterojunction.

Owing to the large built-in field for efficient charge separation, heterostructures facilitate the simultaneous realization of a low dark current and high photocurrent. The lack of an efficient approach to engineer the depletion region formed across the interfaces of heterojunctions owing to doping differences hinders the realization of high-performance van der Waals (vdW) photodetectors. This study proposes a ferroelectric-controlling van der Waals photodetector with vertically stacked two-dimensional (2D) black phosphorus (BP)/indium selenide (In2 Se3 ) to realize high-sensitivity photodetection. The depletion region can be reconstructed by tuning the polarization states generated from the ferroelectric In2 Se3 layers. Further, the energy bands at the heterojunction interfaces can be aligned and flexibly engineered using ferroelectric field control. Fast response, self-driven photodetection, and three-orders-of-magnitude detection improvements are achieved in the switchable visible or near-infrared operation bands. The results of the study are expected to aid in improving the photodetection performance of vdW optoelectronic devices.

Terahertz Nonlinear Hall Rectifiers Based on Spin-Polarized Topological Electronic States in 1T-CoTe2.

The zero-magnetic-field nonlinear Hall effect (NLHE) refers to the second-order transverse current induced by an applied alternating electric field; it indicates the topological properties of inversion-symmetry-breaking crystals. Despite several studies on the NLHE induced by the Berry-curvature dipole in Weyl semimetals, the direct current conversion by rectification is limited to very low driving frequencies and cryogenic temperatures. The nonlinear photoresponse generated by the NLHE at room temperature can be useful for numerous applications in communication, sensing, and photodetection across a high bandwidth. In this study, observations of the second-order NLHE in type-II Dirac semimetal CoTe2 under time-reversal symmetry are reported. This is determined by the disorder-induced extrinsic contribution on the broken-inversion-symmetry surface and room-temperature terahertz rectification without the need for semiconductor junctions or bias voltage. It is shown that remarkable photoresponsivity over 0.1 A W-1 , a response time of approximately 710 ns, and a mean noise equivalent power of 1 pW Hz-1/2 can be achieved at room temperature. The results open a new pathway for low-energy photon harvesting via nonlinear rectification induced by the NLHE in strongly spin-orbit-coupled and inversion-symmetry-breaking systems, promising a considerable impact in the field of infrared/terahertz photonics.

Uniaxial compressions induced complementarity and anisotropic behaviors in CuVP2S6.

Uniaxial compressions in layered materials can change their electronic structures and properties. In this work, a bimetallic compound CuVP2S6is simulated by using Density Functional Theory (DFT) in the presence of uniaxial compressions. Our results clearly show vertical compressions could lead to anisotropic behaviors, which include the compression effect caused by interlayer compression and the anisotropy of intralayer stretching. The vertical compressions change the V-S bonds and the P-S bonds respectively in AA and AB structures. The complementarity between intralayer stretching and interlayer compression could also result in adjustable bandgaps and degeneracy breakdown of V atoms. Results from the electron localization function analysis demonstrate that the free electrons of AA and AB structures tend to delocalize, and ionic features in V-S bonds could be weakened with increasing vertical compressions. Moreover, the two internal binding energies of AA and AB structures and the charge density difference analysis show that the anisotropy in the intralayer stretch and the charge transfer between metal atoms and S atoms increases gradually.

PRPF19 Limits Porcine Epidemic Diarrhea Virus Replication through Targeting and Degrading Viral Capsid Protein.

Porcine epidemic diarrhea (PED) indicates the disease of the acute and highly contagious intestinal infection due to porcine epidemic diarrhea virus (PEDV), with the characteristics of watery diarrhea, vomiting, and dehydration. One of the reasons for diarrhea and death of piglets is PEDV, which leads to 100% mortality in neonatal piglets. Therefore, it is necessary to explore the interaction between virus and host to prevent and control PEDV. This study indicated that the host protein, pre-mRNA processing factor 19 (PRPF19), could be controlled by the signal transducer as well as activator of transcription 1 (STAT1). Thus, PEDV replication could be hindered through selective autophagy. Moreover, PRPF19 was found to recruit the E3 ubiquitin ligase MARCH8 to the N protein for ubiquitination. For the purpose of degradation, the ubiquitin N protein is acknowledged by the cargo receptor NDP52 and transported to autolysosomes, thus inhibiting virus proliferation. To conclude, a unique antiviral mechanism of PRPF19-mediated virus restriction was shown. Moreover, a view of the innate immune response and protein degradation against PEDV replication was provided in this study. IMPORTANCE The highly virulent porcine epidemic diarrhea virus (PEDV) emerged in 2010, and causes high mortality rates in newborn pigs. There are no effective and safe vaccines against the highly virulent PEDV. This virus has caused devastating economic losses in the pork industry worldwide. Studying the relationship between virus and host antiviral factors is important to develop the new antiviral strategies. This study identified the pre-mRNA processing factor 19 (PRPF19) as a novel antiviral protein in PEDV replication and revealed its viral restriction mechanisms for the first time. PRPF19 recruited the E3 ubiquitin ligase MARCH8 to the PEDV N protein for ubiquitination, and the ubiquitin N protein was acknowledged by the cargo receptor NDP52 and transported to autolysosomes for degradation. Our findings provide new insights in host antiviral factors PRPF19 that regulate the selective autophagy protein degradation pathway to inhibit PEDV replication.

Nonstructural Protein 2 Is Critical to Infection Efficiency of Highly Pathogenic Porcine Reproductive and Respiratory Syndrome Virus on PAMs and Influence Virulence In Vivo.

Porcine reproductive and respiratory syndrome (PRRS) is an important viral disease, causing significant economic losses to the swine industry worldwide. Atypical cases caused by highly pathogenic PRRS virus (HP-PRRSV) emerged in 2006 in China. The vaccine strain HuN4-F112 has been developed from the wild-type HP-PRRSV HuN4 through repeated passages on MARC-145 cells. However, the mechanisms of attenuation have yet to be defined. Previous studies have shown that the vaccine strain HuN4-F112 could not effectively replicate in porcine alveolar macrophages (PAMs). In the present study, a series of chimeric and mutant PRRSVs were constructed to investigate regions associated with the virus attenuation. Firstly, the corresponding genome regions (ORF1a, ORF1b and ORFs 2-7) were exchanged between two infectious clones of HuN4 and HuN4-F112, and then the influence of small regions in ORF1a and ORF2-7 was evaluated, then influence of specific amino acids on NSP2 was tested. NSP2 was determined to be the key gene that regulated infection efficiency on PAMs, and amino acids at 893 and 979 of NSP2 were the key amino acids. The results of in vivo study indicated that NSP2 was not only important for infection efficiency in vitro, but also influenced the virulence, which was indicated by the results of survival rate, temperature, viremia, lung score and tissue score.

Identification and Characterization of Cell Lines HepG2, Hep3B217 and SNU387 as Models for Porcine Epidemic Diarrhea Coronavirus Infection.

Porcine epidemic diarrhea virus (PEDV), a member of the genera alphacoronavirus, causes acute watery diarrhea and dehydration in suckling piglets and results in enormous economic losses in the swine industry worldwide. Identification and characterization of different cell lines are not only invaluable for PEDV entry and replication studies but also important for the development of various types of biological pharmaceuticals against PEDV. In this study, we present an approach to identify suitable permissive cell lines for PEDV research. Human cell lines were screened for a high correlation coefficient with the established PEDV infection model Huh7 based on RNA-seq data from the Cancer Cell Line Encyclopedia (CCLE). Experimentally testing permissiveness towards PEDV infection, three highly permissive human cell lines, HepG2, Hep3B217, and SNU387 were identified. The replication kinetics of PEDV in HepG2, Hep3B217, and SNU387 cells were similar to that in Vero and Huh7 cells. Additionally, the transcriptomes analysis showed robust induction of transcripts associated with the innate immune in response to PEDV infection in all three cell lines, including hundreds of inflammatory cytokine and interferon genes. Moreover, the expression of inflammatory cytokines and interferons were confirmed by qPCR assay. Our findings indicate that HepG2, Hep3B217, and SNU387 are suitable cell lines for PEDV replication and innate immune response studies.

Experimental Study on the Diversion Characteristic of a Viscous Fluid in a Heterogeneous Reservoir.

As a typical feature of a reservoir, heterogeneity is the main reason for low oil recovery and the poor effect of acidizing measures. Diversion is the main measure to improve the acidizing effect. Over the years, technological progress has mainly focused on the material development of diverting agents. In this study, the diverting effect and influencing factors for a viscous fluid were systematically studied by the heterogeneous dual-core flooding experiment. The results are as follows: First, increasing the displacement pressure in heterogeneous reservoirs can improve the diverting effect, which is consistent with maximum differential pressure and injection rate (MADPIR) theory, but the diverting effect is weak. The injection pressure difference is increased by 50 times, and the diverting effect is improved by 16.27% at most. Second, taking a viscous fluid as the stimulation fluid can partially realize the diversion for heterogeneous reservoir and further improve the acidizing effect, and the breaking through PV can be improved by 78% at most. Using a viscous fluid as a diverting agent can achieve 100% balanced acid injection. Third, compared with a viscoelastic surfactant, a relatively uniform and stable polymer solution as the diverting agent has the possibility to completely block the low-permeability layer. So, a 5% viscoelastic surfactant as the diverting agent is more suitable for acidizing. Finally, any diverter injected into the formation will enter all layers. The conclusion that the diverting agent only enters the high-permeability layer but not the low-permeability layer is not tenable. Diverting acidizing is only effective for near-well zones, which is difficult to fundamentally solve the seepage problem of heterogeneous reservoirs.