VP2 mediates the release of the feline calicivirus RNA genome by puncturing the endosome membrane of infected cells.

Feline calicivirus (FCV) is one of the few members of the Caliciviridae family that grows well in cell lines and, therefore, serves as a surrogate to study the biology of other viruses in the family. Conley et al. (14) demonstrated that upon the receptor engagement to the capsid, FCV VP2 forms a portal-like assembly, which might provide a channel for RNA release. However, the process of calicivirus RNA release is not yet fully understood. Our findings suggest that the separation of the FCV capsid from its genome RNA (gRNA) occurs rapidly in the early endosomes of infected cells. Using a liposome model decorated with the FCV cell receptor fJAM-A, we demonstrate that FCV releases its gRNA into the liposomes by penetrating membranes under low pH conditions. Furthermore, we found that VP2, which is rich in hydrophobic residues at its N-terminus, functions as the pore-forming protein. When we substituted the VP2 N-terminal hydrophobic residues, the gRNA release efficacy of the FCV mutants decreased. In conclusion, our results suggest that in the acidic environment of early endosomes, FCV VP2 functions as the pore-forming protein to mediate gRNA release into the cytoplasm of infected cells. This provides insight into the mechanism of calicivirus genome release.IMPORTANCEResearch on the biology and pathogenicity of certain caliciviruses, such as Norovirus and Sapovirus, is hindered by the lack of easy-to-use cell culture system. Feline calicivirus (FCV), which grows effectively in cell lines, is used as a substitute. At present, there is limited understanding of the genome release mechanism in caliciviruses. Our findings suggest that FCV uses VP2 to pierce the endosome membrane for genome release and provide new insights into the calicivirus gRNA release mechanism.

Blood-brain barrier dysfunction mediated by the EZH2-Claudin-5 axis drives stress-induced TNF-α infiltration and depression-like behaviors.

Growing evidence suggests that neurovascular dysfunction characterized by blood-brain barrier (BBB) breakdown underlies the development of psychiatric disorders, such as major depressive disorder (MDD). Tight junction (TJ) proteins are critical modulators of homeostasis and BBB integrity. TJ protein Claudin-5 is the most dominant BBB component and is downregulated in numerous depression models; however, the underlying mechanisms remain elusive. Here, we demonstrate a molecular basis of BBB breakdown that links stress and depression. We implemented an animal model of depression, chronic unpredictable mild stress (CUMS) in male C57BL/6 mice, and showed that hippocampal BBB breakdown was closely associated with stress vulnerability. Concomitantly, we found that dysregulated Cldn5 level coupled with repression of the histone methylation signature at its promoter contributed to stress-induced BBB dysfunction and depression. Moreover, histone methyltransferase enhancer of zeste homolog 2 (EZH2) knockdown improved Cldn5 expression and alleviated depression-like behaviors by suppressing the tri-methylation of lysine 27 on histone 3 (H3K27me3) in chronically stressed mice. Furthermore, the stress-induced excessive transfer of peripheral cytokine tumor necrosis factor-α (TNF-α) into the hippocampus was prevented by Claudin-5 overexpression and EZH2 knockdown. Interestingly, antidepressant treatment could inhibit H3K27me3 deposition at the Cldn5 promoter, reversing the loss of the encoded protein and BBB damage. Considered together, these findings reveal the importance of the hippocampal EZH2-Claudin-5 axis in regulating neurovascular function and MDD development, providing potential therapeutic targets for this psychiatric illness.

3D-printed coloured tooth model for inlay preparation in pre-clinical dental education.

INTRODUCTION: Accurate inlay preparation is extremely important in pre-clinical training. However, there is a lack of tools to guide students to efficiently practise inlay preparation. Therefore, a 3D-printed coloured tooth model for inlay preparation was designed to guide beginners to practise inlay preparation by themselves according to different colour prompts. This study aimed to evaluate the benefits of using a 3D-printed coloured tooth model in the pre-clinical training on inlay preparation. MATERIALS AND METHODS: Twenty-eight students in their fourth-year undergraduate dental program participated in this study. The participants were randomly assigned to two groups for the inlay preparation. Group 1 prepared a plain tooth model for the first and fourth attempts and a 3D-printed coloured tooth model for the second and third attempts (n = 14). Group 2 prepared four plain tooth models (n = 14). The first and fourth tooth models prepared by both groups were scored using an evaluation system (Fair Grade 2000, NISSIN). Next, questionnaires answered by students were used to evaluate the benefits of using a 3D-printed coloured tooth model and self-evaluate hands-on ability using a grading system (1 = strongly agree, 2 = agree, 3 = neutral, 4 = disagree, and 5 = strongly disagree). The scores were evaluated statistically using the Mann-Whitney U test, and the given grades are displayed as percentages and mean values. RESULTS: There was an overall increase in the clinical confidence of all students after repeated attempts to prepare an inlay; however, students from group 1, who had used the 3D-printed coloured tooth model, had more positive experiences and comments. The 3D-printed coloured tooth model for inlay preparation has been widely praised by participants. Comparing the average score of the first and fourth preparations, the average score of group 1 increased by 12% (Ø 54.46 ± 8.33, Ø 61.11 ± 7.13, p = .090), while that of group 2 increased by 0.72% (Ø 56.39 ± 9.59, Ø 56.80 ± 8.46, p = .925). CONCLUSION: Students favoured the use of the 3D-printed coloured tooth model, and this improved the average score for inlay preparation. The 3D-printed coloured tooth model for inlay preparation is expected to play an important role in dental education in the future.

Norepinephrine promotes glioma cell migration through up-regulating the expression of Twist1.

BACKGROUND: Glioma cells are characterized by high migration ability, resulting in aggressive growth of the tumors and poor prognosis of patients. It has been reported that the stress-induced hormone norepinephrine (NE) contributes to tumor progression through mediating a number of important biological processes in various cancers. However, the role of NE in the regulation of glioma migration is still unclear. Epithelial-to-mesenchymal transition (EMT) is one of the most important steps for tumor migration and metastasis. Twist1, as a key regulator of EMT, has been found to be elevated during glioma migration. But it is still unknown whether Twist1 is involved in the effect of NE on the migration of glioma cells. METHODS: Wound healing assay and transwell assay were conducted to evaluate the migration of glioma cells upon different treatments. The mesenchymal-like phenotype and the expression of Twist1 after NE treatment were assessed by cell diameters, real-time PCR, western blot and immunofluorescence staining. The gain-and loss-of-function experiments were carried out to investigate the biological function of Twist1 in the migration induced by NE. Finally, the clinical significance of Twist1 was explored among three public glioma datasets. RESULTS: In this study, our finding revealed a facilitative effect of NE on glioma cell migration in a ß-adrenergic receptor (ADRB)-dependent way. Mechanistically, NE induced mesenchymal-like phenotype and the expression of Twist1. Twist1 overexpression promoted glioma cells migration, while knockdown of Twist1 abolished the discrepancy in the migration ability between NE treated glioma cells and control cells. In addition, the clinical analysis demonstrated that Twist1 was up-regulated in malignant gliomas and recurrent gliomas, and predicted a poor prognosis of glioma patients. CONCLUSIONS: NE enhanced the migration ability of glioma cells through elevating the expression of Twist1. Our finding may provide potential therapeutic target for protecting patients with glioma from the detrimental effects of stress biology on the tumor progression.

Production and application of mouse monoclonal antibodies targeting linear epitopes in pB602L of African swine fever virus.

African swine fever (ASF) is an acute hemorrhagic disease of domestic pigs. The causative agent of ASF, ASF virus (ASFV), is a double-stranded DNA virus, the sole member in the family Asfarviridae. The non-structural protein pB602L of ASFV is a molecular chaperone of the major capsid protein p72 and plays a key role in icosahedral capsid assembly. This protein is antigenic and is a target for developing diagnostic tools for ASF. To generate monoclonal antibodies (mAbs) against pB602L, a prokaryotically expressed recombinant pB602L protein was produced, purified, and used as an antigen to immunize mice. A total of eight mouse mAbs were obtained, and their binding epitopes were screened by Western blot using an overlapping set of polypeptides from pB602L. Three linear epitopes were identified and designated epitope 1 (366ANRERYNY373), epitope 2 (415GPDAPGLSI423), and epitope 3 (498EMLNVPDD505). Based on the epitope recognized, the eight mAbs were placed into three groups: group 1 (B2A1, B2F1, and B2D10), group 2 (B2H10, B2B2, B2D8, and B2A3), and group 3 (B2E12). The mAbs B2A1, B2H10, and B2E12, each representing one of the groups, were used to detect pB602L in ASFV-infected porcine alveolar macrophages (PAMs) and pig tissues, using an indirect fluorescence assay (IFA) and immunohistochemical staining, respectively. The results showed that pB602L was detectable with all three mAbs in immunohistochemical staining, but only B2H10 was suitable for detecting the proteins in ASFV-infected PAMs by IFA. In summary, we developed eight anti-pB602L mouse mAbs recognizing three linear epitopes in the protein, which can be used as reagents for basic and applied research on ASFV.

High stretchability, strength, and toughness of living cells enabled by hyperelastic vimentin intermediate filaments.

In many developmental and pathological processes, including cellular migration during normal development and invasion in cancer metastasis, cells are required to withstand severe deformations. The structural integrity of eukaryotic cells under small deformations has been known to depend on the cytoskeleton including actin filaments (F-actin), microtubules (MT), and intermediate filaments (IFs). However, it remains unclear how cells resist severe deformations since both F-actin and microtubules yield or disassemble under moderate strains. Using vimentin containing IFs (VIFs) as a model for studying the large family of IF proteins, we demonstrate that they dominate cytoplasmic mechanics and maintain cell viability at large deformations. Our results show that cytoskeletal VIFs form a stretchable, hyperelastic network in living cells. This network works synergistically with other cytoplasmic components, substantially enhancing the strength, stretchability, resilience, and toughness of cells. Moreover, we find the hyperelastic VIF network, together with other quickly recoverable cytoskeletal components, forms a mechanically robust structure which can mechanically recover after damage.

The Sec1/Munc18-like proteins TgSec1 and TgVps45 play pivotal roles in assembly of the pellicle and sub-pellicle network in Toxoplasma gondii.

Post-Golgi vesicle trafficking is indispensable for precise movement of proteins to the pellicle, the sub-pellicle network and apical secretory organelles in Apicomplexa. However, only a small number of molecular complexes involved in trafficking, tethering and fusion of vesicles have been identified in Toxoplasma gondii. Consequently, it is unclear how complicated vesicle trafficking is accomplished in this parasite. Sec1/Munc18-like (SM) proteins are essential components of protein complexes involved in vesicle fusion. Here, we found that depletion of the SM protein TgSec1 using an auxin-inducible degron-based conditional knockout strategy led to mislocalization of plasma membrane proteins. By contrast, conditional depletion of the SM protein TgVps45 led to morphological changes, asymmetrical loss of the inner membrane complex and defects in nucleation of sub-pellicular microtubules, polarization and symmetrical assembly of daughter parasites during repeated endodyogeny. TgVps45 interacts with the SNARE protein TgStx16 and TgVAMP4-1. Conditional ablation of TgStx16 causes the similar growth defect like TgVps45 deficiency suggested they work together for the vesicle fusion at TGN. These findings indicate that these two SM proteins are crucial for assembly of pellicle and sub-pellicle network in T. gondii respectively.

Identification, characterization, and functional investigation of circular RNAs in subventricular zone of adult rat brain.

Adult neural stem cells (NSCs) are able to self-renew and generate new neural cells. Identifying regulators of NSCs is significant for the development of NSC-based therapies for neurodegenerative diseases and brain injuries. Recently, circular RNAs (circRNAs) have been characterized in various cell lines and brain tissues, and found to participate in multiple biological processes. However, the expression pattern of circRNAs in adult NSCs is still unknown. Here, the subventricular zone (SVZ) of the lateral ventricle was isolated as the niche of NSCs in adult rat brain for RNA sequencing and the characteristics of circRNAs profiling in both SVZ and cerebral cortex were also investigated. As a result, 29 049 and 31 975 circRNAs were identified in SVZ and cortex, respectively. Among them, 41 were SVZ-specific and 48 were cortex-specific. 467 circRNAs were also found to express predominately in SVZ, while the cortex had other 423 circRNAs. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses revealed that the SVZ-specific circRNAs have close relationship with the regulation of NSC expansion and NSC-niche interaction, while the other differentially expressed circRNAs might be involved in neural cellular construction and nerve system function. Furthermore, the interactions between circRNAs and microRNAs were also explored, and the result showed that one SVZ-specific circRNA was capable to competitively bind miR-138-5p as a potential derepressive regulator in NSCs proliferation. Hence, our work has laid the foundations to decipher regulation mechanisms of circRNAs in adult NSCs and to develop circRNAs as novel biomarkers for adult NSCs.

The VicRK Two-Component System Regulates Streptococcus mutans Virulence.

Streptococcus mutans is considered the predominant etiological agent of dental caries with the ability to form biofilm on the tooth surface. And, its abilities to obtain nutrients and metabolize fermentable dietary carbohydrates to produce acids contribute to its pathogenicity. The responses of S. mutans to environmental stresses are essential for its survival and role in cariogenesis. The VicRK system is one of the 13 putative TCS of S. mutans. The conserved functions of the VicRK signal transduction system is the key regulator of bacterial oxidative stress responses, acidification, cell wall metabolism, and biofilm formation. In this paper, it was discussed how the VicRK system regulates S. mutans virulence including bacterial physiological function, operon structure, signal transduction, and even post-transcriptional control in its regulon. Thus, this emerging subspecialty of the VicRK regulatory networks in S. mutans may strengthen our understandings aimed at providing a basis for the prevention of dental caries.

Mechanistic insights revealed by the crystal structure of a histidine kinase with signal transducer and sensor domains.

Two-component systems (TCSs) are important for the adaptation and survival of bacteria and fungi under stress conditions. A TCS is often composed of a membrane-bound sensor histidine kinase (SK) and a response regulator (RR), which are relayed through sequential phosphorylation steps. However, the mechanism for how an SK is switched on in response to environmental stimuli remains obscure. Here, we report the crystal structure of a complete cytoplasmic portion of an SK, VicK from Streptococcus mutans. The overall structure of VicK is a long-rod dimer that anchors four connected domains: HAMP, Per-ARNT-SIM (PAS), DHp, and catalytic and ATP binding domain (CA). The HAMP, a signal transducer, and the PAS domain, major sensor, adopt canonical folds with dyad symmetry. In contrast, the dimer of the DHp and CA domains is asymmetric because of different helical bends in the DHp domain and spatial positions of the CA domains. Moreover, a conserved proline, which is adjacent to the phosphoryl acceptor histidine, contributes to helical bending, which is essential for the autokinase and phosphatase activities. Together, the elegant architecture of VicK with a signal transducer and sensor domain suggests a model where DHp helical bending and a CA swing movement are likely coordinated for autokinase activation.

Peste des petits ruminants virus in Heilongjiang province, China, 2014.

During March 25-May 5, 2014, we investigated 11 outbreaks of peste des petits ruminants in Heilongjiang Province, China. We found that the most likely source of the outbreaks was animals from livestock markets in Shandong. Peste des petits ruminants viruses belonging to lineages II and IV were detected in sick animals.

Antibacterial effect of dental adhesive containing dimethylaminododecyl methacrylate on the development of Streptococcus mutans biofilm.

Antibacterial bonding agents and composites containing dimethylaminododecyl methacrylate (DMADDM) have been recently developed. The objectives of this study were to investigate the antibacterial effect of novel adhesives containing different mass fractions of DMADDM on Streptococcus mutans (S. mutans) biofilm at different developmental stages. Different mass fractions of DMADDM were incorporated into adhesives and S. mutans biofilm at different developmetal stages were analyzed by MTT assays, lactic acid measurement, confocal laser scanning microscopy and scanning electron microscopy observations. Exopolysaccharides (EPS) staining was used to analyze the inhibitory effect of DMADDM on the biofilm extracellular matrix. Dentin microtensile strengths were also measured. Cured adhesives containing DMADDM could greatly reduce metabolic activity and lactic acid production during the development of S. mutans biofilms (p < 0.05). In earlier stages of biofilm development, there were no significant differences of inhibitory effects between the 2.5% DMADDM and 5% DMADDM group. However, after 72 h, the anti-biofilm effects of adhesives containing 5% DMADDM were significantly stronger than any other group. Incorporation of DMADDM into adhesive did not adversely affect dentin bond strength. In conclusion, adhesives containing DMADDM inhibited the growth, lactic acid production and EPS metabolism of S. mutans biofilm at different stages, with no adverse effect on its dentin adhesive bond strength. The bonding agents have the potential to control dental biofilms and combat tooth decay, and DMADDM is promising for use in a wide range of dental adhesive systems and restoratives.

Simulation Study on the Charge Collection Mechanism of FinFET Devices in Single-Event Upset.

Planar devices and FinFET devices exhibit significant differences in single-event upset (SEU) response and charge collection. However, the charge collection process during SEU in FinFET devices has not been thoroughly investigated. This article addresses this gap by establishing a FinFET SRAM simulation structure and employing simulation software to delve into the charge collection process of FinFET devices during single-event upset. The results reveal substantial differences in charge collection between NMOS and PMOS, and that direct incidence of PMOS leads to the phenomenon of multiple-node charge collection causing SRAM unit upset followed by recovery.

The antibodies against the A137R protein drive antibody-dependent enhancement of African swine fever virus infection in porcine alveolar macrophages.

African swine fever virus (ASFV) is the causative agent of African swine fever (ASF), a highly contagious disease that can kill up to 100% of domestic pigs and wild boars. It has been shown that the pigs inoculated with some ASF vaccine candidates display more severe clinical signs and die earlier than do pigs not immunized. We hypothesize that antibody-dependent enhancement (ADE) of ASFV infection may be caused by the presence of some unidentified antibodies. In this study, we found that the ASFV-encoded structural protein A137R (pA137R) can be recognized by the anti-ASFV positive sera, indicating that the anti-pA137R antibodies are induced in the ASFV-infected pigs. Interestingly, our results demonstrated that the anti-pA137R antibodies produced in rabbits or pigs enhanced viral replication of different ASFV strains in primary porcine alveolar macrophages (PAMs), the target cells of ASFV. Mechanistic investigations revealed that anti-pA137R antibodies were able to promote the attachment of ASFV to PAMs and two types of Fc gamma receptors (FcγRs), FcγRII and FcγRIII, mediated the ADE of ASFV infection. Taken together, anti-pA137R antibodies are able to drive ASFV ADE in PAMs. These findings shed new light on the roles of anti-ASFV antibodies and have implications for the pathophysiology of the disease and the development of ASF vaccines.

Avian ANP32A incorporated in avian influenza A virions promotes interspecies transmission by priming early viral replication in mammals.

Species-specific differences in acidic nuclear phosphoprotein 32 family member A (ANP32A) determine the restriction of avian-signature polymerase in mammalian cells. Mutations that evade this restriction, such as PB2-E627K, are frequently acquired when avian influenza A viruses jump from avian hosts to mammalian hosts. However, the mechanism underlying this adaptation process is still unclear. Here, we report that host factor ANP32 proteins can be incorporated into influenza viral particles through combination with the viral RNA polymerase (vPol) and then transferred into targeted cells where they support virus replication. The packaging of the ANP32 proteins into influenza viruses is dependent on their affinity with the vPol. Avian ANP32A (avANP32A) delivered by avian influenza A virions primes early viral replication in mammalian cells, thereby favoring the downstream interspecies transmission event by increasing the total amount of virus carrying adaptive mutations. Our study clarifies one role of avANP32A where it is used by avian influenza virus to help counteract the restriction barrier in mammals.

[Functional analysis of VicK kinase activity in Streptococcus mutans].

OBJECTIVE: To investigate the regulatory function on physiology and virulence of VicK kinase activity in Streptococcus mutans. METHODS: PCR ligation mutagenesis was used to construct a vicK knock-out mutant, and kinase activity abolished VicK was expressed by a streptococcal vector in this vicK null mutant. Colony morphology, overnight culture, biofilm formation and gene expression involved in biofilm formation were analyzed. Delta VicK, strains harboring a complemented wild-type vicK, and a vector without insert were used as controls. RESULTS: Colonies of VicK(H217A) were smoother and more elevated than that of wild-type UA159 and complementary strain SMCVicK; cells from VicK(H217A) overnight culture coaggregated on the bottom of glass tubes; no obvious alteration was observed in VicK(H217A) biofilm; expressions of gbpB, ftf, gtfD were repressed while gtfB/C were up-regulated (P < 0.05). CONCLUSION: VicK kinase activity is important for maintaining normal growth, biofilm formation and expression of genes involved in biofilm formation in Streptococcus mutans.

Composite Sophora Colon-Soluble Capsule Ameliorates DSS-Induced Ulcerative Colitis in Mice via Gut Microbiota-Derived Butyric Acid and NCR+ ILC3.

OBJECTIVE: To investigate the effects of composite Sophora colon-soluble Capsule (CSCC) on gut microbiota-mediated short-chain fatty acids (SCFAs) production and downstream group 3 innate lymphoid cells (ILC3s) of dextran sulfate sodium (DSS)-induced ulcerative colitis (UC) mice model. METHODS: The main components of CSCC were analyzed by hybrid ultra-high-performance liquid chromatography ion mobility spectromety quadrupole time-of-flight mass spectrometry (UHPLC-IM-QTOF/MS). Twenty-four male BALB/c mice were randomly divided into 4 groups (n=6) by using a computer algorithm-generated random digital, including control, DSS model, mesalazine, and CSCC groups. A DSS-induced colitis mice model was established to determine the effects of CSCC by recording colonic weight, colonic length, index of colonic weight, and histological colonic score. The variations in ILC3s were assessed by immunofluorescence and flow cytometry. The results of gut microbiota and SCFAs were acquired by 16s rDNA and gas chromatography-mass spectrometry (GC-MS) analysis. The expression levels of NCR+ ILC3-, CCR6+ Nkp46- (Lti) ILC3-, and ILCreg-specific markers were detected by enzyme-linked immunosorbent assay, and real-time quantitative polymerase chain reaction and Western blot, respectively. RESULTS: The main components of CSCC were matrine, ammothamnine, Sophora flavescens neoalcohol J, and Sophora oxytol U. After 7 days of treatment, CSCC significantly alleviated colitis by promoting the reproduction of intestinal probiotics manifested as upregulation of the abundance of Bacteroidetes species and specifically the Bacteroidales_S24-7 genus (P<0.05). Among the SCFAs, the content of butyric acid increased the most after CSCC treatment. Meanwhile, compared with the model group, Lti ILC3s and its biomarkers were significantly downregulated and NCR+ ILC3s were significantly elevated in the CSCC group (P<0.01). Further experiments revealed that ILC3s were differentiated from Lti ILC3s to NCR+ ILC3s, resulting in interleukin-22 production which regulates gut epithelial barrier function. CONCLUSION: CSCC may exert a therapeutic effect on UC by improving the gut microbiota, promoting metabolite butyric acid production, and managing the ratio between NCR+ ILC3s and Lti ILC3s.

vicR overexpression in Streptococcus mutans causes aggregation and affects interspecies competition.

Streptococcus mutans is considered to be a major causative agent of dental caries. VicRK is a two-component signal transduction system (TCSTS) of S. mutans, which can regulate the virulence of S. mutans, such as biofilm formation, exopolysaccharide production, acid production, and acid resistance. Meanwhile, it can also regulate the production of mutacins (nlmC) through the TCSTS ComDE. In this study, we found that the vicR-overexpressing strain was more likely to aggregate to form cell clusters, leading to the formation of abnormal biofilm; the overexpression of vicR increased the length of the chain of S. mutans. Furthermore, the expression of the mutacins in the vicR overexpression strain was increased under aerobic conditions. Compared with the control strain and the parental strain, the vicR overexpression strain was more competitive against Streptococcus gordonii. But there was no significant difference against Streptococcus sanguinis. In clinical strains, the expression level of vicR was positively correlated with their competitive ability against S. gordonii. Transcriptional profiling revealed 24 significantly upregulated genes in the vicR-overexpressing strain, including nlmA, nlmB, nlmC, and nlmD encoding mutacins. Electrophoretic mobility shift assays and DNase I footprinting assays confirmed that VicR can directly bind to the promoter sequence of nlmD. Taken together, our findings further demonstrate that VicRK, an important TCSTS of S. mutans, is involved in S. mutans cell morphology and biofilm formation. VicRK regulates the production of more mutacins in S. mutans in response to oxygen stimulation. VicR can bind to the promoter sequence of nlmD, thereby directly regulating the production of mutacins NlmD.

Spatio-temporal spread and evolution of influenza A (H7N9) viruses.

The influenza A (H7N9) virus has been seriously concerned for its potential to cause an influenza pandemic. To understand the spread and evolution process of the virus, a spatial and temporal Bayesian evolutionary analysis was conducted on 2,052 H7N9 viruses isolated during 2013 and 2018. It revealed that the H7N9 virus was probably emerged in a border area of Anhui Province in August 2012, approximately 6 months earlier than the first human case reported. Two major epicenters had been developed in the Yangtze River Delta and Peral River Delta regions by the end of 2013, and from where the viruses have also spread to other regions at an average speed of 6.57 km/d. At least 24 genotypes showing have been developed and each of them showed a distinct spatio-temporal distribution pattern. Furthermore, A random forest algorithm-based model has been developed to predict the occurrence risk of H7N9 virus. The model has a high overall forecasting precision (> 97%) and the monthly H7N9 occurrence risk for each county of China was predicted. These findings provide new insights for a comprehensive understanding of the origin, evolution, and occurrence risk of H7N9 virus. Moreover, our study also lays a theoretical basis for conducting risk-based surveillance and prevention of the disease.

Artificial intelligence for caries and periapical periodontitis detection.

OBJECTIVES: Periapical periodontitis and caries are common chronic oral diseases affecting most teenagers and adults worldwide. The purpose of this study was to develop an evaluation tool to automatically detect dental caries and periapical periodontitis on periapical radiographs using deep learning. METHODS: A modified deep learning model was developed using a large dataset (4129 images) with high-quality annotations to support the automatic detection of both dental caries and periapical periodontitis. The performance of the model was compared to the classification performance of dentists. RESULTS: The deep learning model automatically distinguished dental caries with an F1-score of 0.829 and periapical periodontitis with an F1-score of 0.828. The comparison of model-only and expert-only detection performance showed that the accuracy of the fully automatic method was significantly higher than that of the young dentists. With deep learning assistance, the experts not only reached a higher diagnostic accuracy with an average F1-score of 0.7844 for dental caries and 0.8208 for periapical periodontitis compared to expert-only scenarios, but also increased inter-observer agreement from 0.585/0.590 to 0.726/0.713 for dental caries and from 0.623/0.563 to 0.752/0.740 for periapical periodontitis. CONCLUSIONS: Based on these experimental results, deep learning can improve the accuracy and consistency of evaluating dental caries and periapical periodontitis on periapical radiographs. CLINICAL SIGNIFICANCE: Deep learning models can improve accuracy and consistency and reduce the workload of dentists, making artificial intelligence a powerful tool for clinical practice.