Superconducting diode effect and interference patterns in kagome CsV3Sb5.

The interplay among frustrated lattice geometry, non-trivial band topology and correlation yields rich quantum states of matter in kagome systems1,2. A series of recent members in this family, AV3Sb5 (A = K, Rb or Cs), exhibit a cascade of symmetry-breaking transitions3, involving the 3Q chiral charge ordering4-8, electronic nematicity9,10, roton pair density wave11 and superconductivity12. The nature of the superconducting order is yet to be resolved. Here we report an indication of dynamic superconducting domains with boundary supercurrents in intrinsic CsV3Sb5 flakes. The magnetic field-free superconducting diode effect is observed with polarity modulated by thermal histories, suggesting that there are dynamic superconducting order domains in a spontaneous time-reversal symmetry-breaking background. Strikingly, the critical current exhibits double-slit superconductivity interference patterns when subjected to an external magnetic field. The characteristics of the patterns are modulated by thermal cycling. These phenomena are proposed as a consequence of periodically modulated supercurrents flowing along certain domain boundaries constrained by fluxoid quantization. Our results imply a time-reversal symmetry-breaking superconducting order, opening a potential for exploring exotic physics, for example, Majorana zero modes, in this intriguing topological kagome system.

Salmonella Enteritidis T1SS protein SiiD inhibits NLRP3 inflammasome activation via repressing the mtROS-ASC dependent pathway.

Inflammasome activation is an essential innate immune defense mechanism against Salmonella infections. Salmonella has developed multiple strategies to avoid or delay inflammasome activation, which may be required for long-term bacterial persistence. However, the mechanisms by which Salmonella evades host immune defenses are still not well understood. In this study, Salmonella Enteritidis (SE) random insertion transposon library was screened to identify the key factors that affect the inflammasome activation. The type I secretion system (T1SS) protein SiiD was demonstrated to repress the NLRP3 inflammasome activation during SE infection and was the first to reveal the antagonistic role of T1SS in the inflammasome pathway. SiiD was translocated into host cells and localized in the membrane fraction in a T1SS-dependent and partially T3SS-1-dependent way during SE infection. Subsequently, SiiD was demonstrated to significantly suppress the generation of mitochondrial reactive oxygen species (mtROS), thus repressing ASC oligomerization to form pyroptosomes, and impairing the NLRP3 dependent Caspase-1 activation and IL-1ß secretion. Importantly, SiiD-deficient SE induced stronger gut inflammation in mice and displayed NLRP3-dependent attenuation of the virulence. SiiD-mediated inhibition of NLRP3 inflammasome activation significantly contributed to SE colonization in the infected mice. This study links bacterial T1SS regulation of mtROS-ASC signaling to NLRP3 inflammasome activation and reveals the essential role of T1SS in evading host immune responses.

Salmonella Enteritidis antitoxin DinJ inhibits NLRP3-dependent canonical inflammasome activation in macrophages.

The inflammasome is a pivotal component of the innate immune system, acting as a multiprotein complex that plays an essential role in detecting and responding to microbial infections. Salmonella Enteritidis have evolved multiple mechanisms to regulate inflammasome activation and evade host immune system clearance. Through screening S. Enteritidis C50336ΔfliC transposon mutant library, we found that the insertion mutant of dinJ increased inflammasome activation. In this study, we demonstrated the genetic connection between the antitoxin DinJ and the toxin YafQ in S. Enteritidis, confirming their co-transcription. The deletion mutant ΔfliCΔdinJ increased cell death and IL-1ß secretion in J774A.1 cells. Western blotting analysis further showed elevated cleaved Caspase-1 product (p10 subunits) and IL-1ß secretion in cells infected with ΔfliCΔdinJ compared to cells infected with ΔfliC. DinJ was found to inhibit canonical inflammasome activation using primary bone marrow-derived macrophages (BMDMs) from Casp-/- C57BL/6 mice. Furthermore, DinJ specifically inhibited NLRP3 inflammasome activation, as demonstrated in BMDMs from Nlrp3-/- and Nlrc4-/- mice. Fluorescence resonance energy transfer (FRET) experiments confirmed the translocation of DinJ into host cells during infection. Finally, we revealed that DinJ could inhibit the secretion of IL-1ß and IL-18 in vivo, contributing to S. Enteritidis evading host immune clearance. In summary, our findings provide insights into the role of DinJ in modulating the inflammasome response during S. Enteritidis infection, highlighting its impact on inhibiting inflammasome activation and immune evasion.

Interlayer-Coupling-Driven High-Temperature Superconductivity in La_{3}Ni_{2}O_{7} under Pressure.

The newly discovered high-temperature superconductivity in La_{3}Ni_{2}O_{7} under pressure has attracted a great deal of attention. The essential ingredient characterizing the electronic properties is the bilayer NiO_{2} planes coupled by the interlayer bonding of 3d_{z^{2}} orbitals through the intermediate oxygen atoms. In the strong coupling limit, the low-energy physics is described by an intralayer antiferromagnetic spin-exchange interaction J_{∥} between 3d_{x^{2}-y^{2}} orbitals and an interlayer one J_{⊥} between 3d_{z^{2}} orbitals. Taking into account Hund's rule on each site and integrating out the 3d_{z^{2}} spin degree of freedom, the system reduces to a single-orbital bilayer t-J model based on the 3d_{x^{2}-y^{2}} orbital. By employing the slave-boson approach, the self-consistent equations for the bonding and pairing order parameters are solved. Near the physically relevant 1/4-filling regime (doping δ=0.3∼0.5), the interlayer coupling J_{⊥} tunes the conventional single-layer d-wave superconducting state to the s-wave one. A strong J_{⊥} could enhance the interlayer superconducting order, leading to a dramatically increased T_{c}. Interestingly, there could exist a finite regime in which an s+id state emerges.

Non-Hermitian Strongly Interacting Dirac Fermions.

Exotic quantum phases and phase transition in the strongly interacting Dirac systems have attracted tremendous interests. On the other hand, non-Hermitian physics, usually associated with dissipation arising from the coupling to environment, emerges as a frontier of modern physics in recent years. In this Letter, we investigate the interplay between non-Hermitian physics and strong correlation in Dirac-fermion systems. We generalize the projector quantum Monte-Carlo (PQMC) algorithm to the non-Hermitian interacting fermionic systems. Employing PQMC simulation, we decipher the ground-state phase diagram of the honeycomb Hubbard model with spin resolved non-Hermitian asymmetric hopping processes. The antiferromagnetic (AFM) ordering induced by Hubbard interaction is enhanced by the non-Hermitian asymmetric hopping. Combining PQMC simulation and renormalization group analysis, we reveal that the quantum phase transition between Dirac semi-metal and AFM phases belongs to Hermitian chiral XY universality class, implying that a Hermitian Gross-Neveu transition is emergent at the quantum critical point although the model is non-Hermitian.

Prevalence and Characteristics of Salmonella from Tibetan Pigs in Tibet, China.

This study aimed to understand the epidemiological characteristics of Salmonella in Tibetan pigs. We isolated, identified, and examined via antimicrobial susceptibility testing on Salmonella from Tibetan pigs breeder farms and slaughterhouses in Tibet, China. A genetic evolutionary tree was constructed on the basis of whole genome sequencing (WGS). A total of 81 Salmonella isolates were isolated from 987 samples. The main serovars were Salmonella Typhimurium and Salmonella London in Tibetan pigs. The isolated Salmonella Typhimurium isolates subjected to antimicrobial susceptibility testing showed varying degrees of resistance to ß-lactams, aminoglycosides, fluoroquinolones, sulfonamides, tetracyclines, and amphenicols. WGS analysis was performed on 20 Salmonella Typhimurium isolates in Tibet (n = 10), Jiangsu (n = 10), and 205 genome sequences downloaded from the Enterobase database to reveal their epidemiological and genetic characteristics. They were divided into two clusters based on core genome single-nucleotide polymorphisms: Cluster A with 112 isolates from Tibet and other regions in China and Cluster B with 113 isolates from Jiangsu and other regions. The isolates in Cluster A were further divided into two subclusters: A-1 with 40 isolates including Tibet and A-2 with 72 isolates from other regions. Virulence factors analysis revealed that all isolates from Tibet carried adeG, but this observation was not as common in Salmonella isolates from Jiangsu and other regions of China. Antibiotic resistance genes (ARGs) analysis showed that all isolates from Tibet carried blaTEM-55 and rmtB, which were absent in Salmonella isolates from Jiangsu and other regions of China. Genetic characteristic analysis and biofilm determination indicated that the biofilm formation capabilities of the isolates from Tibet were stronger than those of the isolates from Jiangsu and other regions of China. Our research revealed the epidemic patterns and genomic characteristics of Salmonella in Tibetan pigs and provided theoretical guidance for the prevention and control of local salmonellosis.

Transcriptome Sequencing Reveals Salmonella Flagellin Activation of Interferon-ß-Related Immune Responses in Macrophages.

The flagellin (FliC) of Salmonella typhimurium is a potential vaccine adjuvant as it can activate innate immunity and promote acquired immune responses. Macrophages are an important component of the innate immune system. The mechanism of flagellin's adjuvant activity has been shown to be related to its ability to activate macrophages. However, few studies have comprehensively investigated the effects of Salmonella flagellin in macrophages using transcriptome sequencing. In this study, RNA-Seq was used to analyze the expression patterns of RAW264.7 macrophages induced by FliC to identify novel transcriptomic signatures in macrophages. A total of 2204 differentially expressed genes were found in the FliC-treated group compared with the control. Gene ontology and KEGG pathway analyses identified the top significantly regulated functional classification and canonical pathways, which were mainly related to immune responses and regulation. Inflammatory cytokines (IL-6, IL-1ß, TNF-α, etc.) and chemokines (CXCL2, CXCL10, CCL2, etc.) were highly expressed in RAW264.7 cells following stimulation. Notably, flagellin significantly increased the expression of interferon (IFN)-ß. In addition, previously unidentified IFN regulatory factors (IRFs) and IFN-stimulated genes (ISGs) were also significantly upregulated. The results of RNA-Seq were verified, and furthermore, we demonstrated that flagellin increased the expression of IFN-ß and IFN-related genes (IRFs and ISGs) in bone marrow-derived dendritic cells and macrophages. These results suggested that Salmonella flagellin can activate IFN-ß-related immune responses in macrophages, which provides new insight into the immune mechanisms of flagellin adjuvant.

A live attenuated DIVA vaccine affords protection against Listeria monocytogenes challenge in sheep.

Listeria monocytogenes (Lm) is a deadly foodborne pathogen that comprises 14 serotypes, among which, serotype 4b Lm is the primary cause of listeriosis outbreaks in humans and animals. Here, we evaluated the safety, immunogenicity, and protective efficacy of a serotype 4b vaccine candidate Lm NTSNΔactA/plcB/orfX in sheep. The infection dynamics, clinical features, and pathological observation verified that the triple genes deletion strain has adequate safety for sheep. Moreover, NTSNΔactA/plcB/orfX significantly stimulated humoral immune response and provided 78% immune protection to sheep against lethal wild-type strain challenge. Notably, the attenuated vaccine candidate could differentiate infected and vaccinated animals (DIVA) via serology determination of the antibody against listeriolysin O (LLO, encoded by hly) and phosphatidylinositol-specific phospholipase C (PI-PLC, encoded by plcB). These data suggest that the serotype 4b vaccine candidate has high efficacy, safety, and DIVA characteristics, and may be used to prevent Lm infection in sheep. Our study provides a theoretical basis for its future application in livestock and poultry breeding.

Long-term effects of the COVID-19 pandemic on five mental and psychological disorders: in terms of the number of disease visits, drug consumption, and scale scores.

BACKGROUND: COVID-19 caused mild to severe infections in humans. The long-term epidemic environment harms people's mental health. To explore the impact of the epidemic on people's mental and psychological conditions, we surveyed in Wenzhou. METHODS: We collected the data of people who visited the First Affiliated Hospital of Wenzhou Medical University for five types of mental and psychological diseases from January 2018 to December 2021. Then, taking December 2019 as the cut-off point, the 48-month data were divided into the pre-epidemic group and the dur-epidemic group. Based on the above data, statistical analysis was done. RESULTS: From 2018 to 2021, the number of initial diagnoses, the number of disease visits, and drug consumption for these five types of mental and psychological diseases were all on the rise. Compared with the number of disease visits for all disorders in both psychiatry and neurology departments, it was found that the growth rate of these five diseases was higher than the growth rate of all disorders. We found that the number of disease visits, drug consumption, and scale scores after the COVID-19 outbreak were significantly different from those before the outbreak (P < 0.05). And the number of disease visits positively correlated with drug consumption (P < 0.0001, r = 0.9503), which verified the stability of the data. CONCLUSION: The epidemic environment has had a long-term and negative impact on people's mental and psychological conditions. Therefore, whether or not the epidemic is receding, we still need to be concerned about the impact of COVID-19 on mental and psychological health.

Bottom-up Synthesis of Single-Crystalline Poly (Triazine Imide) Nanosheets for Photocatalytic Overall Water Splitting.

Poly (triazine imide) (PTI/Li+ Cl- ), one of the crystalline versions of polymeric carbon nitrides, holds great promise for photocatalytic overall water splitting. In principle, the photocatalytic activity of PTI/Li+ Cl- is closely related to the morphology, which could be reasonably tailored by the modulation of the polycondensation process. Herein, we demonstrate that the hexagonal prisms of PTI/Li+ Cl- could be converted to hexagonal nanosheets by adjusting the binary eutectic salts from LiCl/KCl or NaCl/LiCl to ternary LiCl/KCl/NaCl. Results reveal that the extension of in-plane conjugation is preferred, when the polymerisation was performed in the presence of ternary eutectic salts. The hexagonal nanosheets bears longer lifetimes of charge carriers than that of hexagonal prisms due to lower intensity of structure defects and shorter hopping distance of charge carriers along the stacking direction of triazine nanosheets. The optimized hexagonal nanosheets exhibits a record apparent quantum yield value of 25 % (λ=365 nm) for solar hydrogen production by one-step excitation overall water splitting.

Rh/Cr2 O3 and CoOx Cocatalysts for Efficient Photocatalytic Water Splitting by Poly (Triazine Imide) Crystals.

In situ photo-deposition of both Pt and CoOx cocatalysts on the facets of poly (triazine imide) (PTI) crystals has been developed for photocatalytic overall water splitting. However, the undesired backward reaction (i.e., water formation) on the noble Pt surface is a spontaneously down-hill process, which restricts their efficiency to run the overall water splitting reaction. Herein, we demonstrate that the efficiency for photocatalytic overall water splitting could be largely promoted by the decoration of Rh/Cr2 O3 and CoOx as H2 and O2 evolution cocatalysts, respectively. Results reveal that the dual cocatalysts greatly extract charges from bulk to surface, while the Rh/Cr2 O3 cocatalyst dramatically restrains the backward reaction, achieving an apparent quantum efficiency (AQE) of 20.2 % for the photocatalytic overall water splitting reaction.

Resonance-Induced Reduction of Interfacial Tension of Water-Methane and Improvement of Methane Solubility in Water.

Molecular dynamics simulations were performed to study the effect of the periodic oscillating electric field on the interface between water and methane. We propose a new strategy that utilizes oscillating electric fields to reduce the interfacial tension (IFT) between water and methane and increase the solubility of methane in water simultaneously. These are attributed to the hydrogen bond resonance induced by an electric field with a frequency close to the natural frequency of the hydrogen bond. The resonance breaks the hydrogen bond network among water molecules to the maximum, which destroys the hydration shell and reduces the cohesive action of water, thus resulting in the decrease of IFT and the increase of methane solubility. As the frequency of the electric field is close to the optimum resonant frequency of hydrogen bonds, IFT decreases from 56.43 to 5.66 mN/m; water and methane are miscible because the solubility parameter of water reduces from 47.63 to 2.85 MPa1/2, which is close to that of methane (3.43 MPa1/2). Our results provide a new idea for reducing the water-gas IFT and improving the solubility of insoluble gas in water and theoretical guidance in the fields of natural gas exploitation, hydrate generation, and nanobubble nucleation.

Fully Condensed Poly (Triazine Imide) Crystals: Extended π-Conjugation and Structural Defects for Overall Water Splitting.

Conventional polymerization for the synthesis of carbon nitride usually generates amorphous heptazine-based melon with an abundance of undesired structural defects, which function as charge carrier recombination centers to decrease the photocatalytic efficiency. Herein, a fully condensed poly (triazine imide) crystal with extended π-conjugation and deficient structure defects was obtained by conducting the polycondensation in a mild molten salt of LiCl/NaCl. The melting point of the binary LiCl/NaCl system is around 550 °C, which substantially restrain the depolymerization of triazine units and extend the π-conjugation. The optimized polymeric carbon nitride crystal exhibits a high apparent quantum efficiency of 12 % (λ=365 nm) for hydrogen production by one-step excitation overall water splitting, owing to the efficient exciton dissociation and the subsequent fast transfer of charge carriers.

The Gli1-Snail axis contributes to Salmonella Typhimurium-induced disruption of intercellular junctions of intestinal epithelial cells.

Salmonella enterica serovar Typhimurium (S. Typhimurium) is a facultative intracellular pathogen that damages gastrointestinal tissue and causes severe diarrhoea. The mechanisms by which Salmonella disrupts epithelial barrier and increases the paracellular permeability are incompletely understood. Our present study aims to determine the role of Gli1, a transcription factor activated in the sonic hedgehog (Shh) pathway, in decreasing the levels of apical junction proteins in a Salmonella-infected human colonic epithelial cancer cell line, Caco-2, and in the intestinal tissue of Salmonella-infected mice. Here, we report that S. Typhimurium increased the mRNA and protein levels of Gli1 and Snail, a downstream transcription factor that plays an important role in the epithelial-to-mesenchymal transition (EMT). S. Typhimurium also decreased the levels of E-cadherin and three tight junction proteins (ZO-1, claudin-1, and occludin). Gli1 siRNA and GANT61, a Gli1-specific inhibitor, blocked S. Typhimurium-induced Snail expression, restored the levels of E-cadherin and tight junction proteins, and prevented S. Typhimurium-increased paracellular permeability. Further study showed that Gli1 was cross-activated by the MAP and PI-3 kinase pathways. S. Typhimurium devoid of sopB, an effector of the Type 3 secretion system (T3SS) responsible for AKT activation, was unable to induce Snail expression and to decrease the expression of apical junction proteins. Our study uncovered a novel role of Gli1 in mediating the Salmonella-induced disruption of the intestinal epithelial barrier.

The role of the potential field on occurrence and flow of octane in quartz nanopores.

Occurrence and flow of hydrocarbons in nanopores are two important issues in the effective exploitation of shale oil reservoirs. In this study, molecular dynamics simulations are employed to investigate the mechanisms about occurrence and flow of octane in slit-shaped quartz nanopores. We show that the occurrence state of octane and, therefore, its flow behavior are profoundly affected by the potential field from quartz walls and adsorption layers if the nanopore width w becomes less than 50 Å. Two main adsorption layers are always formed, adjacent to the walls and independent of w, due to two potential wells generated by the attractive potentials of the walls. Each pair of symmetrical adsorption layers, each of which can be considered as a solid-like surface, forms a confined environment similar to a nano-slit. The attractive potentials from them are found to be the cause for the formation of the adsorption layers between them. The obvious bulk phase of octane is formed in the pore of w = 50 Å due to the wide zero potential barrier induced by the innermost two adsorption layers. The nonlinear dependence of flow rate on pressure gradient shows that Darcy's law fails to describe the flow in the nanopore. The non-Darcy behavior mainly arises from adsorption effects from the walls and the adsorption layers, slippage between octane and walls and between adjacent two adsorption layers, and the molecular exchange between adsorption layers. A modified microscopic model is established to predict the dependence of flow rate on potential field, pressure gradient and w, which is in a good agreement with our simulation results and verified by the dodecane flow through the nanopore. Our work can be of great importance for revealing the mechanisms of occurrence and transport and guiding the estimation and exploitation of shale oil resources.

Prevalence and Characteristics of Salmonella spp. from a Pig Farm in Shanghai, China.

Salmonella spp. is a major foodborne pathogen that is distributed among most pork production chains worldwide. This study aimed to investigate the dynamic changes in Salmonella spp. along the pig breeding process monthly from April 2018 to March 2019 in a pig farm in Shanghai, China, and identify the potential critical control points during the production. In total, 239 Salmonella spp. isolates were obtained from 1389 samples, in which Salmonella were detected from 26.3% (222/843) of fecal samples, 7.1% (17/240) of feed samples, and 0.0% (0/306) of both water and insect samples. Seven different serotypes were identified, with the predominant serotype being Salmonella Derby (21.8%), followed by Salmonella Typhimurium (18.8%), Salmonella Rissen (16.3%), Salmonella Mbandaka (12.6%), and Salmonella 1,4,[5],12:i:- (11.8%). Most probable number (MPN) analysis revealed that the load of Salmonella spp. gradually increased along the pig production chain, while the highest number of Salmonella spp. isolates was at the fattening stage (MPN value, 11-15 MPN/g). The pulsed-field gel electrophoresis showed that both Salmonella Typhimurium and Salmonella Derby isolates were grouped to six clusters. The antimicrobial resistance analyzed demonstrated that 80.0% of the isolates were of multidrug resistance and resistant to sulfamethoxazole (84.5%), lincomycin (89.4%), ampicillin (96.9%), oxytetracycline (93.8%), and tetracycline (95.1%). We further evaluated the Salmonella spp. Resistance to quaternary ammonium compounds (QACs) showed an increasing trend along with the testing period indicating that the use of QACs could induce the resistance of Salmonella spp. to QACs. Our study confirmed the dynamic changes in Salmonella spp. over time and space in this pig farm and identified feed and the fattening house as the key points for the prevention and control of Salmonella spp. contamination.

Coimmunization with Two Enterotoxigenic Escherichia coli (ETEC) Fimbrial Multiepitope Fusion Antigens Induces the Production of Neutralizing Antibodies against Five ETEC Fimbriae (F4, F5, F6, F18, and F41).

Fimbriae mediate the initial adherence of enterotoxigenic Escherichia coli (ETEC) to the piglet small intestine and play an important role in development of ETEC-driven postweaning diarrhea (PWD). PWD inflicts huge economic losses on the swine industry each year, making development of alternative treatment and prevention measures for PWD essential. Vaccine candidates that induce antifimbria antibodies that block the initial attachment and colonization of ETEC pathogens with fimbriae are one approach that could help prevent PWD. In this study, we constructed two multiepitope fusion antigens (MEFAs) that carried, expressed, and displayed representative epitopes of F4, F5, F6, F18, and F41 ETEC fimbriae. These MEFAs used either the F4 major subunit FaeG or the F18 adhesive subunit FedF as a backbone. To assess the potential of these MEFAs as antifimbria vaccine candidates that could help prevent PWD, we generated computational models of the MEFAs, constructed them, and then tested their immunogenicity by using them to immunize mice. Computational modeling showed that all relevant epitopes were exposed on the MEFA surface. We found that coadministration of our MEFAs in mice successfully induced five fimbria-specific antibodies in accordance with the epitopes included in the MEFA constructs. Furthermore, the induced antibodies can significantly inhibit the ability of ETEC strains that express F4, F5, F6, F18, and F41 fimbriae to adhere to piglet small intestinal IPEC-1 and IPEC-J2 cells. Our findings indicate that the antifimbria antibodies induced by our FaeG-Fim41a-FanC-FasA and FedF-FasA-Fim41a-FanC fimbria MEFAs blocked adherence of five ETEC fimbriae, suggesting these multivalent fimbria MEFAs may be useful for developing broadly protective antifimbria vaccines against PWD caused by ETEC infections.IMPORTANCE Enterotoxigenic Escherichia coli (ETEC)-associated postweaning diarrhea (PWD) is still a leading disease in recently weaned piglets. Vaccination is considered to be the most ideal and efficacious strategy for preventing PWD. Recently, a commercialized live monovalent F4 oral vaccine and a bivalent F4/F18 oral vaccine have been demonstrated to effectively protect piglets in the F4-positive (F4+) and F18+ ETEC challenge models. However, they will not provide cross-protection against F5+, F6+, or F41+ ETEC-associated PWD cases, as they lack all five fimbria antigens. Thus, a multivalent vaccine containing all five ETEC fimbriae would be more effective in preventing ETEC-driven PWD. In this study, we designed two fimbria-targeted MEFAs using the MEFA technology, and further study demonstrated that these coadministered MEFAs in mice can induce protective antibodies against the five fimbriae expressed by ETEC. These MEFAs could be used as an efficient PWD vaccine candidate; furthermore, MEFA-based structural technology provides an alternative and promising strategy for the development of vaccines against pathogens with heterogeneous virulence factors.

Essential role of Salmonella Enteritidis DNA adenine methylase in modulating inflammasome activation.

BACKGROUND: Salmonella Enteritidis (SE) is one of the major foodborne zoonotic pathogens of worldwide importance which can induce activation of NLRC4 and NLRP3 inflammasomes during infection. Given that the inflammasomes play an essential role in resisting bacterial infection, Salmonella has evolved various strategies to regulate activation of the inflammasome, most of which largely remain unclear. RESULTS: A transposon mutant library in SE strain C50336 was screened for the identification of the potential factors that regulate inflammasome activation. We found that T3SS-associated genes invC, prgH, and spaN were required for inflammasome activation in vitro. Interestingly, C50336 strains with deletion or overexpression of Dam were both defective in activation of caspase-1, secretion of IL-1ß and phosphorylation of c-Jun N-terminal kinase (Jnk). Transcriptome sequencing (RNA-seq) results showed that most of the differentially expressed genes and enriched KEGG pathways between the C50336-VS-C50336Δdam and C50336-VS-C50336::dam groups overlapped, which includes multiple signaling pathways related to the inflammasome. C50336Δdam and C50336::dam were both found to be defective in suppressing the expression of several anti-inflammasome factors. Moreover, overexpression of Dam in macrophages by lentiviral infection could specifically enhance the activation of NLRP3 inflammasome independently via promoting the Jnk pathway. CONCLUSIONS: These data indicated that Dam was essential for modulating inflammasome activation during SE infection, there were complex and dynamic interplays between Dam and the inflammasome under different conditions. New insights were provided about the battle between SE and host innate immunological mechanisms.

SspH2 as anti-inflammatory candidate effector and its contribution in Salmonella Enteritidis virulence.

Salmonella enterica serovar Enteritidis (S. Enteritidis) is a facultative intracellular pathogen deploying the type III secretion system (T3SS) encoded by Salmonella Pathogenicity Island 2 (SPI2) to transfer effector proteins into host cells to modify its functions and accomplish intracellular replication. To study the effect of SspH2 on immune response induced by S. Enteritidis, we generated a deletion mutant of the effector gene sspH2 and a plasmid mediated complementary strain in S. Enteritidis C50336. The results of LD50 showed that SspH2 has no obvious effect on the virulence of S. Enteritidis. However, deletion of sspH2 decreased the invasion and intercellular colonization of the bacteria in Caco2 BBE cells. Using bacteriological counts from tissue homogenates the result of colonization in internal organs showed that in spleen and liver tissues, at 3rd and 4th day p.i. there is a significance decreased number of C50336-ΔsspH2 compared to the C50336-WT and C50336-ΔsspH2-psspH2, respectively. The qRT-PCR analysis results of both in vivo and in vitro experiments clearly showed that the mutant strain C50336ΔsspH2 significantly promoted expression of IL-1ß, INF-γ, IL-12, and iNOS cytokines compared to the groups infected with the wild type or complementary strains, while the IL-8 synthesis was decreased in the mutant strain infected group. All of these findings revealed that SspH2 promotes the colonization of S. Enteritidis in host cells, and it is an important anti-inflammatory biased effector in Salmonella.

A multivalent vaccine candidate targeting enterotoxigenic Escherichia coli fimbriae for broadly protecting against porcine post-weaning diarrhea.

Fimbriae-mediated initial adherence is the initial and critical step required for enterotoxigenic Escherichia coli (ETEC) infection. Therefore, vaccine candidates have been developed that target these fimbriae and induce specific anti-fimbriae antibodies to block initial ETEC attachment. While this vaccine effectively protects against ETEC-associated post-weaning diarrhea (PWD), developing a broadly effective vaccine against initial ETEC attachment remains a challenging problem, owing to the immunological heterogeneity among these antigens. Here, we applied multi-epitope fusion antigen (MEFA) technology to construct a FaeG-FedF-FanC-FasA-Fim41a MEFA using the adhesive subunits of predominant fimbriae K88 and F18 as the backbone, which also integrated epitopes from adhesive subunits of the rare fimbriae K99, 987P, and F41; we then generated a MEFA computational model and tested the immunogenicity of this MEFA protein in immunized mice. We next evaluated the potential of the fimbriae-targeted MEFA as a vaccine candidate to effectively prevent PWD using in vitro assessment of its anti-fimbriae, antibody-directed inhibition of bacterial adherence. Computational modeling showed that all relevant epitopes were exposed on the MEFA surface and mice subcutaneously immunized with the MEFA protein developed IgG antibodies to all five fimbriae. Moreover, anti-fimbriae antibodies induced by the MEFA protein significantly inhibited the adhesion of K88+, F18+, K99+, 987P+, and F41+ ETEC strains to piglet small intestinal IPEC-1 and IPEC-J2 cell lines. Taken together, these results indicate that FaeG-FedF-FanC-FasA-Fim41a MEFA protein induced specific anti-fimbriae neutralizing antibodies against the five targeted fimbriae. Critically, these results show the potential of fimbriae-targeted MEFA and indicate their promise as a broad, effective vaccine against PWD.