ZBTB20 is essential for cochlear maturation and hearing in mice.

The mammalian cochlear epithelium undergoes substantial remodeling and maturation before the onset of hearing. However, very little is known about the transcriptional network governing cochlear late-stage maturation and particularly the differentiation of its lateral nonsensory region. Here, we establish ZBTB20 as an essential transcription factor required for cochlear terminal differentiation and maturation and hearing. ZBTB20 is abundantly expressed in the developing and mature cochlear nonsensory epithelial cells, with transient expression in immature hair cells and spiral ganglion neurons. Otocyst-specific deletion of Zbtb20 causes profound deafness with reduced endolymph potential in mice. The subtypes of cochlear epithelial cells are normally generated, but their postnatal development is arrested in the absence of ZBTB20, as manifested by an immature appearance of the organ of Corti, malformation of tectorial membrane (TM), a flattened spiral prominence (SP), and a lack of identifiable Boettcher cells. Furthermore, these defects are related with a failure in the terminal differentiation of the nonsensory epithelium covering the outer border Claudius cells, outer sulcus root cells, and SP epithelial cells. Transcriptome analysis shows that ZBTB20 regulates genes encoding for TM proteins in the greater epithelial ridge, and those preferentially expressed in root cells and SP epithelium. Our results point to ZBTB20 as an essential regulator for postnatal cochlear maturation and particularly for the terminal differentiation of cochlear lateral nonsensory domain.

CD-MOF-1 Growth on Polysaccharide Gels through Only C2-OH/C3-OH or C5-O/C6-OH Group Formed Four-Coordinated K+ Ions for Developing Porous Biogels.

The γ-cyclodextrin (γ-CD) metal-organic frameworks (CD-MOF-1) consist of γ-CD and potassium (K+) ions through coordinating an eight-coordinated K+ ion with two C5-linked oxygen and C6-linked hydroxyl (C5-O/C6-OH) groups in the primary faces of adjacent γ-CD units and two C2- and C3-linked hydroxyl (C2-OH/C3-OH) groups in the secondary faces. Herein, we found polysaccharide gels with only C2-OH/C3-OH or C5-O/C6-OH groups in pyranoid rings can form four-coordinated K+ ions and then coordinate γ-CD in a KOH solution for CD-MOF-1 growth. Exposure of C2-OH/C3-OH or C5-O/C6-OH groups in polysaccharide gels is important to form active four-coordinated K+ ions. Mechanism supporting this work is that four-coordinated K+ ion sites are first formed after coordinating C2-OH/C3-OH groups in pectin and then coordinating C5-O/C6-OH groups in the primary faces of γ-CD units. Alternatively, four-coordinated K+ ions with C5-O/C6-OH groups in chitosan can coordinate the C2-OH/C3-OH groups in the secondary faces of γ-CD units. Mechanism of CD-MOF-1 growing on pectin and chitosan gels through the proposed four-coordinated K+ ions is also universally applicable to other polysaccharide gels with similar C2-OH/C3-OH or C5-O/C6-OH groups such as alginate gel. Based on this mechanism, we developed pectin and chitosan gel-based CD-MOF-1 composites and exemplified applications of them in antibacterial and organic dye removal. To help future research and applications of this mechanism, we share our theoretical assumption for further investigations that any matrices with an ortho-hydroxyl carbon chain or ortho-hydroxyl ether structures may form four-coordinated K+ ions for CD-MOF-1 growth. The proposed mechanism will broaden the development of novel CD-MOF-1 composites in various fields.

Porcine deltacoronavirus nonstructural protein 2 inhibits type I and III IFN production by targeting STING for degradation.

Porcine deltacoronavirus (PDCoV) is an enteropathogenic coronavirus that has been reported to use various strategies to counter the host antiviral innate immune response. The cGAS-STING signalling pathway plays an important role in antiviral innate immunity. However, it remains unclear whether PDCoV achieves immune evasion by regulating the cGAS-STING pathway. Here, we demonstrated that the nonstructural protein 2 (nsp2) encoded by PDCoV inhibits cGAS-STING-mediated type I and III interferon (IFN) responses via the regulation of porcine STING (pSTING) stability. Mechanistically, ectopically expressed PDCoV nsp2 was found to interact with the N-terminal region of pSTING. Consequently, pSTING was degraded through K48-linked ubiquitination and the proteasomal pathway, leading to the disruption of cGAS-STING signalling. Furthermore, K150 and K236 of pSTING were identified as crucial residues for nsp2-mediated ubiquitination and degradation. In summary, our findings provide a basis for elucidating the immune evasion mechanism of PDCoV and will contribute to the development of targets for anti-coronavirus drugs.

Identification of pigeon mitochondrial antiviral signaling protein (MAVS) and its role in antiviral innate immunity.

Pigeons can be infected with various RNA viruses, and their innate immune system responds to viral infection to establish an antiviral response. Mitochondrial antiviral signaling protein (MAVS), an important adaptor protein in signal transduction, plays a pivotal role in amplifying the innate immune response. In this study, we successfully cloned pigeon MAVS (piMAVS) and performed a bioinformatics analysis. The results showed that the caspase recruitment domain (CARD) and transmembrane (TM) domain are highly conserved in poultry and mammals but poorly conserved in other species. Furthermore, we observed that MAVS expression is upregulated both in pigeons and pigeon embryonic fibroblasts (PEFs) upon RNA virus infection. Overexpression of MAVS resulted in increased levels of ß-interferon (IFN-ß), IFN-stimulated genes (ISGs), and interleukin (ILs) mRNA and inhibited Newcastle disease virus (NDV) replication. We also found that piMAVS and human MAVS (huMAVS) induced stronger expression of IFN-ß and ISGs when compared to chicken MAVS (chMAVS), and this phenomenon was also reflected in the degree of inhibition of NDV replication. Our findings demonstrate that piMAVS plays an important role in repressing viral replication by regulating the activation of the IFN signal pathway in pigeons. This study not only sheds light on the function of piMAVS in innate immunity but also contributes to a more comprehensive understanding of the innate immunity system in poultry. Our data also provide unique insights into the differences in innate immunity between poultry and mammal.

Phage cocktail superimposed disinfection: A ecological strategy for preventing pathogenic bacterial infections in dairy farms.

Bovine mastitis (BM) is mainly caused by bacterial infection that has a highly impact on dairy production, affecting both economic viability and animal well-being. A cross-sectional study was conducted in dairy farms to investigate the prevalence and antimicrobial resistance patterns of bacterial pathogens associated with BM. The analysis revealed that Staphylococcus (49%), Escherichia (16%), Pseudomonas (11%), and Klebsiella (6%) were the primary bacterial pathogens associated with mastitis. A significant proportion of Staphylococcus strains displayed multiple drug resistance. The use of disinfectants is an important conventional measure to control the pathogenic bacteria in the environment. Bacteriophages (Phages), possessing antibacterial properties, are natural green and effective disinfectants. Moreover, they mitigate the risk of generating harmful disinfection byproducts, which are commonly associated with traditional disinfection methods. Based on the primary bacterial pathogens associated with mastitis in the investigation area, a phage cocktail, named SPBC-SJ, containing seven phages capable of lysing S. aureus, E. coli, and P. aeruginosa was formulated. SPBC-SJ exhibited superior bactericidal activity and catharsis effect on pollutants (glass surface) compared to chemical disinfectants. Clinical trials confirmed that the SPBC-SJ-based superimposed disinfection group (phage combined with chemical disinfectants) not only cut down the dosage of disinfectants used, but significantly reduced total bacterial counts on the ground and in the feeding trough of dairy farms. Furthermore, SPBC-SJ significantly reduced the abundance of Staphylococcus and Pseudomonas in the environment of the dairy farm. These findings suggest that phage-based superimposed disinfection is a promising alternative method to combat mastitis pathogens in dairy farms due to its highly efficient and environmentally-friendly properties.

Development and mouse model evaluation of a new phage cocktail intended as an alternative to antibiotics for treatment of Staphylococcus aureus-induced bovine mastitis.

Bovine mastitis (BM) is a prevalent infectious disease in dairy herds worldwide, resulting in substantial economic losses. Staphylococcus aureus is a major cause of mastitis in animals, and its antibiotic resistance poses challenges for treatment. Recently, there has been a renewed interest in the development of alternative methods to antibiotic therapy, including bacteriophages (phages), for controlling bacterial infections. In this study, 2 lytic phages (designated as JDYN for vB_SauM_JDYN and JDF86 for vB_SauM_JDF86) were isolated from the cattle sewage effluent samples collected from dairy farms in Shanghai. The 2 phages have a broad bactericidal spectrum against Staphylococcus of various origins. Genomic and morphological analyses revealed that the 2 phages belonged to the Myoviridae family. Moreover, JDYN and JDF86 remained stable under a wide range of temperatures or pH and were almost unaffected in chloroform. In this study, we prepared a phage cocktail designated "PHC-1" which consisted of a 1:1:1 ratio of JDYN, JDF86 and SLPW (a previously characterized phage). PHC-1 showed the strongest bacteriolytic effect and the lowest frequency of emergence of bacteriophage insensitive mutants compared with monophages. The bovine mammary epithelial cells (MAC-T cells) and lactating mice mastitis model were used to evaluate the effectiveness of PHC-1 in vitro and in vivo, respectively. The results demonstrated that PHC-1 treatment significantly reduced bacterial load, alleviated inflammatory response, and improved mastitis pathology. Altogether, these results suggest that PHC-1 has the potential to treat S. aureus-induced bovine mastitis and that phage cocktails can combat antibiotic-resistant S. aureus infections.

The toxicity mechanisms of DON to humans and animals and potential biological treatment strategies.

Deoxynivalenol, also known as vomitotoxin, is produced by Fusarium, belonging to the group B of the trichothecene family. DON is widely polluted, mainly polluting cereal crops such as wheat, barley, oats, corn and related cereal products, which are closely related to lives of people and animals. At present, there have been articles summarizing DON induced toxicity, biological detoxification and the protective effect of natural products, but there is no systematic summary of this information. In addition to ribosome and endoplasmic reticulum, recent investigations support that mitochondrion is also organelles that DON can damage. DON can't directly act on mitochondria, but can indirectly cause mitochondrial damage and changes through other means. DON can indirectly inhibit mitochondrial biogenesis and mitochondrial electron transport chain activity, ATP production, and mitochondrial transcription and translation. This review will provide the latest progress on mitochondria as the research object, and systematically summarizes all the toxic mechanisms of DON. Here, we discuss DON induced mitochondrial-mediated apoptosis and various mitochondrial toxicity. For the toxicity of DON, many methods have been derived to prevent or reduce the toxicity. Biological detoxification and the antioxidant effect of natural products are potentially effective treatments for DON toxicity.

Functional characterization of goose IRF1 in IFN induction and anti-NDV infection.

Interferon regulatory factors (IRFs) play a key role in many aspects of immune response, and IRF1, IRF3, and IRF7 are positive regulators of IFN induction in mammals. However, IRF3, as the most critical regulatory factor in mammals, is naturally absent in birds, which attracts us to study the functions of other members of the avian IRF family. In the present study, we cloned goose IRF1 (GoIRF1) and conducted a series of bioinformatics analyses to compare the protein homology of GoIRF1 with that of IRF1 in other species. The overexpression of GoIRF1 in DF-1 cells induced the activation of IFN-ß, and this activation is independent of the dosage of the transfected GoIRF1 plasmids. The overexpression of GoIRF1 in goose embryonic fibroblasts (GEFs) induced the expression of IFNs, proinflammatory cytokines, and IFN-stimulated genes (ISGs); it also inhibited the replication of green fluorescent protein (GFP)-tagged Newcastle disease virus (NDV) (NDV-GFP) and GFP-tagged vesicular stomatitis virus (VSV) (VSV-GFP). Our results suggest that GoIRF1 is an important regulator of IFNs, proinflammatory cytokines, and ISGs and plays a role in antiviral innate immunity in geese.

Chicken miR-126-5p negatively regulates antiviral innate immunity by targeting TRAF3.

Innate immunity plays an essential role in preventing the invasion of pathogenic microorganisms. However, innate immunity is a double-edged sword, whose excessive activation is detrimental to immune homeostasis and even leads to a "cytokine storm" of the infected host. The host develops a series of negative regulatory mechanisms to balance the immune response. Here, we report a negative regulatory mechanism of chicken innate immunity mediated by miRNA. In the GEO database, we found that miR-126-5p was markedly up-regulated in chickens infected by RNA viruses. Upregulation of miR-126-5p by RNA virus was then further shown via both a cell model and in vivo tests. Overexpression of miR-126-5p significantly inhibited the expression of interferon and inflammatory cytokine-related genes induced by RNA viruses. The opposite result was achieved after the knockdown of miR-126-5p expression. Bioinformatics analysis identified TRAF3 as candidate target gene of miR-126-5p. Experimentally, miR-126-5p can target TRAF3, as shown by the effects of miR-126-5p on the endogenous expression of TRAF3, and by the TRAF3 3'UTR driven luciferase reporter assay. Furthermore, we demonstrated that miR-126-5p negatively regulated innate immunity by blocking the MAVS-TRAF3-TBK1 axis, with a co-expression assay. Overall, our results suggest that miR-126-5p is involved in the negative regulation of chicken innate immunity, which might contribute to maintaining immune balance.

IRF7 Is Involved in Both STING and MAVS Mediating IFN-ß Signaling in IRF3-Lacking Chickens.

IFN regulatory factor (IRF) 3 has been identified as the most critical regulator of both RNA and DNA virus-induced IFN production in mammals. However, ambiguity exists in research on chicken IRFs; in particular IRF3 seems to be missing in chickens, making IFN regulation in chickens unclear. In this study, we comprehensively investigated the potential IFN-related IRFs in chickens and showed that IRF7 is the most critical IFN-ß regulator in chickens. With a chicken IRF7 (chIRF7) knockout DF-1 cell line, we conducted a series of experiments to demonstrate that chIRF7 is involved in both chicken STING (chSTING)- and chicken MAVS (chMAVS)-mediated IFN-ß regulation in response to DNA and RNA viral infections, respectively. We further examined the mechanisms of chIRF7 activation by chSTING. We found that chicken TBK1 (chTBK1) is indispensable for chIRF7 activation by chSTING as well as that chSTING interacts with both chIRF7 and chTBK1 to function as a scaffold in chIRF7 activation by chTBK1. More interestingly, we discovered that chSTING mediates the activation of chIRF7 through a conserved SLQxSyS motif. In short, we confirmed that although IRF3 is missing in chickens, they employ IRF7 to reconstitute corresponding IFN signaling to respond to both DNA and RNA viral infections. Additionally, we uncovered a mechanism of chIRF7 activation by chSTING. The results will enrich and deepen our understanding of the regulatory mechanisms of the chicken IFN system.

A Preliminary Study of Antibiotic Resistance Genes in Domestic Honey Produced in China.

Antibiotic resistance genes (ARGs) are emerging contaminants that pose a health risk to humans worldwide. Little information on ARGs in bee honey is available. This study profiles ARGs in bee honey samples produced in China, the biggest producer in the world. Of 317 known ARGs encoding resistance to 8 classes of antibiotics, 212 were found in collected honey samples by a real-time quantitative polymerase chain reaction approach. Occurrence frequencies of genes providing resistance to FCA (fluoroquinolone, quinolone, florfenicol, chloramphenicol, and amphenicol) and aminoglycosides were 21.0% and 18.5%, respectively. Frequencies of genes encoding efflux pumps were 42.5% and those of destructase genes 36.6%, indicating that these two mechanisms were predominant for resistance. Nine plasmid-mediated quinolone resistance genes were detected. Of the nine transposase genes known to be involved in antibiotic resistance, eight were found in the samples examined, with tnpA-4, tnpA-5, and tnpA-6 being more abundant. The abundance of the transposase genes was associated with genes conferring resistance to tetracyclines (r = 0.648, p < 0.01), macrolide-lincosamide-streptogramin B (r = 0.642, p < 0.01), FCA (r = 0.517, p < 0.01), and aminoglycosides (r = 0.401, 0.01 < p < 0.05). This is the first study on the abundance and diversity of ARGs in Chinese bee honey products. These findings suggest that bee honey may be a significant source of ARGs that might pose threat to public health. Further research is required to collect more samples in diverse geographic regions in China to make a more comprehensive judgment of ARG in bee honey.

Acetylation at K108 of the NS1 protein is important for the replication and virulence of influenza virus.

Non-structural protein 1 (NS1) of influenza virus is a multifunctional protein that plays an important role in virus replication and virulence. In this study, an acetylation modification was identified at the K108 residue of the NS1 protein of H1N1 influenza virus. To further explore the function of the K108 acetylation modification of the NS1 protein, a deacetylation-mimic mutation (K108R) and a constant acetylation-mimic mutation (K108Q) were introduced into the NS1 protein in the background of A/WSN/1933 H1N1 (WSN), resulting in two mutant viruses (WSN-NS1-108R and WSN-NS1-108Q). In vitro and mouse studies showed that the deacetylation-mimic mutation K108R in the NS1 protein attenuated the replication and virulence of WSN-NS1-108R, while the constant acetylation-mimic mutant virus WSN-NS1-108Q showed similar replication and pathogenicity as the wild-type WSN virus (WSN-wt). The results indicated that acetylation at K108 of the NS1 protein has an important role in the replication and virulence of influenza virus. To further explore the potential mechanism, the type I interferon (IFN-I) antagonistic activity of the three NS1 proteins (NS1-108Q, NS1-108R, and NS1-wt) was compared in cells, which showed that the K108R mutation significantly attenuated the IFN-ß antagonistic activity of the NS1 protein compared with NS1-wt and NS1-108Q. Both NS1-wt and NS1-108Q inhibited the IFN-ß response activated by RIG-I CARD domain, MAVS, TBK1, and IRF3 more efficiently than the NS1-108R protein in cells. Taken together, the results indicated that acetylation at NS1 K108 is important for the IFN antagonistic activity of the NS1 protein and virulence of the influenza virus.

Isolation and characterization of a broad-spectrum phage of multiple drug resistant Salmonella and its therapeutic utility in mice.

Salmonella are causes of livestock, poultry, and other animal diseases but they also have the potential to infect people. Currently, antibiotics are the first choice for treatment of Salmonella infections. Thus, the utility of phage has become the research focus for scientists for several reasons. There are efficient, non-toxic, ubiquitous, easy to prepare and can result in the lysis of host bacteria. In this study, a broad spectrum bacteriophage of Salmonella was isolated from the fecal samples of a poultryfarm and we studied the morphological aspects, thermal stability, pH stability, optimal multiplicity of infection (MOI), and one-step growth curve of this phage. This phage was named Salmonella phage SaFB14 and lysed 54.12%(105/194)Salmonella spp. SaFB14 belongs to the Siphoviridae and has a polyhedron head with a diameter approximating 60 × 60 nm and a tail approximating 140 nm. The optimum growth temperature was 37 °C and maintained high activity over a widepH range(pH3-10) with an optimum of pH 7.0. The optimal MOI was 0.1. A one-step growth curve showed that its latency time was 10 min, burst time was 70 min, and burst was 23 particles. In order to study the therapeutic effect of phage SaFB14 in infected mice, mice were challenged with 2 × 109 CFU/mouse Salmonella (cs20130523-001-1). Each mouse was injected to 2 × 1010 PFU SaFB14 1 h later. SaFB14 protected 40% of mice from infection. Then, the same dose of phage was given to mice for 3 days continuously. After 3 days treatment, the survival rate increased to 60%.In conclusion, phage SaFB14 showed wide host range and good activity in vivo, it is promising against diseases caused by Salmonella.

Establishment of rapid detection method and surveillance of budgerigar fledgling disease virus using a TaqMan Real-Time PCR.

Budgerigar fledgling disease virus (BFDV) infection causes sudden death, abdominal distention, and feather abnormality in psittacine birds. In this study, we developed a TaqMan Real-time PCR assay to detect BFDV by targeting a conserved region in VP1 gene. The detection limit of the assay was 30 DNA gene copies, 1000 times more sensitive than conventional PCR. The coefficients of variation were less than 1.09% in either intra- or inter-assays, indicating high reproducibility. By using this method, the prevalence of BFDV in China was evaluated. 56 feces samples were collected from four psittacine birds breeding facilities in China. The results showed 28 out of 56 samples were positive for BFDV in Real-Time PCR assay, while only 19 samples were positive in PCR assay. Three facilities were positive for BFDV with positive rates from 60% to 87.5%. Further sequence analysis of VP1 genes from the positive samples indicated that VP1 genes fell into two different lineages in phylogenetic tree, suggesting that different genotypes BFDV are co-circulating in China.

Classical swine fever virus C-strain with eight mutation sites shows enhanced cell adaptation and protects pigs from lethal challenge.

Control of classical swine fever (CSF) in developing countries is achieved by immunization with attenuated vaccines, such as the lapinized C-strain vaccine that has been widely used in China. However, C-strain has relatively low growth rate in cell cultures, thus affecting productivity of the vaccine for the industry. In this study, eight amino acid residues were mutated on the C-strain backbone, resulting in a cell-adapted strain Cmut8. The mutant strain exhibited rapid growth with titer of about 100 fold higher than its parental C-strain. The mutation sites located at structural proteins Erns and E2 contributed more to cell adaptation than those located in non-structural proteins. Sera collected from pigs inoculated with Cmut8 and C-strain at the same dose showed similar antibody levels and neutralization titers. Pigs inoculated with different doses of Cmut8 (low, medium and high) and with C-strain offered full protection against challenge with a virulent strain, shown as absence of fever and other symptoms, marginal low levels of viral load, and no obvious gross pathological changes in major organs. Unvaccinated control pigs challenged with the virulent strain showed high fever from day 2 post-challenge and apparent clinical symptoms with two deaths. Viral load were markedly elevated in these control pigs after challenge. The pigs inoculated with high dose of Cmut8 did not show fever or other typical CSF symptoms, and no apparent pathological changes were observed in major organs. Besides, the Cmut8 strain did not induce typical fever response in rabbits. These results demonstrate that the cell-adapted Cmut8 strain remains non-pathogenic to the weaned pigs, provides full protection and could be a good candidate vaccine strain for improved yield at lower cost.

A Phage Lysin Fused to a Cell-Penetrating Peptide Kills Intracellular Methicillin-Resistant Staphylococcus aureus in Keratinocytes and Has Potential as a Treatment for Skin Infections in Mice.

Staphylococcus aureus is the main pathogen that causes skin and skin structure infections and is able to survive and persist in keratinocytes of the epidermis. Since the evolution of multidrug-resistant bacteria, the use of phages and their lysins has presented a promising alternative approach to treatment. In this study, a cell wall hydrolase (also called lysin) derived from Staphylococcus phage JD007 (JDlys) was identified. JDlys showed strong lytic activity against methicillin-resistant Staphylococcus aureus (MRSA) strains from different sources and of different multilocus sequence typing (MLST) types. Furthermore, a fusion protein consisting of a cell-penetrating peptide derived from the trans-activating transcription (Tat) factor fused to JDlys (CPPTat-JDlys) was used to kill MRSA bacteria causing intracellular infections. CPPTat-JDlys, in which the fusion of CPPTat to JDlys had almost no effect on the bacteriolytic activity of JDlys, was able to effectively eliminate intracellular MRSA bacteria and alleviate the inflammatory response and cell damage caused by MRSA. Specifically, CPPTat-JDlys was able to combat MRSA-induced murine skin infections and, consequently, expedite the healing of cutaneous abscesses. These data suggest that the novel antimicrobial CPP-JDlys may be a worthwhile candidate as a treatment for skin and skin structure infections caused by MRSA.IMPORTANCES. aureus is the main cause of skin and skin structure infections due to its ability to invade and survive in the epithelial barrier. Due to the overuse of antibiotics in humans and animals, S. aureus has shown a high capacity for acquiring and accumulating mechanisms of resistance to antibiotics. Moreover, most antibiotics are usually limited in their ability to overcome the intracellular persistence of bacteria causing skin and skin structure infections. So, it is critical to seek a novel antimicrobial agent to eradicate intracellular S. aureus In this study, a cell-penetrating peptide fused to lysin (CPP-JDlys) was engineered. Our results show that CPP-JDlys can enter keratinocytes and effectively eliminate intracellular MRSA. Meanwhile, experiments with mice revealed that CPP-JDlys efficiently inhibits the proliferation of MRSA in murine skin and thus shortens the course of wound healing. Our results indicate that the CPP-fused lysin has potential for use for the treatment of skin infections caused by MRSA.

Chicken STING Mediates Activation of the IFN Gene Independently of the RIG-I Gene.

Stimulator of IFN genes (STING) is an adaptor that functions downstream of retinoic acid-inducible gene I (RIG-I) in mammalian cells; however, RIG-I is absent in chickens. We identified chicken STING (chSTING) as a critical mediator of virus-triggered type I IFN signaling in RIG-I-null chicken cells. Overexpression of chSTING in DF-1 cells inhibited Newcastle disease virus and avian influenza virus (AIV) viral replication and activated IRF-7 and NF-κB to induce expression of type I IFNs. Knockdown of endogenous chSTING abolished virus-triggered activation of IRF-7 and IFN-ß and increased viral yield. chSTING was a critical component in the virus-triggered IRF-7 activation pathway and the cellular antiviral response. chSTING predominantly localized to the outer membrane of the endoplasmic reticulum and was also found in the mitochondrial membrane. Furthermore, knockdown of chSTING blocked polyinosinic-polycytidylic acid-, poly(deoxyadenylic-deoxythymidylic) acid-, and melanoma differentiation-associated gene 5 (MDA5)-stimulated induction of IFN-ß. Coimmunoprecipitation experiments indicated that chicken MDA5 could interact with chSTING, and this interaction was enhanced by ectopically expressed chicken mitochondrial antiviral-signaling protein. Together, these results indicated that chSTING is an important regulator of chicken innate immune signaling and might be involved in the MDA5 signaling pathway in chicken cells. These results help with understanding the biological role of STING in innate immunity during evolution.

[Cyclic diadenosine monophosphate--a new second messenger in bacteria--a review].

Cyclic diadenosine monophosphate (c-di-AMP), a new second messenger found recently in bacteria, regulates various aspects of bacterial physiology, including cell growth, cell wall homeostasis and virulence. In addition to its functions in bacterial physiology, c-di-AMP represents a putative bacterial secondary signaling molecule sensed by eukaryotic host cells and triggers innate immunity. The level of c-di-AMP in bacteria is regulated by the activities of diadenylate cyclase (DAC) and phosphodiesterases (PDE) , the former harbors a DisA_N domain, and the latter a DHH or DHH/DHHA1 domain. This review gives an overview on metabolic pathway, regulatory mechanism, receptor proteins and biological function of c-di-AMP in bacteria, as well as its application and trends of development.

[The functional aspects of bacterial CRISPR-cas systems and interactions between phages and its bacterial hosts--a review].

The roles of CRIPR-Cas systems in bacterial host protection against mobile genetic elements ( MGEs) are now well known, but there is mounting evidence that these systems modulate other processes, such as the genetic regulation of group behavior and virulence, DNA repair and genome evolution. Here, we reviewed the structure, types and mechanism of interference of CRISPR-Cas system as well as the additional functions of CRISPR-Cas beyond adaptive immunity. Furthermore, we discussed the mechanisms for phages to overcome bacterial CRISPR-Cas system, and the prospective evolution of interactions between phage and host.

[Effect of Stx2-encoding phage on the motility and gene expression involved in moving of Escherichia coli lysogen].

OBJECTIVE: The effect of flhDC, fliA, fliD and fliE genes involved in moving of Escherichia coli (E. coli) on the motility of lysogened strain by Stx2-encoding phage phiMin27 was explored by gene knockout and phage lysogenic conversion. METHODS: Using the lambda Red recombinase system, the mutant strains of E. coli MG1655 named MG1655 deltaflhDC, MG1655 deltafliA, MG1655 deltafliD and MG1655 deltafliE were constructed. Then the corresponding complemented strains by ligating amplified targeted genes into the low copy vector pUC18 at the BamHI and Hind III sites and transforming these plasmids into mutant strains were acquired. By lysogenic infection of Stx2-encoding phage phiMin27, the lysogens for mutants named MG1655 deltaflhDCphiMin27, MG1655 deltafliAdeltaMin27, MG1655 deltafliDphiMin27 and MG1655 deltafliEphiMin27 were achieved. Subsequently, the motility of wild strain, the mutants, the complemented strains and the lysogens were detected. The changes of expression of the other genes involved in motility between wild strain and the lysogens before and after flhDC deletion by qRT-PCR were analyzed. RESULTS: Lysogenic infection of Stx2-encoding phage phiMin27 could promote the expression of fliA and fliD gene and enhance the motility of MG1655. For flhDC deletion, higher expression of fliA and fliD gene of MG1655 appeared, but the motility had no change. However, lysogen for MG1655 deltaflhDC lost the swimming motility. By gene transcriptional level detection, the expression of fliA and fliD gene of MG1655 deltaflhDCphiMin27 was down-regulated significantly compared with MG1655 deltaflhDC, and no marked variation was observed for fliE gene. The single deletion of fliA, fliD and fliE gene had no effect on the motility of E. coli MG1655 and lysogened strain by Stx2-encoding phage phiMin27. CONCLUSION: The results show that fliA and fliD gene together participated the regulation for flagella motility and flhDC gene could affect the motility of the lysogened strain by phage. It provides the theoretical basis for further research on the mutual regulation between phage lysogenization and host genes.