Catalytic Oxidation of Acetone on SmMn2O5: Effect of Acid Etching and Loading Treatment.

The key of catalytic oxidation technology is to develop a stable catalyst with high activity. It is still a serious challenge to achieve high conversion efficiency of acetone with an integral catalyst at low temperature. In this study, the SmMn2O5 catalyst after acid etching was used as the support, and the manganese mullite composite catalyst was prepared by loading Ag and CeO2 nanoparticles on its surface. By means of SEM, TEM, XRD, N2-BET, XPS, EPR, H2-TPR, O2-TPD, NH3-TPD, DRIFT, and other characterization methods, the related factors and mechanism analysis of acetone degradation activity of the composite catalyst were discussed. Among them, the CeO2-SmMn2O5-H catalyst has the best catalytic activity at 123 and 185 °C for T50 and T100, respectively, and shows excellent water and thermal resistance and stability. In essence, the surface and lattice defects of highly exposed Mn sites were formed by acid etching, and the dispersibility of Ag and CeO2 nanoparticles was optimized. Highly dispersed Ag and CeO2 nanoparticles have a highly synergistic effect with the support SmMn2O5, and the reactive oxygen species provided by CeO2 and the electron transfer brought by Ag further promote the decomposition of acetone on the carrier SMO-H. In the field of catalytic degradation of acetone, a new catalyst modification method of high-quality active noble metals and transition metal oxides supported by acid-etched SmMn2O5 has been developed.

Incomplete autophagy promotes the proliferation of Mycoplasma hyopneumoniae through the JNK and Akt pathways in porcine alveolar macrophages.

Autophagy is an important conserved homeostatic process related to nutrient and energy deficiency and organelle damage in diverse eukaryotic cells and has been reported to play an important role in cellular responses to pathogens and bacterial replication. The respiratory bacterium Mycoplasma hyopneumoniae has been identified to enter porcine alveolar macrophages, which are considered important immune cells. However, little is known about the role of autophagy in the pathogenesis of M. hyopneumoniae infection of porcine alveolar macrophages. Our experiments demonstrated that M. hyopneumoniae infection enhanced the formation of autophagosomes in porcine alveolar macrophages but prevented the fusion of autophagosomes with lysosomes, thereby blocking autophagic flux and preventing the acidification and destruction of M. hyopneumoniae in low-pH surroundings. In addition, using different autophagy regulators to intervene in the autophagy process, we found that incomplete autophagy promoted the intracellular proliferation of M. hyopneumoniae. We also found that blocking the phosphorylation of JNK and Akt downregulated the autophagy induced by M. hyopneumoniae, but pathways related to two mitogen-activated protein kinases (Erk1/2 and p38) did not affect the process. Collectively, M. hyopneumoniae induced incomplete autophagy in porcine alveolar macrophages through the JNK and Akt signalling pathways; conversely, incomplete autophagy prevented M. hyopneumoniae from entering and degrading lysosomes to realize the proliferation of M. hyopneumoniae in porcine alveolar macrophages. These findings raise the possibility that targeting the autophagic pathway may be effective for the prevention or treatment of M. hyopneumoniae infection.

Research Progress of a Composite Metal Oxide Catalyst for VOC Degradation.

Volatile organic compounds (VOCs) are atmospheric pollutants that have been of concern for researchers in recent years because they are toxic, difficult to remove, and widely sourced and easily cause damage to the environment and human body. Most scholars use low-temperature plasma biological treatment, catalytic oxidation, adsorption, condensation, and recovery techniques to treat then effectively. Among them, catalytic oxidation technology has the advantages of a high catalytic efficiency, low energy consumption, high safety factor, high treatment efficiency, and less secondary pollution; it is currently widely used for VOC degradation technology. In this paper, the catalytic oxidation technology for the degradation of multiple types of VOCs as well as the development of a single metal oxide catalyst have been briefly introduced. We also focus on the research progress of composite metal oxide catalysts for the removal of VOCs by comparing and analyzing the metal component ratio, preparation method, and types of precursors and the catalysts' influence on the catalytic performance. In addition, the reason for catalyst deactivation and a correlation between the chemical state of the catalyst and the electron distribution are discussed. Development of a composite metal oxide catalyst for the catalytic oxidation of VOCs has been proposed.

Assessing the inflammatory severity of the terminal ileum in Crohn disease using radiomics based on MRI.

BACKGROUND: Evaluating inflammatory severity using imaging is essential for Crohn's disease, but it is limited by potential interobserver variation and subjectivity. We compared the efficiency of magnetic resonance index of activity (MaRIA) collected by radiologists and a radiomics model in assessing the inflammatory severity of terminal ileum (TI). METHODS: 121 patients were collected from two centers. Patients were divided into ulcerative group and mucosal remission group based on the TI Crohn's disease Endoscopic Severity Index. The consistency of bowel wall thickness (BWT), relative contrast enhancement (RCE), edema, ulcer, MaRIA and features of the region of interest between radiologists were described by weighted Kappa test and intraclass correlation coefficient (ICC), and developed receiver operating curve of MaRIA. The radiomics model was established using reproducible features of logistic regression based on arterial staging of T1WI sequences. Delong test was used to compare radiomics with MaRIA. RESULTS: The consistency between radiologists were moderate in BWT (ICC = 0.638), fair in edema (κ = 0.541), RCE (ICC = 0.461), MaRIA (ICC = 0.579) and poor in ulcer (κ = 0.271). Radiomics model was developed by 6 reproducible features (ICC = 0.93-0.96) and equivalent to MaRIA which evaluated by the senior radiologist (0.872 vs 0.883 in training group, 0.824 vs 0.783 in validation group, P = 0.847, 0.471), both of which were significantly higher than MaRIA evaluated by junior radiologist (AUC: 0.621 in training group, 0.557 in validation group, all, P < 0.05). CONCLUSION: The evaluation of inflammatory severity could be performed by radiomics objectively and reproducibly, and was comparable to MaRIA evaluated by the senior radiologist. Radiomics may be an important method to assist junior radiologists to assess the severity of inflammation objectively and accurately.

Development of an indirect ELISA for detection of anti-Mycoplasma hyopneumoniae IgG in naturally infected pathogen-induced convalescent sera.

BACKGROUND: Immunization of pigs with an inactivated Mycoplasma hyopneumoniae vaccine (bacterin) generates hyperimmune serum that contains high concentrations of anti-M. hyopneumoniae IgG. Commercially available IgG-ELISA kits cannot distinguish between anti-M. hyopneumoniae IgG in inactivated bacterin-induced hyperimmune sera and convalescent sera resulting from natural M. hyopneumoniae infection. Establishment of an ELISA to detect anti-M. hyopneumoniae IgG in convalescent sera will facilitate the evaluation of the M. hyopneumoniae status of pig farms. RESULTS: In this study, we expressed and purified recombinant Mhp366-N protein, which contains an epitope recognized by M. hyopneumoniae convalescent sera but not hyperimmune sera, for use as a coating antigen. For the M. hyopneumoniae convalescent serum IgG-ELISA, the optimal antigen concentration, blocking buffer, blocking time, dilution of serum, incubation time with serum, secondary antibody dilution, secondary antibody incubation time and colorimetric reaction time were 0.25 µg/mL, 2.5 % skim milk, 1 h, 1:500, 0.5 h, 1:10,000, 1 h and 15 min, respectively. Validation of the M. hyopneumoniae convalescent serum IgG-ELISA showed a cut-off value of 0.323, the intra-assay CV ranged from 3.27 to 7.26 %, the inter-assay CV ranged from 3.46 to 5.93 %, and the assay was able to differentiate convalescent sera from antibodies to 7 other porcine respiratory pathogens. The convalescent serum IgG-ELISA detected no anti-M. hyopneumoniae IgG in hyperimmune serum samples while a commercial IgG-ELISA identified 95/145 of these sera as positive. The accuracy of the M. hyopneumoniae convalescent serum IgG-ELISA was comparable to the sIgA-ELISA but better than the commercial IgG-ELISA. CONCLUSIONS: The convalescent serum IgG-ELISA is a reproducible, sensitive, and specific indirect ELISA to detect anti-M. hyopneumoniae IgG in naturally infected pathogen-induced convalescent sera. This ELISA could be used to carry out large scale surveillance of M. hyopneumoniae infection in pig farms regardless of vaccination status.

Development of an indirect ELISA for detecting humoral immunodominant proteins of Mycoplasma hyopneumoniae which can discriminate between inactivated bacterin-induced hyperimmune sera and convalescent sera.

BACKGROUND: Mycoplasma hyopneumoniae (M. hyopneumoniae) is the primary pathogen of porcine enzootic pneumonia, which has been associated with economic losses due to reduced daily weight gain and feed efficiency. Although it has a small genome and no more than 1000 genes, M. hyopneumoniae can be cultured in cell free media. However, some proteins were not expressed or were only expressed in negligible amounts under culture conditions. Nevertheless, some of these proteins can be expressed at a high level and induce a strong and rapid immune response after M. hyopneumoniae infection. The unexpressed or less expressed proteins may play critical roles in pathogenesis and/or immune response. In order to find the differentially expressed proteins of M. hyopneumoniae between culture condition and infected animals, we established an indirect ELISA for the detection of humoral immunodominant proteins which can discriminate between inactivated bacterin-induced hyperimmune sera and convalescent sera by using Mhp366 protein which did not react with sera from bacterin-immunized pigs, but revealed a strong immunoreaction with porcine convalescent sera. RESULTS: The checkerboard titration method was done by using porcine convalescent sera as positive sera and inactivated bacterin-induced hyperimmune sera as negative sera. The bacterial lysates of fusion proteins and free GST protein without dilution were the optimal coating antigens. The optimal blocking buffer was PBS with 10% FBS and 2.5% skimmed milk. In the checkboard ELISAs, when the sera were diluted at 1:500 and the HRP-labeled rabbit anti-pig IgG were diluted at 1:20000, most positive result was obtained for the assay. CONCLUSIONS: This established indirect ELISA can be used as a tool for the detection of humoral immunodominant proteins of M. hyopneumoniae which can discriminate between inactivated bacterin-induced hyperimmune sera and convalescent sera.

Serovar and sequence type distribution and phenotypic and genotypic antimicrobial resistance of Salmonella originating from pet animals in Chongqing, China.

A total of 334 Salmonella isolates were recovered from 6,223 pet rectal samples collected at 50 pet clinics, 42 pet shops, 7 residential areas, and 4 plazas. Forty serovars were identified that included all strains except for one isolate that did not cluster via self-agglutination, with Salmonella Typhimurium monophasic variant, Salmonella Kentucky, Salmonella Enteritidis, Salmonella Pomona, and Salmonella Give being the predominant serovars. Fifty-one sequence types were identified among the isolates, and ST198, ST11, ST19, ST451, ST34, and ST155 were the most common. The top four dominant antimicrobials to which isolates were resistant were sulfisoxazole, ampicillin, doxycycline, and tetracycline, and 217 isolates exhibited multidrug resistance. The prevalence of ß-lactamase genes in Salmonella isolates was 59.6%, and among these isolates, 185 harbored blaTEM, followed by blaCTX-M (66) and blaOXA (10). Moreover, six PMQR genes, namely, including qnrA (4.8%), qnrB (4.2%), qnrD (0.9%), qnrS (18.9%), aac(6')-Ib-cr (16.5%), and oqxB (1.5%), were detected. QRDR mutations (76.6%) were very common in Salmonella isolates, with the most frequent mutation in parC (T57S) (47.3%). Furthermore, we detected six tetracycline resistance genes in 176 isolates, namely, tet(A) (39.5%), tet(B) (8.1%), tet(M) (7.7%), tet(D) (5.4%), tet(J) (3.3%), and tet(C) (1.8%), and three sulfonamide resistance genes in 303 isolates, namely, sul1 (84.4%), sul2 (31.1%), and sul3 (4.2%). Finally, we found 86 isolates simultaneously harboring four types of resistance genes that cotransferred 2-7 resistance genes to recipient bacteria. The frequent occurrence of antimicrobial resistance, particularly in dogs and cats, suggests that antibiotic misuse may be driving multidrug-resistant Salmonella among pets.IMPORTANCEPet-associated human salmonellosis has been reported for many years, and antimicrobial resistance in pet-associated Salmonella has become a serious public health problem and has attracted increasing attention. There are no reports of Salmonella from pets and their antimicrobial resistance in Chongqing, China. In this study, we investigated the prevalence, serovar diversity, sequence types, and antimicrobial resistance of Salmonella strains isolated from pet fecal samples in Chongqing. In addition, ß-lactamase, QRDR, PMQR, tetracycline and sulfonamide resistance genes, and mutations in QRDRs in Salmonella isolates were examined. Our findings demonstrated the diversity of serovars and sequence types of Salmonella isolates. The isolates were widely resistant to antimicrobials, notably with a high proportion of multidrug-resistant strains, which highlights the potential direct or indirect transmission of multidrug-resistant Salmonella from pets to humans. Furthermore, resistance genes were widely prevalent in the isolates, and most of the resistance genes were spread horizontally between strains.

[Development of an ELISA method for detection of antibodies against Mycoplasma hyopneumoniae based on Mhp336 protein].

This study aims to establish an ELISA method with high specificity for the detection of antibodies against Mycoplasma hyopneumoniae. Firstly, we constructed a recombinant strain Escherichia coli BL21(DE3)-pET-32a(+)-mhp336 to express the recombinant protein Mhp336 and used the purified Mhp336 as the coating antigen. Then, we optimized the ELISA parameters, including antigen concentration, blocking buffer, blocking time, dilution of serum, incubation time with serum, secondary antibody dilution, secondary antibody incubation time, colorimetric reaction time, and cut-off value. Afterwards, reproducibility experiments were conducted, and the cross reactivity of Mhp366 with other antisera of porcine major pathogens and the maximum dilution ratios of the sera were determined. Finally, 226 porcine serum samples were detected using the method established in this study, a commercial ELISA kit for M. hyopneumoniae antibody detection, and a convalescent serum ELISA kit for M. hyopneumoniae antibody detection. The detection results of the three methods were compared to evaluate the sensitivity and specificity of the ELISA method established in this study. For this method, the optimal antigen concentration, blocking buffer, blocking time, dilution of serum, incubation time with serum, secondary antibody dilution, secondary antibody incubation time, and colorimetric reaction time were 0.05 µg/mL, PBS containing 2.5% skim milk, 1 h, 1:500, 0.5 h, 1:10 000, 1 h, and 5 min, respectively. Validation of the ELISA method based on Mhp336 showed a cut-off value of 0.332. The coefficients of variation of both intra-batch and inter-batch kits were below 7%. The detection results of porcine serum samples indicated that the method established in this study outperformed the commercial ELISA kit and the convalescent serum ELISA kit for M. hyopneumoniae antibody detection in terms of sensitivity and specificity. We successfully established an ELISA method for detecting the antibodies against M. hyopneumoniae based on Mhp336 protein. This method demonstrated high sensitivity and specificity, serving as a tool for the prevention of mycoplasmal pneumonia of swine in pig farms.

[Advances in innate immune responses induced by Mycoplasma hyopneumoniae infection].

Mycoplasma hyopneumoniae is the pathogen causing swine mycoplasmal pneumonia. The lack of well-established animal models of M. hyopneumoniae infection has delayed the progress of M. hyopneumoniae-related anti-infection immunity studies. This paper reviews the inflammatory response, the recognition of M. hyopneumoniae by the innate immune system, and the role of innate immune cells, complement system, antimicrobial peptides, autophagy, and apoptosis in M. hyopneumoniae infection. The aim was to elucidate the important roles played by the components of the innate immune system in the control of M. hyopneumoniae infection, and prospect key research directions of innate immune response of M. hyopneumoniae infection in the future.

Prevalence, antimicrobial resistance, and staphylococcal toxin genes of blaTEM-1a -producing Staphylococcus aureus isolated from animals in Chongqing, China.

BACKGROUND: Staphylococcus aureus infection of livestock animals and humans is a major public health issue. There are reports of antimicrobial resistance and multiple staphylococcal superantigen genes in many countries and several provinces of China, but the status in Chongqing, China is uncertain. OBJECTIVES: The aim of this study was to determine the prevalence, antimicrobial susceptibility, and other molecular characteristics of S. aureus isolates from livestock animals in Chongqing. METHODS: Staphylococcus aureus was isolated and identified by selective enrichment and amplification of the nuc gene from 1371 samples collected at farms in Chongqing. The agar dilution method was used to determine the resistant phenotype, and extended spectrum ß-lactamase genes were amplified by PCR. Methicillin-resistant S. aureus was verified by the presence of the mecA gene, and the presence or absence of SE, SEl, and TSST-1 genes was detected in the isolates. RESULTS: We cultured 89 S. aureus isolates from 1371 samples between March 2014 and December 2017. These isolates were from pigs, cattle, goats, rabbits, and chickens. There were four methicillin-resistant S. aureus strains (three from pigs and one from a chicken). The 89 isolates had high resistance to penicillin (93.3%) and ampicillin (92.1%), but most were susceptible to amikacin and ofloxacin, with resistance rates below 10%. A total of 62.9% of the isolates had varying degrees of multidrug resistance. Almost all strains, except for three isolates from chickens, were positive for blaTEM-1a . There were 19 of 20 tested staphylococcal SE/SEl/TSST-1 genes present (all except for seq), and the predominant genes were sei (58.4%), tst-1 (56.2%), and seg (51.7%). CONCLUSIONS: The high antimicrobial resistance and prevalence of blaTEM-1a reinforce the need to reduce the usage of antimicrobials in livestock. The universal existence of staphylococcal toxin genes implies a potential threat to public health by animal-to-human transmission via the food chain.

Porcine antibody profiles of 33 Mycoplasma hyopneumoniae fusion proteins from M. hyopneumoniae natural infection but not vaccination.

BACKGROUND: Mycoplasma hyopneumoniae, the primary pathogen responsible for porcine enzootic pneumonia, reduces average daily weight gain and causes substantial economic losses to the pig industry worldwide. Vaccination is the most common strategy to control this disease but offers partial protection. Therefore, developing next-generation vaccines by screening protective antigens is crucial. OBJECTIVES: The aim of this study was to evaluate the antibody response to 33 recombinant proteins in pigs naturally infected with M. hyopneumoniae. METHODS: The genes encoding 33 (hypothetical) membrane proteins or secretory proteins were ligated into pGEX-6P-1, pGEX-6P-2, pGEX-5X-3 or pGEX-4T-3 vectors and transformed into Escherichia coli BL21(DE3) or E. coli XL-1 Blue to construct recombinant bacteria and to express the recombinant proteins. The recombinant bacteria expressing the target proteins reacted with porcine convalescent sera and negative sera to screen immunodominant proteins by ELISA. Then, recombinant bacteria expressing immunodominant proteins were used to identify the discriminating immunodominant proteins that were recognised by convalescent sera nut not hyperimmune sera. RESULTS: All recombinant bacteria could express the target recombinant proteins in soluble form. Twenty-one proteins were shown to present immunodominant antigens, and four proteins were not recognised by convalescent sera. Moreover, six proteins were considered discriminating and reacted with convalescent sera but not with hyperimmune sera. CONCLUSIONS: The identified immunodominant proteins were antigenic and expressed during bacterial infection, suggesting that these proteins, especially those capable of discriminating between sera, can be used to identify protective antigens with the view to develop more effective vaccines against M. hyopneumoniae infection.

BlaTEM-positive Salmonella enterica serovars Agona and Derby are prevalent among food-producing animals in Chongqing, China.

Salmonella is one of the most important foodborne zoonotic pathogens, causing global morbidity and mortality in both humans and animals. Due to the extensive use of antimicrobials in food-producing animals, the antimicrobial resistance of Salmonella has attracted increasing attention globally. There have been many reports concerning the antimicrobial resistance of Salmonella from food-producing animals, meats and the environment. However, few studies on Salmonella from food-producing animals have been reported in Chongqing municipality, China. The aim of the present study was to determine the prevalence, serovar diversity, sequence types, and antimicrobial resistance of Salmonella isolated from livestock and poultry in Chongqing. Meanwhile, we also want to know the presence of ß-lactamase genes, plasmid-mediated quinolone resistance (PMQR) genes and quinolone resistance-determining region (QRDR) mutations of Salmonella isolates. A total of 129 Salmonella strains were recovered from 2,500 fecal samples at 41 farms from pigs, goats, beef cattle, rabbits, chickens, and ducks. Fourteen serovars were identified, with S. Agona and S. Derby being the dominant serovars. The 129 isolates had high resistance to doxycycline (87.6%), ampicillin (80.6%), tetracycline (79.8%), trimethoprim (77.5%), florfenicol (76.7%) chloramphenicol (72.9%), and trimethoprim-sulfamethoxazole (71.3%), but were susceptible to cefepime. A total of 114 (88.4%) isolates showed multidrug resistant phenotypes. The prevalence of ß-lactamase genes in Salmonella isolates was 89.9% (116/129), and among these isolates, 107 (82.9%) harbored blaTEM, followed by blaOXA (26, 20.2%), blaCTX-M (8, 6.2%), and blaCMY (3, 2.3%). In addition, qnrB, qnrD, qnrS, oqxA, oqxB, and aac(6')-Ib-cr were detected in 11, 2, 34, 34, 43, and 72 PMQR-producing isolates, respectively. Moreover, QRDR mutations were very common in PMQR-positive Salmonella isolates (97.2%, 70/72) with mutation(s) in parC or combinative mutations in gyrA and parC. More significantly, 32 extended spectrum beta-lactamase (ESBL)-producing isolates were identified, and 62.5% of them were found to harbor one to four PMQR genes. Furthermore, 11 sequence types were identified from the isolates, and most of ESBL-producing isolates were attributed to ST34 (15.6%) and ST40 (62.5%). The coexistence of PMQR genes with ß-lactamase genes and the extensive mutations in QRDR present in Salmonella isolates from food-producing animals suggest a potential threat to public health. Reasonable utilization and strict control strategies for antimicrobials in animal husbandry and animal treatment are necessary to reduce the emergence and dissemination of drug-resistant Salmonella isolates.

Risk stratification of lung adenocarcinoma using a nomogram combined with ferroptosis-related LncRNAs and subgroup analysis with immune and N6-methyladenosine modification.

BACKGROUND: Determining the prognosis of lung adenocarcinoma (LUAD) is challenging. The present study aimed to identify prognostic ferroptosis-related long noncoding RNAs (FRLs) and construct a prognostic model. Moreover, differential analysis of immune and N6-methyladenosine (m6A)-related genes was systematically conducted. METHODS: A total of 504 patients selected from a dataset from The Cancer Genome Atlas were included. The patients with LUAD were randomly divided into a training group and a test group at a ratio of 1:1. Pearson correlation analysis and univariate Cox regression analysis were used to identify the prognostic FRLs. Then, a prognostic model was constructed from the optimized subset of prognostic FRLs based on the least absolute shrinkage and selection operator (LASSO) algorithm. Subsequently, the receiver operating characteristic (ROC) curve and survival analysis were used to evaluate the performance of the model. The risk score based on the prognostic model was analyzed using Cox regression analysis. Moreover, gene set enrichment analysis and differential analysis of immune- and m6A-related genes were conducted. RESULTS: After univariate Cox regression analysis and LASSO algorithm analysis, a total of 19 prognostic FRLs were selected to construct the final model to obtain the risk score. The area under the ROC curve of the prognostic model for 1-year, 3-year, and 5-year overall survival (OS) was 0.763, 0.745, and 0.778 in the training set and 0.716, 0.724, and 0.736 in the validation set, respectively. Moreover, the OS of the high-risk group was significantly worse than that of the low-risk group in the training group (P < 0.001) and in the test group (P < 0.001). After univariate and multivariate Cox regression analysis, the risk score [hazard ratio (HR) = 1.734; P < 0.001] and stage (HR = 1.557; P < 0.001) were both considered significant prognostic factors for LUAD. A nomogram was constructed based on clinical features and risk score. The expression of 34 checkpoint genes and 13 m6A-related genes varied significantly between the two risk groups. CONCLUSION: This study constructed a prognostic model to effectively predict the OS of patients with LUAD, and these OS-related FRLs might serve as potential therapeutic targets of LUAD.

Crystallization and preliminary crystallographic studies of Campylobacter jejuni ChuZ, a member of a novel haem oxygenase family.

The haem oxygenase ChuZ from Campylobacter jejuni, a major enteric pathogen in humans, is part of the iron-acquisition mechanism that is involved in bacterial survival and persistence in hosts. The ChuZ-haemin complex has been purified and crystallized and diffraction data have been collected to 2.4 Å resolution. The ChuZ-haemin complex crystals belonged to space group C222(1), with unit-cell parameters a = 106.474, b = 106.698, c = 52.464 Å, α = ß = γ = 90°. The asymmetric unit contained one ChuZ monomer, with a Matthews coefficient of 2.58 Å(3) Da(-1).

Incomplete autophagy promotes the replication of Mycoplasma hyopneumoniae.

Autophagy is an important cellular homeostatic mechanism for recycling of degradative proteins and damaged organelles. Autophagy has been shown to play an important role in cellular responses to bacteria and bacterial replication. However, the role of autophagy in Mycoplasma hyopneumoniae infection and the pathogenic mechanism is not well characterized. In this study, we showed that M. hyopneumoniae infection significantly increases the number of autophagic vacuoles in host cells. Further, we found significantly enhanced expressions of autophagy marker proteins (LC3-II, ATG5, and Beclin 1) in M. hyopneumoniae-infected cells. Moreover, immunofluorescence analysis showed colocalization of P97 protein with LC3 during M. hyopneumoniae infection. Interestingly, autophagic flux marker, p62, accumulated with the induction of infection. Conversely, the levels of p62 and LC3-II were decreased after treatment with 3-MA, inhibiting the formation of autophagosomes, during infection. In addition, accumulation of autophagosomes promoted the expression of P97 protein and the survival of M. hyopneumoniae in PK-15 cells, as the replication of M. hyopneumoniae was down-regulated by adding 3-MA. Collectively, these findings provide strong evidence that M. hyopneumoniae induces incomplete autophagy, which in turn enhances its reproduction in host cells. These findings provide novel insights into the interaction of M. hyopneumoniae and host.

Development of an ELISA for distinguishing convalescent sera with Mycoplasma hyopneumoniae infection from hyperimmune sera responses to bacterin vaccination in pigs.

Vaccination with inactivated bacterin is the most popular and practical measure to control enzootic pneumonia. After immunisation with inactivated bacterin, Mycoplasma hyopneumoniae colonised on the respiratory tract and lung stimulates the humoural immune responses and produces IgG and IgA antibodies. ELISA is a widely used serological method to detect M. hyopneumoniae antibodies. However, commercial IgG-ELISA kit cannot distinguish between inactivated bacterin-induced hyperimmune sera and convalescent sera stimulated by natural infection. SIgA-ELISA method needs to collect nasal swabs, but collecting nasal swabs is not easy to operate. Establishment of a discriminative ELISA detecting humoural IgG from convalescent sera but not hyperimmune sera facilitates to evaluate the natural infection of M. hyopneumoniae after inactivated bacterin vaccination. We expressed and purified a recombinant protein named Mhp366-N which contains an epitope recognised by the convalescent sera but not hyperimmune sera. The developed discriminative IgG-ELISA could discriminate between inactivated bacterin-induced hyperimmune sera and convalescent sera and was reproducible, sensitive and specific to M. hyopneumoniae antibody produced by natural infection. Compared to SIgA-ELISA method, discriminative IgG-ELISA was more convenient to detect IgG antibody from sera than IgA from nasal swabs, although it has limited sensitivity in the early stages of infection. Additionally, to some extent, it has a potential to avoid the interference of maternally derived IgG antibodies. The established discriminative IgG-ELISA was efficient to judge the serological IgG antibodies induced from natural infection or inactivated vaccine stimulation and provided a useful method to investigate and evaluate the live organism infection after the application of inactivated bacterin.

[Interaction between Mycoplasma hyopneumoniae and host-a review].

Mycoplasma hyopneumoniae is the pathogen of porcine enzootic pneumonia (PEP). Due to difficulties in studying the pathogenesis of M. hyopneumoniae for blockage on the establishment of gene operation platform and immature animal model, mycoplasmologists still make progress in understanding the interaction between M. hyopneumoniae and host. In this paper, we review the adhesion and damage of M. hyopneumoniae to host cells, the inflammatory response and immune response of host stimulated by M. hyopneumoniae. Meanwhile, we propose research directions of the pathogenesis of M. hyopneumoniae in the future. This review can provide references for the follow-up study on the interaction between M. hyopneumoniae and host, and provide theoretical basis for effective vaccine and drug development.

[Fighting between bacteria and autophagy--death or rebirth].

Autophagy is a highly conserved degradation process that targets cytoplasmic components, maintains metabolic stability in cells, and combates infection with various pathogenic bacteria. Autophagy can help body to eliminate invading pathogens; however, some bacteria have evolved multiple strategies to interfere with the autophagy signaling pathway or inhibit the fusion of autophagosomes with lysosomes to form autolysosomes to escape autophagic degradation, and even use autophagy to promote their growth and proliferation. This review discusses the newest progress in the relationship between pathogens and autophagy of host cell, and the role of autophagy in bacterial infection. We hope that this review provides useful knowledge for the research on autophagy caused by pathogenic infection.

Elevated Mhp462 antibody induced by natural infection but not in vitro culture of Mycoplasma hyopneumoniae.

Mycoplasma hyopneumoniae is the respiratory pathogen of porcine enzootic pneumonia, a chronic respiratory infectious disease that causes substantial pecuniary losses to pig husbandry worldwide. Commercial bacterins only provide incomplete protection and do not prevent the colonization and transmission of M. hyopneumoniae. Identification of new protective antigens is a key imperative for the development of more effective novel vaccine. The objective of this study was to evaluate antibody responses of 27 recombinant proteins in convalescent sera obtained from pigs that were naturally infected with M. hyopneumoniae. Fifteen proteins were identified as serological immunodominant antigens, while 3 proteins were not recognized by any convalescent serum. Moreover, Mhp462, a leucine aminopeptidase, was found to be a discriminative serological immunodominant antigen which reacted with convalescent sera but not with hyperimmune sera. The serological immunodominant proteins were antigenic and were expressed during infection; this suggests that these proteins (especially the discriminative one) are potential candidate antigens for the development of next generation vaccines against M. hyopneumoniae.

Epidemiological survey on Escherichia coli O157 in Chongqing and Three-Gorge Reservoir Areas of China.

Prevalence, presence of virulence and adherence associated genes, genetic diversity, biochemical characteristics, and antibiotic susceptibility were determined for Escherichia coli O157 isolated over 4 months in Chongqing city and Three-Gorge Reservoir Areas. 11 isolates of E. coli O157 were isolated from 1504 samples and 7 of them are O157:H7 and 4 are O157:H? All O157:H7 isolates had eaeA, ehxA, EspA and Tccp genes, but did not have stx1 and stx2. All O157:H? isolates did not have stx1, stx2, eaeA, ehxA, EspA and Tccp genes except for the isolate obtained from Yunyang county which had stx1. When eaeA and ehxA presented in isolates were digested by restriction enzymes, the numbers and the sizes of the segments were the same as the control E. coli O157 strains. This suggests that eaeA and ehxA exhibit poor polymorphism. Most E. coli O157 isolates showed identical biochemical activities to the standard strains for sorbitol and rhamnose, and all E. coli O157:H7 obtained from feces at the same dairy cattle farm had similar biochemical characteristics. Antibiotic susceptibility demonstrated resistance of the isolates to penicillin, ampicillin, bacitracin, cefuroxime, erythromycin, gentamycin and tetracycline, indicating the isolates obtained in this study had a multi-drug resistance.