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Extraintestinal pathogenic Escherichia coli (ExPEC) is an important pathogen that can cause systemic infections in a broad spectrum of mammals and birds. To date, commercial vaccines against ExPEC infections in pigs are rare and antibiotic resistance has become a serious clinical problem. Identification of protective antigens is helpful for developing potentially effective vaccines. In this study, two outer membrane porins, OmpC and OmpF, of porcine ExPEC were cloned and expressed to investigate their immunogenicity. Intraperitoneal immunization of mice with the purified recombinant proteins OmpC and OmpF stimulated strong immunoglobulin G (IgG) antibody responses. Both IgG1 and IgG2a subclasses were induced, with a predominance of IgG1 production. After challenge with 2.5 × 10(7) CFU (5 × LD50 ) of the highly virulent ExPEC strain PCN033, 62.5% and 87.5% protection was observed in mice immunized with OmpC and OmpF, respectively. In addition, both anti-OmpC and anti-OmpF sera can mediate complement-dependent opsonophagocytosis. Phylogenetic analysis showed that the ompC gene was ubiquitously present in all E. coli strains, whereas the ompF gene was mutated in certain strains. Furthermore, the selection analysis indicated that gene ompC may be subject to strong immune pressure. Our results demonstrated that OmpC is a promising vaccine target against ExPEC infections in swine.

Background Extraintestinal pathogenic Escherichia coli (ExPEC) can cause a variety of infections outside the gastrointestinal tract in humans and animals. Infections due to swine ExPECs have been occurring with increasing frequency in China. These ExPECs may now be considered a new food-borne pathogen that causes cross-infections between humans and pigs. Knowledge of the clonal structure and virulence genes is needed as a framework to improve the understanding of phylogenetic traits of porcine ExPECs. Results Multilocus sequence typing (MLST) data showed that the isolates investigated in this study could be placed into four main clonal complexes, designated as CC10, CC1687, CC88 and CC58. Strains within CC10 were classified as phylogroup A, and these accounted for most of our porcine ExPEC isolates. Isolates in the CC1687 clonal complex, formed by new sequence types (STs), was classified as phylogroup D, with CC88 isolates considered as B2 and CC58 isolates as B1. Porcine ExPECs in these four clonal complexes demonstrated significantly different virulence gene patterns. A few porcine ExPECs were indentified in phylogroup B2, the phylogroup in which human ExPECs mainly exist. However some STs in the four clonal groups of porcine ExPECs were reported to cause extraintestinal infections in human, based on data in the MLST database. Conclusion Porcine ExPECs have different virulence gene patterns for different clonal complexes. However, these strains are mostly fell in phylogenentic phylogroup A, B1 and D, which is different from human ExPECs that concentrate in phylogroup B2. Our findings provide a better understanding relating to the clonal structure of ExPECs in diseased pigs and indicate a need to re-evaluate their contribution to human ExPEC diseases.

The weakening groove becomes the weaker link in separating unit since it bears axial load, bending moment and shearing force during operating. The strain distribution of weakening groove is obtained by ARAMIS system based on 3D digital speckle correlation method (DSCM). The result indicates that there is stress concentrate band in each groove, and the strain increased from the lower one to the upper ones. The result also demonstrates that the ARAMIS system performed with good results, especially in 3D deformation and stress concentrate measurement.

Extraintestinal pathogenic Escherichia coli (ExPEC) is an important pathogen which can infect humans and animals and cause many diseases outside the intestine. Here, we report the first draft genome sequence of a porcine ExPEC strain, PCN033, isolated from a pig with meningitis.

On the ground of high resistance to pressure, long life and good retractility, the welded metal bellows are widely used by the space industry. Their performance reductions have a serious effect on the system reliability of space products during the storage. The strength and stiffness analysis of welded metal bellows are performed by theoretical research, numerical simulation and test verification in this paper. Moreover, it is ascertained that the main failure mode of bellows is stress looseness. Then the residual load carrying capacity is confirmed as the failure criterion of bellows. The variation of residual load carrying capacity with time is derived on the base of Larson-Miller model. Then, the assessment model of bellows storage durability is based on stress-strength model. At last, some welded metal bellows storage test data are evaluated through this method, and life evaluation on storage durability of bellows is presented. This method is great guidance significance for optimizing the design of welded metal bellows assembly and assessing storage reliability of space products.