Pathogenic Escherichia coli (E. coli) is an important infectious Gram-negative bacterium causing millions of death every year. Outer membrane protein A (OmpA) has been suggested as a potential vaccine candidate for conferring protection against bacterial infection. In this study, a universal vaccine candidate for E. coli infection was developed and evaluated. Bioinformatics analysis revealed the OmpA protein from E. coli shares 96~100%, 90~94%, and 45% identity with Shigella, Salmonella, and Pseudomonas strains, respectively. The ompA gene was cloned from the genomic DNA of E. coli, and then the OmpA protein was expressed in BL21 (DE3) using the auto-induction method. The recombinant OmpA (rOmpA) protein had an average molecular weight of 36 kDa with the purity of 93.5%. Immunological analysis indicated that the titers of anti-rOmpA sera against rOmpA and whole cells were 1:642,000 and 1:140,000, respectively. Moreover, rOmpA not only conferred a high level of immunogenicity to protect mice against the challenge of E. coli, but also generated cross-protection against Shigella and Salmonella. The anti-rOmpA sera could enhance the phagocytic activity of neutrophils against E. coli. The survive ratios of mice immunized with rOmpA and PBS were 50% and 20% after 48 h post-challenge, indicating mice were protected from E. coli infection after immunization with rOmpA. All these results clearly indicate that rOmpA may be a promising candidate for the development of a subunit vaccine to prevent E. coli infection.

No abstract

No abstract

Multiple microgrids (MMGs) are clusters of interconnected microgrids that have great potential for integrating a large number of distributed renewable energies (DREs). The grid-connected control scheme is important for the exploration of the MMGs’ operation potential. In this paper, a multi-layer coordinated control scheme for DC interconnected MMGs is proposed to optimize their operation and improve their operation friendliness. An adaptive droop control method is designed for the DC connection interfaces of the MMGs to adaptively manage the power exchange among the sub-microgrids. Meanwhile, the strategy of power fluctuation suppression is developed for the hybrid energy storage system (HESS) in the MMGs. The coordination among the sub-microgrids and the HESS is then clarified by the proposed control scheme to optimize the AC tie-line power and make the MMGs a highly coordinated collective. A case study is performed in PSCAD/EMTDC based on the demonstration project in Guangxi, China. The results show that the proposed multi-layer coordinated control scheme realizes the coordinated operation of the MMGs, fully exploits the complementarity of the MMGs, and improves the operation friendliness among the sub-microgrids and the utility grid. Thus the integration and utilization of a large number of DREs is enhanced.