Search

Avian pathogenic Escherichia coli (APEC) causes great economic loss to the poultry industry worldwide. Chicken type II pneumocytes (CP II cells) secrete surfactants and modulate lung immunity to decrease the infection of the invading pathogen. Nevertheless, the pathogenesis of CP II cells to APEC infection remains poorly understood. Therefore, we conducted global gene expression profiling of CP II cells after APEC-O78 infection to explore the host-pathogen interaction. The differentially expressed genes of CP II cells to APEC infection were characterized by RNA-seq with EB-seq algorithm. In consequence, the mRNA of 18996 genes was identified, and CP II cells responded to APEC infection with marked changes in the expression of 1390 genes. Among them, there are 803 down-regulated mRNAs and 587 up-regulated mRNAs. The KEGG prediction and Gene Ontology terms analysis revealed that the major enriched pathways were related to NF-κB signaling pathway, apoptosis pathway, tight junction, and cytokine-cytokine receptor interaction and other pathways. We adopted qRT-PCR to verify the validity of the selected gene expression. The fold induction of qPCR was similar to the RNA-seq results. These results provide a better understanding of the pathogenesis of APEC, especially apoptosis pathway involved in APEC infection., Competing Interests: The authors have declared that no competing interests exist.

The study aimed to investigate whether rutin affects the quorum sensing (QS) of avian pathogenic Escherichia coli (APEC). In this study, APEC-O78 was selected as the test strain. We mainly examined the effects of rutin on the AI-2 secretion by bioluminescence assay, biofilm formation through a crystal violet staining method, and expression of virulence genes of APEC by qRT-PCR. We found that rutin can significantly interfering with QS through reducing the secretion of AI-2, inhibited the biofilm formation, and reduced the expression of virulence genes of APEC. Moreover, rutin markedly decreased adhesion and damage of APEC to chicken type II pneumocytes. These results suggested rutin reduces cell damage of APEC-infected chicken type II pneumocytes through interfering with QS via decreasing AI-2 production, biofilm formation, and the expression of virulence genes. This paper may provide a new evidence for colibacillosis prevention in chicken., (Copyright © 2018. Published by Elsevier Ltd.)

Avian pathogenic Escherichia coli (APEC) infections are responsible for great losses in the poultry industry. Quorum sensing (QS) acts as a global regulatory system that controls genes involved in bacterial pathogenesis, metabolism and protein biosynthesis. However, whether QS of APEC is related to cell damage has not been elucidated. In the present study, we explored the correlation between the damage of chicken type II pneumocytes induced by APEC and the autoinducer-2 (AI-2) activity of APEC. The results showed that when chicken type II pneumocytes were co-cultured with 10 8  CFU/ml of APEC-O78 for 6 h, the release of LDH reached the highest level (192.5 ± 13.4 U/L) (P < 0.01), and the percentages of dead cells followed the same trend in trypan blue exclusion assay. In addition, the AI-2 activity of cell-free culture fluid (CF) reached the maximum value after 6 h co-culture with 10 8  CFU/ml of APEC-O78. At the same time, the mRNA expressions of eight virulence genes (papC, fimA, fimC, hlyE, ompA, luxS, pfs, and qseA) of 10 8  CFU/ml APEC-O78 were significantly increased compared with those of 10 7  CFU/ml, and the mRNA expressions of four virulence genes (hlyE, tsh, iss, and luxS) of 10 8  CFU/ml APEC-O78 were higher than those of 10 9  CFU/ml (p < 0.05) after incubation for 6 h. These results suggested that AI-2-mediated QS is involved in the cell damage induced by APEC-O78, indicating AI-2 may be one new potential target for preventing chicken colibacillosis., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

CobB is a bacterial NAD(+)-dependent protein deacetylase. Although progress has been made in functional studies of this protein in recent years, its substrates and biological functions are still largely unclear. Using proteome microarray technology, potential substrates of Escherichia coli CobB were screened and nine proteins were identified, including N-hydroxyarylamine O-acetyltransferase (NhoA). In vitro acetylation/deacetylation of NhoA was verified by western blotting and mass spectrometry, and two acetylated lysine residues were identified. Site-specific mutagenesis experiments showed that mutation of each acetylated lysine decreased the acetylation level of NhoA in vitro. Further analysis showed that variant NhoA proteins carrying substitutions at the two acetylated lysine residues are involved in both the O-acetyltransferase and N-acetyltransferase activity of NhoA. Structural analyses were also performed to explore the effects of the acetylated lysine residues on the activity of NhoA. These results suggest that reversible acetylation may play a role in the activity of Escherichia coli NhoA., (© 2013 The Authors Journal compilation © 2013 FEBS.)