Avian pathogenic E. coli and human extraintestinal pathogenic E. coli serotypes O1, O2 and O18 strains isolated from different hosts are generally located in phylogroup B2 and ST complex 95, and they share similar genetic characteristics and pathogenicity, with no or minimal host specificity. They are popular objects for the study of ExPEC genetic characteristics and pathogenesis in recent years. Here, we investigated the evolution and genetic blueprint of APEC pathotype by performing phylogenetic and comparative genome analysis of avian pathogenic E. coli strain IMT5155 (O2:K1:H5; ST complex 95, ST140) with other E. coli pathotypes. Phylogeny analyses indicated that IMT5155 has closest evolutionary relationship with APEC O1, IHE3034, and UTI89. Comparative genomic analysis showed that IMT5155 and APEC O1 shared significant genetic overlap/similarities with human ExPEC dominant O18:K1 strains (IHE3034 and UTI89). Furthermore, the unique PAI I5155 (GI-12) was identified and found to be conserved in APEC O2 serotype isolates. GI-7 and GI-16 encoding two typical T6SSs in IMT5155 might be useful markers for the identification of ExPEC dominant serotypes (O1, O2, and O18) strains. IMT5155 contained a ColV plasmid p1ColV5155, which defined the APEC pathotype. The distribution analysis of 10 sequenced ExPEC pan-genome virulence factors among 47 sequenced E. coli strains provided meaningful information for B2 APEC/ExPEC-specific virulence factors, including several adhesins, invasins, toxins, iron acquisition systems, and so on. The pathogenicity tests of IMT5155 and other APEC O1:K1 and O2:K1 serotypes strains (isolated in China) through four animal models showed that they were highly virulent for avian colisepticemia and able to cause septicemia and meningitis in neonatal rats, suggesting zoonotic potential of these APEC O1:K1 and O2:K1 isolates.
BackgroundAvian pathogenic Escherichia coli (APEC) causes avian colibacillosis, which results in economic and welfare costs in the poultry industry worldwide. The pathogenesis of avian pathogenic E. coli strains is not well defined. Here, the function of an outer membrane protein encoded by the ireA gene of avian pathogenic E. coli strain DE205B was investigated.ResultsThe ireA gene was distributed in 32.9 % (46/140) of tested E. coli strains, with high percentages in the phylogenetic ECOR groups B2 (58.8 %, 10/17) and D (55.9 %, 19/34). The gene expression level of ireA of APEC strain DE205B in high Fe M9 media was 1.8 times higher (P < 0.05) than that in low Fe M9 media. An ireA deletion mutant and complementary strain were constructed. Compared with the wild-type strain DE205B, the expression of most ferric uptake genes in the ireA deletion mutant were significantly upregulated (P < 0.05). The adhesion ability of the ireA deletion mutant to DF-1 cells was significantly decreased. The survival rate of ireA deletion mutant was reduced 21.17 % (P < 0.01), 25.42 (P < 0.05) and 70.0 % (P < 0.01) under alkali, high osmolarity, and low temperature (4 °C) conditions, respectively, compared with the wild-type strain.ConclusionsThe results suggested that the protein encoded by the iron-regulated gene ireA has roles in adhesion and stress resistance in avian pathogenic E. coli.Electronic supplementary materialThe online version of this article (doi:10.1186/s12917-016-0800-y) contains supplementary material, which is available to authorized users.
Streptococcus suis and Streptococcus equi subsp. zooepidemicus are capable of infecting humans and various animals, causing significant problems for the worldwide swine industry. As antibiotic resistance has increased, lysosomal enzymes encoded by phages have shown potential for use against pathogenic bacteria. In this study, a novel bacteriophage lysin, Ply30, encoded by the S. suis prophage phi30c, was recombinantly expressed and purified. Ply30 showed high bacteriolysis activity on S. suis and S. equi subsp. zooepidemicus in vitro. The ratio of the optical density at 600 nm (OD 600 ) with treatment versus the OD 600 with no treatment for most tested S. suis and S. equi subsp. zooepidemicus strains decreased from 1 to <0.3 and <0.5, respectively, within 1 h. The results of plate viability assays showed that treated bacteria suffered a 1-to 2-log decrease in CFU within 1 h. The optimal concentration of Ply30 was 50 g/ml, and the optimal pH was 7. Moreover, Ply30 maintained high activity over a wide pH range (pH 6 to 10). The MICs of Ply30 against Streptococcus strains ranged from 16 to 512 g/ml. In vivo, a 2-mg dose of Ply30 protected 90% (9/10 mice) of mice from infection with S. equi subsp. zooepidemicus and 80% (8/10 mice) of mice from infection with S. suis. Seven days after lysin Ply30 treatment, bacterial loads were significantly decreased in all tested organs and blood compared with those at 1 h postinfection without Ply30 treatment. Ply30 showed in vitro and in vivo antimicrobial efficiency and protected mice against two kinds of bacterial infections, indicating that Ply30 may be an effective therapeutic against streptococci. Streptococcus suis and Streptococcus equi subsp. zooepidemicus are emerging zoonotic, pathogenic, Gram-positive bacteria capable of infecting humans and various animals, such as horses, pigs, ruminants, guinea pigs, monkeys, cats, and dogs (1-3). S. suis can cause septicemia, arthritis, and meningitis in pigs (4). Liu et al. identified 33 serotypes (serotypes 1 to 31, 33, and 1/2) of S. suis according to the variation of capsular antigens (5, 6). Two outbreaks of S. suis have occurred in China. One was in Sichuan Province in July 2005, with 215 humans infected. The other was in Jiangsu Province, in 1998, and 25 humans were involved, 14 of whom died (7-9). By the end of 2012, 1,584 cases had been reported in the literature, most of which were associated with pigs and human infections (10). Besides S. suis, S. equi subsp. zooepidemicus is another important pathogen that can cause upper respiratory tract disease in pigs and rheumatic fever and glomerulonephritis in humans (11, 12). S. equi subsp. zooepidemicus shares Ͼ80% DNA sequence similarity and important virulence factors with Streptococcus pyogenes (13). The sequelae of S. pyogenes infections and the symptoms caused by S. equi subsp. zooepidemicus are also similar (12). In recent years, several outbreaks of S. equi subsp. zooepidemicus infections have been reported in different countries (11,14,15).The main and conventional prev...
Low temperature plasma (LTP) exerted beneficial effects on seed germination and crop growth. With application of LTP on seed germination of Platycodon grandiflorum, germination indexes and physiological parameters and transcriptome profile were investigated in this experiment. The results showed the seed germination rate and germinating potential of Platycodon grandiflorum in LTP increased by 24.7% and 30.7% comparing to CK respectively (p < 0.05). The SOD and CAT activity of the seed sprouts increased by 26.78% and 12.41% comparing to CK. Transcriptome results showed that 14342 up-regulated and 4366 down-regulated different expressing genes (DEGs) at LTP and CK. A considerable number of DEGs related to the plant hormone signal transduction, peroxisome, oxidative phosphorylation, starch and surose in response to low temperature plasma were identified in this study. The transcriptomic gene expression profiles present a valuable genomic tool to the molecular mechanisms of Platycodon grandiflorum seed germination underlying low temperature plasma. which can provide theoretical basis and practical guidance for cultivation and planting of Platycodon grandiflorum.
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