| virulence plasmids of enteroinvasive escherichia coli and shigella flexneri integrate into a specific site on the host chromosome: integration greatly reduces expression of plasmid-carried virulence genes. | the ability of enteroinvasive escherichia coli and shigella flexneri to cause disease depends on the presence of a large virulence plasmid (pinv). in this report we show that phn280, the pinv of the o135:k-:h- enteroivasive strain e. coli hn280, and pwr100, the pinv of s. flexneri serotype 5 strain m90t, are able to integrate into a specific site on the host chromosome. pinv-integrated hn280 and m90t strains required methionine (met-) to grow in minimal medium, were noninvasive, did not produce ... | 1991 | 1997431 |
| virulence factors and biochemical characteristics of serotypes of escherichia coli serogroup o29. | escherichia coli strains belonging to serogroup o29 were studied. invasiveness was the most common virulence factor described in this serogroup, but a few papers also reported production of heat-stable (st) enterotoxin. in the present study invasive ability was found in o29:h- strains, whereas production of st-i enterotoxin was observed only in serotype o29:h21 strains, showing that virulence was a characteristic of specific serotypes or bioserotypes within the o29 serogroup. different serotypes ... | 1989 | 2685018 |
| h-ns regulation of virulence gene expression in enteroinvasive escherichia coli harboring the virulence plasmid integrated into the host chromosome. | we have previously shown that integration of the virulence plasmid pinv into the chromosome of enteroinvasive escherichia coli and of shigella flexneri makes these strains noninvasive (c. zagaglia, m. casalino, b. colonna, c. conti, a. calconi, and m. nicoletti, infect. immun. 59:792-799, 1991). in this work, we have studied the transcription of the virulence regulatory genes virb, virf, and hns (virr) in wild-type enteroinvasive e. coli hn280 and in its pinv-integrated derivative hn280/32. whil ... | 1995 | 7642498 |
| expression of the virulence plasmid-carried apyrase gene (apy) of enteroinvasive escherichia coli and shigella flexneri is under the control of h-ns and the virf and virb regulatory cascade. | the transcription of the virulence plasmid (pinv)-carried invasion genes of shigella flexneri and enteroinvasive escherichia coli (eiec) is induced at 37 degreesc and repressed at 30 degreesc. in this work, we report that the o135: k-:h- eiec strain hn280 and s. flexneri sfzm53, m90t, and 454, of serotypes 4, 5, and 2a, respectively, produce apyrase (atp-diphosphohydrolase), the product of the apy gene. in addition, the s. flexneri strains, but not the eiec strain, produce a nonspecific phosphat ... | 1998 | 9746603 |
| enteroinvasive escherichia coli virulence-plasmid-carried apyrase (apy) and ospb genes are organized as a bicistronic operon and are subject to differential expression. | in shigella flexneri and enteroinvasive escherichia coli (eiec) the expression of the virulence-plasmid(pinv)-carried potential pathogenesis-associated apy gene, which encodes apyrase (atp diphosphohydrolase), is regulated by the same regulators that govern the expression of virulence genes. to understand the transcriptional organization of the apy gene, the authors sequenced an 8023 bp psti fragment of the pinv of eiec strain hn280, which encompasses apy as well as its adjacent genes. the psti ... | 2002 | 12177345 |
| comparison of two major forms of the shigella virulence plasmid pinv: positive selection is a major force driving the divergence. | all shigella and enteroinvasive escherichia coli (eiec) strains carry a 230-kb virulence plasmid (pinv) which is essential for their invasiveness. there are two sequence forms, pinv a and pinv b, of the plasmid (r. lan, b. lumb, d. ryan, and p. r. reeves, infect. immun. 69:6303-6309, 2001), and the recently sequenced pinv plasmid from shigella flexneri serotype 5 is a pinv b form. in this study we sequenced the majority of the coding region of the pinv a form from s. flexneri serotype 6 other th ... | 2003 | 14573649 |
| molecular evolutionary relationships of enteroinvasive escherichia coli and shigella spp. | enteroinvasive escherichia coli (eiec), a distinctive pathogenic form of e. coli causing dysentery, is similar in many properties to bacteria placed in the four species of shigella. shigella has been separated as a genus but in fact comprises several clones of e. coli. the evolutionary relationships of 32 eiec strains of 12 serotypes have been determined by sequencing of four housekeeping genes and two plasmid genes which were used previously to determine the relationships of shigella strains. t ... | 2004 | 15322001 |
| [comparative proteomics research on removing of large invasive plasmid pinv of shigella flexneri 2a strain 2457t]. | s. flexneri 2a strain 2457t and its derivative without large invasive plasmid pinv-2457t were cultured to middle logarithm phase. whole cellular protein extracts of the two strains were examined by two dimensional (2d) electrophoresis using immobilized ph gradient (ipg) technology. after in-gel protein digestion, the different-expressed spots were detected by matrix-assisted laser desorption ionization-time of flight mass spectrometry (maldi tof ms). all the peptide mass fingerprints (pmfs) were ... | 2005 | 15989237 |
| plasticity of the p junc promoter of isec11, a new insertion sequence of the is1111 family. | we describe identification and functional characterization of isec11, a new insertion sequence that is widespread in enteroinvasive e. coli (eiec), in which it is always present on the virulence plasmid (pinv) and very frequently also present on the chromosome. isec11 is flanked by subterminal 13-bp inverted repeats (irs) and is bounded by 3-bp terminal sequences, and it transposes with target specificity without generating duplication of the target site. isec11 is characterized by an atypical t ... | 2006 | 16788177 |
| evaluation by real-time pcr of the expression of s. flexneri virulence-associated genes ospb and phon2 under different genetical backgrounds. | under conditions of activated type iii secretion shigella flexneri up-regulates the expression of numerous genes, including the virulence plasmid (pinv)-encoded ospb and phon2 genes. ospb and phon2 are virulence-associated genes which are part of a bicistronic transcriptional unit encoding ospb, a protein (effector) of unknown function secreted by the type iii secretion (tts) apparatus, and phon2 (apyrase or atp-diphosphohydrolase), a periplasmic protein involved in polar icsa localization on th ... | 2008 | 18831939 |
| the multifaceted activity of the virf regulatory protein in the shigella lifestyle. | shigella is a highly adapted human pathogen, mainly found in the developing world and causing a severe enteric syndrome. the highly sophisticated infectious strategy of shigella banks on the capacity to invade the intestinal epithelial barrier and cause its inflammatory destruction. the cellular pathogenesis and clinical presentation of shigellosis are the sum of the complex action of a large number of bacterial virulence factors mainly located on a large virulence plasmid (pinv). the expression ... | 2016 | 27747215 |
| investigating the relatedness of enteroinvasive escherichia coli to other e. coli and shigella isolates by using comparative genomics. | enteroinvasive escherichia coli (eiec) is a unique pathovar that has a pathogenic mechanism nearly indistinguishable from that of shigella species. in contrast to isolates of the four shigella species, which are widespread and can be frequent causes of human illness, eiec causes far fewer reported illnesses each year. in this study, we analyzed the genome sequences of 20 eiec isolates, including 14 first described in this study. phylogenomic analysis of the eiec genomes demonstrated that 17 of t ... | 2016 | 27271741 |