Common and specific genomic sequences of avian and human extraintestinal pathogenic Escherichia coli as determined by genomic subtractive hybridization

<p>Abstract</p> <p>Background</p> <p>Suppression subtractive hybridization (SSH) strategy was used with extraintestinal pathogenic <it>Escherichia coli </it>(EXPEC) that cause avian colibacillosis (avian pathogenic <it>E. coli </it>or APEC) and human urinary tract infections (uropathogenic <it>E. coli </it>or UPEC) to determine if they possessed genes that were host and/or niche specific. Both APEC and UPEC isolates were used as tester and driver strains in 4 different SSHs in order to obtain APEC- and UPEC-specific subtraction fragments (SFs).</p> <p>Results</p> <p>These procedures yielded a total of 136 tester-specific SFs of which 85 were APEC-derived and 51 were UPEC-derived. Most of the APEC-derived SFs were associated with plasmids; whereas, the majority of UPEC-derived sequences matched to the bacterial chromosome. We further determined the distribution of these tester-derived sequences in a collection of UPEC and APEC isolates using polymerase chain reaction techniques. Plasmid-borne, APEC-derived sequences (<it>tsh</it>, <it>cva</it>B, <it>tra</it>R, <it>tra</it>C and <it>sop</it>B) were predominantly present in APEC, as compared to UPEC. Of the UPEC-derived SFs, those encoding hemolysin D and F1C major and minor fimbrial subunits were present only in UPEC. However, two UPEC-derived SFs that showed strong similarity to the uropathgenic-specific protein gene (<it>usp</it>) occurred in APEC, demonstrating that <it>usp </it>is not specific to UPEC.</p> <p>Conclusion</p> <p>This study provides evidence of the genetic variability of ExPEC as well as genomic similarities between UPEC and APEC; it did not identify any single marker that would dictate host and/or niche specificity in APEC or UPEC. However, further studies on the genes that encode putative or hypothetical proteins might offer important insight into the pathogenesis of disease, as caused by these two ExPEC.</p

Mutational and transcriptional analyses of an avian pathogenic Escherichia coli ColV plasmid

<p>Abstract</p> <p>Background</p> <p>Previously we described a 184-kb ColV plasmid, pAPEC-O2-ColV, that contributed to the ability of an <it>E. coli </it>to kill avian embryos, grow in human urine, and colonize the murine kidney. Here, the roles of several genes encoded by this plasmid in virulence were assessed using mutational and transcriptional analyses.</p> <p>Methods</p> <p>Genes chosen for deletion were <it>iss</it>, <it>tsh</it>, <it>iutA</it>, <it>iroN</it>, <it>sitA</it>, and <it>cvaB</it>. In addition, a 35-kb region of the plasmid, containing <it>iss</it>, <it>tsh</it>, and the ColV and <it>iro </it>operons, along with a 15-kb region containing both the aerobactin and <it>sit </it>operons, were deleted. Mutants were compared to the wild-type (APEC O2) for lethality to chick embryos and growth in human urine. Expression of the targeted genes was also assessed under these same conditions using RT-PCR</p> <p>Results</p> <p>No significant differences between the mutants and the wild-type in these phenotypic traits were detected. However, genes encoding known or predicted iron transport systems were up-regulated during growth in human urine, as compared to growth in LB broth, while <it>iss</it>, <it>hlyF</it>, and <it>iroN </it>were strongly up-regulated in chick embryos.</p> <p>Conclusion</p> <p>While no difference was observed between the mutant strains and their wild-type parent in the phenotypic traits assayed, we reasoned that some compensatory virulence mechanism, insensitivity of the virulence assays, or other factor could have obscured changes in the virulence of the mutants. Indeed we found several of these genes to be up-regulated in human urine and/or in the chick embryo, suggesting that certain genes linked to ColV plasmids are involved in the establishment of avian extraintestinal infection.</p

Combined analysis of primary lymphoid tissues' transcriptomic response to extra-intestinal Escherichia coli (ExPEC) infection

AbstractAvian pathogenic Escherichia coli (APEC), an extraintestinal pathogenic E. coli (ExPEC), constitutes an animal health and a potential zoonotic risk. Most studies focus on the response of a single tissue to APEC infection. Understanding interactions among lymphoid tissues is of importance in controlling APEC infection. Therefore, we studied bone marrow, bursa, and thymus transcriptomes because of these tissues' crucial roles in development of pre-lymphocytes, B cells, and T cells, respectively. Using lesion scores of liver, pericardium, and air sacs, infected birds were classified as either resistant or susceptible. Little difference in gene expression was detected in resistant birds in bone marrow versus bursa or thymus, while there were large differences between tissues in susceptible birds. Phagosome, lysosome and cytokine interactions were strongly enhanced in thymus versus bone marrow in susceptible birds, and T cell receptor (TCR), cell cycle, and p53 signaling were significantly decreased. B cell receptor (BCR) was also significantly suppressed in bursa versus bone marrow in susceptible birds. This research provides novel insights into the complex developmental changes in gene expression occurring across the primary lymphoid organs and, therefore, serves as a foundation to understanding the cellular and molecular basis of host resistance to APEC infection