Oligonucleotide primers used in this study.

<p>Oligonucleotide primers used in this study.</p

Physical map showing genomic organization of the 4,975 bp <i>yqi</i> adhesin gene cluster in APEC strain IMT5155.

<p>A hypothetical protein preceeds the putative outer membrane usher protein, followed by the putative chaperone and finally the putative adhesin.</p

Strains and plasmids used in this study.

<p>Strains and plasmids used in this study.</p

Bacterial colonization of the chicken lungs 24 h after intra-tracheal infection with 10⁶ CFU of bacteria.

<p>Differences between IMT5155 and IMT5155Δ<i>yqi</i> were statistically significant with a <i>p</i><0.05 (n = 6). Strain IMT11327 is the negative control (A). Bacterial colonization of the chicken lungs 24 h after intra-tracheal infection with 10⁹ CFU of bacteria. Differences between IMT5155 and IMT5155Δ<i>yqi</i> were statistically significant with a <i>p</i><0.02 (n = 6). Strain IMT11327 is the negative control (B).</p

Bacterial adhesion to chicken fibroblast cells 1.5 h and 3 h after infection with an MOI = 100.

<p>Differences between IMT5155 and IMT5155Δ<i>yqi</i> were statistically significant with a <i>p</i><0.005 at 1.5 h and <i>p</i><0.05 at 3 h (A). Bacterial adhesion to polarized Madin Darby canine kidney (MDCK-1) cells 3 h after infection with an MOI = 100. The difference between IMT5155Δ<i>yqi</i> and IMT5155Δ<i>yqi</i> (pDSK602:<i>yqi</i>) was significant with a <i>p</i><0.04 (B).</p

Score values for severity of organ lesions ± standard deviation in respiratory and other organs.

<p>Infection with IMT5155, IMT5155Δ<i>yqi</i> and IMT11327 at infection dose 10⁹ CFU. Differences in organ scores between IMT5155 and IMT5155Δ<i>yqi</i> and between IMT5155 and negative control IMT11327 were statistically significant for air sacs, lungs and liver with a <i>p</i><0.05^*.</p

Expression of the ExPEC adhesin I (<i>yqi</i>) gene cluster <i>in vitro</i>.

<p>Electron micrographs show negatively stained afimbriate strain <i>E. coli</i> AAEC189 (pKESK:<i>yqi</i>_4975_XB) over-expressed with the <i>yqi</i> adhesin gene cluster at a magnification of 45,000x, 65,000x and 100,000x (A–C), negative control afimbriate strain <i>E. coli</i> AAEC189 (D) and wild type fimbriated <i>E. coli</i> strain IMT5155 (E). The arrows indicate the location of the fimbriae.</p

Phylogenetic analysis of ExPEC adhesin I (<i>yqi</i>).

<p>Maximum Parsimony tree shows distances between <i>yqi</i> gene sequences among strains belonging to different sequence types (ST: Sequence type; STC: Sequence type complex).</p

Graphic illustrating growth of transposon mutant EA7F9 in competition with IMT5155 and separately in Luria Bertani (LB) growth medium.

<p>A competition index (CI) <i>in vitro</i> was calculated at a time point of 4 h.</p

Prevalence of ExPEC adhesin I coding gene <i>yqi</i> among pathogenic <i>E. coli</i> strains and non-pathogenic strains of human and avian origin.

<p>APEC = Avian pathogenic <i>E. coli</i>, UPEC = Uropathogenic <i>E. coli</i>, NMEC = Newborn meningitic <i>E. coli</i>, SePEC = Septicaemia associated <i>E. coli</i>, STEC = Shiga Toxin-producing <i>E. coli</i>, EHEC = Enterohaemorrhagic <i>E. coli</i>, EPEC = Enteropathogenic <i>E. coli</i>, aEPEC = Atypical Enteropathogenic <i>E. coli</i>, ETEC = Enterotoxigenic <i>E. coli</i>, EIEC = Enteroinvasive <i>E. coli</i>, EAEC = Enteroggregative <i>E. coli</i>.</p