Sequence analysis demonstrates the conservation of fimH and variability of fimA throughout Avian Pathogenic Escherichia coli (APEC)

Abstract

-In this study we sequenced and analysed the fimH and fimA genes of 24 avian pathogenic Escherichia coli (APEC) isolates, in order to investigate their possible conserved nature. Additional parameters (serotype, presence of aerobactin receptor, expression of F1 pili and virulence for chickens) were investigated to look for correlations with the obtained sequences. The sequence analysis demonstrated that FimH is highly conserved among all investigated APEC strains (> 99% homology), whereas the major subunit FimA is less conserved, presenting 6 variable regions distributed along the protein. A hydrophilicity analysis suggested several variable domains of FimA to be potential epitopes. We were able to classify the investigated strains into three main groups, on the basis of the amino-acid sequences of the variable regions. This grouping was consistent throughout all variable regions and was independent of serotype, leading to an improved classification of the F1 pili. No correlation was found between the fimH and fimA sequences and the following parameters: avian species, organ of isolation, serotype, presence of aerobactin receptor and virulence for chickens. This study elucidated the molecular structure and the degree of conservation of FimH and FimA among various avian pathogenic E. coli strains. Escherichia coli / avian / APEC / FimH / FimA

Immunization with the binding domain of FimH, the adhesin of type 1 fimbriae, does not protect chickens against avian pathogenicEscherichia coli

“…APEC strain CH2 (O78) was isolated from an infected chicken and is virulent in experimentally infected chickens (P. van Empel, personal communication). This strain contains the fimH gene, as confirmed using a polymerase chain reaction (PCR) assay, and is able to express type 1 fimbriae, as shown by haemagglutination, using protocols described in Vandemaele et al (2003a). APEC 1 (Vandemaele et al , 2003b) is a virulent serotype O45 strain containing the FimH adhesin.…”

“…This strain has been transformed with plasmid pEGFP (Clonetech; BD Biosciences, NJ, USA), containing the gene for EGFP. APEC 54 (Vandemaele et al , 2003a) is a virulent serotype O2 strain, also containing the FimH adhesin. Plasmid pPCR SCRIPT AMP SK (Stratagene, La Jola, CA, USA) was used for direct cloning of blunt-end PCR products and sequencing, and plasmid pET22b (Novagen, Madison, WI, USA) was used as an expression vector.…”

Immunization with the biologically active lectin domain of PapGII induces strong adhesion-inhibiting antibody responses but not protection against avian pathogenicEscherichia coli

“…Strain CH4 was a virulent O2 papG II ' strain ( Van den Bosch et al , 1993). All strains were papG II ' , as verified by polymerase chain reaction (PCR) and sequencing, and expressed P fimbriae, as shown by mannose-resistant haemagglutination of human blood group A erythrocytes using protocols described by Vandemaele et al (2003a). Plasmid pPCR SCRIPT AMP SK (Stratagene, La Jola, California, USA) was used for direct cloning of blunt-end PCR products and sequencing, and plasmid pET22b (Novagen, Madison, Wisconsin, USA) was used as an expression vector.…”

Presence of Multidrug-Resistant <i>E. coli</i>, <i>Enterococcus</i> spp. and <i>Salmonella</i> spp. in Lakes and Fountains of Porto, Portugal

“…The expression of this gene is responsible for fimbriae adhesion to intestinal epithelium and colonization of the mucosa [41]. Previous studies indicated the high conservation of this gene in pathogenic E. coli from avian origin (APEC) (>99% homology), which is a subgroup of the extra-intestinal pathogenic E. coli pathotype (ExPEC) [42]. Additionally, the presence of the cvaC gene (which codifies a toxin) in the majority of the isolates tested (23 out of 26) also suggests the presence of E. coli from birds in these water spots.…”