Novel Molecular Variants of Allele I of the Escherichia coli P Fimbrial Adhesin Gene papG

Abstract

P fimbriae of extraintestinal pathogenic Escherichia coli mediate digalactoside-specific adherence via the tip adhesin molecule PapG, which occurs in three known variants (I to III), which are encoded by the corresponding three alleles of papG. In the present study, newly discovered variants of papG allele I and the respective wild-type source strains were characterized. One of the new papG allele I variants conferred a unique agglutination phenotype that combined the phenotypes associated with papG alleles I, II, and III. Comparative hydrophilicity analysis of predicted PapG peptides revealed regions that might explain the observed phenotypic similarities and differences between the PapG variants. The new papG allele I variants occurred either as the sole papG allele or together with both papG alleles II and III, rather than with only papG allele III, as in archetypal strains J96 and CP9. They also occurred in the absence of the usual F13 papA allele. One of the new papG allele I variants occurred in a serogroup O6 strain that, according to random amplified polymorphic DNA analysis, was phylogenetically distant from the "J96-like" clonal group of E. coli O4:H5, which includes all previously identified examples of papG allele I. Cluster analysis of nucleotide and predicted peptide sequences suggested that papG allele I represents the earliest evolutionary branch from a common papG ancestor. These results demonstrate unexpected diversity within papG allele I and, together with previous findings, suggest that the J96-like clonal group of E. coli O4:H5 may represent the original source of papG within the species.

Virulence Genotypes and Phylogenetic Background ofEscherichia coliSerogroup O6 Isolates from Humans, Dogs, and Cats

“…The present study supersedes previous similar work (3,5,6,8,9,11,13,15,16,20,22,26,(30)(31)(32)(33) in several respects. It involves more isolates and a more extensive battery of VFs than did previous studies and is the first to use sequence-based phylogenetic analysis.…”

“…However, these studies examined only modest numbers of isolates and accessory traits and/or relied on somewhat imprecise phylogenetic methods such as multilocus enzyme electrophoresis, outer membrane protein profiling, or random amplified polymorphic DNA analysis (3,5,6,8,9,11,13,15,16,20,22,26,(30)(31)(32)(33). Accordingly, they leave uncertainty as to the extent of commonality among human-and pet-derived E. coli isolates.…”

“…Several cross-sectional surveys have demonstrated similarities among clinical or fecal E. coli isolates from humans, dogs, and cats with respect to genomic background and virulence-associated accessory traits (virulence factors [VFs]), particularly within serogroups O6 and O4, suggesting possible zoonotic (whether animal-to-human or human-to-animal) transmission (3,5,6,9,11,13,15,16,20,26,(30)(31)(32)(33). Consistent with this possibility, in two longitudinal surveillance studies involving the E. coli flora of human household members and their canine or feline pets, pets were found to be intermittently colonized with the same virulent-appearing E. coli clones that colonized multiple humans and caused acute cystitis in the women (8,22).However, these studies examined only modest numbers of isolates and accessory traits and/or relied on somewhat imprecise phylogenetic methods such as multilocus enzyme electrophoresis, outer membrane protein profiling, or random amplified polymorphic DNA analysis (3,5,6,8,9,11,13,15,16,20,22,26,(30)(31)(32)(33). Accordingly, they leave uncertainty as to the extent of commonality among human-and pet-derived E. coli isolates.…”

“…Several cross-sectional surveys have demonstrated similarities among clinical or fecal E. coli isolates from humans, dogs, and cats with respect to genomic background and virulence-associated accessory traits (virulence factors [VFs]), particularly within serogroups O6 and O4, suggesting possible zoonotic (whether animal-to-human or human-to-animal) transmission (3,5,6,9,11,13,15,16,20,26,(30)(31)(32)(33). Consistent with this possibility, in two longitudinal surveillance studies involving the E. coli flora of human household members and their canine or feline pets, pets were found to be intermittently colonized with the same virulent-appearing E. coli clones that colonized multiple humans and caused acute cystitis in the women (8,22).…”

Multiplex PCR-Based Reverse Line Blot Assay for Simultaneous Detection of 22 Virulence Genes in Uropathogenic Escherichia coli

“…Many UPEC VF genes are polymorphic (2,3,20,21,30), due to point mutations, deletions, or other types of mutation, as reported for cnf1 (12,13,27). From a statistical and epidemiological perspective, infrequent discordance between paired probes should not significantly impair the overall interpretation of the data.…”