[Show abstract][Hide abstract] ABSTRACT: Campylobacter porins are the dominant major outer membrane protein (MOMP) of these bacteria. They are composed of hypervariable, surface-exposed, peptide loops and membrane-embedded, conserved peptide regions. Porins are functionally important and may also be useful for molecular subtyping methods but have not yet been well characterized. We therefore sequenced the porA gene from 39 Campylobacter isolates, including multilocus sequence type (MLST) reference strains, isolates from patients with the Guillain-Barré syndrome, other clinical isolates, and serotyping reference strains. These were compared with additional sequences available from GenBank. Three distinct porA lineages were observed after phylogenetic analysis. Both Campylobacter coli and Campylobacter jejuni were found with group 3 porA sequences, and this was the only group showing any evidence of recombination among porA genes. There was no recombination between porA genes from C. jejuni groups 1 and 2, suggesting there may be functional constraints on changes at this locus. Most of the amino acid differences among the three groups were present in surface-exposed loops, and dissimilar substitutions were found when groups 1 and 2 MOMP were compared. Different MOMP sequence groups may have different biological or antigenic properties, which in turn may be associated with survival in different environments, host adaptation, or virulence.
Canadian Journal of Microbiology 02/2007; 53(1):27-38. DOI:10.1139/w06-099 · 1.22 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The Walkerton (Ontario, Canada) outbreak of waterborne Escherichia coli O157:H7 and Campylobacter jejuni was quite limited in both space and time, making it a good model for exploring the utility of different typing and subtyping
methods for the characterization of relationships among isolates of these organisms. We have extended previous work with these
organisms through analysis by the Oxford multilocus sequence typing (MLST) and the flagellin short variable region (fla-SVR)
sequencing methods. Additional isolates not epidemiologically related to the Walkerton outbreak have also been included. Both
sequencing methods identified and differentiated between Walkerton outbreak strains 1 and 2. When these strains were compared
with isolates that were not part of the outbreak, the information produced by the fla-SVR method more often correlated with
epidemiological findings than that produced by MLST, though both methods were required for optimal discrimination. The MLST
data were more relevant in terms of the overall population structure of the organisms. Both mutation and recombination appeared
to be responsible for generating diversity among the isolates tested.