Submitted to: Applied and Environmental Microbiology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 5/10/2005
Publication Date: 10/1/2005
Citation: Meinersmann, R.J., Phillips, R.W., Hiett, K.L., Cray, P.J. 2005. Differentiation of campylobacter populations demonstrated by flagellin short variable region sequences. Applied and Environmental Microbiology. 71(10):6368-6374. Interpretive Summary: Campylobacter jejuni is a bacteria commonly found in food animals that can cause diarrhea in human consumers. The migration patterns of the organism, and thus the source of animal infection, has been difficult to discern, in part because of the great variability of the organism. In this study, a sensitive system for typing was tested to determine if families of Campylobacter could be distinguished and whether these families were associated with specific sources. It turned out that there were discernable families with source linkage. This may mean that the organism is transmitted through routes that are not shared by different kinds of farm animals. Thus, research on transmission of C. jejuni should focus on factors that are peculiar to each type of food animal.
Technical Abstract: The DNA sequence of the flaA short variable region (SVR) was used to analyze a random population of Campylobacter isolates to investigate the weakly clonal population structure of members of the genus. The SVR sequence from 197 strains of C. jejuni and C. coli isolated from humans, bovine, swine and chickens identified a group of 43 strains containing disparate short variable region sequences compared to the rest of the population. This group contains both C. jejuni and C. coli strains, but disproportionately consisted of bovine isolates. Relative synonymous codon usage analysis of the sequences identified two groups; one that typified C. jejuni, the second group was characteristic for C. coli and the disparate alleles were not clustered. The data show that there is significant differentiation of Campylobacter populations according to the source of the isolate even without considering the disparate isolates. Even though there is significant differentiation of chicken and bovine isolates, the bovine isolates did not show any difference in ability to colonize chickens. It is possible that disparate sequences were obtained through lateral transfer of DNA from Campylobacter species other than C. jejuni and C. coli. It is evident that recombination within the flaA SVR occurs rapidly. However, the rate of migration between populations appears to limit the distribution of sequences and results in a weakly clonal population structure.