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Applied and Environmental Microbiology, February 2009, p. 1208-1210, Vol. 75, No. 4
0099-2240/09/$08.00+0 doi:10.1128/AEM.01879-08
Copyright © 2009, American Society for Microbiology. All Rights Reserved.
Bovine Campylobacter jejuni Strains Differ from Human and Chicken Strains in an Analysis of Certain Molecular Genetic Markers
Manuel Gonzalez,1
Marjaana Hakkinen,2
Hilpi Rautelin,3,4 and
Marja-Liisa Hänninen1*
Department of Food and Environmental Hygiene, University of Helsinki,1
Microbiology Unit, Research Department, Finnish Food Safety Authority,2
Department of Bacteriology and Immunology, Haartman Institute, University of Helsinki,3
HUSLAB, Helsinki University Central Hospital Laboratory, Helsinki, Finland4
Received 13 August 2008/
Accepted 14 December 2008

ABSTRACT
The association of four new genetic markers with a chicken,
bovine, or human host was studied among 645
Campylobacter jejuni isolates. The

-glutamate transpeptidase gene and
dmsA were common
in human and chicken isolates but uncommon among bovine isolates.
In the
t test, bovine isolates differed significantly (
P <
0.05) from human and chicken isolates.

INTRODUCTION
Campylobacter jejuni is a zoonotic human enteric pathogen with
a large number of animal hosts (
12,
19). Campylobacteriosis
is a leading cause of human bacterial gastroenteritis in many
industrialized countries (
19). Epidemiological studies indicate
that exposure to improperly cooked chicken meat, handling of
raw chicken meat, and drinking unpasteurized milk are important
risk factors for campylobacteriosis (
12,
15,
19,
20).
The role of different animal sources in human infections is not well characterized. Molecular typing methods applied for fingerprinting of C. jejuni strains have shown overlapping genotypes between animal and human isolates (5, 16, 17, 21). Population biological studies using multilocus sequence typing (6) have revealed that a host-C. jejuni interaction may leave a signature in the bacterial genome. As a consequence, e.g., chicken- or cattle-associated populations can be assigned to their hosts (18). We investigated host association of C. jejuni isolates from cattle, chickens, and humans using PCR detection of four new genetic markers developed under our study. Using comparative genomics (3), four genetic markers—i.e., ggt, the
-glutamyl transpeptidase gene; dmsA (Cju34), a subunit of the putative tripartite anaerobic dimethyl sulfoxide (DMSO) oxidoreductase (DMSO/trimethylamine N-oxide reductase) gene; Cj1585c, coding for a putative oxidoreductase; and CJJ81176-1371, a putative serine protease gene—were selected from the genomes of C. jejuni strains 81-176 (10), RM1221, and NCTC 11168. ggt is in the genome of 81-176 but not in the genome of NCTC 11168 or RM1221 (10). Gene Cj1585c of NCTC 11168 is replaced in 81-176 by a cluster of four genes (dmsA, dmsB, dmsC, and dmsD) (10). The presence of these four genes in a total of 645 C. jejuni isolates from bovine fecal samples (n = 131) (8), chicken cecal or meat samples (n = 205), and human patients (n = 309) (16, 17) was examined by PCR to find their suitability for host association studies. PCR primers designed for the amplification of the fragments are shown in Table 1. Twelve PCR products for each gene fragment were sequenced. The sequences of each gene were shown to be rather conserved (95.5 to 100% similarity within each gene) because only a few nucleotide positions (from 2 to 9) were found to be variable.
Statistical analyses were performed using SPSS software. The
2 test was used to test for similarity in the frequencies of
marker genes within the isolates from different hosts. In addition,
we used the paired two-tailed Student's
t test for analysis
of host associations for the combined set of four genes.
Frequencies of the genes are shown in Table 2. Similarly, the results of the paired two-tailed t test on the significance of the frequencies of the combined four genes from different hosts are shown in Table 2. These results indicated significant (P < 0.05) association of bovine and chicken isolates with their host source, but a high similarity was observed between the chicken and human isolates (P = 0.9949). Annual frequencies of the genes are presented for human isolates in Table 3 and for chicken isolates in Table 4. The analysis of the annual frequencies of the four genes combined showed that the human isolates were similar in 1996 and 2002 and 2002 and 2003, but differed between 1996 and 2003 (Table 3). The chicken isolates were similar in all study years (Table 4). These results revealed that these genes associated with metabolism and energy production (ggt, oxidoreductases) (2, 11, 22), colonization (ggt) (2, 11), or unknown function (serine protease genes) are not randomly distributed among the isolates from different hosts but show a host association.
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TABLE 2. Frequency of the four marker genes ggt, Cj1585c, dmsA (Cju34), and CJJ81176-1371 in 645 human, chicken, and cattle C. jejuni isolates
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TABLE 3. Frequency of the four marker genes ggt, Cj1585c, dmsA (Cju34), and CJJ81176-1367/1371 in 309 C. jejuni isolates from humans
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TABLE 4. Presence of the four marker genes ggt, Cj1585c, dmsA (Cju34), and CJJ81176-1367/1371 in 205 C. jejuni isolates from chickens
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The intestinal environments of cattle and chicken are quite
different, which may select isolates with variable characteristics,
e.g., related to energy metabolism, adaptation to lower or higher
oxygen contents or amino acid metabolism.
C. jejuni colonization
in dairy cattle can be persistent, as shown by the studies in
which the same genotype was isolated for up to 1 year (
1,
13,
14). The life cycle of cattle is several years, providing a
long potential time span for the adaptation of
C. jejuni with
its host. The life cycle of chickens, in contrast, is much shorter,
5 weeks or more. Our results suggested that host adaptation
of certain
C. jejuni strains is evident. The
dmsA subunit was
more often detected among chicken and human isolates than among
bovine isolates (Table
2). In addition,
dmsA-positive chicken
isolates occurred with similar high annual frequency in 2003,
2006, and 2007 (Table
4), indicating that this characteristic
is most probably important in colonization. The occasional significant
annual fluctuation seen in the frequency of
dmsA-positive human
isolates may reflect variation in the infection sources (Table
3). In a recent study (
9),
dmsB was one of the genes present
in
C. jejuni strain A 74/C, shown to be robust colonizer in
chickens, but absent from
C. jejuni 11168(GS), a poorly colonizing
strain (
7). The
C. jejuni NCTC 11168, 81116, and 81-176 strains
have another putative DMSO oxidoreductase gene (homologous to
Cj0264c) that differs from Cju34. In opposition, the Cj1585c-type
oxidoreductase was more frequently present in isolates from
cattle than in those from chickens or humans (Table
2). Analyses
of
C. jejuni genomes have predicted a branched complex electron
transport chain capable of utilizing multiple electron donors
and acceptors (
22), and our results suggest flexibility in the
oxidoreductase systems as well.
ggt (
-glutamyl transpeptidase) has been shown to be important in the persistent colonization of C. jejuni in chickens (2), and recent studies (11) further extend the significance of this gene in the glutamine and glutathione metabolism and colonization of C. jejuni. In our study, the frequency of the ggt-positive human and chicken isolates was high (Table 2) and the frequencies remained similar over the study years (Tables 3 and 4). These results further reveal the importance of
-glutamyl transpeptidase in colonization and pathogenesis. In contrast, a low frequency of ggt-positive isolates (8.4%) was found among bovine isolates (Table 2), suggesting that this type of metabolism is not crucial for colonization of the bovine gut. Similar variable frequencies to those in our study were found in the study by Barnes et al. (2).
The genomes of NCTC 11168, RM1221, and 81-176 have a subtilase-type serine protease gene homologous to CJJ81176-1367, which is located close to the CJJ81176-1371 gene in the genome of 81-176 (10). The G+C composition of this gene is 29%, whereas the G+C composition of CJJ81176-1371 is 36%, indicating that these genes most probably have different evolutionary origins. In our study, the serine gene was common among bovine isolates (Table 2) and less common among chicken and human isolates. The primers we used may amplify both types of the subtilase genes. Proteases in C. jejuni have a role in stress tolerance (4). Whether the serine protease is important in the pathogenesis of campylobacteriosis remains to be elucidated.
The genetic markers associated with metabolism, colonization, or an unknown protease function allowed assignment of the chicken or bovine source of C. jejuni. These results suggest that metabolic diversity is an important adaptive factor in host adaptation.

ACKNOWLEDGMENTS
We acknowledge financial support from the Academy of Finland
(Elvira) and EU project no. 036272 (Biotracer).

FOOTNOTES
* Corresponding author. Mailing address: Department of Food and Environmental Hygiene, P.O. Box 66, 0014 University of Helsinki, Finland. Phone: 358-9-19157113. Fax: 358-9-19157101. E-mail:
marja-liisa.hanninen{at}helsinki.fi 
Published ahead of print on 19 December 2008. 

REFERENCES
1 - Bae, W., K. N. Kaya, D. D. Hancock, D. R. Call, Y. H. Park, and T. E. Besser. 2005. Prevalence and antimicrobial resistance of thermophilic Campylobacter spp. from cattle farms in Washington State. Appl. Environ. Microbiol. 71:169-174.[Abstract/Free Full Text]
2 - Barnes, I. H., M. C. Bagnall, D. D. Browning, S. A. Thompson, G. Manning, and D. G. Newell. 2007. Gamma-glutamyl transpeptidase has a role in the persistent colonization of the avian gut by Campylobacter jejuni. Microb. Pathog. 43:198-207.[CrossRef][Medline]
3 - Chaudhuri, P. C., and M. J. Pallen. 2006. xBASE, a collection of online databases for bacterial comparative genomics. Nucleic Acids Res. 34:D335-D337.[Abstract/Free Full Text]
4 - Cohn, M. T., H. Ingmer, F. Mulholland, K. Jørgensen, J. M. Wells, and L. Brøndsted. 2007. Contribution of conserved ATP-dependent proteases of Campylobacter jejuni to stress tolerance and virulence. Appl. Environ. Microbiol. 73:7803-7813.[Abstract/Free Full Text]
5 - Denis, M., B. Chidaine, M. J. Laisney, I. Kempf, K. Rivoal, F. Mégraud, and P. Fravalo. 2008. Comparison of genetic profiles of Campylobacter strains isolated from poultry, pig and Campylobacter human infections in Brittany, France. Pathol. Biol. (Paris). doi:10.1016/j.patbio.2008.04007.
6 - Dingle, K. E., F. M. Colles, D. R. A. Wareing, R. Ure, A. J. Fox, F. E. Bolton, H. J. Bootsma, R. J. L. Willems, R. Urwin, and M. C. J. Maiden. 2001. Multilocus sequence typing system for Campylobacter jejuni. J. Clin. Microbiol. 39:14-23.[Abstract/Free Full Text]
7 - Gaynor, E. C., S. Cawthraw, G. Manning, J. K. MacKichan, S. Falkow, and D. G. Newell. 2004. The genome-sequenced variant of Campylobacter jejuni NCTC 11168 and the original clonal clinical isolate differ markedly in colonization, gene expression, and virulence-associated phenotypes. J. Bacteriol. 186:503-517.[Abstract/Free Full Text]
8 - Hakkinen, M., H. Heiska, and M.-L. Hänninen. 2007. Prevalence of Campylobacter spp. in cattle in Finland and antimicrobial susceptibility of bovine Campylobacter jejuni strains. Appl. Environ. Microbiol. 73:3232-3238.[Abstract/Free Full Text]
9 - Hiett, K. L., A. Stintzi, T. M. Andacht, R. L. Kuntz, and B. S. Seal. 2008. Genomic differences between Campylobacter jejuni isolates identify surface membrane and flagellar function gene products potentially important for colonizing the chicken intestine. Funct. Integr. Genomics 8:407-420.[CrossRef][Medline]
10 - Hofreuter, D., J. Tsai, R. O. Watson, V. Novik, B. Altman, M. Benitez, C. Clark, C. Perbost, T. Jarvie, L. Du, and J. E. Galan. 2006. Unique features of a highly pathogenic Campylobacter jejuni strain. Infect. Immun. 74:4694-4707.[Abstract/Free Full Text]
11 - Hofreuter, D., V. Novik, and J. E. Galan. 2008. Metabolic diversity in Campylobacter jejuni enhances specific tissue colonization. Cell Host Microbe 4:425-433.[CrossRef][Medline]
12 - Humphrey, T., S. O'Brien, and M. Madsen. 2007. Campylobacters as zoonotic pathogens: a food production perspective. Int. J. Food Microbiol. 117:237-257.[CrossRef][Medline]
13 - Inglis, G. D., L. D. Kalischuk, and H. W. Busz. 2004. Chronic shedding of Campylobacter species in beef cattle. J. Appl. Microbiol. 97:410-420.[CrossRef][Medline]
14 - Johnsen, G., K. Zimmerman, B. A. Lindstedt, T. Vardund, H. Herikstad, and G. Kapperud. 2006. Intestinal carriage of Campylobacter jejuni and Campylobacter coli among cattle from south-western Norway and comparative genotyping of bovine and human isolates by amplified-fragment length polymorphism. Acta Vet. Scand. 48:4-9.[Medline]
15 - Kapperud, G., G. Espeland, E. Wahl, A. Walde, H. Herikstad, S. Gustavsen, I. Tveit, O. Natås, L. Bevanger, and A. Digranes. 2003. Factors associated with increased and decreased risk of Campylobacter infection: a prospective case-control study in Norway. Am. J. Epidemiol. 158:234-242.[Abstract/Free Full Text]
16 - Kärenlampi, R., H. Rautelin, M. Hakkinen, and M.-L. Hänninen. 2003. Temporal and geographical distribution and overlap of Penner heat-stable serotypes and pulsed-field electrophoresis genotypes of Campylobacter jejuni isolates collected from humans and chickens in Finland during a seasonal peak. J. Clin. Microbiol. 41:4870-4872.[Abstract/Free Full Text]
17 - Kärenlampi, R., H. Rautelin, D. Schönberg-Norio, L. Paulin, and M.-L. Hänninen. 2007. Longitudinal study of Finnish Campylbacter jejuni and Campylobacter coli isolates from humans, using multilocus sequence typing, including comparison with epidemiological data and isolates from poultry and cattle. Appl. Environ. Microbiol. 73:148-155.[Abstract/Free Full Text]
18 - McCarthy, N. D., F. M. Colles, K. E. Dingle, M. C. Bagnall, G. Manning, M. C. Maiden, and D. Falush. 2007. Host-associated genetic import in Campylobacter jejuni. Emerg. Infect. Dis. 13:267-272.[Medline]
19 - Olson, K. C., S. Ethelberg, W. van Pelt, and R. V. Tauxe. 2008. Epidemiology of Campylobacter jejuni infections in industrialized nations, p. 163-189. In I. Nachamkin, C. M. Szymanski, and M. J. Blaser (ed.), Campylobacter, 3rd ed. American Society for Microbiology, Washington, DC.
20 - Schönberg-Norio, D., J. Takkinen, M.-L. Hänninen, M.-L. Katila, S. S. Kaukoranta, L. Mattila, and H. Rautelin. 2004. Swimming and Campylobacter infections. Emerg. Infect. Dis. 10:1474-1477.[Medline]
21 - Wassenaar, T. M., and D. G. Newell. 2000. Genotyping of Campylobacter spp. Appl. Environ. Microbiol. 66:1-9.[Free Full Text]
22 - Weingarten, R. A., J. L. Grimes, and J. W. Olson. 2008. Role of Campylobacter jejuni respiratory oxidases and reductases in host colonization. Appl. Environ. Microbiol. 74:1367-1375.[Abstract/Free Full Text]
Applied and Environmental Microbiology, February 2009, p. 1208-1210, Vol. 75, No. 4
0099-2240/09/$08.00+0 doi:10.1128/AEM.01879-08
Copyright © 2009, American Society for Microbiology. All Rights Reserved.