Generation of Campylobacter jejuni genetic diversity in vivo.
Molecular epidemiology studies suggest that horizontal genetic exchange is a major cause of pathogen biodiversity. We tested this concept for the bacterial enteropathogen Campylobacter jejuni by seeking direct in vivo evidence for the exchange of genetic material among Campylobacter strains. For this purpose, two antibiotic resistance markers were inserted into the hipO or htrA gene of genetically distinct and naturally transformable C. jejuni strains. Genetic exchange of the resistance markers was analysed after co-cultivation of homologous and heterologous strains in vitro and in vivo during experimental infection of chickens. Double-resistant recombinants were obtained both in vitro and from the chicken intestine for all combinations of strains tested. Bidirectional genetic exchange of DNA between homologous and heterologous strains was confirmed by Southern blotting in combination with flaA polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), amplified fragment length polymorphism (AFLP) and pulsed field gel electrophoresis (PFGE). Extensive PFGE analyses of isolated recombinants indicated the frequent occurrence of genetic rearrangements during the experimental infection, in addition to the homologous recombination of the antibiotic resistance genes. Together, the data indicate unequivocally that interstrain genetic exchange as well as intragenomic alterations do occur in vivo during C. jejuni infection. These events probably explain the genome plasticity observed for this pathogen.
de Boer
Paulo
P
Institute for Animal Science and Health, Division of Infectious Diseases and Food Chain Quality, PO Box 65, 8200 AB Lelystad, The Netherlands. p.deboer@id.wag-ur.nl
Wagenaar
Jaap A
JA
Achterberg
René P
RP
van Putten
Jos P M
JP
Schouls
Leo M
LM
Duim
Birgitta
B
D000818:Animals; D001483:Base Sequence; D002169:Campylobacter Infections / Q000188:drug therapy; D016123:Campylobacter jejuni / Q000235:genetics*; D002645:Chickens; D003227:Conjugation, Genetic; D017931:DNA Primers; D004269:DNA, Bacterial / Q000235:genetics / Q000302:isolation & purification; D019020:Directed Molecular Evolution / Q000379:methods; D004352:Drug Resistance, Microbial / Q000235:genetics*; D016521:Electrophoresis, Gel, Pulsed-Field; D005819:Genetic Markers; D014644:Genetic Variation; D005838:Genotype; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D011995:Recombination, Genetic; D012481:Salmonella Infections, Animal / Q000188:drug therapy; D014170:Transformation, Genetic
D017931:DNA Primers; D004269:DNA, Bacterial; D005819:Genetic Markers