Genetic instability is associated with changes in the colonization potential of Campylobacter jejuni in the avian intestine.
OBJECTIVE
A panel of pulsed field gel electrophoresis (PFGE) type variants of Campylobacter jejuni, previously identified as of clonal origin, were investigated to determine whether genomic instability could be observed during competitive growth.


RESULTS
Upon recovery from frozen storage, some variants had undergone alterations in PFGE profiles, but subsequent culture produced constant genotypes. Individual variants did not display differences in colonization potential when tested in orally challenged 1-day-old chickens. However, competitive colonization using mixtures of two or three PFGE types generally resulted, by 4 weeks postchallenge, in one predominant PFGE type in all birds. For some variant mixtures, a minor population of novel PFGE types was detected in individual birds. The creation of new variants appeared to be dependent on the extent of competition and of the individual host. Genomic rearrangements most likely explain this increase in genetic diversity, apparently without the involvement of natural transformation or plasmid acquisition. In vitro cultivation of mixed inoculations were again selected for particular variants; but genetic diversity was not generated, suggesting that the selection pressures in vitro differed from those active in vivo.


CONCLUSIONS
These observations support the hypothesis that by generating genetic diversity, C. jejuni can improve its phenotypic fitness to survive and colonize subsequent hosts.


CONCLUSIONS
The consequences of such observations for the development of campylobacter control strategies for poultry may be substantial.
Ridley
A M
AM
Veterinary Laboratories Agency (Weybridge), New Haw, Surrey, United Kingdom. a.ridley@vla.defra.gsi.gov.uk
Toszeghy
M J
MJ
Cawthraw
S A
SA
Wassenaar
T M
TM
Newell
D G
DG
D000818:Animals; D002169:Campylobacter Infections / Q000382:microbiology* / Q000662:veterinary*; D016123:Campylobacter jejuni / Q000235:genetics* / Q000254:growth & development; D002645:Chickens; D016521:Electrophoresis, Gel, Pulsed-Field / Q000379:methods; D005516:Food Microbiology; D014644:Genetic Variation; D016680:Genome, Bacterial; D042822:Genomic Instability; D006801:Humans; D007422:Intestines / Q000382:microbiology; D011201:Poultry Diseases / Q000382:microbiology*