Niche-adaptive evolution in Campylobacter jejuni

Campylobacter jejuni is the leading causative agent of human bacterial gastroenteritis. Human C. jejuni infection (campylobacteriosis) is frequently associated with poultry; through consumption of undercooked products, cross contamination from raw meats, or through direct contact with birds or their faecal matter, however it is established that poultry is not the sole cause of C. jejuni infection in humans. This research reveals new information on the MLST ST403 Clonal Complex, a previously identified C. jejuni lineage associated with the porcine host. ST403CC C. jejuni have also been linked with other mammalian hosts to a lesser degree, and have been implicated in human campylobacteriosis, however to date this clonal complex has not been linked to poultry. The original hypothesis of this research predicted that due to sharing a host niche commonly associated with C. coli, the porcine ST403CC may show evidence of increased recombination with C. coli, however this was not observed. Six ST403CC isolates of porcine origin were subjected to phenotype testing and whole genome sequencing; these isolates were capable of invasion in vitro, and were revealed both to have acquired seemingly lineage specific content, in the form of Restriction-Modification (R-M) system associated genes, and to have undergone degredation of certain loci. The ST403CC isolates also exhibited a distinct pattern of reduced genomic recombination compared to non-ST403CC C. jejuni, with evidence of lineage specific recombination events. Both generalist & specialist lineages have previously been revealed in C. jejuni. The research presented here identifies a new specialist lineage which is associated with mammalian hosts, and not found in poultry.

Name dc:type.qualificationname

phd

Level dc:type.qualificationlevel

doctoral

Grantor dc:publisher.institution

Nottingham Trent University

Year dc:date.issued

2014

Author dc:creator

• Morley, L

Language dc:language

en