Bioinformatic Analysis for Iron-Uptake System of Campylobacter spp. in humans and chickens

Asymptomatic Campylobacter jejuni colonisation is highly prevalent in chickens, however, it’s a major cause of bacterial foodborne disease in humans. Iron is an essential co-factor in many physiological processes and Campylobacter strains employ several non-redundant iron acquisition systems for survival and colonization. The outer membrane receptors CfrA and CfrB are involved in iron acquisition fromcatecholamine siderophores and are required for colonisation of the chicken GI tract. In contrast, ChuAB are part of an uptake system, enabling the utilization of iron in haem and is not required for colonisation. This study aims to compare differences in the iron-uptake systems present in Campylobacter strains isolated from chickens or humans.

Analysis of Campylobacter jejuni/coli genome sequences in PubMLST (https://pubmlst.org/organisms/campylobacter-jejunicoli [https://pubmlst.org/organisms/campylobacter-jejunicoli]) added from the UK in 2018 reveals differences in sequence type (ST) and chuA, chuB, cfrA and cfrB between isolates from chicken (CI) or human (HI) sources. ST828 was the most common ST for the C. coliCI (45%) and ST827 (32%) for the HI. C. jejuniST5136 was the most common of the HI (10%) and CI (13%), ST50 (8%) for the HI and ST21 (7%) for the CI. >95% of isolates contained chuAand chuB, we also found the Chu system to be highly conserved. For cfrA81% of HI and 74% of CI contained the gene, and 92% of HI and 96% of CI harboured cfrB.<3% of all isolates had neither cfrAor cfrB, cfrBmore associated with CI than HI. This data analysis reveals potential gene targets towards vaccine development against Campylobacter strains.