Role of Cecal Microbiota in the Differential Resistance of Inbred Chicken Lines to Colonization by Campylobacter jejuni

Abstract

Campylobacteriosis is the leading foodborne bacterial diarrheal illness in many countries, with up to 80% of human cases attributed to the avian reservoir. The only control strategies currently available are stringent on-farm biosecurity and carcass treatments. Heritable differences in the resistance of chicken lines to Campylobacter colonization have been reported and resistance-associated quantitative trait loci are emerging, although their impact on colonization appears modest. Recent studies indicated a protective role of the microbiota against colonization by Campylobacter in chickens. Furthermore, in murine models, differences in resistance to bacterial infections can be partially transferred between lines by transplantation of gut microbiota. In this study, we investigated whether heritable differences in colonization of inbred chicken lines by Campylobacter jejuni are associated with differences in cecal microbiota. We performed homologous and heterologous cecal microbiota transplants between line 61 (resistant) and line N (susceptible) by orally administering cecal contents collected from 3-week-old donors to day-of-hatch chicks. Recipient birds were challenged (day 21) with C. jejuni 11168H. In birds given homologous microbiota, the differential resistance of lines to C. jejuni colonization was reproduced. Contrary to our hypothesis, transfer of cecal microbiota from line 61 to line N significantly increased C. jejuni colonization. No significant difference in the overall composition of the cecal microbial communities of the two lines was identified, although line-specific differences for specific operational taxonomic units were identified. Our data suggest that while heritable differences in avian resistance to Campylobacter colonization exist, these are not explained by significant variation in the cecal microbiota. IMPORTANCE Campylobacter is a leading cause of foodborne diarrheal disease worldwide. Poultry are a key source of human infections, but there are currently few effective measures against Campylobacter in poultry during production. One option to control Campylobacter may be to alter the composition of microbial communities in the avian intestines by introducing beneficial bacteria, which exclude the harmful ones. We previously described two inbred chicken lines which differ in resistance to intestinal colonization by Campylobacter. Here, we investigated the composition of the microbial communities in the gut of these lines and whether transferring gut bacteria between the resistant and susceptible lines alters their resistance to Campylobacter. No major differences in microbial populations were found, and resistance or susceptibility to colonization was not conferred by transferring gut bacteria between lines. The data suggest that gut microbiota did not play a role in resistance to Campylobacter colonization, at least in the lines used.

Transcriptomic analysis of caecal tissue in inbred chicken lines that exhibit heritable differences in resistance to Campylobacter jejuni

“…At 5 dpi, no signi cant difference in caecal colonisation by C. jejuni was observed between the two lines. These results indicate that line 6 1 is relatively resistant to C. jejuni M1 during early colonisation, as reported for other strains [20,21,29].…”

“…Previously, Boyd et al reported resistance to cloacal and caecal colonisation was apparent in line 6 1 compared to line N from 4 to 20 dpi [20], a discrepancy with this study likely due, in part, to the different C. jejuni strains used by Boyd (C. jejuni 14N and 81-176) and in this report (C. jejuni M1). Chintoan-Uta et al recently reported line N birds to be colonised by C. jejuni 11168H at c. 10 4 CFU/g caecal contents 9 dpi at 3 weeks-of-age whereas the challenge strain was absent at the limit of detection by direct plating at this time in line 6 1 birds [29]. M1 rapidly colonises the chicken caeca from doses as low as 100 CFU [33,34] and both the rate of colonisation and caecal burden have proven greater than for other C. jejuni strains tested in the same model, including 11168H (Stevens et al, unpublished data).…”

“…GZMA was also more highly expressed in line N, corresponding to a microarray study where GZMA expression was higher in the caeca of C. jejuni-colonised compared to non-colonised birds, indicating GZMA is linked with elevated C. jejuni levels in the caeca [16]. Recent studies have identi ed mostly limited differences in the microbial communities present in the caeca of lines 6 1 and N at the age they were inoculated herein, but the extent to which these differences drive distinct patterns of gene expression in the gut, or vice versa, is unknown [29].…”

Transcriptomic analysis of caecal tissue in inbred chicken lines that exhibit heritable differences in resistance to Campylobacter jejuni

“…Line 6 1 and N chickens not only differ in resistance to Campylobacter, but to gut colonisation by Salmonella enterica serovar Typhimurium and genetic associations have been mapped using a backcross [28]. We recently demonstrated that limited differences exist between lines 6 1 and N in their caecal microbiota and reciprocal transplants of caecal microbiota did not alter their resistance to C. jejuni colonisation, suggesting a role for host factors [29]. Here, we used RNA-Seq to investigate the caecal transcriptome of line 6 1 and N chickens, both in uninfected birds to identify differences between the lines that may underlie differential resistance to pathogens and following experimental challenge with C. jejuni.…”

Impact of Host Genetics on Caecal Microbiota Composition and on Salmonella Carriage in Chicken

“…Since we analysed caecal microbiota composition after infection, we cannot exclude that the infection by Salmonella affected this microbiota composition. Does the higher susceptibility of line A study on Campylobacter resistance between lines N and 6 1 was conducted by Chintoan-Uta and colleagues [46]. Their objectives were to transfer microbiota from the resistant line to the susceptible line and to study the Campylobacter carriage.…”