Campylobacter jejuni influences the expression of nutrient transporter genes in the intestine of chickens

Supplementation of lactobacillus-fermented rapeseed meal in broiler diet reduces Campylobacter jejuni cecal colonization and limits the l-tryptophan and l-histidine biosynthesis pathways

BACKGROUND

Campylobacter jejuni (C. jejuni), a widely distributed global foodborne pathogen, primarily linked with contaminated chicken meat, poses a significant health risk. Reducing the abundance of this pathogen in poultry meat is challenging but essential. This study assessed the impact of Lactobacillus-fermented rapeseed meal (LFRM) on broilers exposed to C. jejuni-contaminated litter, evaluating growth performance, Campylobacter levels, and metagenomic profile.

RESULTS

By day 35, the litter contamination successfully colonized broilers with Campylobacter spp., particularly C. jejuni. In the grower phase, LFRM improved (P < 0.05) body weight and daily weight gain, resulting in a 9.2% better feed conversion ratio during the pre-challenge period (the period before artificial infection; days 13-20). The LFRM also reduced the C. jejuni concentration in the ceca (P < 0.05), without altering alpha and beta diversity. However, metagenomic data analysis revealed LFRM targeted a reduction in the abundance of C. jejuni biosynthetic pathways of l-tryptophan and l-histidine and gene families associated with transcription and virulence factors while also possibly leading to selected stress-induced resistance mechanisms.

CONCLUSION

The study demonstrated that LFRM inclusion improved growth and decreased cecal Campylobacter spp. concentration and the relative abundance of pivotal C. jejuni genes. Performance benefits likely resulted from LFRM metabolites. At the molecular level, LFRM may have reduced C. jejuni colonization, likely by decreasing the abundance of energy transduction and l-histidine and l-tryptophan biosynthesis genes otherwise required for bacterial survival and increased virulence. © 2024 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

The effect of gut microbiota-derived carnosine on mucosal integrity and immunity in broiler chickens challenged with Eimeria maxima

In the first study, an in vitro culture system was developed to investigate the effects of carnosine on macrophage proinflammatory cytokine response using an established chicken macrophage cell line (CMC), gut integrity using a chicken intestinal epithelial cell line (IEC), muscle differentiation in quail muscle cells (QMCs) and primary chicken embryonic muscle cells (PMCs), and direct anti-parasitic effect against Eimeria maxima sporozoites. Cells to be tested were seeded in 24-well plates and treated with carnosine at 4 different concentrations (0.1, 1.0, and 10.0 µg). After 18 h of incubation, cells were harvested to measure gene expression of proinflammatory cytokines in CMC, tight junction (TJ) proteins in IECs, and muscle cell growth markers in QMCs and PMCs. In vivo trials were conducted to investigate the effect of dietary carnosine on disease parameters in broiler chickens challenged with E. maxima. One hundred and twenty male broiler chickens (0-day-old) were allocated into 4 treatment groups: 1) basal diet without infection (NC), 2) basal diet with E. maxima infection (PC), 3) carnosine at 10.0 mg/kg feed with PC (HCS), and 4) carnosine at 1.0 mg/kg feed with PC (LCS). All groups except NC were orally infected with E. maxima on d 14. Jejunal samples were collected for lesion scoring and jejunum gut tissues were used for transcriptomic analysis of cytokines and TJ proteins. In vitro, carnosine treatment significantly decreased IL-1β gene expression in CMC following LPS stimulation. In vivo feeding studies showed that dietary carnosine increased BW and ADG of chickens in E. maxima-infected groups and reduced the jejunal lesion score and fecal oocyst shedding in HCS group. Jejunal IL-1β, IL-8, and IFN-γ expression were suppressed in the HCS group compared to PC. The expression levels of claudin-1 and occludin in IECs were also increased in HCS following carnosine treatment. In conclusion, these findings highlight the beneficial effects of dietary carnosine supplementation on intestinal immune responses and gut barrier function in broiler chickens exposed to E. maxima infection.

Investigation of the Effect of Three Commercial Water Acidifiers on the Performance, Gut Health, and Campylobacter jejuni Colonization in Experimentally Challenged Broiler Chicks

This study investigated the effect of three commercial water acidifiers on the performance, gut health, and C. jejuni colonization in experimentally challenged broiler chicks. A total of 192 one-day-old broiler chicks (Ross 308^®) were randomly allocated into 6 treatment groups with 4 replicates according to the following experimental design: group A, birds were not challenged and received tap water; group B, birds were challenged and received tap water; groups C, D, E, and F, birds were challenged and received tap water treated with 0.1% v/v SPECTRON^®, with 0.1-0.2% v/v ProPhorce™ SA Exclusive, with 0.1-0.2% v/v Premium acid, and with 0.1-0.2% v/v Salgard^® Liquid, respectively. The continuous water acidification evoked undesirable effects on broilers' performance and to an increased number of birds with ulcers and erosions in the oral cavity and the upper esophageal area. ProPhorce™ SA Exclusive and Premium acid significantly reduced the C. jejuni counts in the crop, whereas Salgard^® Liquid significantly reduced the C. jejuni counts in the ceca of birds. At slaughter age, only Premium acid significantly reduced C. jejuni counts in the ceca of birds. All the tested products ameliorated the changes induced by C. jejuni infection in the pH in the ceca of birds. It can be concluded that besides the effectiveness of the tested products in controlling C. jejuni in broilers, their continuous application evoked undesirable effects on broilers' performance, leading to the need to modify the dosage scheme in future investigations.

Plasmid DNA Prime/Protein Boost Vaccination against Campylobacter jejuni in Broilers: Impact of Vaccine Candidates on Immune Responses and Gut Microbiota

Campylobacter infections, traced to poultry products, are major bacterial foodborne zoonoses, and vaccination is a potential solution to reduce these infections. In a previous experimental trial using a plasmid DNA prime/recombinant protein boost vaccine regimen, two vaccine candidates (YP437 and YP9817) induced a partially protective immune response against Campylobacter in broilers, and an impact of the protein batch on vaccine efficacy was suspected. This new study was designed to evaluate different batches of the previously studied recombinant proteins (called YP437A, YP437P and YP9817P) and to enhance the immune responses and gut microbiota studies after a C. jejuni challenge. Throughout the 42-day trial in broilers, caecal Campylobacter load, specific antibodies in serum and bile, the relative expression of cytokines and β-defensins, and caecal microbiota were assessed. Despite there being no significant reduction in Campylobacter in the caecum of vaccinated groups, specific antibodies were detected in serum and bile, particularly for YP437A and YP9817P, whereas the production of cytokines and β-defensins was not significant. The immune responses differed according to the batch. A slight change in microbiota was demonstrated in response to vaccination against Campylobacter. The vaccine composition and/or regimen must be further optimised.

Effect of individual or combination of dietary betaine and glycine on productive performance, stress response, liver health, and intestinal barrier function in broiler chickens raised under heat stress conditions

The current experiment was conducted to investigate the effect of individual or combination of dietary betaine (Bet) and glycine (Gly) on productive performance, stress response, liver health, and intestinal barrier function in broiler chickens raised under heat stress (HS) conditions. A total of four hundred twenty 21-d-old Ross 308 broiler chickens were randomly allotted to 1 of 5 dietary treatments with 7 replicates. Birds in treatment 1 were raised under the thermoneutral condition (TN; 23 ± 0.6°C). Birds in other 4 treatment groups were subjected to a cyclic HS by exposing them to 32 ± 0.9°C for 8 h/d (from 09:00 to 17:00 h) and 28 ± 1.2°C for the remaining time for 14 d. Birds were fed a basal diet in TN condition (TN-C) and one group in HS conditions (HS-C), whereas other birds raised under HS conditions were fed the basal diet supplemented with 0.20% Bet (HS-Bet), 0.79% Gly (HS-Gly), or their combination (0.20% Bet + 0.79% Gly; HS-Bet+Gly). Results indicated that birds in HS-Bet, HS-Gly, or HS-Bet+Gly treatment had higher (P < 0.05) final BW and BW gain, but lower (P < 0.05) feed conversion ratio (FCR) than those in HS-C treatment. However, values for improved final BW, BW gain, and FCR by dietary treatments were lower (P < 0.05) than those measured in TN-C treatment. Under HS conditions, birds in HS-Bet, HS-Gly, or HS-Bet+Gly treatment had lower (P < 0.05) heterophil to lymphocyte ratio than those in HS-C treatment. Birds in HS-Gly or HS-Bet+Gly treatment had higher (P < 0.05) villus height and goblet cell number than birds in HS-C treatment. Intestinal permeability was higher (P < 0.05) in all HS-treatment groups than in TN-C treatment, but it was not affected by dietary treatment. In conclusion, individual supplementation of 0.20% Bet or 0.79% Gly in diets alleviates the negative effect of HS in broiler chickens. However, the synergistic effect of the combination of 0.20% Bet and 0.79% Gly in broiler diets seems lower than expected.

The effect of Campylobacter jejuni and Campylobacter coli colonization on the gut morphology, functional integrity, and microbiota composition of female turkeys

BACKGROUND

Campylobacter (C.) species are the most common bacterial cause of foodborne diarrhea in humans. Despite colonization, most animals do not show clinical signs, making recognition of affected flocks and disruption of the infection chain before slaughter challenging. Turkeys are often cocolonized with C. jejuni and C. coli. To understand the pathogen-host-interaction in the context of two different Campylobacter species, we compared the colonization patterns and quantities in mono- and co-colonized female commercial turkeys. In three repeated experiments we investigated the impact on gut morphology, functional integrity, and microbiota composition as parameters of gut health at seven, 14, and 28 days post-inoculation.

RESULTS

Despite successful Campylobacter colonization, clinical signs or pathological lesions were not observed. C. coli persistently colonized the distal intestinal tract and at a higher load compared to C. jejuni. Both strains were isolated from livers and spleens, occurring more frequently in C. jejuni- and co-inoculated turkeys. Especially in C. jejuni-positive animals, translocation was accompanied by local heterophil infiltration, villus blunting, and shallower crypts. Increased permeability and lower electrogenic ion transport of the cecal mucosa were also observed. A lower relative abundance of Clostridia UCG-014, Lachnospiraceae, and Lactobacillaceae was noted in all inoculated groups compared to controls.

CONCLUSIONS

In sum, C. jejuni affects gut health and may interfere with productivity in turkeys. Despite a higher cecal load, the impact of C. coli on investigated parameters was less pronounced. Interestingly, gut morphology and functional integrity were also less affected in co-inoculated animals while the C. jejuni load decreased over time, suggesting C. coli may outcompete C. jejuni. Since a microbiota shift was observed in all inoculated groups, future Campylobacter intervention strategies may involve stabilization of the gut microbiota, making it more resilient to Campylobacter colonization in the first place.

Increased arginine, lysine, and methionine levels can improve the performance, gut integrity and immune status of turkeys but the effect is interactive and depends on challenge conditions

Arginine (Arg), lysine (Lys), and methionine (Met) can be used to support the health status of turkeys. The present study investigated selected performance, gut integrity, and immunological parameters in turkeys reared in optimal or challenge conditions. The experiment lasted for 28 days, and it had a completely randomized 2 × 3 factorial design with two levels of dietary Arg, Lys and Met (high or low) and challenge with Clostridium perfringens (C. perfringens), Escherichia coli lipopolysaccharide (LPS) or no challenge (placebo). Increased dietary levels of Arg, Lys and Met had a beneficial effect on turkey performance and immunological parameters, and it improved selected indicators responsible for maintaining gut integrity in different challenge conditions. Under optimal conditions (with no challenge), high ArgLysMet diets did not compromise bird performance and they improved selected performance parameters in challenged birds. The immune system of turkeys was not excessively stimulated by high ArgLysMet diets, which did not disrupt the redox balance and had no negative effect on gut integrity. High ArgLysMet diets increased the expression levels of selected genes encoding nutrient transporters and tight junction proteins. However, the influence exerted by different dietary inclusion levels of Arg, Lys and Met on gut integrity was largely determined by the stressor (C. perfringens vs. LPS). Further studies are required to investigate the role of Arg, Lys and Met levels in the diet on the immune response, gut function and performance of turkeys in different challenge conditions.

Paracellular intestinal permeability of chickens induced by DON and/or C. jejuni is associated with alterations in tight junction mRNA expression

Toxins, antigens, and harmful pathogens continuously challenge the intestinal mucosa. Therefore, regulation of the intestinal barrier is crucial for the maintenance of mucosal homeostasis and gut health. Intercellular complexes, namely, tight junctions (TJs), regulate paracellular permeability. TJs are mainly composed of claudins (CLDN), occludin (OCLN), tight junction associated MARVEL-domain proteins (TAMPS), the scaffolding zonula occludens (ZO) proteins and junction-adhesion molecules (JAMs). Different studies have shown that a Campylobacter infection can lead to a phenomenon so-called "leaky gut", including the translocation of luminal bacteria to the underlying tissue and internal organs. Based on the effects of C. jejuni on the chicken gut, we hypothesize that impacts on TJ proteins play a crucial role in the destructive effects of the intestinal barrier. Likewise, the mycotoxin deoxynivalenol (DON) can also alter gut permeability in chickens. Albeit DON and C. jejuni are widely distributed, no data are available on their effect on the tight junctions' barrier in the broiler intestine and consequences for permeability. Therefore, the aim of this study was to analyze the interaction between DON and C. jejuni on the gut barrier by linking permeability with gene expression of TJ proteins and to determine the relationships between the measurements. Following oral infection of birds with C. jejuni NCTC 12744 at 14 days of age, we demonstrate that the co-exposure with DON has considerable consequences on gut permeability as well as on gut TJ mRNA expression. Co-exposure of DON and C. jejuni enhanced the negative effect on paracellular permeability of the intestine, which was also noticed for the bacteria or the mycotoxin alone by the Ussing chamber technique at certain time points in both jejunum and caecum. Furthermore, the increased paracellular permeability was associated with significant changes in TJ mRNA expression in the small and large intestine. The actual study demonstrates that co-exposure of broiler chickens to DON and C. jejuni resulted in a decreased barrier function via up-regulation of pore-forming tight junctions (CLDN7 and CLDN10), as well as the cytosolic TJ protein occludin (OCLN) that can shift to various paracellular locations and are therefore able to alter the epithelial permeability. These findings indicate that the co-exposure of broiler chickens to DON and C. jejuni affects the paracellular permeability of the gut by altering the tight junction proteins. Furthermore, analysing of correlations between TJs revealed that the mRNA expression levels of most tight junctions were correlated with each other in both jejunum and caecum. Finally, the findings indicate that the molecular composition of tight junctions can be used as a marker for gut health and integrity.

In ovo threonine supplementation affects ileal gene expression of nutrient transporters in broilers inoculated post-hatch with Salmonella Enteritidis

The effect of in ovo threonine (Thr) supplementation on the ileal expression of glucose, peptide and amino acid transporters was assessed in Salmonella Enteritidis-challenged broiler chicks. At 17.5 days of incubation, fertile eggs were supplemented in the amniotic fluid with sterile saline or 3.5% threonine. Hatchlings were individually weighed, and Salmonella Enteritidis negative status was confirmed. At 2 days of age, half of the birds of each group were inoculated with sterile nutrient broth or Salmonella Enteritidis inoculum. Relative expression of sodium-dependent glucose transporter 1 (SGLT1), glucose transporter 2 (GLUT2), di- and tri-peptide transporter 1 (PepT1) and alanine, serine, cysteine, threonine transporter (ASCT1) was assessed at hatch, 2 and 9 days of age, i.e., before inoculation and 7 days post-inoculation (dpi). At 9 days of age (7dpi), threonine increased SGLT1 and GLUT2 expression, whereas GLUT2 expression decreased in Salmonella-challenged birds. There was a significant interaction between threonine and Salmonella for PepT1 and ASCT1. Threonine increased PepT1 expression only in non-challenged birds. In addition, in ovo supplementation increased expression of ASCT1 regardless of post-hatch inoculation; Salmonella inoculation resulted in decreased expression of ASCT1 only in supplemented birds. The results suggest that while intra-amniotic threonine administration in broiler embryos increases the expression of genes related to the absorption of monosaccharides and amino acids, Salmonella challenge may negatively affect the expression of protein related transporters in the ileum of broilers.

Impact of Campylobacter spp. on the Integrity of the Porcine Gut

Campylobacter (C.) is the most common food-borne zoonosis in humans, which mainly manifests with watery to bloody diarrhoea. While C. jejuni is responsible for most cases of infection, C. coli is less frequently encountered. The object of the study was to prove the clinical impact of mono- and co-colonisation of C. coli and C. jejuni on weaned piglets in an infection model and to investigate the impact on transepithelial transport processes in the jejunum and caecum. At an age of eight weeks, eight pigs were infected with C. coli (ST-5777), 10 pigs with C. jejuni (ST-122), eight pigs with both strains, and 11 piglets served as control. During the four-week observation period, no clinical signs were observed. During dissection, both strains could be isolated from the jejunum and the caecum, but no alteration of the tissue could be determined histopathologically. Mono-infection with C. jejuni showed an impact on transepithelial ion transport processes of the caecum. An increase in the short circuit current (I_sc) was observed in the Ussing chamber resulting from carbachol- and forskolin-mediated Cl^- secretion. Therefore, we speculate that caecal colonisation of C. jejuni might affect the transport mechanisms of the intestinal mucosa without detectable inflammatory reaction.

Exogenous Enzymes Influenced Eimeria-Induced Changes in Cecal Fermentation Profile and Gene Expression of Nutrient Transporters in Broiler Chickens

Two 21-day experiments were conducted to investigate the effects of exogenous enzymes on growth performance, tight junctions, and nutrient transporters, jejunal oligosaccharides and cecal short-chain fatty acids (SCFA) of broiler chickens challenged with mixed Eimeria. Two different basal diets: high fiber-adequate protein (HFAP; Expt. 1) or low fiber-low protein (LFLP; Expt. 2) were used in the two experiments. In each experiment, birds were allocated to four treatments in a 2 × 2 factorial arrangement (with or without protease and xylanase combination; with or without Eimeria challenge). In Expt. 1, with HFAP diets, Eimeria upregulated (p < 0.05) the expression of claudin-1, but downregulated (p < 0.05) glucose transporters GLUT2/GLUT5. On the contrary, enzymes downregulated (p < 0.05) claudin-1 and alleviated the Eimeria-depressed GLUT2/GLUT5 expression. In both experiments, Eimeria decreased (p < 0.05) cecal saccharolytic SCFA and increased (p < 0.05) cecal branched-chain fatty acids. The challenge × enzyme interaction (p < 0.05) showed that enzymes reversed the Eimeria effects on fermentation pattern shift. In conclusion, Eimeria altered tight junctions and nutrient transporters expression promoted cecal proteolytic fermentation and inhibited saccharolytic fermentation. Exogenous enzymes showed the potential of alleviating the Eimeria-induced intestinal gene expression changes and reversing the unfavorable cecal fermentation pattern.

Deepoxy-deoxynivalenol (DOM-1), a derivate of deoxynivalenol (DON), exhibits less toxicity on intestinal barrier function, Campylobacter jejuni colonization and translocation in broiler chickens

Background

Intestinal epithelial cells are challenged by mycotoxins and many bacterial pathogens. It was previously shown that the mycotoxin deoxynivalenol (DON) as well as Campylobacter (C.) jejuni have a negative impact on gut integrity. Recently, it was demonstrated that DON increased the load of C. jejuni in the gut and inner organs. Based on this finding, it was hypothesized the DON metabolite (deepoxy-deoxynivalenol, DOM-1) should be able to reduce the negative effects of DON on colonization and translocation of C. jejuni in broilers, since it lacks the epoxide ring, which is responsible for the toxicity of DON.

Methods

A total of 180 broiler chickens were housed in floor pens on wood shavings with feed and water provided ad libitum. Birds were divided into six groups (n = 30 with 5 replicates/group): 1. Control, 2. DOM-1, 3. DON, 4. DOM-1 + C. jejuni, 5. DON + C. jejuni, 6. C. jejuni. At day 14, birds of groups 4, 5 and 6 were orally inoculated via feeding tube (gavage) with 1-ml of a PBS suspension containing 1 × 10⁸ CFU of C. jejuni NCTC 12744. The performance parameters: body weight (BW), body weight gain (BWG), and feed intake of the birds were determined. At 7, 14, and 21 days post infection, samples from liver, spleen, duodenum, jejunum and cecum were aseptically collected and processed for bacteriological investigations. Finally, at each killing time point, segments of duodenum, jejunum and cecum were harvested and prepared for Ussing chamber studies to measure the paracellular mannitol fluxes.

Results

A significant decrease in body weight was observed for chickens receiving the DON diet with or without C. jejuni compared to the other groups. Furthermore, it was found that the co-exposure of birds to DON and C. jejuni resulted in a higher C. jejuni load not only in the gut but also in liver and spleen due to increased paracellular permeability of the duodenum, jejunum and cecum. On the contrary, DOM-1 supplementation in the feed improved the birds’ performance and led to a better feed conversion ratio throughout the trial. Furthermore, DOM-1 did not negatively affect gut permeability and decreased the C. jejuni counts in the intestine and internal organs.

Conclusion

Altogether, the presence of DOM-1 in the feed as a result of the enzymatic biotransformation of DON leads to a lower C. jejuni count in the intestine and better feed conversion ratio. Moreover, this study demonstrates that the detoxification product of DON, DOM-1, does not have negative effects on the gastrointestinal tract and reduces the Campylobacter burden in chickens and also the risk for human infection.

Transversal gene expression panel to evaluate intestinal health in broiler chickens in different challenging conditions

There is a high interest on gut health in poultry with special focus on consequences of the intestinal diseases, such as coccidiosis and C. perfringens-induced necrotic enteritis (NE). We developed a custom gene expression panel, which could provide a snapshot of gene expression variation under challenging conditions. Ileum gene expression studies were performed through high throughput reverse transcription quantitative real-time polymerase chain reaction. A deep review on the bibliography was done and genes related to intestinal health were selected for barrier function, immune response, oxidation, digestive hormones, nutrient transport, and metabolism. The panel was firstly tested by using a nutritional/Clostridium perfringens model of intestinal barrier failure (induced using commercial reused litter and wheat-based diets without exogenous supplementation of enzymes) and the consistency of results was evaluated by another experiment under a coccidiosis challenge (orally gavaged with a commercial coccidiosis vaccine, 90× vaccine dose). Growth traits and intestinal morphological analysis were performed to check the gut barrier failure occurrence. Results of ileum gene expression showed a higher expression in genes involved in barrier function and nutrient transport in chickens raised in healthy conditions, while genes involved in immune response presented higher expression in C.perfringens-challenged birds. On the other hand, the Eimeria challenge also altered the expression of genes related to barrier function and metabolism, and increased the expression of genes related to immune response and oxidative stress. The panel developed in the current study gives us an overview of genes and pathways involved in broiler response to pathogen challenge. It also allows us to deep into the study of differences in gene expression pattern and magnitude of responses under either a coccidial vaccine or a NE.

Quantitative trait loci and transcriptome signatures associated with avian heritable resistance to Campylobacter

Campylobacter is the leading cause of bacterial foodborne gastroenteritis worldwide. Handling or consumption of contaminated poultry meat is a key risk factor for human campylobacteriosis. One potential control strategy is to select poultry with increased resistance to Campylobacter. We associated high-density genome-wide genotypes (600K single nucleotide polymorphisms) of 3000 commercial broilers with Campylobacter load in their caeca. Trait heritability was modest but significant (h² = 0.11 ± 0.03). Results confirmed quantitative trait loci (QTL) on chromosomes 14 and 16 previously identified in inbred chicken lines, and detected two additional QTLs on chromosomes 19 and 26. RNA-Seq analysis of broilers at the extremes of colonisation phenotype identified differentially transcribed genes within the QTL on chromosome 16 and proximal to the major histocompatibility complex (MHC) locus. We identified strong cis-QTLs located within MHC suggesting the presence of cis-acting variation in MHC class I and II and BG genes. Pathway and network analyses implicated cooperative functional pathways and networks in colonisation, including those related to antigen presentation, innate and adaptive immune responses, calcium, and renin–angiotensin signalling. While co-selection for enhanced resistance and other breeding goals is feasible, the frequency of resistance-associated alleles was high in the population studied and non-genetic factors significantly influenced Campylobacter colonisation.

The Mycotoxin Deoxynivalenol (DON) Promotes Campylobacter jejuni Multiplication in the Intestine of Broiler Chickens With Consequences on Bacterial Translocation and Gut Integrity

Deoxynivalenol (DON) is one of the major health concern in poultry production as it targets epithelial cells of the gastrointestinal tract and contributes to the loss of the epithelial barrier function. It is well-documented that DON severely compromises various important intestinal functions in coincidence with aggravated clinical symptoms in livestock. In addition, a prolonged persistence of intestinal pathogens (e.g., Salmonella, Clostridium) in the gut has also been reported in pigs and chickens, respectively. Similar to DON, recent studies demonstrated that an experimental Campylobacter infection has severe consequences on gut health. Through experimental infection, it was found that Campylobacter (C.) jejuni negatively affects the integrity of the intestine and promotes the translocation of bacteria from the gut to inner organs. So far, no data are available investigating the simultaneous exposure of DON and C. jejuni in broilers albeit both are widely distributed. Thus, the aim of the present study was to explore the interaction between DON and C. jejuni which is of a significant public and animal health concern as it may affect the prevalence and the ability to control this pathogen. Following oral infection of birds at 14 days of age with C. jejuni NCTC 12744, we show that the co-exposure to DON and C. jejuni has a considerable consequence on C. jejuni loads in chicken gut as well as on gut permeability of the birds. A reduced growth performance was found for DON and/or C. jejuni exposed birds. Furthermore, it was found that the co-exposure of DON and C. jejuni aggravated the negative effect on paracellular permeability of the intestine already noticed for the bacteria or the mycotoxin alone by the Ussing chamber technique at certain times or intestinal segments. Furthermore, the increased paracellular permeability promotes the translocation of C. jejuni and E. coli to inner organs, namely liver and spleen. Interestingly, C. jejuni loads in the intestine were higher in DON-fed groups indicating a supportive growth effect of the mycotoxin. The actual study demonstrates that co-exposure of broiler chickens to DON and C. jejuni has not only considerable consequences on gut integrity but also on bacterial balance. These findings indicate that the co-exposure of broiler chickens to DON and C. jejuni could have a significant impact on gut health and bacteria translocation leading to an increased risk for public health.

Campylobacter jejuni increases the paracellular permeability of broiler chickens in a dose-dependent manner

In recent years, several studies emphasize the deleterious effects of Campylobacter jejuni on the chicken intestine. In this context, it was shown that C. jejuni, contrary to the general belief, has a negative influence on the gut barrier in chickens. More precisely, we demonstrated that C. jejuni affects gut physiology characterized by changes in ion transport and transepithelial ion conductance, but the underlying mechanism is yet to be investigated. In the actual study, to determine epithelial paracellular permeability, the mucosal to serosal flux of 14C-mannitol in the small and large intestine was measured applying Ussing chamber. A total of seventy-five 1-day-old Ross 308 broiler chickens were housed in floor pens on wood shavings with feed and water provided ad libitum. Birds were randomly allocated to 3 different groups (n = 25 with 5 replicates/group) and infected at 14 d of age with a high (108 colony forming units [CFU]) or a low (104 CFU) dose of C. jejuni and a third group kept as noninfected control. Infection with the low dose of C. jejuni resulted in delayed cecal colonization but equalized at 21 d postinfection, independent of the dose. Invasion of liver and spleen with C. jejuni was only noticed in birds infected with 108 (CFU). Body weight (BW) and body weight gain of all birds infected with C. jejuni were lower than in the control group and varied with the dose of infection, confirming a negative correlation between the infection dose and birds BW. Mannitol flux in jejunum and cecum was significantly (P < 0.05) higher in all C. jejuni infected birds compared with control birds. Likewise, significant differences in mannitol flux of both jejunum and cecum were detected depending on the infection dose of C. jejuni. The correlation analyses revealed a positive relationship between Campylobacter dose and mannitol flux of both jejunum and cecum. Altogether, the actual results emphasize that the adverse effect of C. jejuni on gut permeability arises in a dose-dependent manner.

Vibrio parahaemolyticus infection impaired intestinal barrier function and nutrient absorption in Litopenaeus vannamei

The intestine is the primary target of pathogenic microbes during invasion. However, the interaction of Vibrio parahaemolyticus (V. parahaemolyticus) with intestinal epithelial cells and its effects on the intestinal function of Litopenaeus vannamei (L. vannamei) are poorly studied. Therefore, the aim of this study was to investigate the influence of V. parahaemolyticus infection on intestinal barrier function and nutrient absorption in L. vannamei. In the present study, a total of 90 shrimp were randomly divided into two groups including the control group and V. parahaemolyticus infection group (final concentration of 1 × 10⁵ CFU/mL), with three replicates per group. The result showed that compared with the control group, V. parahaemolyticus infection increased (P < 0.05) serum diamine oxidase activity and endotoxin quantification, and down-regulated (P < 0.05) the mRNA levels of intestinal peroxinectin, integrin, midline fasciclin at 48 h and 72 h; V. parahaemolyticus infection decreased (P < 0.05) the mRNA expression of intestinal amino acid transporter (CAT1, EAAT3 and ASCT1) and glucose transporter (SGLT-1, GLUT) at 24 h, 48 h and 72 h, and increased (P < 0.05) serum glucose and amino acid (Asp, Thr, Ser, Glu, Gly, Ala, Val, Ile, Leu, Tyr, Phe, Lys, His and Arg) concentration at 24 h. The results indicated that V. parahaemolyticus infection increased intestinal permeability, inhibited absorption of glucose and amino acid in L. vannamei.

Campylobacter in chicken - Critical parameters for international, multicentre evaluation of air sampling and detection methods

The present pilot study aimed at evaluating air sampling as a novel method for monitoring Campylobacter in poultry farms. We compared the bacteriological isolation of Campylobacter from boot swabs and air filter samples using ISO 10272-1:2017. A secondary aim was to evaluate the use of molecular methods, i.e. real time PCR, on the same sample set. Samples from 44 flocks from five European countries were collected, and included air samples, in parallel with boot swabs. Campylobacter spp. was isolated from seven of 44 boot swabs from three of five partners using the enrichment method. Two of these positive boot swab samples had corresponding positive air samples. Using enrichment, one positive air sample was negative in the corresponding boot swabs, but Campylobacter spp. was isolated from direct plating of the boot swab sample. One partner isolated Campylobacter spp. from six of 10 boot swabs using direct plating. Overall, 33 air filter samples were screened directly with PCR, returning 14 positive results. In conclusion, there was a lack of correspondence between results from analysis of boot swabs and air filters using ISO 10272-1:2017. In contrast, the combination of air filters and direct real-time PCR might be a way forward. Despite the use of the detailed ISO protocols, there were still sections that could be interpreted differently among laboratories. Air sampling may turn into a multi-purpose and low-cost sampling method that may be integrated into self-monitoring programs.

Effect of manganese source on manganese absorption and expression of related transporters in the small intestine of broilers

An experiment was conducted to investigate the effect of manganese (Mn) source on Mn absorption and expressions of Mn, amino acid, and peptide transporters in the small intestine of broilers. A total of 320 Mn-deficient 15-day-old Arbor Acres male broilers were randomly assigned to 5 treatments with 8 replicates/treatment and 8 chicks/replicate and fed an Mn-unsupplemented control diet or the control diet supplemented with 110 mg Mn/kg from either MnSO4, or 1 of 3 organic Mn chelates with weak (OW), moderate (OM), or strong (OS) chelation strength for 14 D. The plasma Mn contents were higher (P < 0.03) in supplemental Mn groups than in the control group, in OS group than in OM group, and in OM group than in OW and MnSO4 groups on day 28. Broilers fed diets supplemented with Mn had higher (P < 0.02) duodenal divalent metal transporter 1 (DMT1) and ferroportin 1 (FPN1) mRNA levels and FPN1 protein level on both days 21 and 28 than those fed the control diet. Duodenal DMT1 mRNA and protein levels were higher (P < 0.05) in OM and OS groups than in OW and MnSO4 groups on day 28. The mRNA levels of amino acid transporters [b0, +-type amino acid transporter 1 (B0AT1) and excitatory amino acid transporter 3 (EAAT3)] were higher (P < 0.0005), and peptide transporter 1 was lower (P < 0.04) in the ileum than in the duodenum and jejunum; however, Mn source did not affect (P > 0.05) mRNA levels of amino acid and peptide transporters in the small intestine of broilers. The results from the present study indicate that both DMT1 and FPN1 facilitated Mn absorption, however, the amino acid and peptide transporters might not be involved in the transport of the organic Mn chelates; organic Mn chelates with moderate and strong chelation strength, especially strong chelation strength, showed higher Mn absorption possibly due to enhanced DMT1 expression in the duodenum of broilers.

Colonization of a commercial broiler line by Campylobacter is under limited genetic control and does not significantly impair performance or intestinal health

Campylobacter is the leading bacterial cause of foodborne diarrheal illness in humans and source attribution studies unequivocally identify handling or consumption of poultry meat as a key risk factor. Campylobacter colonizes the avian intestines in high numbers and rapidly spreads within flocks. A need therefore exists to devise strategies to reduce Campylobacter populations in poultry flocks. There has been a great deal of research aiming to understand the epidemiology and transmission characteristics of Campylobacter in poultry as a means to reduce carriage rates in poultry and reduce infection in humans. One potential strategy for control is the genetic selection of poultry for increased resistance to colonization by Campylobacter. The potential for genetic control of colonization has been demonstrated in inbred populations following experimental challenge with Campylobacter where quantitative trait loci associated with resistance have been identified. Currently in the literature there is no information of the genetic basis of Campylobacter colonization in commercial broiler lines and it is unknown whether these QTL are found in commercial broiler lines. The aim of this study was to estimate genetic parameters associated with Campylobacter load and genetic correlations with gut health and production traits following natural exposure of broiler chickens to Campylobacter.The results from the analysis show a low but significant heritability estimate (0.095 ± 0.037) for Campylobacter load which indicates a limited genetic basis and that non-genetic factors have a greater influence on the level of Campylobacter found in the broiler chicken.Furthermore, through examination of macroscopic intestinal health and absorptive capacity, our study indicated that Campylobacter has no detrimental effects on intestinal health and bird growth following natural exposure in the broiler line under study. These data indicate that whilst there is a genetic component to Campylobacter colonization worthy of further investigation, there is a large proportion of phenotypic variance under the influence of non-genetic effects. As such the control of Campylobacter will require understanding and manipulation of non-genetic host and environmental factors.

Expression of nutrient transporters and host defense peptides in Campylobacter challenged broilers

Campylobacter is a bacterium that colonizes the lower gastrointestinal tract of poultry and may influence the intestinal environment to promote its survival. The objective of this study was to characterize the effects of Campylobacter challenge on the mRNA abundance of nutrient transporters and host defense peptides (HDP), such as the avian β-defensins (AvBD) and liver expressed antimicrobial peptide 2 (LEAP2). On the day of hatch, broiler chicks were challenged with one of three (106, 107, 108 colony-forming units, cfu) levels of Campylobacter jejuni. Quantitative PCR analysis revealed that there were dose-, tissue-, and age-specific changes in gene expression for both nutrient transporters and HDP. Expression of zinc transporter 1 (ZnT1) mRNA increased on d 7 in the duodenum, ileum, and cecum of birds challenged with 106 cfu of C. jejuni. At d 14, there was upregulation of the amino acid transporter bo,+AT mRNA in the duodenum, jejunum, and ileum of birds challenged with 106 cfu of C. jejuni. Other transporters such as EAAT3, GLUT2, SGLT1, and ZnT1 showed upregulation of mRNA in the ileum of the 106 cfu challenged group. There was a delayed response of the HDP to the C. jejuni challenge, with only a few HDP changed at d 7 but all HDP changed at d 14. At d 7, there was upregulation of AvBD10 mRNA in the duodenum of the 106 cfu challenged group but downregulation of AvBD10 in the ileum and AvBD12 and LEAP2 in the cecum of the 108 cfu challenged group. At d 14, there was upregulation of AvBD1, AvBD6, AvBD8, AvBD10, AvBD11, AvBD12, and AvBD13 mRNA in the ileum and cecum of the 106 cfu challenged group but not the 107 and 108 cfu challenged groups compared to control. These results indicated that at a low dose (106 cfu) of C. jejuni, intestinal cells increased nutrient transporter and AvBD mRNA abundance to try to counter the infection, but that at higher doses the cellular response was suppressed.

Dietary supplementation with ferric tyrosine improves zootechnical performance and reduces caecal Campylobacter spp. load in broilers

1. The objective of this study was to evaluate the effect of ferric tyrosine on the reduction of Campylobacter spp. and zootechnical performance in broilers exposed to Campylobacter spp. using a natural challenge model to simulate commercial conditions. Additionally, the minimum inhibitory concentrations (MICs) of ferric tyrosine against common enteropathogens were evaluated. 2. At the start of the trial, 840 healthy male 1-d-old birds (Ross 308) were randomly allocated to 6 replicate pens of 35 birds each and fed diets containing different concentrations of ferric tyrosine (0, 0.02, 0.05 and 0.2 g/kg) in mash form for 42 d. 3. Broilers fed diets containing ferric tyrosine showed significantly higher body weight at d 42 and weight gain compared to the control group. However, birds fed ferric tyrosine ate significantly more than the control birds so significant improvements in feed conversion rate were not observed. 4. Microbiological analyses of caecal samples collected on d 42 of the study showed, per gram of sample, 2-3 log₁₀ reduction in Campylobacter spp. and 1 log₁₀ reduction in Escherichia coli in the groups fed diets containing ferric tyrosine compared to the control. 5. The MICs of ferric tyrosine was >400 mg/l for C. jejuni and >200 mg/l for E. coli and Salmonella enterica, indicating that ferric tyrosine did not exert antimicrobial activity. 6. The results showed that birds fed ferric tyrosine grew faster and consumed more feed compared to the control group, indicating potential benefits of faster time to reach slaughter weight with no significant reduction on feed efficiency. Moreover, ferric tyrosine significantly reduced caecal Campylobacter spp. and E. coli indicating potential as a non-antibiotic feed additive to lower the risk of infections transmitted through the food chain.

Re-thinking the chicken-Campylobacter jejuni interaction: a review

Chickens are recognized as an imperative source of thermophilic Campylobacter spp., carrying this microorganism in high numbers in their intestinal tract. For a long time, Campylobacter jejuni has been considered as a commensal microorganism which colonizes its primary host rather than infecting it, in the absence of any obvious clinical signs. However, recent studies question this and argue for a deeper understanding of the host-bacteria interaction. Following oral uptake, it was demonstrated that C. jejuni interacts intimately with the gut epithelium and influences cellular functions of the host, with consequences on nutrient absorption. The immune reaction of the host which was revealed in some studies confirmed the infectious nature of C. jejuni. In agreement with this, an increased expression of pro-inflammatory cytokine genes was noticed. The ability to induce intestinal damage and to modulate the barrier function of the intestinal epithelia has further consequences on gut integrity, as it facilitates the paracellular passage of C. jejuni into the underlying tissues and it supports the translocation of luminal bacteria such as Escherichia coli to internal organs. This is associated with an alteration of the gut microbiota as infected birds have a significantly lower abundance of E. coli in different parts of the intestine. Some studies found that the gut microbiota influences the infection and translocation of C. jejuni in chickens in various ways. The effects of C. jejuni on the intestinal function of chickens already indicate a possible interference with bird performance and welfare, which was confirmed in some experimental studies. Furthermore, it could be demonstrated that a Campylobacter infection has an influence on the movement pattern of broiler flocks, supporting experimental studies. The intense interaction of C. jejuni with the chicken supports its role as an infectious agent instead of simply colonizing the gut. Most of the findings about the impact of Campylobacter on chickens are derived from studies using different Campylobacter isolates, a specific type of bird and varying experimental design. However, experimental studies demonstrate an influence of the aforementioned parameters on the outcome of a certain trial, arguing for improved standardization. This review summarizes the actual knowledge of the host-pathogen interaction of C. jejuni in chickens, emphasizing that there are still major gaps despite recently gained knowledge. Resolving the cascade from oral uptake to dissemination in the organism is crucial to fully elucidating the interaction of C. jejuni with the chicken host and to assess the clinical and economic implications with possible consequences on preventive interventions.

Nutrient sensing, taste and feed intake in avian species

The anatomical structure and function of beaks, bills and tongue together with the mechanics of deglutition in birds have contributed to the development of a taste system denuded of macrostructures visible to the human naked eye. Studies in chickens and other birds have revealed that the avian taste system consists of taste buds not clustered in papillae and located mainly (60 %) in the upper palate hidden in the crevasses of the salivary ducts. That explains the long delay in the understanding of the avian taste system. However, recent studies reported 767 taste buds in the oral cavity of the chicken. Chickens appear to have an acute sense of taste allowing for the discrimination of dietary amino acids, fatty acids, sugars, quinine, Ca and salt among others. However, chickens and other birds have small repertoires of bitter taste receptors (T2R) and are missing the T1R2 (related to sweet taste in mammals). Thus, T1R2-independent mechanisms of glucose sensing might be particularly relevant in chickens. The chicken umami receptor (T1R1/T1R3) responds to amino acids such as alanine and serine (known to stimulate the umami receptor in rodents and fish). Recently, the avian nutrient chemosensory system has been found in the gastrointestinal tract and hypothalamus related to the enteroendocrine system which mediates the gut-brain dialogue relevant to the control of feed intake. Overall, the understanding of the avian taste system provides novel and robust tools to improve avian nutrition.

TYPLEX® Chelate, a novel feed additive, inhibits Campylobacter jejuni biofilm formation and cecal colonization in broiler chickens

Reducing Campylobacter spp. carriage in poultry is challenging, but essential to control this major cause of human bacterial gastroenteritis worldwide. Although much is known about the mechanisms and route of Campylobacter spp. colonization in poultry, the literature is scarce on antibiotic-free solutions to combat Campylobacter spp. colonization in poultry. In vitro and in vivo studies were conducted to investigate the role of TYPLEX® Chelate (ferric tyrosine), a novel feed additive, in inhibiting Campylobacter jejuni (C. jejuni) biofilm formation and reducing C. jejuni and Escherichia coli (E. coli) colonization in broiler chickens at market age. In an in vitro study, the inhibitory effect on C. jejuni biofilm formation using a plastic bead assay was investigated. The results demonstrated that TYPLEX® Chelate significantly reduces biofilm formation. In an in vivo study, 800 broilers (one d old) were randomly allocated to 4 dietary treatments in a randomized block design, each having 10 replicate pens with 20 birds per pen. At d 21, all birds were challenged with C. jejuni via seeded litter. At d 42, cecal samples were collected and tested for volatile fatty acid (VFA) concentrations and C. jejuni and E. coli counts. The results showed that TYPLEX® Chelate reduced the carriage of C. jejuni and E. coli in poultry by 2 and 1 log10 per gram cecal sample, respectively, and increased cecal VFA concentrations. These findings support TYPLEX® Chelate as a novel non-antibiotic feed additive that may help produce poultry with a lower public health risk of Campylobacteriosis.

Effects of dietary tryptophan levels on performance and biochemical variables of plasma and intestinal mucosa in yellow-feathered broiler breeders

The effects of dietary tryptophan (Trp) levels on performance and biochemical variables of plasma and intestinal mucosa in broiler breeder hens were investigated in this study. A total of 780 Lingnan yellow-feathered broiler breeder hens were randomly assigned in one of five dietary treatments with six replicates per treatment (26 birds per replicate). The breeder hens were fed either the basal diet (0.11% Trp) or the basal diet supplemented to 0.15%, 0.19%, 0.23% and 0.27% Trp, from 197 to 259 days of age. Graded levels of Trp from 0.11% to 0.27% in the diet produced quadratic (p < .05) responses in laying rate, average daily egg production, and feed conversion ratio, and quadratic (p < .01) responses in total large follicle weight and average large follicle weight. An increase in fertilization rate of total eggs was observed in breeders fed 0.27% Trp, and hatchability was higher in breeders fed 0.23% and 0.27% Trp than with 0.19% Trp (p < .05). The content of uric acid N decreased with 0.15% and 0.23% dietary Trp (p < .05). The content of GSH and the GSH-to-GSSG ratio in plasma were reduced by 0.15%, 0.19% and 0.27% Trp diets (p < .05). A higher activity of GST in plasma was observed with 0.15% Trp in relation to 0.23% and 0.27% Trp (p < .05). The activity of Na⁺ -K⁺ -ATPase of plasma in birds fed 0.27% Trp was lower than in those fed 0.15% Trp and the control birds (p < .05). There were significant influences of dietary Trp levels on S6K1, B⁰ AT1, Nrf2, TLR4, TNF-α and IL-6 transcripts of ileal mucosa (p < .05). The optimal dietary Trp level was 0.203% or 254 mg per hen per day, for Chinese yellow-feathered broiler breeder hens aged from 197 to 259 days.

Administration of Lactobacillus johnsonii FI9785 to chickens affects colonisation by Campylobacter jejuni and the intestinal microbiota

1. Campylobacter jejuni is the most common bacterial cause of human food-borne gastroenteritis in the world. A major source of human infection is the consumption of contaminated meat, particularly poultry. New control measures to reduce or eliminate this pathogen from the animal gastrointestinal tract are urgently required, and the use of probiotics as competitive exclusion agents is a promising biocontrol measure to reduce C. jejuni in the food chain. 2. In this study, we assessed the potential of Lactobacillus johnsonii FI9785, which has shown efficacy against Clostridium perfringens, to combat C. jejuni. The effect of prophylactic administration of L. johnsonii on the ability of C. jejuni to colonise chickens was determined. 3. Two doses of L. johnsonii given a week apart led to a reduction in C. jejuni colonisation in the caecal contents, but this biocontrol seemed reliant upon a high level of initial colonisation by the probiotic. 4. The microbial composition in the chicken gut was significantly altered by the probiotic treatment, as shown by denaturing gradient gel electrophoresis of 16S rRNA gene amplicons. 5. Together these results demonstrate the potential of this probiotic strain to be tested further as a competitive exclusion agent in poultry against C. jejuni.

Enteric Pathogens and Their Toxin-Induced Disruption of the Intestinal Barrier through Alteration of Tight Junctions in Chickens

Maintaining a healthy gut environment is a prerequisite for sustainable animal production. The gut plays a key role in the digestion and absorption of nutrients and constitutes an initial organ exposed to external factors influencing bird’s health. The intestinal epithelial barrier serves as the first line of defense between the host and the luminal environment. It consists of a continuous monolayer of intestinal epithelial cells connected by intercellular junctional complexes which shrink the space between adjacent cells. Consequently, free passing of solutes and water via the paracellular pathway is prevented. Tight junctions (TJs) are multi-protein complexes which are crucial for the integrity and function of the epithelial barrier as they not only link cells but also form channels allowing permeation between cells, resulting in epithelial surfaces of different tightness. Tight junction’s molecular composition, ultrastructure, and function are regulated differently with regard to physiological and pathological stimuli. Both in vivo and in vitro studies suggest that reduced tight junction integrity greatly results in a condition commonly known as “leaky gut”. A loss of barrier integrity allows the translocation of luminal antigens (microbes, toxins) via the mucosa to access the whole body which are normally excluded and subsequently destroys the gut mucosal homeostasis, coinciding with an increased susceptibility to systemic infection, chronic inflammation and malabsorption. There is considerable evidence that the intestinal barrier dysfunction is an important factor contributing to the pathogenicity of some enteric bacteria. It has been shown that some enteric pathogens can induce permeability defects in gut epithelia by altering tight junction proteins, mediated by their toxins. Resolving the strategies that microorganisms use to hijack the functions of tight junctions is important for our understanding of microbial pathogenesis, because some pathogens can utilize tight junction proteins as receptors for attachment and subsequent internalization, while others modify or destroy the tight junction proteins by different pathways and thereby provide a gateway to the underlying tissue. This review aims to deliver an overview of the tight junction structures and function, and its role in enteric bacterial pathogenesis with a special focus on chickens. A main conclusion will be that the molecular mechanisms used by enteric pathogens to disrupt epithelial barrier function in chickens needs a much better understanding, explicitly highlighted for Campylobacter jejuni, Salmonella enterica and Clostridium perfringens. This is a requirement in order to assist in discovering new strategies to avoid damages of the intestinal barrier or to minimize consequences from infections.

Age-Related Differences in the Luminal and Mucosa-Associated Gut Microbiome of Broiler Chickens and Shifts Associated with Campylobacter jejuni Infection

Despite the importance of gut microbiota for broiler performance and health little is known about the composition of this ecosystem, its development and response towards bacterial infections. Therefore, the current study was conducted to address the composition and structure of the microbial community in broiler chickens in a longitudinal study from day 1 to day 28 of age in the gut content and on the mucosa. Additionally, the consequences of a Campylobacter (C.) jejuni infection on the microbial community were assessed. The composition of the gut microbiota was analyzed with 16S rRNA gene targeted Illumina MiSeq sequencing. Sequencing of 130 samples yielded 51,825,306 quality-controlled sequences, which clustered into 8285 operational taxonomic units (OTUs; 0.03 distance level) representing 24 phyla. Firmicutes, Proteobacteria, Bacteroidetes, Actinobacteria, and Tenericutes were the main components of the gut microbiota, with Proteobacteria and Firmicutes being the most abundant phyla (between 95.0 and 99.7% of all sequences) at all gut sites. Microbial communities changed in an age-dependent manner. Whereas, young birds had more Proteobacteria, Firmicutes, and Tenericutes dominated in older birds (>14 days old). In addition, 28 day old birds had more diverse bacterial communities than young birds. Furthermore, numerous significant differences in microbial profiles between the mucosa and luminal content of the small and large intestine were detected, with some species being strongly associated with the mucosa whereas others remained within the luminal content of the gut. Following oral infection of 14 day old broiler chickens with 1 × 10⁸ CFU of C. jejuni NCTC 12744, it was found that C. jejuni heavily colonized throughout the small and large intestine. Moreover, C. jejuni colonization was associated with an alteration of the gut microbiota with infected birds having a significantly lower abundance of Escherichia (E.) coli at different gut sites. On the contrary, the level of Clostridium spp. was higher in infected birds compared with birds from the negative controls. In conclusion, the obtained results demonstrate how the bacterial microbiome composition changed within the early life of broiler chickens in the gut lumen and on the mucosal surface. Furthermore, our findings confirmed that the Campylobacter carrier state in chicken is characterized by multiple changes in the intestinal ecology within the host.

Recent Advances in Screening of Anti-Campylobacter Activity in Probiotics for Use in Poultry

Campylobacteriosis is the most common cause of bacterial gastroenteritis worldwide. Campylobacter species involved in this infection usually include the thermotolerant species Campylobacter jejuni. The major reservoir for C. jejuni leading to human infections is commercial broiler chickens. Poultry flocks are frequently colonized by C. jejuni without any apparent symptoms. Risk assessment analyses have identified the handling and consumption of poultry meat as one of the most important sources of human campylobacteriosis, so elimination of Campylobacter in the poultry reservoir is a crucial step in the control of this foodborne infection. To date, the use of probiotics has demonstrated promising results to reduce Campylobacter colonization. This review provides recent insights into methods used for probiotic screening to reduce the prevalence and colonization of Campylobacter at the farm level. Different eukaryotic epithelial cell lines are employed to screen probiotics with an anti-Campylobacter activity and yield useful information about the inhibition mechanism involved. These in vitro virulence models involve only human intestinal or cervical cell lines whereas the use of avian cell lines could be a preliminary step to investigate mechanisms of C. jejuni colonization in poultry in the presence of probiotics. In addition, in vivo trials to evaluate the effect of probiotics on Campylobacter colonization are conducted, taking into account the complexity introduced by the host, the feed, and the microbiota. However, the heterogeneity of the protocols used and the short time duration of the experiments lead to results that are difficult to compare and draw conclusions at the slaughter-age of broilers. Nevertheless, the combined approach using complementary in vitro and in vivo tools (cell cultures and animal experiments) leads to a better characterization of probiotic strains and could be employed to assess reduced Campylobacter spp. colonization in chickens if some parameters are optimized.

Chicken Anti-Campylobacter Vaccine - Comparison of Various Carriers and Routes of Immunization

Campylobacter spp, especially the species Campylobacter jejuni, are important human enteropathogens responsible for millions of cases of gastro-intestinal disease worldwide every year. C. jejuni is a zoonotic pathogen, and poultry meat that has been contaminated by microorganisms is recognized as a key source of human infections. Although numerous strategies have been developed and experimentally checked to generate chicken vaccines, the results have so far had limited success. In this study, we explored the potential use of non-live carriers of Campylobacter antigen to combat Campylobacter in poultry. First, we assessed the effectiveness of immunization with orally or subcutaneously delivered Gram-positive Enhancer Matrix (GEM) particles carrying two Campylobacter antigens: CjaA and CjaD. These two immunization routes using GEMs as the vector did not protect against Campylobacter colonization. Thus, we next assessed the efficacy of in ovo immunization using various delivery systems: GEM particles and liposomes. The hybrid protein rCjaAD, which is CjaA presenting CjaD epitopes on its surface, was employed as a model antigen. We found that rCjaAD administered in ovo at embryonic development day 18 by both delivery systems resulted in significant levels of protection after challenge with a heterologous C. jejuni strain. In practice, in ovo chicken vaccination is used by the poultry industry to protect birds against several viral diseases. Our work showed that this means of delivery is also efficacious with respect to commensal bacteria such as Campylobacter. In this study, we evaluated the protection after one dose of vaccine given in ovo. We speculate that the level of protection may be increased by a post-hatch booster of orally delivered antigens.

The genomic architecture of resistance to Campylobacter jejuni intestinal colonisation in chickens

BACKGROUND

Campylobacter is the leading cause of foodborne diarrhoeal illness in humans and is mostly acquired from consumption or handling of contaminated poultry meat. In the absence of effective licensed vaccines and inhibitors, selection for chickens with increased resistance to Campylobacter could potentially reduce its subsequent entry into the food chain. Campylobacter intestinal colonisation levels are influenced by the host genetics of the chicken. In the present study, two chicken populations were used to investigate the genetic architecture of avian resistance to colonisation: (i) a back-cross of two White Leghorn derived inbred lines [(61 x N) x N] known to differ in resistance to Campylobacter colonisation and (ii) a 9(th) generation advanced intercross (61 x N) line.

RESULTS

The level of colonisation with Campylobacter jejuni following experimental infection was found to be a quantitative trait. A back-cross experiment using 1,243 fully informative single nucleotide polymorphism (SNP) markers revealed quantitative trait loci (QTL) on chromosomes 7, 11 and 14. In the advanced intercross line study, the location of the QTL on chromosome 14 was confirmed and refined and two new QTLs were identified located on chromosomes 4 and 16. Pathway and re-sequencing data analysis of the genes located in the QTL candidate regions identified potential pathways, networks and candidate resistance genes. Finally, gene expression analyses were performed for some of the candidate resistance genes to support the results.

CONCLUSION

Campylobacter resistance in chickens is a complex trait, possibly involving the Major Histocompatibility Complex, innate and adaptive immune responses, cadherins and other factors. Two of the QTLs for Campylobacter resistance are co-located with Salmonella resistance loci, indicating that it may be possible to breed simultaneously for enhanced resistance to both zoonoses.

Changes in expression of an antimicrobial peptide, digestive enzymes, and nutrient transporters in the intestine of E. praecox-infected chickens

Coccidiosis is a major intestinal disease of poultry, caused by several species of the protozoan Eimeria. The objective of this study was to examine changes in expression of digestive enzymes, nutrient transporters, and an antimicrobial peptide following an Eimeria praecox challenge of chickens at days 3 and 6 post-infection. Gene expression was determined by real-time PCR and analyzed by one-way ANOVA. In the duodenum, the primary site of E. praecox infection, a number of genes were downregulated at both d3 and d6 post-infection. These genes included liver expressed antimicrobial peptide 2 (LEAP2), the cationic (CAT1), anionic (EAAT3), and L-type (LAT1) amino acid transporters, the peptide transporter PepT1 and the zinc transporter ZnT1. Other transporters were downregulated either at d3 or d6. At both d3 and d6, there was downregulation of B(o)AT and CAT1 in the jejunum and downregulation of LEAP2 and LAT1 in the ileum. LEAP2, EAAT3, and ZnT1 have been found to be downregulated following challenge with other Eimeria species, suggesting a common cellular response to Eimeria.

Increased intracellular calcium level and impaired nutrient absorption are important pathogenicity traits in the chicken intestinal epithelium during Campylobacter jejuni colonization

Although a high number of chickens carry Campylobacter jejuni, the mechanistic action of colonization in the intestine is still poorly understood. The current study was therefore designed to investigate the effects of C. jejuni on glucose uptake, amino acids availability in digesta, and intracellular calcium [Ca(2+)]i signaling in the intestines of broiler chickens. For this, we compared: control birds (n = 60) and C. jejuni-infected birds (n = 60; infected orally with 1 × 10(8) CFU of C. jejuni NCTC 12744 at 14 days of age). Our results showed that glucose uptake was reduced due to C. jejuni infection in isolated jejunal, but not in cecal mucosa at 14 days postinfection (dpi). The decrease in intestinal glucose absorption coincided with a decrease in body weight gain during the 2-week post-infectious period. A reduction in the amount of the amino acids (serine, proline, valine, leucine, phenylalanine, arginine, histidine, and lysine) in ileal digesta of the infected birds at 2 and/or 7 dpi was found, indicating that Campylobacter utilizes amino acids as a carbon source for their multiplication. Applying the cell-permeable Ca(2+) indicator Fluo-4 and two-photon microscopy, we revealed that [Ca(2+)]i was increased in the jejunal and cecal mucosa of infected birds. The muscarinic agonist carbachol induced an increase in [Ca(2+)]i in jejunum and cecum mucosa of control chickens, a response absent in the mucosa of infected chickens, demonstrating that the modulation of [Ca(2+)]i by Campylobacter might be involved in facilitating the necessary cytoskeletal rearrangements that occur during the bacterial invasion of epithelial cells. In conclusion, this study demonstrates the multifaceted interactions of C. jejuni with the gastrointestinal mucosa of broiler chickens. For the first time, it could be shown that a Campylobacter infection could interfere with intracellular Ca(2+) signaling and nutrient absorption in the small intestine with consequences on intestinal function, performance, and Campylobacter colonization. Altogether, these findings indicate that Campylobacter is not entirely a commensal and can be recognized as an important factor contributing to an impaired chicken gut health.

Expression of digestive enzymes and nutrient transporters in Eimeria-challenged broilers

Avian coccidiosis is a disease caused by the intestinal protozoa Eimeria. The site of invasion and lesions in the intestine is species-specific, for example E. acervulina affects the duodenum, E. maxima the jejunum, and E. tenella the ceca. Lesions in the intestinal mucosa cause reduced feed efficiency and body weight gain. The growth reduction may be due to changes in expression of digestive enzymes and nutrient transporters in the intestine. The objective of this study was to compare the expression of digestive enzymes, nutrient transporters and an antimicrobial peptide in broilers challenged with either E. acervulina, E. maxima or E. tenella. The genes examined included digestive enzymes (APN and SI), peptide and amino acid transporters (PepT1, ASCT1, b(0,+)AT/rBAT, B(0)AT, CAT1, CAT2, EAAT3, LAT1, y(+)LAT1 and y(+)LAT2), sugar transporters (GLUT1, GLUT2, GLUT5 and SGLT1), zinc transporter (ZnT1) and an antimicrobial peptide (LEAP2). Duodenum, jejunum, ileum and ceca were collected 7 days post challenge. E. acervulina challenge resulted in downregulation of various nutrient transporters or LEAP2 in the duodenum and ceca, but not the jejunum or ileum. E. maxima challenge produced both downregulation and upregulation of nutrient transporters and LEAP2 in all three segments of the small intestine and ceca. E. tenella challenge resulted in the downregulation and upregulation of nutrient transporters and LEAP2 in the jejunum, ileum and ceca, but not the duodenum. At the respective target tissue, E. acervulina, E. maxima and E. tenella infection caused common downregulation of APN, b(0,+)AT, rBAT, EAAT3, SI, GLUT2, GLUT5, ZnT1 and LEAP2. The downregulation of nutrient transporters would result in a decrease in the efficiency of protein and polysaccharide digestion and uptake, which may partially explain the weight loss. The downregulation of nutrient transporters may also be a cellular response to reduced expression of the host defense protein LEAP2, which would diminish intracellular pools of nutrients and inhibit pathogen replication.