Efficacy of Scrophularia striata hydroalcoholic extract and mannan-oligosaccharide on productive performance, intestinal bacterial community, and immunity in broiler chickens after infection with Campylobacter jejuni

The Role of Dietary Supplementation of Yeast Cell Walls in Response to a Campylobacter jejuni Inoculation in Broiler Chickens

Controlling Campylobacter jejuni during broiler production is a topic of interest from a public health standpoint, as colonized birds can contaminate poultry products during processing and sicken humans if not properly cooked or handled before consumption. The aim of this study was to evaluate dietary yeast cell wall (YCW) as a potential alternative to antibiotic growth promoters with or without a C. jejuni challenge. A total of 2240 day-old Ross 708 males were randomly assigned within 8 experimental groups with a 4 × 2 factorial design, with 4 diets (negative control [CTL-], positive control [CTL+, bacitracin, 50 g/ ton], YCW constant dose [400 g/ton], and YCW step-down dose [SD, 800, 400, and 200 g/ton in the starter, grower, and finisher periods, respectively]) and with or without a Day-16 C. jejuni oral gavage challenge at a 103-colony-forming-units (CFU)/ml dose. Body weights and feed consumption were measured on Days 0, 14, 28, and 41 to determine broiler performance. Ileum tissue samples were collected from 24 birds per treatment on Days 17 and 24 (1 and 8 days postinoculation [PI]) for relative gene expression (RGE) analysis. Cecal content samples were collected from 24 birds per treatment on Days 24, 34, and 42 for C. jejuni enumeration and prevalence calculation. A total of 80 birds per treatment were processed to determine carcass yield on Day 44, and on Day 45, 16 carcass rinsates per treatment were collected for C. jejuni enumeration and prevalence calculation. The interaction between diet and inoculation did not influence growth performance (P > 0.05). However, a diet effect was observed in the starter period where birds fed SD diet had a lower feed conversion ratio than birds fed CTL- diet (P = 0.0165). Additionally, the treatment of birds inoculated with C. jejuni fed with SD had a trend to a lower feed conversion ratio during the grower period (P = 0.0550). The RGE of interleukin 1β and interleukin 10 was similar in all treatments 1 and 8 days PI. The RGE of avian beta defensin 10 was similar in all treatments on Day 1 PI, but different on Day 8 PI (P = 0.0476). All birds inoculated with C. jejuni had similar CFU per milliliter counts in the cecal contents at Days 24, 34, and 42 (P > 0.05), and all birds inoculated with phosphate-buffered saline were negative for C. jejuni after prevalence testing. After processing 1) carcass yield was similar in all treatments (P > 0.05); 2) C. jejuni-inoculated birds fed CTL- had lower CFU per milliliter counts than birds provided CTL+ and constant-dose diets (P = 0.0383); and 3) all birds inoculated with PBS were negative for Campylobacter. Overall, under the conditions of this study, the addition of YCW during a C. jejuni challenge did not have an impact on growth performance, innate immune response, cecal colonization, carcass yield, or carcass colonization after processing.

Campylobacter jejuni: targeting host cells, adhesion, invasion, and survival

Campylobacter jejuni, causing strong enteritis, is an unusual bacterium with numerous peculiarities. Chemotactically controlled motility in viscous milieu allows targeted navigation to intestinal mucus and colonization. By phase variation, quorum sensing, extensive O-and N-glycosylation and use of the flagellum as type-3-secretion system C. jejuni adapts effectively to environmental conditions. C. jejuni utilizes proteases to open cell-cell junctions and subsequently transmigrates paracellularly. Fibronectin at the basolateral side of polarized epithelial cells serves as binding site for adhesins CadF and FlpA, leading to intracellular signaling, which again triggers membrane ruffling and reduced host cell migration by focal adhesion. Cell contacts of C. jejuni results in its secretion of invasion antigens, which induce membrane ruffling by paxillin-independent pathway. In addition to fibronectin-binding proteins, other adhesins with other target structures and lectins and their corresponding sugar structures are involved in host-pathogen interaction. Invasion into the intestinal epithelial cell depends on host cell structures. Fibronectin, clathrin, and dynein influence cytoskeletal restructuring, endocytosis, and vesicular transport, through different mechanisms. C. jejuni can persist over a 72-h period in the cell. Campylobacter-containing vacuoles, avoid fusion with lysosomes and enter the perinuclear space via dynein, inducing signaling pathways. Secretion of cytolethal distending toxin directs the cell into programmed cell death, including the pyroptotic release of proinflammatory substances from the destroyed cell compartments. The immune system reacts with an inflammatory cascade by participation of numerous immune cells. The development of autoantibodies, directed not only against lipooligosaccharides, but also against endogenous gangliosides, triggers autoimmune diseases. Lesions of the epithelium result in loss of electrolytes, water, and blood, leading to diarrhea, which flushes out mucus containing C. jejuni. Together with the response of the immune system, this limits infection time. Based on the structural interactions between host cell and bacterium, the numerous virulence mechanisms, signaling, and effects that characterize the infection process of C. jejuni, a wide variety of targets for attenuation of the pathogen can be characterized. The review summarizes strategies of C. jejuni for host-pathogen interaction and should stimulate innovative research towards improved definition of targets for future drug development. KEY POINTS: • Bacterial adhesion of Campylobacter to host cells and invasion into host cells are strictly coordinated processes, which can serve as targets to prevent infection. • Reaction and signalling of host cell depend on the cell type. • Campylobacter virulence factors can be used as targets for development of antivirulence drug compounds.

Effects of dietary yeast cell wall supplementation on growth performance, intestinal Campylobacter jejuni colonization, innate immune response, villus height, crypt depth, and slaughter characteristics of broiler chickens inoculated with Campylobacter jejuni at d 21

A study was conducted to assess the effects of a dietary yeast cell wall (YCW) with and without a Campylobacter jejuni (CJ) challenge. A total of 2,240-day-old Ross 708 males were randomly assigned within 8 treatments with a 4 × 2 factorial design, with 4 diets (negative control, positive control, YCW constant dose (400 g/ton), and YCW step-down dose (800/400/200 g/ton in the starter/grower/finisher diets, respectively) and with and without d 21 CJ oral gavage challenge at 5.2 × 10⁷ CFU/mL. At d 0, 14, 28, and 41 body weights and feed consumption were measured to determine performance. At d 14, 28, and 42, 8 jejunal and ileal histology samples per treatment were collected for villi morphology measurements. At d 22 and 28 (1- and 7-days postinoculation), 24 ileal tissue samples per treatment were collected for relative gene expression analysis. At d 42, 24 cecal content samples per treatment were collected for CJ enumeration. Finally, on d 44, 96 birds per treatment were processed to determine carcass yield and 16 carcass rinses per treatment were collected to determine CJ prevalence after processing. Diet or inoculation did not impact broiler performance (P > 0.05). Limited differences were observed in intestinal morphology, and villus height and crypt depth were different only in the ileum at d 42 (P = 0.0280 and P = 0.0162, respectively). At d 1 postinoculation, differences between treatments inoculated with CJ and PBS were observed in the expression of avian beta defensin 10 (AvBD10), interleukin 1ß (IL-1ß), and interleukin 10 (IL-10) (P < 0.05). At d 7 postinoculation, expression of AvBD10, IL-1ß, and IL-10 was similar among all treatments (P > 0.05). At d 42, all birds, regardless the inoculation, had similar levels of CJ recovered from cecal contents (P > 0.05). After processing, carcass yield and CJ prevalence postchilling was similar in all treatments (P > 0.05). Overall, under the conditions of this study, the addition of YCW during a CJ challenge did not have an impact in growth performance, innate immune response, cecal colonization, carcass yield, or CJ prevalence after processing.