Salmonella Enteritidis Challenge Research Articles

Short communication: Effects of a commercial triple-strain Bacillus-based probiotic on cecal colonization with Salmonella Enteritidis in commercial layer pullets

A commercial triple-strain Bacillus-based probiotic was tested to determine its effect on the colonization of the ceca by Salmonella Enteritidis (SE) in commercial layer pullets. Two treatments were tested, each with containing 128 day-of-hatch LSL layer chicks. On top of a standard diet: 1) no supplement (Control, CON), and 2) Probiotic (GalliPro® Fit, 500 g/MT, 1.6 × 106 CFU/g of finished feed, PRO). Environmental swabs were collected from each treatment group and tested to ensure freedom from SE prior to challenge. At 21 days of age, the SE challenge strain was administered orally at a dose of 3.3 × 108 CFU/bird. Pullets from each treatment group (n=32) were euthanized at 6-, 10-, 14-, and 18-days post infection (dpi). Contents from the ceca were aseptically collected and assessed for presence and abundance of SE. No differences in the prevalence of SE positive ceca following oral inoculation (P>0.05) were observed between treatment groups at 6-, 10-, 14-, or 18-dpi. Counts of SE in the ceca of the PRO group were not significantly different (P>0.05) from those of CON at 6- or 10-dpi. However, significantly lower counts of SE in the ceca of the PRO group were observed at 14-dpi (P<0.05) and 18-dpi (P<0.05) compared with CON. SE counts were 1.24 and 1.34 logs lower than CON at 14- and 18-dpi, respectively. In conclusion, supplementation of the triple-strain Bacillus-based probiotic resulted in lower cecal counts of SE compared to those that did not receive an effective probiotic, thereby reducing the risk of foodborne pathogens prior to harvest through sustainable, natural methods.

Bacitracin Methylene Disalicylate (BMD) Treatment Affects Spleen Proteome in Broiler Chicks Infected with Salmonella enteritidis.

Bacitracin Methylene Disalicylate (BMD), as a feed additive to poultry diets, enhances digestion, prevents Salmonella enteritidis (SE) colonization, and treats current infections. The objective of this study was to utilize a quantitative proteomic approach to determine the effect of BMD feed additive on broiler chickens challenged with SE in the spleen proteome. At 1 d of age, chicks were randomly allocated into four groups: control with and without SE challenge (CON, n = 60; CON-SE, n = 60), BMD with and without SE challenge (BMD, n = 60; BMD-SE, n = 60). Birds in the CON-SE and BMD-SE treatment were administered SE inoculum by oral gavage. On day three and day seven post-gavage, the spleen was collected aseptically from birds in each treatment group (CON, n = 4/day; CON-SE, n = 4/day; BMD, n = 4/day; BMD-SE, n = 4/day). Proteomic analysis by liquid chromatography-tandem mass spectrometry (LC-MS/MS) showed an increased abundance of 115 proteins and decreased of 77 due to the BMD. Proteins that decreased in abundance were enriched for fibrinogen complex and extracellular space, whereas proteins that increased in abundance were enriched for proteasome-mediated ubiquitin-dependent protein catabolic process and mitochondrion. Analysis of the interaction between BMD and the Salmonella challenge found 230 differentially abundant proteins including proteins associated with RNA binding, spliceosome, protein transport, and cell adhesion among the upregulated proteins, and those associated with protein folding, carbon metabolism, biosynthesis of nucleotide sugars, response to oxidative stress, positive regulation of NIK/NF-kappaB signaling, and inflammatory response among the downregulated proteins. The impact of BMD treatment on spleen proteome indicates an anti-apoptotic effect. BMD also modified the response of the spleen to the SE challenge with a marked decrease in proteins that prompt cytokine synthesis and an increase in proteins involved in the selective removal of unfolded proteins.

Red osier dogwood extract versus Trimethoprim-sulfadiazine (Part 1). Effects on the growth performance, blood parameters, gut histomorphometry, and Salmonella excretion of broiler chickens orally challenged with Salmonella Enteritidis

The poultry industry has not been spared from the prevalent incidence of diseases caused by invasive pathogens, especially Salmonella. Due to the pressing need to identify a suitable antibiotic alternative for use in poultry production, this study investigated the efficacy of red osier dogwood (ROD) extract on the growth, blood parameters, gut morphology, and Salmonella excretion in broiler chickens orally challenged with Salmonella Enteritidis (SE). A 4×2 factorial experiment was conducted based on 2 main factors, namely dietary treatments, and SE challenge. A total of 404, one-day-old male Ross broiler chicks were randomly assigned to 4 dietary treatments; 1) Negative control (NC), 2) NC+0.075 ppm of Trimethoprim-sulfadiazine (TMP/SDZ)/kg of diet, 3) NC+0.3% ROD extract, and 4) NC+0.5% ROD extract. The absence of SE in the fecal samples obtained from chick delivery boxes was confirmed on d 0. On d 1, half of the birds were orally gavaged with 0.5 mL of phosphate-buffered saline each (noninfected group) and the remaining with 0.5 mL of 3.1×105 CFU/mL SE (infected group) in all treatment groups. Dietary treatments were randomly assigned to 8 replicate cages at 6 birds/cage. On 1-, 5-, 12-, and 18-day postinfection (DPI), cloacal fecal samples were collected on the 6 birds/cage to assess SE excretion. Average weight gain (AWG), average feed intake (AFI), feed conversion ratio (FCR), and mortality were determined weekly. On d 21, 10 chickens/treatment were euthanized to perform hematology, gut histomorphometry, serum immunoglobulins G and M (IgG and IgM), and superoxide dismutase measurements. Both ROD extract levels did not affect (P > 0.05) growth performance; however, the SE-infected birds showed increased (P < 0.05) AFI and FCR throughout the experimental period. Regardless of the SE-infection, both ROD extract levels improved (P < 0.05) duodenal villus height: crypt depth compared to other treatments. 0.5% ROD extract improved (P < 0.05) ileal villus width (VW) of noninfected birds and ileal crypt depth of infected birds, but it decreased (P < 0.05) the ileal VW of infected birds, compared to other treatments. The SE-infected birds showed lower (P < 0.05) lymphocytes (L) but increased (P < 0.05) heterophils (H), H:L, and monocytes (MON). Both ROD extract levels did not affect (P > 0.05) white blood cell differential, while dietary 0.3% ROD extract increased (P < 0.05) MON of the birds, regardless of infection model. Regardless of infection model, both TMP/SDZ and 0.5% ROD extract reduced the concentration of IgM in the serum, compared to the control and 0.3% ROD (P=0.006). Conclusively, both ROD extract levels improved duodenal histomorphology and body defense against SE infection in broiler chickens; however, the 0.3% ROD extract was better.

Effect of a Saccharomyces cerevisiae Postbiotic Feed Additive on Salmonella Enteritidis Colonization of Cecal and Ovarian Tissues in Directly Challenged and Horizontally Exposed Layer Pullets.

Determining the efficacy of feed-additive technologies utilized as pre-harvest food-safety interventions against Salmonella enterica may be influenced by factors including, but not limited to, mechanism of action, experimental design variables, Salmonella serovar(s), exposure dose, route, or duration in both controlled research and real-world field observations. The purpose of this study was to evaluate the dietary inclusion of a Saccharomyces cerevisiae fermentation-derived postbiotic (SCFP) additive (Diamond V, Original XPC®) on the colonization of cecal and ovarian tissues of commercial pullets directly and indirectly exposed to Salmonella Enteritidis (SE). Four hundred and eighty commercial, day-of-age W-36 chicks were randomly allotted to 60 cages per treatment in two identical BSL-2 isolation rooms (Iowa State University) with four birds per cage and fed control (CON) or treatment (TRT) diets for the duration of study. At 16 weeks, two birds per cage were directly challenged via oral gavage with 1.1 × 109 CFU of a nalidixic-acid-resistant SE strain. The remaining two birds in each cage were thus horizontally exposed to the SE challenge. At 3, 7, and 14 days post-challenge (DPC), 20 cages per group were harvested and sampled for SE prevalence and load. No significant differences were observed between groups for SE prevalence in the ceca or ovary tissues of directly challenged birds. For the indirectly exposed cohort, SE cecal prevalence at 7 DPC was significantly lower for TRT (50.0%) vs. CON (72.5%) (p = 0.037) and, likewise, demonstrated significantly lower mean SE cecal load (1.69 Log10) vs. CON (2.83 Log10) (p = 0.005). At 14 DPC, no significant differences were detected but ~10% fewer birds remained positive in the TRT group vs. CON (p > 0.05). These findings suggest that diets supplemented with SCFP postbiotic may be a useful tool for mitigating SE colonization in horizontally exposed pullets and may support pre-harvest food-safety strategies.

Red osier dogwood extract vs. trimethoprim-sulfadiazine (Part 2). Pharmacodynamic effects on ileal and cecal microbiota of broiler chickens challenged orally with Salmonella Enteritidis

With the subsisting restrictions on the use of antibiotics in poultry production, the use of plant extracts has shown some promising antimicrobial capacity similar to antibiotics; however, such capacity is largely dependent on their total polyphenol concentration and profile. Given the emerging antimicrobial potential of red osier dogwood (ROD) extract, the study aimed to investigate the pharmacodynamic effect of ROD extract on the ileal and cecal microbiota of broiler chickens challenged orally with Salmonella Enteritidis (SE). A 21 d 4×2 factorial experiment was conducted based on 2 main factors, including diets and SE challenge. A total of 384 one-day-old mixed-sex Cobb-500 broiler chicks were randomly allotted to 4 dietary treatments; Negative control (NC), NC+0.075 mg trimethoprim-sulfadiazine (TMP/SDZ)/kg of diet, and NC containing either 0.3 or 0.5% ROD extract. On d 1, half of the birds were orally challenged with 0.5 mL of phosphate-buffered saline (Noninfected group) and the remaining half with 0.5 mL of 3.1×105 CFU/mL SE (Infected group). Dietary treatments were randomly assigned to 8 replicate cages at 6 birds/cage. On d 21, 10 birds/treatment were euthanized and eviscerated to collect ileal and cecal digesta for gut microbiota analysis. The ileal and cecal microbiota was dominated by phyla Firmicutes, Proteobacteria, and Actinobacteriota. The SE infection decreased (P < 0.05) the relative abundance of Proteobacteria and Actinobacteriota in the ileum and ceca, respectively, however, it increased (P < 0.05) Proteobacteria in the ceca. Both 0.3 and 0.5% ROD extracts (P < 0.05) depressed the relative abundance of Actinobacteriota in the ileum but marginally improved (P < 0.05) it in the ceca compared to the TMP/SDZ treatment. Dietary TMP/SDZ increased (P < 0.05) genus Bifidobacterium at the ileal and cecal segments compared to other treatments. Dietary 0.3 and 0.5% marginally improved (P < 0.05) Bifidobacterium in the ceca and depressed (P < 0.05) Weissella and was comparably similar to TMP/SDZ in the ileum. Regardless of the dietary treatments and SE infection, alpha diversity differed (P < 0.05) between ileal and cecal microbiota. Beta diversity was distinct (P < 0.05) in both ileal and cecal digesta along the SE infection model. Conclusively, both ROD extract levels yielded a pharmacodynamic effect similar to antibiotics on ileal and cecal microbiota.

Cytokines and cecal microbiome modulations conferred by a dual vaccine in Salmonella-infected layers

Zoonotic Salmonella infection is a critical and challenging issue for public health. Since human infections are mainly associated with consuming contaminated chicken products, strategies to reduce Salmonella carriage and shedding are essential. Here we investigate the mechanisms of the live attenuated Salmonella vaccine (AviPro Salmonella Duo) against Salmonella Enteritidis (SE) infection. We focused on inflammatory-related cytokine expressions and cecal microbiota modulations in specific-pathogen-free (SPF) and field layers. Forty-eight 2-day-old SPF layers were randomly allotted into S.SEvc, S.SEc, S.Vc, and S.Ct groups in trial 1. The equal number of filed layers at 25 wk were allocated into SEvc, SEc, Vc, and Ct groups in trial 2. Each group contained 12 layers. Groups were further assigned for vaccination (S.Vc and Vc groups), SE challenge (S.SEc and SEc groups), vaccination and the following SE challenge (S.SEvc and SEvc groups), or the placebo treatment (S.Ct and Ct groups). Cecal tissues and contents of layers on day 14 post-SE-challenges were collected for cytokine mRNA expression and 16S rRNA metagenomic analyses. We found that SE challenges significantly upregulated expressions of IFNγ, IL-1β, IL-12β, and NFκB1A in SPF layers. The vaccine notably counteracted the levels of IFNα, IFNγ, and NFκB1A activated by SE attacks. The vaccination, SE challenge, and their combination did not significantly affect alpha diversities but promoted dissimilarities in microbial communities between groups. Eubacterium_coprostanoligenes and Faecalibacterium_prausnitzii were identified as contributory taxa in the cecal microbiota of SE-challenged and vaccinated SPF layers. A significantly higher abundance of Faecalibacterium_prausnitzii in the ceca further correlated with the vaccination conferred protection against SE infection. In contrast, Oscillibacter_valericigenes and Mediterraneibacter_glycyrrhizinilyticus were featured taxa in Salmonella-infected field layers. Megamonas_hypermegale and Megamonas_rupellensis were identified as featured taxa in vaccinated field layers compared to SE-infected layers. To conclude, applying a dual Salmonella vaccine in this study modulated expressions of inflammatory-related cytokines and the cecal microbiome in layers, contributing to protection against SE infection. The feature microbes are promising for developing predictive indices and as antibiotic alternatives added to feed to reduce the risk of Salmonella shedding and contamination.

The functional role of fecal microbiota transplantation on Salmonella Enteritidis infection in chicks

The intestinal microbiota plays important roles in animal health and growth. We investigated the efficacy and mechanisms of fecal microbiota transplantation (FMT) from adult SPF chickens against Salmonella Enteritidis (SE) infection in chicks. We transplanted 160 recipient SPF chicks (1-day-old) that were randomly divided into four groups, Ca (challenge), Cb (non-challenge), Fa (FMT and challenge) and Fb (FMT without challenge). The experiment lasted 40 days. We found that FMT reduced mortality as well as liver inflammatory lesions, promoted weight gain, improved immunity, ameliorated the digestion and absorption ability and inhibited SE colonization in the liver of challenged chicks. 16S rRNA gene high-throughput sequencing indicated that SE challenge caused a significant increase in the relative abundance of Parasutterella in the cecal microbiota of the recipient chicks (P < 0.05). FMT led to the maturation of the intestinal flora of recipients and the relative abundance of the Bacteroides, Rikenellaceae_ RC9_ gut_ group, Prevotellaceae_ UCG_ 001, Prevotellaceae_ Ga6A1_ group and Parabacteroides was significantly increased (P < 0.05). FMT from adult SPF chickens regulated the intestinal microbiota of chicks and increased resistance to SE infection.

Vitamin K alleviates bone calcium loss caused by Salmonella Enteritidis through carboxylation of osteocalcin

BackgroundThe present study aimed at evaluating the effect of vitamin K (VK) supplementation on bone health of laying hens challenged by Salmonella Enteritidis.MethodsA total of 80 32-week-old double negative salmonella-free brown-egg laying hens were randomly assigned to 4 treatments with 20 replicates each (1 bird per replicate) according to a 2 × 2 factorial design with 2 dietary VK supplementation levels [0 mg/kg (VK0) vs 2 mg/kg VK (VK2) and 2 challenge treatments [Salmonella Enteritidis (SE) vs physiological saline solution (PS)]. During the last 3 days of week 43 of age, birds of both VK treatments were either orally challenged with 1.0 mL suspension of 109 cfu/mL S. Enteritidis daily or received the same volume of PS.ResultsThe laying rate, daily egg mass, tibia strength, CT, cOC and cOC/(cOC + ucOC) of VK2 treatment increased (P < 0.05) in contrast to VK0, however, the medullary area and ucOC of VK2 treatment decreased (P < 0.05) in contrast to VK0. Mortality, medullary area, serum Ca content of SE treatments increased (P < 0.05) in contrast to PS treatments. In both SE treatments, the decrease (P < 0.05) in birds’ tibia strength was associated with higher (P < 0.05) Ca levels in serum. There is an interaction (P < 0.05) between SE challenge and VK levels with regard to tibia strength and serum Ca levels. At week 42, serum CT was positively correlated with cOC (R = 0.99, P = 0.009); at week 44, tibia strength was positively correlated with BMD (R = 0.95, P = 0.045), but negatively correlated with medullary area (R = − 0.98, P = 0.018).ConclusionsVK (2 mg/kg) supplementation to diets of laying hens can enhance bone strength under challenge situations with Salmonella Enteritidis. Medullary area has proven to be a sensitive biomarker for bone calcium loss caused by SE infection.

Evaluation of transfer of maternal immunity to the offspring of broiler breeders vaccinated with a candidate recombinant vaccine against Salmonella Enteritidis

Salmonella Enteritidis (SE) is a major cause of foodborne diseases in humans being frequently related to the consumption of poultry products. Therefore, guaranteeing early immunity to chicks is an important tool to prevent the colonization and infection by this pathogen. The present study evaluated the effectiveness of a candidate recombinant vaccine against SE. Thirty female and five male broiler breeders that were ten weeks-old were divided into 3 groups: unvaccinated (UV), vaccinated with recombinant vaccine candidate (VAC) and vaccinated with commercial bacterin (BAC). Samples of serum and embryonated egg were collected at seven and twelve weeks after the booster dose to quantify the transfer rate of IgY to egg yolks and offspring. Subsequently, forty day-old offspring were divided into two groups (UV and VAC) and challenged on the following day with 107 CFU/chick of SE. Samples of serum, intestine, liver, and cecal content were harvested. Throughout the experiment period, significantly higher levels of IgY were observed in the egg yolk and also in the serum of broiler breeders and offspring of the VAC group in comparison to the UV group. In addition, increased transfer rates of IgY were observed in the VAC group when compared to the BAC group. Furthermore, higher villus-crypt ratios were found out in duodenum, jejunum and ileum at four days post-infection in the offspring from the VAC group. A high challenge dose of SE (107 CFU per chick) was used and despite the stronger humoral immune response provoked by the candidate vaccine, there were no statistical differences in the recovery of viable SE cells from the offspring cecal contents. Therefore, the effect of vaccination to improve intestinal quality may affect the development of the chickens and consequently increase the resistance to lower SE challenge doses.

Effects of Essential Oils-Based Supplement and Salmonella Infection on Gene Expression, Blood Parameters, Cecal Microbiome, and Egg Production in Laying Hens.

Simple SummarySalmonellosis is one of the most severe zoonotic diseases transmitted to humans through animal products (especially poultry meat and eggs). Essential oils (EOs)-based feed additives in poultry nutrition are a possible alternative replacement of antimicrobials to fight this infection. In the present study on laying hens, we tested a phytobiotic, Intebio®, and elucidated formation of immune response and changes in cecal microbiocenosis and biochemical/immunological variables in blood caused by Salmonella. Changes in differential gene expression were observed at both one and seven days post-inoculation in the hens’ intestines, revealing similarities with known mammalian/human tissue-specific expression. The results of this study suggest that the challenge of birds with Salmonella had a negative effect, while phytobiotic intake had a positive effect on the status of their gastrointestinal microbiome, their level of metabolism, and their performance.One of the main roles in poultry resistance to infections caused by Salmonella is attributed to host immunity and intestinal microbiota. We conducted an experiment that involved challenging Lohmann White laying hens with Salmonella Enteritidis (SE), feeding them a diet supplemented with an EOs-based phytobiotic Intebio®. At 1 and 7 days post-inoculation, the expression profiles of eight genes related to immunity, transport of nutrients in the intestine, and metabolism were examined. Cecal microbiome composition and blood biochemical/immunological indices were also explored and egg production traits recorded. As a result, the SE challenge of laying hens and Intebio® administration had either a suppressive or activating effect on the expression level of the studied genes (e.g., IL6 and BPIFB3), the latter echoing mammalian/human tissue-specific expression. There were also effects of the pathogen challenge and phytobiotic intake on the cecal microbiome profiles and blood biochemical/immunological parameters, including those reflecting the activity of the birds’ immune systems (e.g., serum bactericidal activity, β-lysine content, and immunoglobulin levels). Significant differences between control and experimental subgroups in egg performance traits (i.e., egg weight/number/mass) were also found. The phytobiotic administration suggested a positive effect on the welfare and productivity of poultry.

Dietary Inulin Supplementation Modulates Short-Chain Fatty Acid Levels and Cecum Microbiota Composition and Function in Chickens Infected With Salmonella.

The current study investigated the effects of inulin on the gut microbiota, microbiome functions, and short-chain fatty acids (SCFAs) levels in specific pathogen-free (SPF) chickens infected with Salmonella enteritidis (SE). SPF Arbor Acres chickens (n = 240, 1-day-old) were divided into four groups: a control group (CON) fed a basal diet without inulin supplementation or SE infection, and three groups fed a basal diet supplemented with inulin 0, 0.5, and 1% (SE, 0.5%InSE, 1%InSE, respectively) up to 28-days-old, followed by SE challenge at 28 days of age. Cecal SCFA contents and microbiome composition and function were analyzed at 1-day post-infection. The results showed that SE infection significantly decreased cecal butyrate concentrations compared with the CON group (p < 0.05), while inulin supplementation reversed these changes compared with the SE group (p < 0.05). Inulin supplementation at 1% significantly increased the abundances of Lactobacillus and Streptococcus, and significantly decreased the abundances of Subdoligranulum and Sellimonas compared with the SE group (p < 0.05). The functional profiles of microbial communities based on metagenomic sequencing analysis showed that SE infection significantly increased the abundances of pathways related to carbohydrate metabolism, amino acid metabolism, energy metabolism, metabolism of cofactors and vitamins, and glycan biosynthesis and metabolism (p < 0.05), and significantly decreased the abundances of pathways related to nucleotide metabolism, translation, and replication and repair compared with the CON group (p < 0.05), and these effects were reversed by inulin supplementation (0.5 and 1%) (p < 0.05). In conclusion, inulin modulated the dysbiosis induced by SE infection via affecting SCFA metabolism and microbial functional profiles.

Dietary supplementation with vitamin C ameliorates the adverse effects of Salmonella Enteritidis-challenge in broilers by shaping intestinal microbiota

Salmonella Enteritidis (SE) infection is not only a leading cause of poor production performance and compromised animal welfare in broilers but also a potential threat to public health. Two experiments were conducted to evaluate the effects of dietary supplemental vitamin C (VC) on SE challenged-broilers. In experiment 1, one hundred eighty 1-day-old Arbor Acre broilers were randomly allocated into 3 treatments, with 0, 500, or 1,000 mg/kg VC included in the diet. In experiment 2, dietary VC at 0 or 500 mg/kg, with or without SE challenge was applied in a 2 × 2 factorial arrangement in 6 randomized complete blocks. In experiment 1, addition with 500 mg/kg VC increased BW and infectious bursal disease (IBD) titer of broilers on 35 D (P < 0.05), whereas 1,000 mg/kg VC had no effects on the IBD titer (P > 0.05) compared with the control group. In experiment 2, SE challenge depressed BW on 11 and 21 D (P < 0.05 and P = 0.088, respectively), whereas increased mortality and hepatic bacterial translocation (P < 0.05) on 21 D. Further, SE challenge resulted in lower villus height in jejunum, lower microbial richness, and diversity, whereas higher abundance of Enterobacteriaceae in cecum (P < 0.05). Importantly, supplementation with VC increased BW on both 21 and 35 D (P < 0.05 and P = 0.088, respectively) and enhanced the intestinal health by improving villus morphology and microbial structure as indicated by higher cecal microbial richness and Firmicutes to Bacteroidetes ratio, while lower abundance of Enterobacteriaceae (P < 0.05). In addition, birds fed with 500 mg/kg VC in the diet had significantly increased jejunal secretory immunoglobulin A levels, T lymphocytes stimulation index, and serum total antioxidant capability compared with groups without VC (P < 0.05). In conclusion, SE challenge induced lower production performance and higher mortality in broilers. However, dietary supplementation with VC ameliorated SE-caused damage in broilers by improving the intestinal health, partly mediated by shaping the structure of cecal microbiota.

The Simultaneous Administration of a Probiotic or Prebiotic with Live Salmonella Vaccine Improves Growth Performance and Reduces Fecal Shedding of the Bacterium in Salmonella-Challenged Broilers.

Simple SummaryThe current study was performed to study the efficacy of live Salmonella Enteritidis (SE) vaccine alone and with simultaneous administration of probiotic or prebiotic on broiler chickens. The using of probiotic or prebiotic products administered via drinking water enhanced the growth performance of broiler chickens experimentally challenged with SE at the 28th day of age. The use of probiotic or prebiotic simultaneously with the live Salmonella vaccine can diminish the negative effect of live vaccines in terms of the growth performance, mortality rate, fecal shedding and organ re-isolation of SE. It is therefore a good strategy to relieve the negative effect of the harmful bacterium and improve the growth performance of broilers.Salmonellosis is one of the most important bacterial diseases in poultry, causing heavy economic losses, increased mortality and reduced production. The aim of this study was the comparative efficacy of a commercial probiotic and/or prebiotic with a live attenuated Salmonella Enteritidis (SE) vaccine on the protection of broiler chickens from SE challenge. The efficacy of probiotic or prebiotic products, as well as a live Salmonella Enteritidis (SE) vaccine at the 7th day of age, administered via drinking water, were evaluated for clinical protection and effects on growth performance of broiler chickens experimentally challenged with SE at the 28th day of age. The use of probiotic or prebiotic simultaneously with the live Salmonella vaccine can diminish the negative effect of live vaccine growth performance, reducing mortality rate, fecal shedding, and re-isolation of SE from liver, spleen, heart and cecum. The use of probiotic or prebiotic simultaneously with the application of the live Salmonella vaccine is a good practice to diminish the negative effect of the harmful bacteria and improve the growth performance of broilers. Thus, further studies may be carried out with layers and breeders.

Protective Effect of Vitamin E on laying performance, antioxidant capacity, and immunity in laying hens challenged with Salmonella Enteritidis

Vitamin E (VE) has proven to function as potent lipid-soluble antioxidant, a signaling molecule, and a regulator of the immune system. The objective of the study was to assess the protective effect of VE on laying performance, antioxidant capacity, and immunity in laying hens exposed to Salmonella Enteritidis (SE). A total of 80 32-week-old salmonella-free double negative Hy-Line brown laying hens were randomly assigned to 4 treatments with 20 replicates each (1 bird per replicate) according to a 2 × 2 factorial design with 2 VE supplementation levels [0IU/kg (VE0) vs. 30IU/kg (VE30)], and 2 challenge treatments [SE vs. physiological saline solution (PS)]. During the last 3 D of week 43 of age, birds were orally challenged with 1.0mL suspension of 109 cfu/mL S. Enteritidis daily, whereas the birds of negative treatments (VE0) received the same volume of PS. The egg mass of VE0 treatment decreased (P < 0.05) in contrast to VE treatment after challenge. The serum concentrations of interleukins (IL-1β and IL-6) and malondialdehyde (MDA) levels of SE treatments increased (P < 0.05) at week 44 and week 46, respectively. In both VE30 treatments, the decrease (P < 0.05) in birds' mortality was associated with higher IgA, IgG, IgM concentrations at week 44, and higher IgA, IgM concentrations at week 46. There is an interaction (P < 0.05) between SE challenge and VE levels with regard to feed conversion, daily egg mass, and serum MDA, IgA, and IgM levels. It can be concluded that supplemental VE (30IU/kg) in diets for laying hens may alleviate oxidative and immune stress due to SE challenge.

Comparative transcriptome analysis reveals PERP upregulated during Salmonella Enteritidis challenge in laying ducks.

Salmonella Enteritidis (SE) can be transmitted to eggs through cecum or the ovary from infected layers and causes food poisoning in humans. The mechanism of cecal transmission has been extensively studied. However, the mechanism and route of transovarian transmission of SE remain unclear. In this study, the ducks were orally inoculated with SE, and the ovarian follicles and stroma were collected to detect SE infection. The immune responses were triggered and the innate and adaptive immune genes (TLR4, NOD1, AvβD7, and IL-1β) were upregulated significantly during the SE challenge. Moreover, the ovary tissues (small follicle and stroma) of susceptible and resistant-laying ducks were performed by RNA sequencing. We obtained and identified 23 differentially expressed genes (DEGs) between susceptible and resistant-laying ducks in both small follicle and stroma tissues ( p < 0.05). The DEGs were predominately identified in the p53 signaling pathway. The expression of key genes (p53, MDM2, PERP, caspase-3, and Bcl-2) involved in the signaling pathway was significantly higher in granulosa cells (dGCs) from SE-infected ducks than those from uninfected ducks. Moreover, the overexpression of PERP resulted in further induction of p53, MDM2, caspase-3, and Bcl-2 during SE infection in dGCs. Whereas, an opposite trend was observed with the knockdown of PERP. Besides, it is further revealed that the PERP could enhance cell apoptosis, SE adhesion, and SE invasion in SE-infected dGCs overexpression. Altogether, our results demonstrate the duck PERP involved in the ovarian local immune niche through p53 signaling pathway in dGCs challenged with SE.

Effect of dietary Bacillus coagulans supplementation on growth performance and immune responses of broiler chickens challenged by Salmonella enteritidis.

This study was conducted to evaluate the protective efficacy of dietary Bacillus coagulans (B. coagulans) supplementation in birds receiving Salmonella enteritidis (SE). Two hundred and forty 1-day-old Cobb broilers were randomly assigned to 2 × 2 factorial arrangements of treatments with 2 levels of dietary B. coagulans (0 or 400mg/kg) and 2 levels of SE challenge (0 or 1 × 109 SE between d 9 to 11). Results showed that SE infection did not affect growth performance, but caused intestinal inflammation and barrier function impairment by reducing intestinal goblet cells and beneficial bacteria numbers, increasing cecal Salmonella colonization and liver Salmonella invasion, downregulating jejunal mucin-2 (at 7 and 17 d post-infection, DPI), TLR2 (at 7 and 17 DPI), TLR4 (at 17 DPI), TNFSF15 (at 7 and 17 DPI) gene mRNA levels, and upregulating jejunal IFN-γ mRNA levels (at 17 DPI) compared to uninfected birds. Moreover, SE infection also elevated the concentration of jejunal anti-Salmonella IgA and sera anti-Salmonella IgG compared to uninfected birds. However, chickens received B. coagulans diets showed significant increase in body weight gain and weight gain to feed intake ratio from d 15 to 21, alkaline phosphatase activity (at 7 DPI), cecal Lactobacilli and Bifidobacterium numbers (at 7 DPI; at 17 DPI), villous height: crypt ratio (at 17 DPI), and goblet cell numbers (at 7 and 17 DPI), whereas exhibiting reduced jejunal crypt depth (at 17 DPI), cecal Escherichia coli (at 7, 17, and 31 DPI), and Salmonella (at 7 and 17 DPI) levels compared with the non-supplemented birds, regardless of SE infection. In addition, B. coagulans supplement upregulated lysozyme mRNA levels (at 17 DPI), downregulated IFN-γ mRNA levels (at 7 and 17 DPI), showed an increased trend in Fowlicidin-2 mRNA levels (at 7 DPI) and a reduced trend in liver Salmonella load compared to the non-supplemented control. These data indicated that B. coagulans has a protective effect in SE infected broilers.

Effect of dietary supplementation of nitrocompounds on Salmonella colonization and ileal immune gene expression in laying hens challenged with Salmonella Enteritidis

Foodborne disease caused by Salmonella Enteritidis (SE) is one of the important public health and economic concerns. A study was conducted to determine the effect of supplementation with 2-nitroethanol (NE) and 2-nitropropanol (NP) on Salmonella recovery of internal organs as well as on the immune gene expression in the ileum of laying hens. Thirty-six White Leghorns were orally gavaged with nalidixic acid resistant Salmonella Enteritidis (SENR). Hens were housed individually in wire-laying cages and randomly assigned to six dietary treatments: T1 = SENR unchallenged (negative control), T2 = SENR challenged (positive control), T3 = SENR challenged + 100ppm NE, T4 = SENR challenged + 200ppm NE, T5 = SENR challenged + 100ppm NP, and T6 = SENR challenged + 200ppm NP. Hens were sampled at 7 days post inoculation (dpi). Ceca, liver with gall bladder (L/GB), and ovary samples were collected for bacteriology, and ileum samples were collected for analysis of immune gene expression. T3 and T6 significantly reduced (P <0.05) cecal SENR count, whereas T4 and T5 were not different from T2, the SENR challenged control. There was no significant difference in SENR reduction in the L/GB or ovary after supplementation of either nitrocompounds. Pro- and anti-inflammatory cytokines such as interferon (IFN)-γ, interleukin (IL)-1B, IL-6, toll-like receptors (TLR)-4, and IL-10 all were significantly upregulated (P <0.05) after SENR challenge. Supplementation at both levels of NE and NP showed a significant immune gene expression response in the ileum with reduction of IFN-γ, IL-6, TLR-4, and IL-10 mRNA expression. Overall, nitrocompounds such as NE and NP can be used in the intervention strategy to reduce Salmonella infection in hens.

Protection Mechanism of Clostridium butyricum against Salmonella Enteritidis Infection in Broilers.

This study was designed to evaluate the protection mechanism of oral administration of Clostridium butyricum against Salmonella enteritidis (SE) colonization in broilers. In the current study, 180 one-day-old healthy Arbor Acres (AA) broilers were meanly grouped into three, with three replicates of 20 birds each. An negative control group was fed basal diet without SE challenge and a positive control (PC) group was fed the basal diet and challenged with SE [106 colony forming unit (CFU)/0.2 mL]. An experimental (EXP) group was fed the basal diet, orally administered with C. butyricum (106 CFU/mL) and challenged with SE (106 CFU/0.2 mL). The results showed that compared to the PC group, the SE loads in livers, spleens, and cecal contents of chickens in EXP group were significantly reduced (P < 0.05) except in spleens at the 2-day post-infection; the production of interferon-γ, interleukin (IL)-1β, IL-8, and tumor necrosis factor-α in the livers, spleens, and cecal tissues of chickens in EXP group were decreased to different extents. The results of quantitative real-time polymerase chain reaction further revealed that the inflammation of chickens in EXP group was alleviated by C. butyricum via down-regulating TLR4, MyD88, and NF-κB-dependent pathways. Collectively, these findings indicated that oral administration of C. butyricum could be a suitable alternative for preventing SE infection in broilers.

Immunization with Salmonella Enteritidis secreting mucosal adjuvant labile toxin confers protection against wild type challenge via augmentation of CD3+CD4+ T-cell proliferation and enhancement of IFN-γ, IL-6 and IL-10 expressions in chicken

The protective efficacy and immunological profiles of chickens immunized with an attenuated Salmonella Enteritidis (SE) constitutively secreting double mutant heat labile enterotoxin (dmLT) were investigated. The dmLT is a detoxified variant of Escherichia coli heat labile toxin and is a potent mucosal adjuvant capable of inducing both humoral and cell-mediated immunity. In this study, four-week-old chickens were inoculated with SE-dmLT strain JOL1641, parental SE strain JOL1087 or phosphate buffered saline control. Peripheral blood mononuclear cells of SE-dmLT inoculated birds showed significant proliferation upon stimulation with SE antigens as compared to the control and JOL1087 groups (P⩽0.05). One week post-challenge, the ratio of CD3+CD4+ to CD3+CD8+ T-cells showed a significant increase in the immunized groups. Significant increases in IFN-γ levels were observed in JOL1641 birds immunized via oral and intramuscular routes. While immunizations with the JOL1087 strain via the intramuscular route also induced significant increases in IFN-γ, immunization via the oral route did not trigger significant changes. Pro-inflammatory cytokine IL-6 was also elevated significantly in immunized birds; a significant elevation of IL-10 was observed only in oral immunization with JOL1641 (P⩽0.05). JOL1641 immunized birds showed significant reduction of challenge bacterial-organ recovery as compared to JOL1087 and non-immunized birds. Collectively, our results revealed that immunization with the adjuvant-secreting S. Enteritidis confers protection against wild type SE challenge via induction of strong cell proliferative response, augmentation of CD3+CD4+: CD3+CD8+ T-cells ratio and enhancement of IFN-γ, IL-6 and IL-10 cytokine secretion.

Yeast β-d-glucans induced antimicrobial peptide expressions against Salmonella infection in broiler chickens

The present study was designed to investigate the effects of yeast β-d-glucans (YG) on gene expression of endogenous β-defensins (AvBDs), cathelicidins (Cath) and liver-expressed antimicrobial peptide-2 (LEAP-2) in broilers challenged with Salmonella enteritidis (SE). 240 day-old Cobb male broilers were randomly assigned to 2×2 factorial arrangements of treatments with two levels of dietary YG (0 or 200mg/kg in diet) and two levels of SE challenge (0 or 1×109 SE at 7–9 days of age). The results showed SE infection reduced growth performance,and increased salmonella cecal colonization and internal organs invasion, increased concentration of intestinal specific IgA and serum specific IgG antibody, as compared to uninfected birds. SE challenge differentially regulated AvBDs, Caths and LEAP-2 gene expression in the jejunum and spleen of broiler chickens during the infection period. However, YG supplementation inhibited the growth depression by SE challenge, and further increased level of serum specific IgG and intestinal specific IgA antibody. Higher level of salmonella colonization and internal organs invasion in the SE-infected birds were reduced by YG. SE-induced differentially expression patterns of AMPs genes was inhibited or changed by YG. Results indicated YG enhance chicken's resistance to salmonella infection.