Nonimmunized egg yolk powder can suppress the colonization of Salmonella typhimurium, Escherichia coli O157:H7, and Campylobacter jejuni in laying hens

Natural anti-adhesive components against pathogenic bacterial adhesion and infection in gastrointestinal tract: case studies of Helicobacter pylori, Salmonella enterica, Clostridium difficile, and diarrheagenic Escherichia coli

Antimicrobial resistance (AMR) poses a global public health concern. Recognizing the critical role of bacterial adhesion in pathogenesis of infection, anti-adhesive therapy emerges as a promising approach to impede initial bacterial attachment, thus preventing pathogenic colonization and infection. Natural anti-adhesive agents derived from food sources are generally safe and have the potential to inhibit the emergence of resistant bacteria. This comprehensive review explored diverse natural dietary components exhibiting anti-adhesive activities against several model enteric pathogens, including Helicobacter pylori, Salmonella enterica, Clostridium difficile, and three key diarrheagenic Escherichia coli (i.e., enterotoxigenic E. coli, enteropathogenic E. coli, and enterohemorrhagic E. coli). Investigating various anti-adhesive products will advance our understanding of current research of the field and inspire further development of these agents as potential nutraceuticals or adjuvants to improve the efficacy of conventional antibiotics.

Passive immunotherapy using chicken egg yolk antibody (IgY) against diarrheagenic E. coli: A systematic review and meta-analysis

BACKGROUND

Animal diarrhea due to diarrheagenic Escherichia coli (E. coli) has been a major concern in the field of livestock farming leading to a severe loss of domesticated animals. This systematic review aims to analyze medical shreds of evidence available in the literature and to discover the effect of IgY in treatment and protection against E. coli diarrhea.

METHODS AND RESULTS

Research reports that aimed to evaluate the effect of IgY against E. coli diarrhea were searched and collected from several databases (Science Direct, Springer link, Wiley, T&F). The collected studies were screened based on the inclusion criteria. 19 studies were identified and included in the meta-analysis. The pooled relative risk ratios were calculated for the studies and found to be statistically significant to support the therapeutic effect of IgY against E. coli diarrhea but the 95% confidence interval of a majority of studies includes a relative risk of 1. This variability between the effect of IgY in the overall estimate and individual studies accounts due to the presence of methodological heterogeneity. In addition, subgroup analysis revealed the grounds for heterogeneity.

CONCLUSIONS

This systematic review and meta-analysis provide concrete evidence for the favorable effect of IgY as a prophylactic and therapeutic modality against E. coli diarrhea. Yet, more research pieces of evidence with standardized animal studies aimed to utilize IgY against E. coli are vital. Further studies and trials on human subjects could open new perspectives in the application IgY as a therapeutic agent.

Evaluation of the Immunogenic Response of a Novel Enterobactin Conjugate Vaccine in Chickens for the Production of Enterobactin-Specific Egg Yolk Antibodies

Passive immunization with specific egg yolk antibodies (immunoglobulin Y, IgY) is emerging as a promising alternative to antibiotics to control bacterial infections. Recently, we developed a novel conjugate vaccine that could trigger a strong immune response in rabbits directed against enterobactin (Ent), a highly conserved siderophore molecule utilized by different Gram-negative pathogens. However, induction of Ent-specific antibodies appeared to be affected by the choice of animal host and vaccination regimen. It is still unknown if the Ent conjugate vaccine can trigger a specific immune response in layers for the purpose of production of anti-Ent egg yolk IgY. In this study, three chicken vaccination trials with different regimens were performed to determine conditions for efficient production of anti-Ent egg yolk IgY. Purified Ent was conjugated to three carrier proteins, keyhole limpet hemocyanin (KLH), bovine serum albumin (BSA) and CmeC (a subunit vaccine candidate), respectively. Intramuscular immunization of Barred Rock layers with KLH-Ent conjugate four times induced strong immune response against whole conjugate vaccine but the titer of Ent-specific IgY did not change in yolk with only a 4 fold increase detected in serum. In the second trial, three different Ent conjugate vaccines were evaluated in Rhode Island Red pullets with four subcutaneous injections. The KLH-Ent or CmeC-Ent conjugate consistently induced high level of Ent-specific IgY in both serum (up to 2,048 fold) and yolk (up to 1,024 fold) in each individual chicken. However, the Ent-specific immune response was only temporarily and moderately induced using a BSA-Ent vaccination. In the third trial, ten White Leghorn layers were subcutaneously immunized three times with KLH-Ent, leading to consistent and strong immune response against both whole conjugate and the Ent molecule in each chicken; the mean titer of Ent-specific IgY increased approximately 32 and 256 fold in serum and yolk, respectively. Consistent with its potent binding to various Ent derivatives, the Ent-specific egg yolk IgY also inhibited in vitro growth of a representative Escherichia coli strain. Together, this study demonstrated that the novel Ent conjugate vaccine could induce strong, specific, and robust immune response in chickens. The Ent-specific hyperimmune egg yolk IgY has potential for passive immune intervention against Gram-negative infections.

Research Note: Lyophilization of hyperimmune egg yolk: effect on antibody titer and protection of broilers against Campylobacter colonization

Oral administration of antibodies is a promising strategy against various infectious diseases. Previously, it was demonstrated that passive immunization by providing hyperimmune egg yolk through the feed reduces Campylobacter jejuni colonization in broilers. Campylobacteriosis is the most commonly reported bacterial foodborne zoonosis worldwide, and poultry products are the number one origin of these bacteria for human infection. To date, no effective control measures exist to limit Campylobacter colonization in the chicken's intestinal tract. Here, the effect of lyophilization of hyperimmune egg yolk on protection of broilers against C. jejuni was investigated. During an in vivo trial, broiler chickens were prophylactically given feed with lyophilized hyperimmune or non-immunized egg yolk powder starting from day 1 after hatch. At day 11, broilers were inoculated with C. jejuni according to a seeder model. Five days later, all broilers were euthanized and cecal content was examined for C. jejuni colonization. No decrease in C. jejuni colonization was found. The freeze-drying resulted in a 16-fold decrease of the antibody titer in the yolk powder compared to the fresh yolks, presumably caused by structural changes in the antibodies. In conclusion, applying freeze-dried hyperimmune egg yolk failed to protect broilers against C. jejuni colonization, possibly because lyophilization affected the antibodies' functionality.

Catalytic properties of wheat phytase that favorably degrades long-chain inorganic polyphosphate

Objective

This study was conducted to determine catalytic properties of wheat phytase with exopolyphosphatase activity toward medium-chain and long-chain inorganic polyphosphate (polyP) substrates for comparative purpose.

Methods

Exopolyphosphatase assay of wheat phytase toward polyP75 (medium-chain polyP with average 75 phosphate residues) and polyP1150 (long-chain polyP with average 1150 phosphate residues) was performed at pH 5.2 and pH 7.5. Its activity toward these substrates was investigated in the presence of Mg²⁺, Ni²⁺, Co²⁺, Mn²⁺, or ethylenediaminetetraacetic acid (EDTA). Michaelis constant (K_m) and maximum reaction velocity (V_max) were determined from Lineweaver-Burk plot with polyP75 or polyP1150. Monophosphate esterase activity toward p-nitrophenyl phosphate (pNPP) was assayed in the presence of polyP75 or polyP1150.

Results

Wheat phytase dephosphorylated polyP75 and polyP1150 at pH 7.5 more effectively than that at pH 5.2. Its exopolyphosphatase activity toward polyP75 at pH 5.2 was 1.4-fold higher than that toward polyP1150 whereas its activity toward polyP75 at pH 7.5 was 1.4-fold lower than that toward polyP1150. Regarding enzyme kinetics, K_m for polyP75 was 1.4-fold lower than that for polyP1150 while V_max for polyP1150 was 2-fold higher than that for polyP75. The presence of Mg²⁺, Ni²⁺, Co²⁺, Mn²⁺, or EDTA (1 or 5 mM) exhibited no inhibitory effect on its activity toward polyP75. Its activity toward polyP1150 was inhibited by 1 mM of Ni²⁺ or Co²⁺ and 5 mM of Ni²⁺, Co²⁺, or Mg²⁺. Ni²⁺ inhibited its activity toward polyP1150 the most strongly among tested additives. Both polyP75 and polyP1150 inhibited the monophosphate esterase activity of wheat phytase toward pNPP in a dose-dependent manner.

Conclusion

Wheat phytase with an unexpected exopolyphosphatase activity has potential as a therapeutic tool and a next-generational feed additive for controlling long-chain polyP-induced inappropriate inflammation from Campylobacter jejuni and Salmonella typhimurium infection in public health and animal husbandry.

In vitro efficacy of potentiated egg yolk powder against Campylobacter jejuni does not correlate with in vitro efficacy

Campylobacter jejuni is a zoonotic agent responsible for the foodborne gastroenteritis campylobacteriosis. Control of C. jejuni load in the poultry primary production is recognized as an avenue to reduce human exposure to the pathogen. As for now, no commercially applicable control methods exist at the farm. Several studies tested egg yolk powders, potentiated or not against C. jejuni, as feed additives for chicken and suggested that the quantity and quality of the antibodies presence in the yolk are determinant factors for the full success of this approach. Unfortunately, data from these studies inconsistently showed a reduction of cecal C. jejuni carriage. Our first goal wwas to characterize (quantification by ELISA, agglutination test, bacterial antigen recognition profiles by Western blot, bactericidal effect by serum killing assays and C. jejuni mobility by soft agar migation) the antibodies extracted from egg yolk powders originating from different egg production protocols. Secondly, these powders were microencapsulated and recharacterized. Finally the protected powders were tested as a feed additive to destabilize C. jejuni colonization in an in vivo assay. Despite the in vitro results indicating the ability of the egg yolk powders to recognize Campylobacter and potentially alter its colonization of the chicken caecum, these results were not confirmed in the in vivo trial despite that specific caecal IgY directed toward Campylobacter were detected in the groups receiving the protected powders. More research is needed on Campylobacter in order to effectively control this pathogen at the farm.

Specific Chicken Egg Yolk Antibody Improves the Protective Response against Gallibacterium anatis Infection

Gallibacterium anatis is a pathogen associated with peritonitis and salpingitis in chickens and other avian species. Novel safety prevention strategies are urgently needed because of widespread multidrug resistance and antigenic diversity. The objective of this study was to produce a specific chicken egg yolk antibody and evaluate its protective response against a G. anatis infection model in 4-week-old chicks. Enzyme-linked immunosorbent assays showed that hens immunized with the recombinant N terminus of Gallibacterium toxin A (GtxA-N) had significantly increased antibody titers against GtxA-N in serum and egg yolk IgY. Western blotting showed that IgY antibody had specificity against GtxA-N in the egg yolks of immunized hens. The growth of G. anatis in brain heart infusion (BHI) broth and agar was significantly inhibited by the GtxA-N-specific IgY antibody. The protective effects of the specific IgY antibody were evaluated in G. anatis-infected chicks after intramuscular injection (10 mg/ml). The anti-GtxA-N antibody titers in the sera of G. anatis-challenged chicks following an injection of specific IgY antibody were significantly higher than those of the control and the nonspecific IgY groups, but lower lesion scores for the peritoneum, liver, and duodenum were found after specific IgY antibody treatment. The results from this study suggest that the GtxA-N-specific IgY antibody could potentially improve the protective response against G. anatis infection in chicks.

Production and characterization of anti-Campylobacter jejuni IgY derived from egg yolks

Background

Campylobacter jejuni is a major cause of foodborne disease having chickens as an important reservoir. Its control at the farm would lower the contamination of the final products and therefore also lower the risk of transmission to humans. At the farm, C. jejuni is rarely found in chickens before they reach 2 weeks of age. Past studies have shown that maternal antibodies could hamper C. jejuni gut colonization. The objective of this study was to compare protocols to use in order to produce anti-C. jejuni antibodies derived from egg yolks in the perspective to be used as feed additives for the control of chicken C. jejuni colonization. Laying hens were naturally contaminated with four well-characterized strains or injected with either outer membrane proteins or formalin-killed whole bacteria derived from these same strains. Eggs were collected and IgYs present in the yolks were extracted. The amount and the specificity of the recovered antibodies were characterized.

Results

It was observed that injection yielded eggs with superior concentrations of both total and anti-C. jejuni antibodies. Equivalent performances for antibodies recovered from all protocols were observed for the ability of the antibodies to agglutinate the live C. jejuni homologous strains, to hinder their motility or to lyse the bacteria. Western blot analyses showed that proteins from all strains could be recognized by all IgY extracts. All these characteristics were strain specific. The characterization assays were also made for heterologous strains and weaker results were observed when compared to the homologous strains.

Conclusions

Based on these results, only an IgY quantitative based selection can be made in regards to which protocol would give the best anti-C. jejuni IgY enriched egg-yolks as all tested protocols were equivalent in terms of the recovered antibody ability to recognized the tested C. jejuni strains.

Bioactive peptides from egg: a review

Purpose

– The aim of the article was to focus on various peptides identified in the egg and their probable application as novel ingredients in the development of functional food products. Bioactive peptides of egg origin have attracted increasing interest as one of the prominent candidates for development of various health-promoting functional and designer foods.

Design/methodology/approach

– Traditionally known as a source of highly valuable proteins in human nutrition, eggs are nowadays also considered as an important source of many bioactive peptides which may find wide application in medicine and food production. These specific protein fragments from egg proteins which, above and beyond their nutritional capabilities, have a positive impact on the body’s function or condition by affecting the digestive, endocrine, cardiovascular, immune and nervous systems, and may ultimately influence health.

Findings

– Several peptides that are released in vitro or in vivo from egg proteins have been attributed to different health effects, including antihypertensive effects, antimicrobial properties, antioxidant activities, anticancer activity, immunomodulating activity, antiadhesive properties and enhancement of nutrient absorption and/or bioavailability. Extensive research has been undertaken to identify and characterize these biologically active peptides of egg origin which has changed the image of egg as a new source of biologically active ingredients for the development of functional foods with specific benefits for human health and treatment and prevention of diseases.

Originality/value

– The paper mainly describes the above-stated properties of bioactive peptides derived from egg proteins.

Evaluation of passive immunotherapeutic efficacy of hyperimmunized egg yolk powder against intestinal colonization of Campylobacter jejuni in chickens

Campylobacter jejuni is a leading cause of foodborne bacterial gastroenteritis in human. Chickens are the reservoir host of C. jejuni, and contaminated chicken meat is an important source of human infection. Therefore, control of C. jejuni in chickens can have direct effect on human health. In this study we tested the passive immunotherapeutic efficacy of the chicken egg-yolk-derived antibodies, in the form of hyperimmunized egg yolk powder (HEYP), against 7 colonization-associated proteins of C. jejuni, namely, CadF (Campylobacter adhesion to fibronectin), FlaA (flagellar proteins), MOMP (major outer membrane protein), FlpA (fibronectin binding protein A), CmeC (Campylobacter multidrug efflux C), Peb1A (Campylobacter putative adhesion), and JlpA (Jejuni lipoprotein A). Three chicken experiments were performed. In each experiment, chickens were treated orally via feed supplemented with 10% (wt/wt) egg yolk powder. In experiment 1, chicken groups were experimentally infected with C. jejuni (10(8) cfu) followed by treatment with 5 HEYP (CadF, FlaA, MOMP, FlpA, CmeC) for 4 d either individually or as a cocktail containing equal parts of each HEYP. In experiment 2, chickens were treated for 21 d with cocktail containing equal parts of 7 HEYP before and after experimental infection with C. jejuni (10(8) cfu). In experiment 3, chickens were treated with feed containing a cocktail of 7 HEYP before and after (prophylaxis), and after (treatment) experimental infection with C. jejuni (10(5) cfu). Intestinal colonization of C. jejuni was monitored by culturing cecal samples from chickens euthanized at the end of each experiment. The results showed that there were no differences in the cecal colonization of C. jejuni between HEYP treated and nontreated control chickens, suggesting that use of HEYP at the dose and the regimens used in the current study is not efficacious in reducing C. jejuni colonization in chickens.

Production and evaluation of chicken egg-yolk-derived antibodies against Campylobacter jejuni colonization-associated proteins

Campylobacter jejuni is one of the most important causes of foodborne gastroenteritis. Chickens are considered a reservoir host of C. jejuni, and epidemiological studies have shown that contaminated chicken meat is a primary source of human infection. The objective of this study was to produce chicken egg-yolk-derived antibody (IgY) against the five C. jejuni colonization-associated proteins or CAPs (CadF, FlaA, MOMP, FlpA, and CmeC). Recombinant C. jejuni CAPs were expressed in Escherichia coli and were purified by affinity chromatography. Specific-pathogen-free laying hens were hyperimmunized with each recombinant CAP to induce production of α-CAP-specific IgY. Egg yolks were collected from immunized and nonimmunized hens and were lyophilized to obtain egg-yolk powder (EYP) with or without α-C. jejuni CAP-specific IgY. IgY was purified from EYP, and the antibody response in serum and egg yolk was tested by indirect enzyme-linked immunosorbent assay. The α-C. jejuni CAP-specific IgY levels were significantly (p<0.05) higher in both serum and EYP obtained from immunized hens as compared with the nonimmunized hens. Each α-C. jejuni CAP-specific IgY reacted with the C. jejuni cells and recombinant CAPs as detected by immunofluorescence microscopy and Western blot assays, respectively. We also show that α-CadF, α-MOMP, and α-CmeC IgY significantly reduced adherence of C. jejuni to the chicken hepatocellular carcinoma (LMH) cells, suggesting that these α-C. jejuni CAP-specific IgY may be useful as a passive immunotherapeutic to reduce C. jejuni colonization in chickens.

Salmonella in chicken: current and developing strategies to reduce contamination at farm level

Salmonella is a human pathogen that frequently infects poultry flocks. Consumption of raw or undercooked contaminated poultry products can induce acute gastroenteritis in humans. Faced with the public health concerns associated with salmonellosis, the European Union has established a European regulation forcing member states to implement control programs aimed at reducing Salmonella prevalence in poultry production, especially at the primary production level. The purpose of the present review article is to summarize the current research and to suggest future developments in the area of Salmonella control in poultry, which may be of value to the industry in the coming years. The review will focus especially on preventive strategies that have been developed and that aim at reducing the incidence of Salmonella colonization in broiler chickens at the farm level. In addition to the usual preventive hygienic measures, other strategies have been investigated, such as feed and drinking water acidification with organic acids and immune strategies based on passive and active immunity. Modification of the diet by changing ingredients and nutrient composition with the intent of reducing a bird's susceptibility to Salmonella infection also has been examined. Because in ovo feeding accelerates small intestine development and enhances epithelial cell function, this approach could be an efficient tool for controlling enteric pathogens. Feed additives such as antibiotics, prebiotics, probiotics, and synbiotics that modify the intestinal microflora are part of another field of investigation, and their success depends on the additive used. Other control methods such as the use of chlorate products and bacteriophages also are under study.

Avian (IgY) anti-methanogen antibodies for reducing ruminal methane production: in vitro assessment of their effects

In vitro dry matter disappearance (IVDMD) and production of methane, volatile fatty acids (VFA) and ammonia from an early lactation diet or from freeze-dried alfalfa were assessed in the presence of anti-methanogen antibody treatments in two in vitro ruminal incubations (experiments 1 and 2). In experiment 1, hens were immunised with crude cell preparations of Methanobrevibacter smithii, Methanobrevibacter ruminantium or Methanosphaera stadtmanae and complete Freund’s adjuvant (CFA). Semipurified egg antibodies (IgY) prepared from the hens’ eggs (α-SMICFA, α-RUMCFA, or α-STADCFA, respectively) were dispensed into 24 replicate vials (400 μL per vial) containing 500 mg of an early lactation total mixed ration (18% crude protein; 33% neutral detergent fibre; DM basis). Vials containing an equal volume of semipurified antibodies from eggs of non-immunised hens were included as a control. In experiment 2, hens were immunised with one of the three antigenic preparations combined with Montanide ISA 70 adjuvant. Triplicate vials per time point included 0.6 g of freeze-dried egg powder (α-SMIMon, α-RUMMon, α-STADMon; 19.0 ± 2.6 mg IgY/g) or a mixture of all three (ComboMon) and 500 mg of freeze-dried alfalfa. Total gas, methane production and pH were measured at intervals over 24 h. After 24 h, samples were analysed for VFA, ammonia and IVDMD. In experiment 1, cumulative CH4 production was similar (P > 0.05) among treatments at each sampling time. At 24 h, average CH4 production across treatments was 27.03 ± 0.205 mg/g DM. In experiment 2, α-SMIMon, α-STADMon and ComboMon reduced methane production at 12 h (P ≤ 0.05) compared with the control, but by 24 h, CH4 levels in all treatments were similar (P > 0.05) to the control. At 24 h, total VFA concentrations were lower (P < 0.05) in α-RUMMon and α-SMIMon than in the control. The transient nature of the inhibition of methane production by the antibodies may have arisen from instability of the antibodies in ruminal fluid, or to the presence of non-culturable methanogens unaffected by the antibody activity that was administered.

A model of Salmonella infection within industrial house hens

Salmonella is one of the major sources of toxi-infection in humans. Incidences of human salmonellosis have greatly increased over the past 20 years and this can largely be attributed to epidemics of Salmonella enteritidis phage type 4 within poultry. The main concern with this bacterium is the existence of silent carriers, i.e. animals harbouring S. enteritidis without expressing any visible symptoms. In this article, we formulate a model for S. enteritidis transmission in hen houses, considering both the hens and the environmental bacterium contamination. By considering the hen's individual development of the disease, we build a model for the production of eggs contaminated by S. enteritidis. The objectives are to analyse the dynamic of the disease, and to provide understanding of measures to avoid the endemicity of S. enteritidis in industrial hen houses.

Effects of Nonimmunized Egg Yolk Powder–Supplemented Feed on Salmonella Enteritidis Prevention and Elimination in Broilers

Chicken consumption is a newly identified risk factor in Salmonella enterica serovar Enteritidis (SE) infection in humans. SE is widely distributed in commercial chicken flocks and high levels of cecal carriage and shedding may lead to broiler meat contamination. In the present study, the preventive and eliminative effect of nonimmunized freeze-dried egg yolk powder (EYP) on SE in broilers was investigated. In the prevention trial, reduced SE counts were observed in liver (P < or = 0.05), cecal contents, and fecal shedding (P < or = 0.05) in birds fed 10% or 5% EYP. Histological examination of cecal wall and cecal tonsils at 23 days postinfection indicated a lesser degree of intestinal pathology. In the elimination trial, a significantly lower (P < or = 0.05) number of SE reached the liver and spleen, and a reduction in cecal carriage and fecal shedding was observed. The histological changes in the cecal mucosa and cecal tonsils reflected an apparent inflammation and mucosal repair and also suggested that the infection had not completely resolved, confirming SE bacterial isolations in the cecal tissue. The present study indicates that supplementing the diets of broilers with 5% nonimmunized EYP, at the early stages of the growing period, reduces preharvest Salmonella load with a minimal degree of intestinal pathology.

Reducing the Carriage of Foodborne Pathogens in Livestock and Poultry

Several foodborne pathogens, including Salmonella species and campylobacters, are common contaminants in poultry and livestock. Typically, these pathogens are carried in the animal's intestinal tract asymptomatically; however, they can be shed in feces in large populations and be transmitted by other vectors from feces to animals, produce, or humans. A wide array of interventions has been developed to reduce the carriage of foodborne pathogens in poultry and livestock, including genetic selection of animals resistant to colonization, treatments to prevent vertical transmission of enteric pathogens, sanitation practices to prevent contamination on the farm and during transportation, elimination of pathogens from feed and water, feed and water additives that create an adverse environment for colonization by the pathogen, and biological treatments that directly or indirectly inactivate the pathogen within the host. To successfully reduce the carriage of foodborne pathogens, it is likely that a combination of intervention strategies will be required.