Alexander YitbarekMcGill University | McGill · Department of Animal Science
Alexander Yitbarek
PhD
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62
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Publications
Publications (62)
The impact of low pathogenic influenza viruses such as subtype H9N2, which infect the respiratory and the gastrointestinal tracts of chickens, on microbial composition are not known. Twenty day-old specific pathogen free chickens were assigned to two treatment groups, control (Uninfected) and H9N2-infected (challenged via the oral-nasal route). Fec...
Commensal gut microbes play a critical role in shaping host defences against pathogens, including influenza viruses. The current study was conducted to assess the role and mechanisms of action of commensal gut microbiota on the innate and antibody-mediated responses of layer chickens against influenza virus subtype H9N2. A total of 104 one-day-old...
Commensal gut microbiota plays an important role in health and disease. The current study was designed to assess the role of gut microbiota of chickens in the initiation of antiviral responses against avian influenza virus. Day-old layer chickens received a cocktail of antibiotics for 12 (ABX-D12) or 16 (ABX-D16) days to deplete their gut microbiot...
Newly hatched chickens are confronted by a wide array of pathogenic microbes when their adaptive immune defenses have limited capabilities to control these pathogens. In such circumstances and within this age group, innate responses provide a degree of protection. Moreover, as the adaptive immune system is relatively naïve to foreign antigens, syne...
Vitamins are nutritional elements which are necessary for essential activities such as development, growth and metabolism of cells. In addition to these conventional functions, vitamins A, D, E and C have vital roles in normal function of the immune system as their deficiency is known to impair innate and adaptive host responses. By altering transc...
![Vaccination trials for C. jejuni infection in poultry (modified from [49]).](publication/366832303/figure/tbl1/AS:11431281110816731@1672751002482/Vaccination-trials-for-C-jejuni-infection-in-poultry-modified-from-49_Q320.jpg)
Campylobacter is one of the most common bacterial pathogens of food safety concern. Campylobacter jejuni infects chickens by 2–3 weeks of age and colonized chickens carry a high C. jejuni load in their gut without developing clinical disease. Contamination of meat products by gut contents is difficult to prevent because of the high numbers of C. je...
Dietary antibiotics, including antibiotic growth promoters (AGPs), have been commonly used to improve health and growth of poultry. The present study investigated the effects of therapeutic doses of dietary antibiotics, including bacitracin methylene disalicylate (BMD), penicillin G potassium (PP) and an ionophore (salinomycin, SA), on the cecal mi...
1. This study evaluated the effect of folic acid (FA) supplementation on the proinflammatory and antiviral molecular pathways of B-lymphocytes infected with a modified live IBDV (ST-12) mild vaccine strain during a timed post-infection analysis.
2. A chicken B-lymphocytes (DT-40) cell line was cultured in triplicate at a concentration of 5 × 10⁵ ce...
Avian influenza virus (AIV) H9N2 subtype is an infectious pathogen that can affect both the respiratory and gastrointestinal systems in chickens and continues to have an important economic impact on the poultry industry. While the host innate immune response provides control of virus replication in early infection, the adaptive immune response aids...
1- The objective of this study was to investigate the potential immunomodulatory effects of yeast (Saccharomyces cerevisiae) and yeast-derived products treated with a cell wall lytic enzyme mixture on the gene expression of toll-like receptors and cytokines of chicken B cell line (DT 40) stimulated with lipopolysaccharide.
2-:
The effect of brewe...
• This study evaluated and characterised the effect of folic acid (FA) on chromosomal DNA methylation and the epigenetic result on gene expression control mechanisms in chicken B cells as a model of antigen presenting cells.
• After FA supplementation, the methylation pattern on the proximal promoter area and mRNA expression of toll-like receptor...
It has been demostrated that vitamin D (Vit D) included in diets offers a beneficial effect by improving innate immune responses in chickens. However, its mechanisms of action and the effect on immunosupresive pathogens, such as infectious bursal disease virus (IBDV), are not yet known. In the present study, we have studied the immunomodulatory eff...
Selenium is a trace mineral that has antioxidant activities and can influence the immune system. However, antiviral effects of selenium have not been well studies in chickens. Chickens were therefore fed diets supplemented with two levels of two different sources of selenium (organic: selenium enriched yeast; SEY or inorganic: sodium selenite; SS)....
Chickens infected with avian influenza virus (AIV) transmit the virus via respiratory and cloacal shedding. While previous mathematical models have shown that the innate immune response is necessary for the early suppression of virus production in infected respiratory cells, the different pathways by which the innate immune response can affect cloa...
Intestinal epithelial cells are major producers of antimicrobial proteins, which play an important role in innate immunity. In addition to defensins, the ribonuclease -A Superfamily includes important anti-microbial proteins involved in host-defense mechanisms in vertebrates. Angiogenin-4 (Ang4), a member of this RNase superfamily, has been demonst...
Variations in the composition of commensal gut microbiota have been reported to be major contributors to differences in responses to vaccination among individuals. In chickens, there is limited information on the role of gut microbiota in responses to vaccination. The current study studied the role of gut microbiota in cell- and antibody-mediated i...
Objective:
Infection of chickens with low pathogenic avian influenza virus, such as H9N2 virus, culminates in decreased egg production and increased mortality and morbidity if co-infection with other respiratory pathogens occurs. We have previously observed the induction of antibody- and cell-mediated immune responses after intramuscular administr...
Selenium supplementation in poultry feeds has been known to have beneficial effects on the bird health and performance; however antiviral effects of selenium have remained largely unknown. In this study, we have evaluated the effects of supplementation of chicken diets with organic (Selenium Enriched Yeast; SEY) and inorganic selenium (Sodium Selen...
Nucleotide-rich yeast extract (YN) was investigated for effects on growth performance, jejunal physiology, and cecal microbial activity in Eimeria-challenged broiler chickens. A total of 360-day-old male chicks (Ross × Ross 708) were placed on floor pens and provided a corn-soybean meal-based diet without or with YN (500 g/MT; n = 12). On d 10, 6 r...
Marek’s Disease Virus (MDV) is the causative agent of a lymphoproliferative disease, Marek’s disease (MD) in chickens. MD is only controlled by mass vaccination; however, immunity induced by MD vaccines is unable to prevent MDV replication and transmission. The herpesvirus of turkey (HVT) vaccine is one of the most widely used MD vaccines in poultr...
Mucosal vaccine delivery systems have paramount importance for the induction of mucosal antibody responses. Two studies were conducted to evaluate immunogenicity of inactivated AIV antigens encapsulated in poly(D,L-lactide-co-glycolide) (PLGA) nanoparticles (NPs). In the first study, seven groups of specific pathogen free (SPF) layer-type chickens...
A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper.
Low pathogenic avian influenza virus (AIV) infection in chickens can result in economic losses and has impacts on human health. Poultry vaccination is a tool that can be used to decrease infection and transmission of AIVs. Prior research has demonstrated that Toll-like receptor (TLR) ligands can act as vaccine adjuvants and their addition to inacti...
Campylobacter jejuni is a leading bacterial cause of human gastroenteritis. Reducing Campylobacter numbers in the intestinal tract of chickens will minimize transmission to humans, thereby reducing the incidence of infection. We have previously shown that oral pre-treatment of chickens with C. jejuni lysate and Poly D, L-lactide-co-glycolide polyme...
Several types of avian influenza virus (AIV) vaccines exist, including live-attenuated, vectored, and whole inactivated virus (WIV) vaccines. Inactivated vaccines offer some advantages compared to other types of vaccines, including ease of production and lack of ability to revert to a virulent state. However, WIV are poorly immunogenic, especially...
One of the economically important diseases in the poultry industry is Marek's disease (MD) which is caused by Marek's disease virus (MDV). The use of current vaccines provides protection against clinical signs of MD in chickens. However, these vaccines do not prevent the transmission of MDV to susceptible hosts, hence they may promote the developme...
There is limited data on yeast nucleotides (YN) effects on poultry cecal microbial activity in the context of enteric disease challenge. 360 d old male broiler chicks (Ross 708) were used to evaluate effects of YN on cecal digesta short chain fatty acids (SCFA) concentration and microbial communities upon Eimeria challenge. Birds were housed in flo...
Campylobacter jejuni (C. jejuni) is a major cause of bacterial food-borne illness in humans. It is considered a commensal organism of the chicken gut and infected chickens serve as a reservoir and shed bacteria throughout their lifespan. Contaminated poultry products are considered the major source of infection in humans. Therefore, to reduce the r...
Campylobacter jejuni (C. jejuni) is a leading bacterial cause of food-borne illness in humans. Contaminated chicken meat is an important source of infection for humans. Chickens are not clinically affected by colonization, and immune responses following natural infection have limited effects on bacterial load in the gut. Induction of intestinal imm...
Effects of supplementing swine diets with phytase on manure composition and greenhouse gas (GHG) emissions from soil after manure application were investigated. The experiment was laid out in a completely randomised 3×2×2 factorial design, with three manure treatments (no manure, manure from unsupplemented diet and manure from phytase supplemented)...
An experiment was carried out to evaluate the short-term effect of supplementing a nucleotide-rich yeast extract (NRYE) on growth performance, gut structure, immunity and microflora of piglets raised under sanitary and unsanitary conditions. A total of 84, 21-day old piglets were used in this study; 42 piglets were raised in a room designated as th...
Three experiments were conducted to evaluate the effect of yeast-derived carbohydrates (YDC), and a blend of probiotics and YDC (synbiotic, SNB) on serum IgG concentration, maternal-derived antibody (MDA) decay, and specific antibody-mediated immune response in chick pullets following immunization with T-cell dependent antigens. A total of 300 day-...
Vitamin D requirement is estimated to be higher than recommended values for the first two weeks of a broiler chicken's life,
and is heavily dependent on the concentrations of Ca and P in the diet. There are data indicating the beneficial effect of
higher vitamin D levels on performance and overall health of the chickens. However, data on the role o...
This study evaluated the effect of yeast-derived products on growth performance, serum antibody levels, and mRNA gene expression of pattern-recognition receptors, and cytokines in broiler chickens. Two hundred and sixteen one-day-old male broiler chickens (Ross-308) were randomly assigned to six dietary treatments with six replicates (cage) of 6 bi...
The effect of organic trace mineral supplementation on performance, intestinal morphology, immune organ weights (bursa of Fabricius and spleen), expression of innate immune response related genes, blood heterophils/lymphocytes ratio, chemical metabolic panel, natural antibodies (IgG), and oxidative stress of broiler chickens was studied. A total of...
Prebiotics and synbiotics are considered to be among the most promising replacements for in-feed antibiotic growth promoters (AGP) in poultry feed. The current study was designed to study the effect of Bacitracin methylene disalicylate (BMD) (Control), yeast-derived carbohydrates (YDC), and a blend of YDC and probiotics [Lactobacillus acidophilus,...
This study compared needle-free and needle-based injection devices for vaccination of calves against Clostridium chauvoei in warm and cold conditions. Both devices elicited comparable antibody responses in calves. Needle-free injection devices can be used to vaccinate calves provided appropriate precautions are taken in cold weather.
Direct-fed microbials (DFM) are used to improve livestock health and performance. The effects of 2 DFM products, a blend of
3 Bacillus strains (DFMB) and a Propionibacteriumspp. (DFMP), on broiler performance, nutrient utilization, and immune responses were investigated. Day-old (n = 120) male
broilers were divided into 24 groups of 5 birds and fed...
The turnover of intestinal epithelial cells is a dynamic process that includes adequate cell proliferation and maturation in the presence of microbiota and migration and seeding of immune cells in early gut development in chickens. We studied the effect of yeast-derived macromolecules (YDM) on performance, gut health, and immune system gene express...
The gut epithelial cells and intraepithelial lymphocytes are now recognized to play a major role in innate immunity, forming a highly specialized physical and functional barrier by responding directly to colonizing bacteria using specific cell-surface pattern recognition receptors (PRRs) to detect and respond to the presence of microbial-associated...
This study was conducted to compare the effectiveness of a needle-free (NF) injection device and needle syringe (NS) when used to vaccinate two-month old calves against infectious bovine rhinotracheitis (IBR) and Clostridium chauvoei. Two independent trials were conducted in the spring and fall with 96 crossbred beef calves (106.24 ± 16.68 kg) and...
This study was conducted to compare the effectiveness of a needle-free (NF) injection device and needle syringe (NS) when used to vaccinate two-month old calves against infectious bovine rhinotracheitis (IBR) and Clostridium chauvoei. Two independent trials were conducted in the spring and fall with 96 crossbred beef calves (106.24 ± 16.68 kg) and...
A study was conducted to assess the effect of yeast-derived carbohydrates (YDC) on performance and innate immune responses of broiler chickens. In total, 1,080 one-day-old birds were randomly assigned to one of 3 dietary treatments (n = 360): a standard broiler diet containing monensin (control), control + bacitracin methylene disalycylate (BMD), a...
In this study, antibody response was measured in calves following vaccination against bovine viral diarrhea virus (BVDV) using either needle-free (Pulse 250) or needle-syringe (NS) vaccination techniques. The Pulse 250 needle-free (NF) injection device utilizes compressed carbon dioxide to power vaccine injections. At 2 mo of age (d 0), calves were...
Necrotic enteritis (NE) caused by Clostridium perfringens is a reemerging disease of economic importance in areas of the world where antibiotic growth promoters have been banned.
The effect of mannan-oligosaccharide (MOS) supplementation in organic diets of broilers challenged with C. perfringens on performance, gut morphology, and innate immunity...
The combined effects of probiotics (Lactobacillus acidophilus, Lactobacillus casei, Streptococcus faecium, and Saccharomyces cerevisiae) and organic acids (sorbic and citric acid) on intestinal morphology and expression of immune-related genes were investigated. One-day-old chicks were randomly assigned to 1 of 3 groups: birds not receiving probiot...
Microbial phytase has been used to reduce P excretion from swine to mitigate environmental pollution. The objective of the study was to quantify the effect of feeding a low-P phytase-supplemented diet on growth and P utilization in growing pigs using mathematical models. A total of 20 weaned piglets (BW = 6.5 kg) housed in metabolism cages were ran...
Questions
Question (1)
When we are running TCID50 to detect low pathogenic avian influenza shedding from the cloacal swabs, we are running into a problem where the first two and sometimes three wells are always totally destroyed making it extremely difficult to detect the virus if a bird is shedding at a lower titer. This is not an issue with orophryngeal swabs. In the case of oropharyngeal swabs, the monolayers are intact. We played around with increasing antibiotic dose and pH of transport media to no avail. Does anyone have a recommendation on how we could rectify this problem.
Thanks in advance.
Projects
Projects (2)
To understand the understand the injected bolus as a function of machine settings and the resulting reactions/efficacy in injected animals. This work began with laboratory studies of Needle Free Injectors initiated by Tyler Grant and continued with a field study of cattle led by Kimberly Ominski and her student Mitch Rey.