Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

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Phylogenomic investigation of IncI1-I plasmids harboring blaCMY-2 and blaSHV-12 in salmonella enterica and Escherichia coli in multiple countries
Castellanos, Luis Ricardo ; Graaf-Van Bloois, Linda van der; Donado-Godoy, Pilar ; Mevius, Dik J. ; Wagenaar, Jaap A. ; Hordijk, Joost ; Zomer, Aldert L. - \ 2019
Antimicrobial Agents and Chemotherapy 63 (2019)7. - ISSN 0066-4804
Blc - Broiler - Chicken - DeoR - IS1294 - IS26 - ISEcp1 - S. Heidelberg - Salmonella Paratyphi B var. Java - SugE - Tn1721

The objective of this study was to elucidate the genetic and evolutionary relatedness of blaCMY-2- and blaSHV-12-carrying IncI1-I plasmids. Phylogenomic analysis based on core genome alignments and gene presence/absence was performed for different IncI1-I sequence types (STs). Most IncI1-I/ST12 and IncI1-I/ ST231 plasmids had near-identical core genomes. The data suggest that widely occurring blaCMY-2-carrying IncI1-I/ST12 plasmids originate from a common ancestor. In contrast, blaSHV-12 was inserted independently into different IncI1-I/ST231-related plasmids.

A new chicken 55K SNP genotyping array
Liu, Ranran ; Xing, Siyuan ; Wang, Jie ; Zheng, Maiqing ; Cui, Huanxian ; Crooijmans, Richard P.M.A. ; Li, Qinghe ; Zhao, Guiping ; Wen, Jie - \ 2019
BMC Genomics 20 (2019)1. - ISSN 1471-2164 - 1 p.
Chicken - Commercial line - Genotyping array - SNP

BACKGROUND: China has the richest local chicken breeding resources in the world and is the world's second largest producer of meat-type chickens. Development of a moderate-density SNP array for genetic analysis of chickens and breeding of meat-type chickens taking utility of those resources is urgently needed for conventional farms, breeding industry, and research areas. RESULTS: Eight representative local breeds or commercial broiler lines with 3 pools of 48 individuals within each breed/line were sequenced and supplied the major SNPs resource. There were 7.09 million - 9.41 million SNPs detected in each breed/line. After filtering using multiple criteria such as preferred incorporation of trait-related SNPs and uniformity of distribution across the genome, 52.18 K SNPs were selected in the final array. It consists of: (i) 19.22 K SNPs from the genomes of yellow-feathered, cyan-shank partridge and white-feathered chickens; (ii) 5.98 K SNPs related to economic traits from the Illumina 60 K SNP Bead Chip, which were found as significant associated SNPs with 15 traits in a Beijing-You crossed Cobb F2 resource population by genome-wide association study analysis; (iii) 7.63 K SNPs from 861 candidate genes of economic traits; (iv) the 0.94 K SNPs related to residual feed intake; and (v) 18.41 K from chicken SNPdb. The polymorphisms of 9 extra local breeds and 3 commercial lines were examined with this array, and 40 K - 47 K SNPs were polymorphic (with minor allele frequency > 0.05) in those breeds. The MDS result showed that those breeds can be clearly distinguished by this newly developed genotyping array. CONCLUSIONS: We successfully developed a 55K genotyping array by using SNPs segregated from typical local breeds and commercial lines. Compared to the existing Affy 600 K and Illumina 60 K arrays, there were 21,41 K new SNPs included on our Affy 55K array. The results of the 55K genotyping data can therefore be imputed to high-density SNPs genotyping data. The array offers a wide range of potential applications such as genomic selection breeding, GWAS of interested traits, and investigation of diversity of different chicken breeds.

Selective breeding for high natural antibody level increases resistance to avian pathogenic Escherichia coli (APEC) in chickens
Berghof, T.V.L. ; Matthijs, M.G.R. ; Arts, J.A.J. ; Bovenhuis, H. ; Dwars, R.M. ; Poel, J.J. van der; Visker, M.H.P.W. ; Parmentier, H.K. - \ 2019
Developmental and Comparative Immunology 93 (2019). - ISSN 0145-305X - p. 45 - 57.
APEC - Breeding - Chicken - Disease resistance - Escherichia coli - Natural antibody

Keyhole limpet hemocyanin (KLH)-binding natural antibody (NAb) titers in chickens are heritable, and higher levels have previously been associated with a higher survival. This suggests that selective breeding for higher NAb levels might increase survival by means of improved general disease resistance. Chickens were divergently selected and bred for total NAb levels binding KLH at 16 weeks of age for six generations, resulting in a High NAb selection line and a Low NAb selection line. To for test differences in disease resistance, chickens were challenged with avian pathogenic Escherichia coli (APEC) in two separate experiments. Chickens at 8 days of age received one of four intratracheal inoculations of 0.2 mL phosphate buffered saline (PBS): 1) mock inoculate, 2) with 0.2 mL PBS containing 108.20 colony-forming units (CFU)/mL APEC, 3) with 0.2 mL PBS containing 106.64 CFU/mL APEC, and 4) with 0.2 mL PBS containing 107.55 CFU/mL APEC. Mortality was recorded during 7 days post inoculation. Overall, 50–60% reduced mortality was observed in the High line compared to the Low line for all APEC doses. In addition, morbidity was determined of the surviving chickens at 15 days of age. The High line had lower morbidity scores compared to the Low line. We conclude that selective breeding for high KLH-binding NAb levels at 16 weeks of age increase APEC resistance in early life. This study and previous studies support the hypothesis that KLH-binding NAb might be used as an indicator trait for to selective breed for general disease resistance in an antigen non-specific fashion.

Applicability of the poultry qPCR method to detect DNA of poultry processed animal protein materials
Scholtens, Ingrid M.J. ; Prins, Theo W. ; Margry, Rob J.C.F. ; Dahlmans, Harald ; Raamsdonk, Leo W.D. van - \ 2019
Food Control 96 (2019). - ISSN 0956-7135 - p. 53 - 58.
Bovine spongiform encephalopathy (BSE) - Chicken - Duck - Feed - Geese - Poultry - Processed animal proteins (PAPs) - Sensitivity - Species-to-species ban - Transmissible spongiform encephalopathy (TSE) - Turkey

After the Bovine Spongiform Encephalitis (BSE) crisis most processed animal proteins (PAPs) were banned from use in animal feed. For the foreseen reintroduction of pork PAPs in poultry feed, and poultry PAPs in pork feed and to comply with the species-to-species ban that prohibits cannibalism, a sensitive and specific TaqMan PCR detection method for poultry DNA has been designed and published. This poultry method is able to detect DNA of chicken, turkey, duck and geese in one PCR reaction. PAPs however, are a difficult and variable matrix. Therefore, the usability of the poultry method was investigated on a range of different poultry PAPs. It was shown that the poultry detection method is capable of detecting poultry DNA in eight out of nine different poultry PAPs mixed at a 0.1% level in chicken feed. The method can also detect at least 0.1% poultry PAPs mixed in pork PAPs. These results show that the poultry method fulfils the 0.1% detection limit requirement in the EU legislation.

Genomic characterization of extended-spectrum cephalosporin-resistant Salmonella enterica in the Colombian poultry chain
Castellanos, Luis Ricardo ; Graaf-van Bloois, Linda van der; Donado-Godoy, Pilar ; León, Maribel ; Clavijo, Viviana ; Arévalo, Alejandra ; Bernal, Johan F. ; Mevius, Dik J. ; Wagenaar, Jaap A. ; Zomer, Aldert ; Hordijk, Joost - \ 2018
Frontiers in Microbiology 9 (2018)OCT. - ISSN 1664-302X
Chicken - Latin America - MLST - pMLST - S. Heidelberg - S. Java - S. paratyphi B d-tartrate positive

Salmonella enterica serovars have been isolated from Colombian broilers and broiler meat. The aim of this study was to investigate the diversity of ESBL/pAmpC genes in extended-spectrum cephalosporin resistant Salmonella enterica and the phylogeny of ESBL/pAmpC-carrying Salmonella using Whole Genome Sequencing (WGS). A total of 260 cefotaxime resistant Salmonella isolates, obtained between 2008 and 2013 from broiler farms, slaughterhouses and retail, were included. Isolates were screened by PCR for ESBL/pAmpC genes. Gene and plasmid subtyping and strain Multi Locus Sequence Typing was performed in silico for a selection of fully sequenced isolates. Coregenome-based analyses were performed per ST encountered. blaCMY-2-like was carried in 168 isolates, 52 carried blaCTX-M-2 group, 7 blaSHV, 5 a combination of blaCMY-2-like-blaSHV and 3 a combination of blaCMY-2-likeblaCTX-M-2 group. In 25 isolates no ESBL/pAmpC genes that were screened for were found. WGS characterization of 36 selected strains showed plasmid-encoded blaCMY-2 in 21, blaCTX-M-165 in 11 and blaSHV-12 in 7 strains. These genes were mostly carried on IncI1/ST12, IncQ1, and IncI1/ST231 plasmids, respectively. Finally, 17 strains belonged to S. Heidelberg ST15, 16 to S. Paratyphi B variant Java ST28, 1 to S. Enteritidis ST11, 1 to S. Kentucky ST152 and 1 to S. Albany ST292. Phylogenetic comparisons with publicly available genomes showed separate clustering of Colombian S. Heidelberg and S. Paratyphi B var. Java. In conclusion, resistance to extended-spectrum cephalosporins in Salmonella from Colombian poultry is mainly encoded by blaCMY-2 and blaCTX-M-165 genes. These genes are mostly associated with IncI1/ST12 and IncQ1 plasmids, respectively. Evolutionary divergence is observed between Colombian S. Heidelberg and S. Paratyphi B var. Java and those from other countries..

A novel loss-of-function variant in transmembrane protein 263 (TMEM263) of autosomal dwarfism in chicken
Wu, Zhou ; Derks, Martijn F.L. ; Dibbits, Bert ; Megens, Hendrik Jan ; Groenen, Martien A.M. ; Crooijmans, Richard P.M.A. - \ 2018
Frontiers in Genetics Livestock Genomics 9 (2018). - ISSN 1664-8021
Autosomal dwarfism - Body size - Chicken - Loss-of-function mutation - Recessive trait

Autosomal dwarfism (adw) in chickens is a growth deficiency caused by a recessive mutation. Characteristic for adw is an approximately 30% growth reduction with short shank. The adw variant was first recognized in the Cornell K-strain of White Leghorns, but the genetic causal variant remained unknown. To identify the causal variant underlying the adw phenotype, fine mapping was conducted on chromosome 1, within 52-56 Mb. This region was known to harbor the causal variant from previous linkage studies. We compared whole-genome sequence data of this region from normal-sized and adw chickens in order to find the unique causal variant. We identified a novel nonsense mutation NP_001006244.1:p.(Trp59*), in the transmembrane protein 263 gene (TMEM263), completely associated with adw. The nonsense mutation truncates the transmembrane protein within the membrane-spanning domain, expected to cause a dysfunctional protein. TMEM263 is reported to be associated with bone mineral deposition in humans, and the protein shows interaction with growth hormone 1 (GH1). Our study presents molecular genetic evidence for a novel loss-of-function variant, which likely alters body growth and development in autosomal dwarf chicken.

Effects of early feeding and dietary interventions on development of lymphoid organs and immune competence in neonatal chickens : A review
Taha-Abdelaziz, Khaled ; Hodgins, Douglas C. ; Lammers, Aart ; Alkie, Tamiru Negash ; Sharif, Shayan - \ 2018
Veterinary Immunology and Immunopathology 201 (2018). - ISSN 0165-2427 - p. 1 - 11.
Antimicrobial peptides - Chicken - Dietary supplementation - Early feeding - Feed additives - Heat stress - Immune system - In ovo feeding - Lymphoid organs - Nanoparticles - Phytobiotics - Prebiotics - Probiotics - TLR ligands
With the ongoing intensification of the poultry industry and the continuous need to control pathogens, there is a critical need to extend our understanding of the avian immune system and the role of nutritional interventions on development of immune competence in neonatal chicks. In this review, we will focus on the ontogeny of the lymphoid organs during embryonic life and the first 2 weeks post-hatch, and how early feeding practices improve heath and modulate the development and function of the immune system in young chicks. The evidence for the positive impact of the nutrition of breeder hens on embryonic development and on the survival and immunity of their chicks will also be outlined. Additionally, we will discuss the vital role of supplemental feeding either in ovo or immediately post-hatch in chick health and immunity and the importance of these approaches in ameliorating immune system functions of heat-stressed chicks. To conclude, we provide some perspectives on a number of key issues, concerning the mechanisms of nutritional modulation of immunity, that need to be addressed. A thorough investigation of these mechanisms may assist in the formulation of diets to improve the immunity and general health status.
Chicken immune response following in ovo delivery of bacterial flagellin
Vaezirad, M.M. ; Koene, M.G. ; Wagenaar, J.A. ; Putten, J.P.M. van - \ 2018
Vaccine 36 (2018)16. - ISSN 0264-410X - p. 2139 - 2146.
Chicken - Flagellin - Humoral Response - In ovo immunization - Toll-like receptor - Vaccine
In ovo immunization of chicken embryos with live vaccines is an effective strategy to protect chickens against several viral pathogens. We investigated the immune response of chicken embryos to purified recombinant protein. In ovo delivery of Salmonella flagellin to 18-day old embryonated eggs resulted in elevated pro-inflammatory chIL-6 and chIL-8 (CXCL8-CXCLi2) cytokine transcript levels in the intestine but not in the spleen at 24 h post-injection. Analysis of the chicken Toll-like receptor (TLR) repertoire in 19-day old embryos revealed gene transcripts in intestinal and spleen tissue for most chicken TLRs, including TLR5 which recognizes Salmonella flagellin (FliC). The in ovo administration of FliC did not alter TLR transcript levels, except for an increase in intestinal chTLR15 expression. Measurement of the antibody response in sera collected at day 11 and day 21 post-hatch demonstrated high titers of FliC-specific antibodies for the animals immunized at the late-embryonic stage in contrast to the mock-treated controls. The successful in ovo immunization with purified bacterial antigen indicates that the immune system of the chicken embryo is sufficiently mature to yield a strong humoral immune response after single exposure to purified protein. This finding strengthens the basis for the development of in ovo protein-based subunit vaccines.
Antigen-dependent effects of divergent selective breeding based on natural antibodies on specific humoral immune responses in chickens
Berghof, T.V.L. ; Arts, J.A.J. ; Bovenhuis, H. ; Lammers, A. ; Poel, J.J. van der; Parmentier, H.K. - \ 2018
Vaccine 36 (2018)11. - ISSN 0264-410X - p. 1444 - 1452.
Breeding - Chicken - General disease resistance - Keyhole limpet hemocyanin (KLH) - Natural antibody - Specific antibody
NAb are defined as antigen binding antibodies present without a known previous exposure to this antigen. NAb are suggested to enhance specific antibody (SpAb) responses, but consequences of different NAb levels on immunization are largely unknown. Layer chickens were divergently selected and bred for keyhole limpet hemocyanin (KLH)-binding NAb titers, resulting in a High line and a Low line. In this study, we investigated: (1) the relation of NAb levels with SpAb titers; and (2) the effect of immunization on NAb titers. The 50 highest females of the High line and the 50 lowest females of the Low line of generation 2 were intramuscularly immunized at 33 weeks of age with 1 mL phosphate buffered saline (PBS) containing one of four treatments: (1) negative control (no antigen), (2) 500 μg KLH, (3) 100 μg avian tuberculin purified protein derivative of Mycobacterium avium (PPD), or (4) 250 μg human serum albumin (HuSA). IgM and IgG titers of NAb and SpAb in plasma were determined prior to immunization and weekly for 5 weeks post immunization by indirect ELISA. In addition, antibody affinity was investigated. No differences in SpAb and NAb response against KLH and PPD were observed as a consequence of different NAb titers, but increased and prolonged SpAb and NAb titer responses against HuSA were observed for the High line compared to the Low line. Different natural antibody titers did not impair SpAb dynamics and SpAb affinity. NAb titers were not, or for only short-term, affected by immunization. We show here that NAb may enhance SpAb responses, but that this effect is antigen-dependent. We hypothesize that NAb play a role in general disease resistance through enhancement of the humoral adaptive immune response.
A ‘meta-analysis’ of effects of post-hatch food and water deprivation on development, performance and welfare of chickens
Jong, I.C. de; Riel, J.W. van; Bracke, M.B.M. ; Brand, H. van den - \ 2017
PLoS ONE 12 (2017)12. - ISSN 1932-6203 - 20 p.
Chicken - Body weight - Yolk Sac - Gastrointestinal tract - animal performance - poultry - jejunum - meta-analysis
A ‘meta-analysis’ was performed to determine effects of post-hatch food and water deprivation (PHFWD) on chicken development, performance and welfare (including health). Two types of meta-analysis were performed on peer-reviewed scientific publications: a quantitative ‘meta-analysis’ (MA) and a qualitative analysis (QA). Previously reported effects of PHFWD were quantified in the MA, for variables related to performance, mortality and relative yolk sac weight. The QA counted the number of studies reporting (non-)significant effects when five or more records were available in the data set (i.e. relative heart, liver and pancreas weight; plasma T3, T4 and glucose concentrations; relative duodenum, jejunum and ileum weight; duodenum, jejunum and ileum length; and villus height and crypt depth in duodenum, jejunum and ileum). MA results indicated that 24 hours of PHFWD (i.e. ≥12–36 hours) or more resulted in significantly lower body weights compared to early-fed chickens up to six weeks of age. Body weights and food intake were more reduced as durations of PHFWD (24, 48, 72, ≥84 hours) increased. Feed conversion rate increased in chickens up to 21 and 42 days of age after ≥84 hours PHFWD in comparison with chickens fed earlier. Total mortality at day 42 was higher in chickens after 48 hours PHFWD compared to early fed chickens or chickens after 24 hours PHFWD. First week mortality was higher in chickens after ≥84 hours PHFWD than in early fed chickens. The MA for relative yolk sac weight was inconclusive for PHFWD. The QA for plasma T3, T4 and glucose concentrations indicated mainly short-term decreases in T3 and glucose in PHFWD chickens compared to early fed chickens, and no effects of PHFWD on T4 concentrations. Relative weights of liver, pancreas and heart were lower after PHFWD, but only in the first week of life. A retarded development of gut segments (duodenum, jejunum and ileum) was found in the first week of life, measured as shorter, lower relative weight, and lower villus height and crypt depth. It is concluded that 48 hours (≥36–60 hours) PHFWD leads to lower body weights and higher total mortality in chickens up to six weeks of age, the latter suggesting compromised chicken welfare, but effects of PHFWD on organ development and physiological status appear to be mainly short-term.
Genetic aspects of auto-immune profiles of healthy chickens
Parmentier, Henk K. ; Vaart, Priscilla S. van der; Nieuwland, Mike G.B. ; Savelkoul, Huub F.J. - \ 2017
Developmental and Comparative Immunology 74 (2017). - ISSN 0145-305X - p. 90 - 100.
Chicken - Natural (auto) antibodies - Selection lines - Western blot

Auto-antibody profiles binding liver antigens differed between chicken lines divergently selected for specific antibody responses to SRBC, and were affected by ageing suggesting both genetic and environmental effects. Presence and levels of IgM and IgG antibodies binding chicken liver cell lysate (CLL) fragments in plasma at 5 weeks of age from 10 individual full sibs and their parents from 5 Hsrbc and 5 Lsrbc line families was studied to reveal genetic relations. Non-genetic maternal effects were studied by comparing auto-antibody profiles of 36 weeks old hens from 2 other unrelated lines with the profiles from their chicks at hatch. IgM and IgG antibodies from parents and progeny from both Hsrbc and Lsrbc lines bound CLL fragments. Significant line and generation differences and their interactions were found for both isotypes. Higher staining of CLL fragments was usually found for Hsrbc line birds. Lines were clustered by auto-antibody profiles, but staining by birds of both lines in both generations was very individual for IgG and IgM. The current data with full sibs therefore not supported a genetic basis for auto-antibody profiles. IgG but not IgM auto-antibody profiles of chicks correlated with maternal auto-antibody profiles. The results suggest that the auto-antibody repertoire of healthy chickens is largely stochastically initiated and may be affected by environmental challenges during ageing, but genetic mechanisms may underlie staining intensity of individual bound CLL fragments. The present results suggest that identification of fragments or profiles to be used at early age for genetic selection for health traits is not feasible yet. Secondly, the IgM profile of neonatal chickens seems non-organised independent of the maternal profile, but the neonatal IgG profile is much more related with the maternal profile. Consequences of these findings for disease susceptibility or breeding for optimal health are discussed.

Brain monoamine levels and behaviour of young and adult chickens genetically selected on feather pecking
Kops, M.S. ; Kjaer, J.B. ; Güntürkün, O. ; Westphal, K.G.C. ; Korte-Bouws, G.A.H. ; Olivier, B. ; Korte, S.M. ; Bolhuis, J.E. - \ 2017
Behavioural Brain Research 327 (2017). - ISSN 0166-4328 - p. 11 - 20.
Brain monoamines - Chicken - Development - Dopamine - Genetic selection - Hyperactivity - Laying hen - Poultry welfare - Serotonin - Severe feather pecking

Severe feather pecking (SFP) in chickens is a detrimental behaviour with possibly neurochemical deficits at its base. Recent neurological studies depicted conflicting results on the role of serotonin (5-hydroxytryptamine, 5-HT) and dopamine (DA) in the development and display of feather pecking. We studied brain monoamine levels and behaviour in domestic chickens divergently genetically selected on feather pecking behaviour, the Low Feather Pecking (LFP) and High Feather Pecking (HFP) lines, both at a young age and when adult, to elucidate the role of 5-HT and DA in feather pecking. Also pecking behaviour and the behavioural response to challenging test situations was determined. At 8 weeks of age, HFP had lower 5-HT and DA turnover in several brain areas than LFP, whereas these differences had disappeared or were even reversed at 25 weeks of age. Line differences in central monoamine activity were found both in emotion-regulating and motor-regulating areas. As expected from previous generations, HFP exceeded LFP in most types of pecking at other birds, including severe feather pecking. Furthermore, HFP responded more actively in most behavioural tests conducted, and seem more impulsive or (hyper)active in their way of coping with challenges. This paper shows different developmental trajectories of the neurochemical systems (5-HT and DA) for chickens divergently selected on feather pecking behaviour, and a remarkable reversion of differences in monoamine activity at a later stage of life. Whether this is a cause or consequence of SFP needs further investigation.

Colonization of Enteroaggregative Escherichia coli and Shiga toxin-producing Escherichia coli in chickens and humans in southern Vietnam
Trung, Nguyen Vinh ; Nhung, Hoang Ngoc ; Carrique-Mas, Juan J. ; Mai, Ho Huynh ; Tuyen, Ha Thanh ; Campbell, James ; Nhung, Nguyen Thi ; Minh, Pham Van; Wagenaar, Jaap A. ; Mai, Nguyen Thi Nhu ; Hieu, Thai Quoc ; Schultsz, Constance ; Hoa, Ngo Thi - \ 2016
BMC Microbiology 16 (2016)1. - ISSN 1471-2180
Chicken - E. coli - EAEC - Humans - STEC - Vietnam

Background: Enteroaggregative (EAEC) and Shiga-toxin producing Escherichia coli (STEC) are a major cause of diarrhea worldwide. E. coli carrying both virulence factors characteristic for EAEC and STEC and producing extended-spectrum beta-lactamase caused severe and protracted disease during an outbreak of E. coli O104:H4 in Europe in 2011. We assessed the opportunities for E. coli carrying the aggR and stx genes to emerge in 'backyard' farms in south-east Asia. Results: Faecal samples collected from 204 chicken farms; 204 farmers and 306 age- and gender-matched individuals not exposed to poultry farming were plated on MacConkey agar plates with and without antimicrobials being supplemented. Sweep samples obtained from MacConkey agar plates without supplemented antimicrobials were screened by multiplex PCR for the detection of the stx1, stx2 and aggR genes. One chicken farm sample each (0.5 %) contained the stx1 and the aggR gene. Eleven (2.4 %) human faecal samples contained the stx1 gene, 2 samples (0.4 %) contained stx2 gene, and 31 (6.8 %) contained the aggR gene. From 46 PCR-positive samples, 205 E. coli isolates were tested for the presence of stx1, stx2, aggR, wzx O104 and fliC H4 genes. None of the isolates simultaneously contained the four genetic markers associated with E. coli O104:H4 epidemic strain (aggR, stx2, wzx O104 and fliC H4 ). Of 34 EAEC, 64.7 % were resistant to 3rd-generation cephalosporins. Conclusion: These results indicate that in southern Vietnam, the human population is a more likely reservoir of aggR and stx gene carrying E. coli than the chicken population. However, conditions for transmission of isolates and/or genes between human and animal reservoirs resulting in the emergence of highly virulent E. coli strains are still favorable, given the nature of'backyard' farms in Vietnam.

Effects of early life dextran sulfate sodium administration on pathology and immune response in broilers and layers
Simon, K. ; Arts, J.A.J. ; Vries Reilingh, G. De; Kemp, B. ; Lammers, A. - \ 2016
Poultry Science 95 (2016)7. - ISSN 0032-5791 - p. 1529 - 1542.
Chicken - DSS - Immune response - Intestinal homeostasis

Intestinal pathology early in life may affect immune development and therefore immune responses later in life. Dextran sulfate sodium (DSS) induces colitis in rodents and is a widely used model for inflammatory bowel diseases. The present study investigated DSS as a model for early life intestinal pathology and its consequences on intestinal pathology, ileal cytokine, and immunoglobulin mRNA expression levels as well as the antibody response towards an immunological challenge later in life in chickens. Broiler and layer chicks received 2.5% DSS in drinking water during d 11 through d 18 post hatch or plain drinking water as a control. As an immunological challenge all birds received a combination of Escherichia coli lipopolysaccharide (LPS) and human serum albumin (HuSA) intramuscularly (i.m.) at d 35, and antibody titers against LPS, HuSA, and keyhole limpet hemocyanin (KLH) were determined to investigate effects of intestinal inflammation early in life on humoral immunity later in life. DSS treated birds showed a decrease in BW from which broilers quickly recovered, but which persisted for several weeks in layers. Histological examination of intestinal samples showed symptoms similar to those in rodents, including shortening and loss of villi and crypts as well as damage of the epithelial cell layer of different parts of the intestine. Effects of DSS on intestinal morphology were less severe in broilers that also showed a lower mortality in response to DSS than layers. No effect of DSS on ileal cytokine expression levels could be observed, but ileal immunoglobulin expression levels were decreased in DSS treated broilers that also showed lower antibody titers against LPS in response to the challenge. In conclusion, DSS may serve as a model for intestinal pathology early in life, although more research on the appropriate dose is necessary and is likely to differ between breeds. Results from the present study could indicate that broilers are less susceptible to DSS compared with layers or have a better capacity to recover from intestinal pathology.

Long-term effects of early life microbiota disturbance on adaptive immunity in laying hens
Simon, K. ; Verwoolde, M.B. ; Zhang, J. ; Smidt, H. ; Vries Reilingh, G. De; Kemp, B. ; Lammers, A. - \ 2016
Poultry Science 95 (2016)7. - ISSN 0032-5791 - p. 1543 - 1554.
Antibiotics - Chicken - Immune response - Microbiota

Due to an interplay between intestinal microbiota and immune system, disruption of intestinal microbiota composition during immune development may have consequences for immune responses later in life. The present study investigated the effects of antibiotic treatment in the first weeks of life on the specific antibody response later in life in chickens. Layer chicks received an antibiotic cocktail consisting of vancomycin, neomycin, metronidazole, and amphotericin-B by oral gavage every 12 h, and ampicillin and colistin in drinking water for the first week of life. After the first week of life, chicks received ampicillin and colistin in drinking water for two more weeks. Control birds received no antibiotic cocktail and plain drinking water. Fecal microbiota composition was determined during antibiotic treatment (d 8 and 22), two weeks after cessation of antibiotic treatment (d 36), and at the end of the experimental period at d 175 using a 16S ribosomal RNA gene targeted microarray, the Chicken Intestinal Tract Chip (ChickChip). During antibiotic treatment fecal microbiota composition differed strongly between treatment groups. Fecal microbiota of antibiotic treated birds consisted mainly of Proteobacteria, and in particular E.coli, whereas fecal microbiota of control birds consisted mainly of Firmicutes, such as lactobacilli and clostridia. Two weeks after cessation of antibiotic treatment fecal microbiota composition of antibiotic treated birds had recovered and was similar to that of control birds. On d 105, 12 weeks after cessation of antibiotic treatment, chicks of both treatment groups received an intra-tracheal lipopolysaccharide (LPS)/human serum albumin (HuSA) challenge. Antibody titers against LPS and HuSA were measured 10 days after administration of the challenge. While T cell independent antibody titers (LPS) were not affected by antibiotic treatment, antibiotic treated birds showed lower T cell dependent antibody titers (HuSA) compared with control birds. In conclusion, intestinal microbial dysbiosis early in life may still have effects on the specific antibody response months after cessation of antibiotic treatment and despite an apparent recovery in microbiota composition.

Quantification of interferon signaling in avian cells
Kint, Joeri ; Forlenza, Maria - \ 2015
In: Coronaviruses: Methods and Protocols Springer New York LLC - ISBN 9781493924387 - p. 251 - 259.
Bioassay - Chicken - Interferon - Real-time quantitative PCR

Activation of the type I interferon (IFN) response is an essential defense mechanism against invading pathogens such as viruses. This chapter describes two protocols to quantify activation of the chicken IFN response through analysis of gene expression by real-time quantitative PCR and by quantification of bioactive IFN protein using a bioassay.

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