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ABSTRACT: Toll-like receptors (TLR) recognize evolutionarily conserved molecular motifs (pathogen-associated molecular patterns) of infectious microbes and initiate innate immune response upon activation with relevant pathogens. This study investigated the acute effect of Salmonella Enteritidis challenge on TLR mRNA expression in cecum and spleen of birds from 3 distinct genetic lines. Chicks from broiler, Leghorn, and Fayoumi lines were inoculated or mock-inoculated with Salmonella Enteritidis. The mRNA expression levels of TLR2, TLR4, and TLR5 genes were assessed by quantitative reverse transcription-PCR of cecum and spleen tissue harvested at 2 or 18 h postinoculation (PI). There were no significant genetic line effects on TLR mRNA expression in spleen or cecum of mock-infected birds, or in the cecum of infected birds. Genetic line effect was significant (P < 0.05) on TLR mRNA expression in the spleen of Salmonella Enteritidis-infected birds. The Fayoumi line had higher TLR2 and TLR4 expression than Leghorn, higher TLR2 mRNA expression than broiler, and the broiler line had higher TLR5 expression than Leghorn and Fayoumi. In Salmonella Enteritidis-infected birds, the TLR2 expression in both cecum and spleen and TLR4 expression in spleen were significantly higher at 18 h PI than 2 h PI. The results demonstrate a significant genetic line effect on TLR expression in the spleen of Salmonella Enteritidis-infected birds, which may partly explain genetic variability in immune response to Salmonella Enteritidis.
Poultry Science 04/2009; 88(4):744-9. · 1.73 Impact Factor
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ABSTRACT: Understanding the changes in host gene expression that occur with bacterial infection will help to elucidate the basis of molecular genetic control of disease resistance. The effect of infecting chicks with Salmonella enterica serovar Enteritidis on the RNA expression level of Toll-like receptor (TLR) genes, and the correlation between TLR RNA expression level and bacterial burden in the cecum and spleen of young birds was studied. Chicks from two advanced intercross lines were either infected or mock infected with S. enteritidis at 1 day of age. The RNA expression levels of TLR2, TLR4 and TLR5 genes were assessed by quantitative reverse transcriptase-PCR (qRT-PCR) in cecum and spleen tissues harvested at one week post-infection. Infected chicks had significant upregulation of TLR2 RNA expression in spleen, TLR4 RNA expression in both cecum and spleen, and downregulation of TLR5 RNA expression in cecum. Bacterial burden of S. enteritidis in infected birds was not correlated with TLR RNA expression level. Infecting chicks with S. enteritidis caused an increase in TLR2, TLR4 and TLR5 RNA expression level in spleen in males but not in females. The effect of sex on response to S. enteritidis infection suggests a role for TLR signaling pathways in sex-based modulation of immune response to pathogens. High correlation between TLR2 and TLR4 mRNA expression level in cecum of S. enteritidis infected birds suggests coordinated regulation or simultaneous stimulation of these genes by S. enteritidis. In conclusion, this study clearly showed that young chicks respond to S. enteritidis infection by upregulating TLR2, TLR4 RNA expression. The downregulation of TLR5 RNA expression was observed in cecum by S. enteritidis infection, which might be beneficial to protect host cells from overstimulation by bacterial flagellin.
Veterinary Immunology and Immunopathology 07/2008; 123(3-4):314-23. · 2.08 Impact Factor
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ABSTRACT: Cytokines are secreted proteins involved with cell recruitment and regulation of both innate and adaptive immune responses. They are essential for an effective host immune response to pathogens. The objective of this study was to determine the effect of Salmonella enterica serovar Enteritidis (S. Enteritidis) exposure and genetic line on cytokine mRNA expression level of cultured chicken peripheral blood mononuclear cells (PBMC). Interleukin-2, interleukin-6 (IL-6), CXCLi2, and transforming growth factor-beta4 (TGF-B4) messenger ribonucleic acid expression was measured by quantitative reverse transcription-PCR assays in PBMC from 3 chicken lines (broiler, Leghorn, Fayoumi) after in vitro exposure to S. Enteritidis. The PBMC were isolated from uninfected birds and cultured overnight. The next day, live pathogenic S. Enteritidis was added to half of the cultures. All cultures were harvested after 2 or 4 h of exposure. Exposure to S. Enteritidis downregulated IL-6, CXCLi2, and TGF-beta4 but not interleukin-2 mRNA expression. No significant genetic line or exposure time effects were detected. These findings demonstrate that exposure of chicken PBMC to S. Enteritidis can induce a rapid change in both proinflammatory (IL-6, CXCLi2) and antiinflammatory (TGF-beta4) cytokine gene expression.
Poultry Science 12/2006; 85(11):1907-11. · 1.73 Impact Factor
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ABSTRACT: To determine the role of genetics in baseline lymphocyte parameters, several distinct lines of chickens were examined for differences in peripheral blood leukocyte (PBL) populations. Four highly inbred chicken lines (MHC congenic Fayoumi lines M15.2 and M5.1, and MHC congenic Leghorn lines G-B1 and G-B2), two advanced intercrosses [F5 (Broiler x G-B2) and F5 (Broiler x M15.2)], and an outbred population of broilers were used. Leukocytes isolated from healthy adult birds were labeled with monoclonal antibodies: chCD3, chCD4, chCD8, chBu-1, and hCD14. Flow cytometry was used to determine the total percentage of positively labeled cells for each surface marker in a sample, as well as the mean fluorescent intensity, or surface marker density, of a labeled subset. Significant line differences for percentage positive CD3 T cells and the ratio of B cells:T cells (represented by the Bu-1:CD3 ratio) were found. The effect of line was also significant for CD3 and CD8 T cell receptor density. Effects of sex and MHC on PBL cell surface marker expression were not significant in the lines examined. This study demonstrates the effect of genetic line on resting leukocyte composition of peripheral blood in the chicken lines examined. Observed PBL differences add to our growing knowledge of the varied roles that immune system status (defined by specific cell populations) and genetic background have in determining susceptibility and disease progression in chickens.
Poultry Science 07/2004; 83(6):911-6. · 1.73 Impact Factor
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Animal Genetics 05/2004; 35(2):158-9. · 2.40 Impact Factor
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ABSTRACT: A potential limitation of the use of a dominant molecular marker system such as DNA fingerprinting (DFP) is the inability to distinguish homozygous from heterozygous allele state in an individual, and a resulting inaccuracy in estimating effects of the marker alleles. The objective of this study was to accurately estimate the effect of DFP markers on egg-production traits. A BC1 population was produced from two distinct layer lines. Four DFP bands, each originating predominantly in one of the two parental lines, were evaluated for linkage with egg-production quantitative trait loci in the BC1 population. The egg-production traits consisted of eight early period and seven late period measurements. Eight marker-trait linkages were identified out of 60 total statistical tests. By utilizing information on frequency of DFP bands in two parental lines, selecting F1 sires with DFP bands present, and backcrossing to the line lacking these bands, the population design allowed definitive identification of the DFP zygosity in the BC1 resource population hens. In this manner, accurate estimates of marker allele effects on egg-production traits were obtained from the dominant marker system of DNA fingerprinting.
Animal Genetics 11/2003; 34(5):334-8. · 2.40 Impact Factor
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ABSTRACT: Salmonella enteritidis (SE) contamination of poultry products is of global food-safety concern. The natural resistance-associated macrophage protein 1 (NRAMP1) affects host innate immunity to intracellular bacteria because of its ability to transport divalent cations in late endosome/lysosomes. Studying the association of the NRAMP1 gene and chicken innate immune response to SE can, therefore, aid understanding and enhancement of chicken genetic resistance to SE. The chicken NRAMP1 gene was investigated as a candidate gene for SE response in a unique resource population. Outbred broiler sires and three diverse, highly inbred dam lines (two major histocompatibility complex-congenic Leghorn and one Fayoumi line) produced F1 progeny that were evaluated as young chicks for either bacterial load in spleen and cecum after pathogenic SE inoculation or antibody level after SE vaccination. Thirty-seven single nucleotide polymorphisms (SNP) were identified in 3.1 kb of genomic DNA of the NRAMP1 gene. A PCR-RFLP assay was developed to identify a SNP in a conserved transport motif. The sire NRAMP1 gene SNP was associated (P < 0.02) with antibody level to SE vaccine for Sire 8170 offspring in the two Leghorn crosses. In Sire 8296 offspring, NRAMP1 was associated (P < 0.02) with spleen bacterial load in the combined dam-line crosses. This study demonstrated the association of a SNP polymorphism in a highly conserved region of NRAMP1 with SE vaccine and pathogen challenge response in young chicks, indicating that either NRAMP1 or a linked gene controls these SE-response traits.
Poultry Science 02/2003; 82(2):259-66. · 1.73 Impact Factor
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ABSTRACT: Salmonellosis is a zoonotic disease that is problematic for both animal production and food safety. A novel genetic cross, named the Iowa Salmonella response resource population (ISRRP), was established to elucidate the genetic control of resistance to Salmonella enteritidis (SE) colonization in young chicks, to characterize unique resistance alleles, and to estimate gene interaction effects. Outbred broiler sires were mated with dams of diverse, highly inbred, light-bodied lines to produce an F(1) generation that was informative for all heterozygous alleles of the sires. Mating F(1) sires back to dams of the corresponding inbred line produced a backcross generation. To mimic the natural route of exposure and thus afford the opportunity to investigate mucosal immunity, pathogenic SE were inoculated into the esophagus of day-old chicks. After 1 week, the SE colonizing the cecal lumen and the spleen were enumerated. Candidate genes were selected for analysis based upon one of the two criteria. Functional candidates were genes with reported activity related to the tested traits. Positional candidates were genes mapped near microsatellites that were linked, in other phases of this project, with antibody levels to SE vaccine. Broiler sire alleles of the MHC class I, NRAMP1, PSAP, and IAP1 genes showed association with SE colonization in the F(1) generation of this novel disease resistance resource population.
Veterinary Immunology and Immunopathology 10/2002; 87(3-4):423-8. · 2.08 Impact Factor
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ABSTRACT: Contamination of poultry and poultry products by Salmonella enterica Serovar Enteritidis (SE) continues to be problematic even though biosafety management practices have aided in reduction of the SE burden. Identification of molecular markers linked to disease resistance loci would further reduce SE burden by enabling selection for genetic resistance. The objectives of this study were therefore to evaluate specific genomic regions for resistance to SE burden in young broiler-cross chicks and to evaluate the interaction of allele with dam line and sex. Three hatches of F1 chicks were produced by crossing sires from a broiler breeder male line with hens from three highly inbred lines (Fayoumi 15.2, and MHC-congenic G-B1 and G-B2 Leghorn). At 1 d of age, the chicks were intraesophageally inoculated with SE phage type 13a. Spleen and cecal content samples were harvested at 1 wk, and the levels of SE were quantified by serial plate dilution. Each of the F1 chicks was genotyped with four microsatellites that had previously been shown to be linked to antibody response to SE vaccine. All four microsatellites had a significant (P < or = 0.05) main effect or interaction with dam line or sex on the level of SE in spleen and cecal contents.
Poultry Science 06/2002; 81(5):657-63. · 1.73 Impact Factor
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ABSTRACT: Reduction in Salmonella enteritidis (SE) contamination is of importance for poultry production as well as for food safety. The objectives of this study were to identify potential genetic markers of antibody response to SE vaccine in young broiler chicks and then to confirm this linkage in broiler-cross offspring, as well as to explore interactions of marker alleles with dam line and sex. The initial identification of suggestive quantitative trait loci (QTL) markers for antibody response to SE vaccine was conducted by using bulked segregant analysis (BSA) with 58 microsatellite markers in a broiler breeder male line. Four unlinked microsatellites that had allele frequency differences between the high and low antibody response DNA pools were selected for subsequent analysis in a linkage study. Antibody response was measured in an F1 population (n = 379) that was derived by crossing each of four males of the broiler line with several dams from four genetically distant, highly inbred lines (Spanish, Fayoumi, and MHC-congenic G-B1 and G-B2 Leghorn). These crosses enabled us to evaluate the broiler sire QTL-marker allele effects and to explore QTL interactions with the dam lines by individual genotyping. Each of the four microsatellites identified by BSA in the broiler population had a significant (P < 0.05) association with F1 population antibody response in one or more sire families. The effect of the interaction of microsatellite allele with dam line or sex on antibody response was frequently significant. Microsatellite markers linked to antibody response QTL were identified, and genetic interactions with dam line and sex were detected.
Poultry Science 03/2002; 81(2):193-201. · 1.73 Impact Factor
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ABSTRACT: Early infection may result in long-term colonization of layers with Salmonella enterica sv. enteritidis (S. enteritidis, SE), resulting in shedding into table or hatching eggs. To evaluate genetic factors underlying early response to SE, genetic line differences in mortality and pathogen load at two sites (cecal lumen and spleen) were investigated. At day of hatch, chicks of four genetic lines were intra-esophageally inoculated with one of three doses of SE phage type 13a. There was a significant effect (P < 0.001) of genetic line on chick 6-d survival. The effect of genetic line was significant (P < 0.05) on survivors' SE burden in cecal content but not on SE burden per gram of spleen. The SE pathogen load of the spleen and the cecal content were not significantly correlated, indicating that independent host mechanisms are partly responsible for these two traits. Genetic line differences in chick survival and SE colonization of cecal content were demonstrated in young layer chicks.
Poultry Science 08/2001; 80(8):1105-8. · 1.73 Impact Factor
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ABSTRACT: Two independent broiler chicken populations were genotyped with microsatellite markers to determine genetic polymorphisms within and among broiler populations. Birds were genotyped with primers from the US Poultry Genome Mapping Kits 1 and 2. The 59 primer sets selected for this study provided wide genomic coverage. All 59 primer sets amplified a polymerase chain reaction product in Population L, whereas 57 primer sets produced a product in Population C. The average allele number per line per microsatellite was 2.8 and 2.9 for Populations L and C, respectively. Considering the 57 primer pairs generating product in both lines, 72.3% of the total alleles were unique to one or the other population. This study illustrates the high polymorphism level in broiler populations of microsatellites amplified from primers developed from Red Jungle Fowl or White Leghorn sequences.
Poultry Science 06/2000; 79(5):626-8. · 1.73 Impact Factor
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ABSTRACT: The major histocompatibility complex (MHC) region was examined as a set of candidate genes for association between DNA markers and antibody response. Intercross F2 families of chickens were generated from a cross between high (HC) and low (LC) Escherichia coli(i) antibody lines. Restriction fragment length polymorphism (RFLP) analysis was conducted by using three MHC-related cDNA probes: chicken MHC class IV (B-G), chicken MHC class I (B-F), and human MHC-linked Tap2. Association between RFLP bands and three antibody response traits (E. coli, sheep red blood cells and Newcastle disease virus) were determined by two methods: by statistically analyzing each band separately and also by analyzing all bands obtained from the three probes by using multiple regression analysis to account for the multiple comparisons. The MHC class IV probe was the highest in polymorphisms but had the lowest number of bands associated with antibody response. The MHC class I probe yielded 15 polymorphic bands of which four exhibited association with antibody response traits. The Tap2 probe yielded 20 different RFLP bands of which five were associated with antibody production. Some Tap2 bands were associated with multiple antibody response traits. The multiband analysis of the three probes' bands revealed more significant effects than the analysis of each band separately. This study illustrates the efficacy of using multiple MHC region probes as candidate markers for quantitative trait loci (QTLs) controlling antibody response in chickens.
Animal Genetics 05/1999; 30(2):92-101. · 2.40 Impact Factor
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ABSTRACT: Broiler breeder chicks of two different genetic lines were evaluated for early antibody response to Salmonella enteritidis (SE) vaccine. Antibody responses to three dosages of SE vaccine administered at 22 d of age were measured at 3, 6, and 10 d postvaccination. Within each line, antibody levels at 10 d postvaccination were significantly higher than at either 3 or 6 d postvaccination. At all vaccine dosages, there was a significant antibody-response difference between the genetic lines at 6 and 10 d postvaccination. The vaccine dosage significantly affected antibody levels in one of the two genetic lines. These results demonstrate a genetic component of early antibody response to SE vaccine in broiler breeder chicks.
Poultry Science 03/1998; 77(2):271-5. · 1.73 Impact Factor
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ABSTRACT: This study utilized DNA fingerprints and crosses of two genetically distinct lines of layer-type chickens to identify genetic markers linked to quantitative trait loci (QTL). In phase I, backcross (BC1) hens were separately ranked for each of eight traits and then blood pools were produced in groups along each phenotypic distribution. The DNA was isolated from the blood pools and used in a gradient analysis to screen for DNA fingerprint bands that exhibited intensity gradients associated with the phenotypic traits. To identify linkage of bands with QTL and to estimate band effects, F2 progeny were produced in phase II from the phase I BC1 population. A single-trait animal model was used for analysis of associations of all individual DNA fingerprint bands of sires and their progeny phenotypic performance. Twenty fingerprint bands, only two of which had shown trait-associated gradients in phase I, were identified by the animal model analysis of the progeny test as QTL linked (P < or = 0.05) to specific traits of growth, reproduction and egg quality. These 20 bands warrant further study as potentially valuable molecular markers for QTL.
Animal Genetics 03/1996; 27(1):1-8. · 2.40 Impact Factor
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ABSTRACT: Thirteen highly inbred chicken lines were analysed at the DNA level by DNA fingerprinting (DEP) and by polymerase chain reaction (PCR) using random primers. In general, the DFP patterns of individuals within a line were identical. The DFP band-sharing (BS) values among lines from different breeds (Leghorn, Fayoumi, Spanish) ranged from 0.10 to 0.20. The DFP BS values among Leghorn lines from different genetic backgrounds ranged from 0.42 to 0.79. The DFP BS values among lines selected for different major histocompatibility complex serotypes from a common genetic background ranged from 0.70 to 0.95. Some randomly amplified polymorphic DNA (RAPD) PCR products were specific to a single line, some to all lines from the same genetic base, and some to all lines from the same breed. The RAPD-PCR band-sharing values ranged from 0.66 to 0.99 for all between-line comparisons. Thus, the ability to detect biodiversity at the DNA level was greater in this study for DFP than for RAPD-PCR. The possible origin of line-specific bands, relative advantages of detecting biodiversity by using different molecular screening techniques and uses of highly inbred chicken lines in molecular analysis are discussed.
Animal Genetics 07/1995; 26(3):163-70. · 2.40 Impact Factor
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ABSTRACT: Two genetic model systems, consisting of a series of sublines differing in linkage between the B blood group (Ea-B) and a gene that encodes immune response to glutamic acid-alanine-tyrosine (Ir-GAT) and a series of highly inbred lines of chickens, were used to examine the relationship between genetic control of levels of interleukin-2-like (IL-2-like) activity and genetic control of mitogen response to concanavalin A (Con A). Results obtained by using the highly inbred lines suggested that levels of IL-2-like activity were associated with levels of mitogen response to Con A. Results obtained by using the Ea-B/Ir-GAT sublines, however, suggested that levels of IL-2-like activity were not associated with the mitogen response to Con A. Levels of IL-2-like activity were associated with Ea-B but not with Ir-GAT, whereas the mitogen response to Con A was associated with both. High levels of IL-2-like activity were demonstrated in birds that had low levels of mitogen response to Con A. Previous genetic events that have occurred within these sublines may have resulted in the dissociation of genetic control of levels of IL-2-like activity and the response to the blastogenesis-inducing mitogen. This demonstrates the independence of genetic control of IL-2-like activity from that of proliferative response to the inducing mitogen.
Poultry Science 02/1990; 69(1):65-71. · 1.73 Impact Factor
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ABSTRACT: The relationship between antibody response to Salmonella enteritidis vaccine and internal organ burden of S. enteritidis is not fully understood. The genetic relationship, therefore, between postchallenge S. enteritidis burden and antibody response to S. enteritidis vaccine was determined in broiler breeder chicks. Sibling chicks from a broiler breeder male line were either inoculated with a pathogenic S. enteritidis or vaccinated with a commercial S. enteritidis vaccine. Spleen, liver, cecal wall, and cecal content samples from S. enteritidis-challenged chicks (n = 120) were cultured for enumeration of bacteria. Unchallenged chicks (n = 314) were vaccinated at 11 days of age, and serum samples were taken at 10 days postvaccination. Antibody response to vaccination and number of S. enteritidis in cecal content cultures were negatively correlated (-0.772), demonstrating that genetic potential for greater antibody response to S. enteritidis vaccine is associated with lesser S. enteritidis bacterial burden in cecal content of broiler breeder chicks. The findings suggest that genetic selection for vaccine antibody responsiveness can lower bacterial burden in the gut lumenal content and, thus, potentially reduce contamination of poultry products at processing.
Avian Diseases 46(1):25-31. · 1.46 Impact Factor
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ABSTRACT: Understanding the changes in host gene expression that occur with bacterial infection will help to elucidate the basis of molecular genetic control of disease resistance. The effect of infecting chicks with Salmonella enterica serovar Enteritidis on the RNA expression level of Toll-like receptor (TLR) genes, and the correlation between TLR RNA expression level and bacterial burden in the cecum and spleen of young birds was studied. Chicks from two advanced intercross lines were either infected or mock infected with S. enteritidis at 1 day of age. The RNA expression levels of TLR2, TLR4 and TLR5 genes were assessed by quantitative reverse transcriptase-PCR (qRT-PCR) in cecum and spleen tissues harvested at one week post-infection. Infected chicks had significant upregulation of TLR2 RNA expression in spleen, TLR4 RNA expression in both cecum and spleen, and downregulation of TLR5 RNA expression in cecum. Bacterial burden of S. enteritidis in infected birds was not correlated with TLR RNA expression level. Infecting chicks with S. enteritidis caused an increase in TLR2, TLR4 and TLR5 RNA expression level in spleen in males but not in females. The effect of sex on response to S. enteritidis infection suggests a role for TLR signaling pathways in sex-based modulation of immune response to pathogens. High correlation between TLR2 and TLR4 mRNA expression level in cecum of S. enteritidis infected birds suggests coordinated regulation or simultaneous stimulation of these genes by S. enteritidis. In conclusion, this study clearly showed that young chicks respond to S. enteritidis infection by upregulating TLR2, TLR4 RNA expression. The downregulation of TLR5 RNA expression was observed in cecum by S. enteritidis infection, which might be beneficial to protect host cells from overstimulation by bacterial flagellin.
Veterinary Immunology and Immunopathology.
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Developmental and Comparative Immunology 30 (2006) 5.
