Host response to successive challenges with lentogenic and velogenic Newcastle disease virus in local chickens of Ghana.

Newcastle disease (ND) is a highly contagious viral disease that constantly threatens poultry production. The velogenic (highly virulent) form of ND inflicts the most damage and can lead to 100% mortality in unvaccinated village chicken flocks. This study sought to characterize responses of local chickens in Ghana after challenging them with lentogenic and velogenic Newcastle disease virus (NDV) strains. At 4 wk of age, chicks were challenged with lentogenic NDV. Traits measured were pre- and post-lentogenic infection growth rates (GR), viral load at 2 and 6 d post-lentogenic infection (DPI), viral clearance rate and antibody levels at 10 DPI. Subsequently, the chickens were naturally exposed to velogenic NDV (vNDV) after anti-NDV antibody titers had waned to levels ≤1:1,700. Body weights and blood samples were again collected for analysis. Finally, chickens were euthanized and lesion scores (LS) across tissues were recorded. Post-velogenic exposure GR; antibody levels at 21 and 34 days post-velogenic exposure (DPE); LS for trachea, proventriculus, intestines, and cecal tonsils; and average LS across tissues were measured. Variance components and heritabilities were estimated for all traits using univariate animal models. Mean pre- and post-lentogenic NDV infection GRs were 6.26 g/day and 7.93 g/day, respectively, but mean post-velogenic NDV exposure GR was -1.96 g/day. Mean lesion scores ranged from 0.52 (trachea) to 1.33 (intestine), with males having significantly higher (P < 0.05) lesion scores compared to females. Heritability estimates for the lentogenic NDV trial traits ranged from moderate (0.23) to high (0.55) whereas those for the vNDV natural exposure trial were very low (≤ 0.08). Therefore, in contrast to the vNDV exposure trial, differences in the traits measured in the lentogenic challenge were more affected by genetics and thus selection for these traits may be more feasible compared to those following vNDV exposure. Our results can form the basis for identifying local chickens with improved resilience in the face of NDV infection for selective breeding to improve productivity.

Differential expression of intestinal nutrient transporters and host defense peptides in Eimeria maxima-infected Fayoumi and Ross chickens.

Fayoumi chickens are believed to be more disease resistant compared to commercial broiler chickens. The objective of this study was to compare mRNA expression of intestinal nutrient transporters, digestive enzymes, and host defense peptides (HDP) between Eimeria maxima-challenged Fayoumi and Ross broiler chickens. At 21 d of age, Ross broilers and Fayoumi lines M5.1 and M15.2 were challenged with 1,000 E. maxima oocysts. Control birds were not challenged. Duodenum, jejunum, and ileum were sampled (n = 6) at 7 d post challenge. Gene expression was analyzed using relative quantification PCR. Data were analyzed by ANOVA and significance level was set at P < 0.05. There was numerical, but not statistically significant, differential weight gain depression for Ross (15%) and Fayoumi lines M5.1 (21%) and M15.2 (22%) and significant line-specific changes in gene expression. For nutrient transporters, there was downregulation of mRNA for the brush border membrane, amino acid transporters b0,+AT/rBAT, BoAT, and EAAT3 in different segments of the small intestine of Ross and both lines of Fayoumi chickens, indicating that E. maxima challenge likely caused a decrease in nutrient uptake. For HDP, there was downregulation of avian beta defensin (AvBD) 1, 6, 10, 12, and 13 mRNA in the jejunum of the 2 Fayoumi lines, but no change in the Ross broilers. In the duodenum, there was upregulation of AvBD10 mRNA in the Ross and both Fayoumi lines and additionally upregulation of AvBD11, 12, and 13 mRNA in only Fayoumi line M15.2. Liver expressed antimicrobial peptide 2 (LEAP2) mRNA was downregulated in the duodenum and jejunum of Ross and Fayoumi line M5.1 but not in Fayoumi line M15.2. The homeostatic, non-challenged levels of AvBD mRNA were greater in Fayoumi line M15.2 than Ross and Fayoumi line M5.1 in the duodenum and ileum. This study demonstrates tissue- and genetic line-specific transcriptional responses to E. maxima, highlights novel potential candidate genes for response to coccidiosis, and confirms a role for several previously reported genes in response to coccidiosis.

Meningococcal Disease in Northern Ireland - Past, Present & Future: MeningoNI Forum.

Meningococcal disease has had devastating consequences in Northern Ireland since its first description locally in 1859. The incidence of this disease has significantly declined in recent years, however it is important to understand reasons for this changing epidemiology and to acknowledge the diagnostic and clinical management developments that have been made locally. This review aims to examine the changing face of this disease in Northern Ireland over the years, with particular reference to local disease prevention, epidemiology, diagnosis, clinical treatment and management, post-disease sequelae and the role of meningitis charities locally, in terms of patient support and research.

Physiological responses to heat stress in two genetically distinct chicken inbred lines.

High ambient temperature is one of the most important environmental factors negatively impacting poultry production and health. Genetics is an important contributor in mitigating the stress response to heat. Two genetically distinct highly inbred lines of similar body size (Leghorn and Fayoumi) were characterized for phenotypic differences in response to heat. At 14 days of age, birds were exposed to 38°C with 50% humidity for 4 hours, then 35°C until the conclusion of the experiment. Non-treated individuals were kept at 29.4°C for the first week and then 25°C throughout the experiment. Birds in the heat-stress group were inoculated at day (d) 21 with Newcastle disease virus (NDV) La Sota strain to investigate the effects of heat stress and NDV infection. Thirteen blood parameters were measured using the iSTAT blood analyzer at three stages: 4 h, 6 d, and 9 d post heat-stress treatment, representing acute heat (AH) exposure, chronic heat (CH1) exposure, and chronic heat exposure after virus infection (CH2), respectively. Most blood parameters were significantly changed with heat stress in Leghorns at AH and in Fayoumis at CH1 and CH2. The Leghorn line had significant acute responses with disrupted acid-base balance and metabolic disorders. The heat-resilient Fayoumis maintained a relatively well-balanced acid-base balance. The current study provides the comprehensive profile of biomarker signatures in blood associated with heat tolerance and suggests that PO2, TCO2, HCO3, and base excess can be served as potential biomarkers that can be used to genetically improve heat tolerance in poultry.

Single nucleotide variant discovery of highly inbred Leghorn and Fayoumi chicken breeds using pooled whole genome resequencing data reveals insights into phenotype differences.

BACKGROUND: Analyses of sequence variants of two distinct and highly inbred chicken lines allowed characterization of genomic variation that may be associated with phenotypic differences between breeds. These lines were the Leghorn, the major contributing breed to commercial white-egg production lines, and the Fayoumi, representative of an outbred indigenous and robust breed. Unique within- and between-line genetic diversity was used to define the genetic differences of the two breeds through the use of variant discovery and functional annotation. RESULTS: Downstream fixation test (F ST ) analysis and subsequent gene ontology (GO) enrichment analysis elucidated major differences between the two lines. The genes with high F ST values for both breeds were used to identify enriched gene ontology terms. Over-enriched GO annotations were uncovered for functions indicative of breed-related traits of pathogen resistance and reproductive ability for Fayoumi and Leghorn, respectively. CONCLUSIONS: Variant analysis elucidated GO functions indicative of breed-predominant phenotypes related to genomic variation in the lines, showing a possible link between the genetic variants and breed traits.

Thymus transcriptome reveals novel pathways in response to avian pathogenic Escherichia coli infection.

Avian pathogenic Escherichia coli (APEC) can cause significant morbidity in chickens. The thymus provides the essential environment for T cell development; however, the thymus transcriptome has not been examined for gene expression in response to APEC infection. An improved understanding of the host genomic response to APEC infection could inform future breeding programs for disease resistance and APEC control. We therefore analyzed the transcriptome of the thymus of birds challenged with APEC, contrasting susceptible and resistant phenotypes. Thousands of genes were differentially expressed in birds of the 5-day post infection (dpi) challenged-susceptible group vs. 5 dpi non-challenged, in 5 dpi challenged-susceptible vs. 5 dpi challenged-resistant birds, as well as in 5 dpi vs. one dpi challenged-susceptible birds. The Toll-like receptor signaling pathway was the major innate immune response for birds to respond to APEC infection. Moreover, lysosome and cell adhesion molecules pathways were common mechanisms for chicken response to APEC infection. The T-cell receptor signaling pathway, cell cycle, and p53 signaling pathways were significantly activated in resistant birds to resist APEC infection. These results provide a comprehensive assessment of global gene networks and biological functionalities of differentially expressed genes in the thymus under APEC infection. These findings provide novel insights into key molecular genetic mechanisms that differentiate host resistance from susceptibility in this primary lymphoid tissue, the thymus.

Genomic analysis of Ugandan and Rwandan chicken ecotypes using a 600 k genotyping array.

BACKGROUND: Indigenous populations of animals have developed unique adaptations to their local environments, which may include factors such as response to thermal stress, drought, pathogens and suboptimal nutrition. The survival and subsequent evolution within these local environments can be the result of both natural and artificial selection driving the acquisition of favorable traits, which over time leave genomic signatures in a population. This study's goals are to characterize genomic diversity and identify selection signatures in chickens from equatorial Africa to identify genomic regions that may confer adaptive advantages of these ecotypes to their environments. RESULTS: Indigenous chickens from Uganda (n = 72) and Rwanda (n = 100), plus Kuroilers (n = 24, an Indian breed imported to Africa), were genotyped using the Axiom® 600 k Chicken Genotyping Array. Indigenous ecotypes were defined based upon location of sampling within Africa. The results revealed the presence of admixture among the Ugandan, Rwandan, and Kuroiler populations. Genes within runs of homozygosity consensus regions are linked to gene ontology (GO) terms related to lipid metabolism, immune functions and stress-mediated responses (FDR < 0.15). The genes within regions of signatures of selection are enriched for GO terms related to health and oxidative stress processes. Key genes in these regions had anti-oxidant, apoptosis, and inflammation functions. CONCLUSIONS: The study suggests that these populations have alleles under selective pressure from their environment, which may aid in adaptation to harsh environments. The correspondence in gene ontology terms connected to stress-mediated processes across the populations could be related to the similarity of environments or an artifact of the detected admixture.

Comparing the immune responses of two genetically B-complex disparate Fayoumi chicken lines to Eimeria tenella.

The present study was conducted to compare the susceptibility of congenic Fayoumi lines to Eimeria tenella infection and to assess genetic differences in Eimeria egression. Chickens were orally inoculated with 5 × 10(4) sporulated E. tenella oocysts and challenged with 5 × 10(6) oocysts on the 10th day after the primary infection. The Fayoumi M5.1 line exhibited higher levels of body weight gain, less oocyst shedding and higher percentages of B and CD4(+)/CD8(+) T cells than the M15.2 chickens. These results demonstrate that M5.1 line is more resistant to E. tenella infection than M15.2 line. Furthermore, the percentage of sporozoite egress from peripheral blood mononuclear cells (PBMCs) was higher in the M5.1 line. The results of this study suggest that enhanced resistance of Fayoumi M5.1 to E. tenella infection may involve heightened cell-mediated and adaptive immunity, resulting in reduced intracellular development of Eimeria parasites.

Effects of dietary fiber on cecal short-chain fatty acid and cecal microbiota of broiler and laying-hen chicks.

This experiment was conducted to evaluate the effects of feeding dietary fiber on cecal short-chain fatty acid (SCFA) concentration and cecal microbiota of broiler and laying-hen chicks. The lower fiber diet was based on corn-soybean meal (SBM) and the higher fiber diet was formulated using corn-SBM-dried distillers grains with solubles (DDGS) and wheat bran to contain 60.0 g/kg of both DDGS and wheat bran from 1 to 12 d and 80.0 g/kg of both DDGS and wheat bran from 13 to 21 d. Diets were formulated to meet or exceed NRC nutrient requirements. Broiler and laying-hen chicks were randomly assigned to the high and low fiber diets with 11 replicates of 8 chicks for each of the 4 treatments. One cecum from 3 chicks was collected from each replicate: one cecum underwent SCFA concentration analysis, one underwent bacterial DNA isolation for terminal restriction fragment length polymorphism (TRFLP), and the third cecum was used for metagenomics analyses. There were interactions between bird line and dietary fiber for acetic acid (P = 0.04) and total SCFA (P = 0.04) concentration. There was higher concentration of acetic acid (P = 0.02) and propionic acid (P < 0.01) in broiler chicks compared to laying-hen chicks. TRFLP analysis showed that cecal microbiota varied due to diet (P = 0.02) and chicken line (P = 0.03). Metagenomics analyses identified differences in the relative abundance of Helicobacter pullorum and Megamonas hypermegale and the genera Enterobacteriaceae, Campylobacter, Faecalibacterium, and Bacteroides in different treatment groups. These results provide insights into the effect of dietary fiber on SCFA concentration and modulation of cecal microbiota in broiler and laying-hen chicks.

Copy number variation in Fayoumi and Leghorn chickens analyzed using array comparative genomic hybridization.

Copy number variation refers to regions along chromosomes that harbor a type of structural variation, such as duplications or deletions. Copy number variants (CNVs) play a role in many important traits as well as in genetic diversity. Previous analyses of chickens using array comparative genomic hybridizations or single-nucleotide polymorphism chip assays have been performed on various breeds and genetic lines to discover CNVs. In this study, we assessed individuals from two highly inbred (inbreeding coefficiency > 99.99%) lines, Leghorn G-B2 and Fayoumi M15.2, to discover novel CNVs in chickens. These lines have been previously studied for disease resistance, and to our knowledge, this represents the first global assessment of CNVs in the Fayoumi breed. Genomic DNA from individuals was examined using the Agilent chicken 244 K comparative genomic hybridization array and quantitative PCR. We identified a total of 273 CNVs overall, with 112 CNVs being novel and not previously reported. Quantitative PCR using the standard curve method validated a subset of our array data. Through enrichment analysis of genes within CNV regions, we observed multiple chromosomes, terms and pathways that were significantly enriched, largely dealing with the major histocompatibility complex and immune responsiveness. Using an additional round of computational and statistical analysis with a different bioinformatic pipeline, we identified 43 CNVs among these as high-confidence regions, 14 of which were found to be novel. We further compared and contrasted individuals of the two inbred lines to discover regions that have a significant difference in copy number between lines. A total of 40 regions had significant deletions or duplications between the lines. Gene Ontology analysis of genomic regions containing CNVs between lines also was performed. This between-line candidate CNV list will be useful in studies with these two unique genetic lines, which may harbor variations that underlie quantitative trait loci for disease resistance and other important traits. Through the global discovery of novel CNVs in chicken, these data also provide resources for further genetic and functional genomics studies.

RNA-seq analysis revealed novel genes and signaling pathway associated with disease resistance to avian influenza virus infection in chickens.

Avian influenza virus (AIV) is a type A virus of the family Orthomyxoviridae. Avian influenza virus infection can cause significant economic losses to the poultry industry, and raises a great public health threat due to potential host jump from animals to humans. To develop more effective intervention strategies to prevent and control AIV infection in poultry, it is essential to elucidate molecular mechanisms of host response to AIV infection in chickens. The objective of this study was to identify genes and signal pathways associated with resistance to AIV infection in 2 genetically distinct highly inbred chicken lines (Fayoumi, relatively resistant to AIV infection, and Leghorn, susceptible to AIV infection). Three-week-old chickens were inoculated with 10(7) EID50 of low pathogenic H5N3 AIV, and lungs and trachea were harvested 4 d postinoculation. Four cDNA libraries (1 library each for infected and noninfected Leghorn, and infected and noninfected Fayoumi) were prepared from the lung samples and sequenced by Illumina Genome Analyzer II, which yielded a total of 116 million, 75-bp single-end reads. Gene expression levels of all annotated chicken genes were analyzed using CLC Genomics Workbench. DESeq was used to identify differentially expressed transcripts between infected and noninfected birds and between genetic lines (false discovery rate < 0.05 and fold-change > 2). Of the expressed transcripts in a total of 17,108 annotated chicken genes in Ensembl database, 82.44 and 81.40% were identified in Leghorn and Fayoumi birds, respectively. The bioinformatics analysis suggests that the hemoglobin family genes, the functional involvements for oxygen transportation and circulation, and cell adhesion molecule signaling pathway play significant roles in disease resistance to AIV infection in chickens. Further investigation of the roles of these candidate genes and signaling pathways in the regulation of host-AIV interaction can lead new directions for the development of antiviral drugs or vaccines in poultry.

Accuracy of genomic prediction using an evenly spaced, low-density single nucleotide polymorphism panel in broiler chickens.

One approach for cost-effective implementation of genomic selection is to genotype training individuals with a high-density (HD) panel and selection candidates with an evenly spaced, low-density (ELD) panel. The purpose of this study was to evaluate the extent to which the ELD approach reduces the accuracy of genomic estimated breeding values (GEBV) in a broiler line, in which 1,091 breeders from 3 generations were used for training and 160 progeny of the third generation for validation. All birds were genotyped with an Illumina Infinium platform HD panel that included 20,541 segregating markers. Two subsets of HD markers, with 377 (ELD-1) or 766 (ELD-2) markers, were selected as ELD panels. The ELD-1 panel was genotyped using KBiosciences KASPar SNP genotyping chemistry, whereas the ELD-2 panel was simulated by adding markers from the HD panel to the ELD-1 panel. The training data set was used for 2 traits: BW at 35 d on both sexes and hen house production (HHP) between wk 28 and 54. Methods Bayes-A, -B, -C and genomic best linear unbiased prediction were used to estimate HD-marker effects. Two scenarios were used: (1) the 160 progeny were ELD-genotyped, and (2) the 160 progeny and their dams (117 birds) were ELD-genotyped. The missing HD genotypes in ELD-genotyped birds were imputed by a Gibbs sampler, capitalizing on linkage within families. In scenario (1), the correlation of GEBV for BW (HHP) of the 160 progeny based on observed HD versus imputed genotypes was greater than 0.94 (0.98) with the ELD-1 panel and greater than 0.97 (0.99) with the ELD-2 panel. In scenario (2), the correlation of GEBV for BW (HHP) was greater than 0.92 (0.96) with the ELD-1 panel and greater than 0.95 (0.98) with the ELD-2 panel. Hence, in a pedigreed population, genomic selection can be implemented by genotyping selection candidates with about 400 ELD markers with less than 6% loss in accuracy. This leads to substantial savings in genotyping costs, with little sacrifice in accuracy.

Gene expression analysis of host spleen responses to Marek's disease virus infection at late tumor transformation phase.

Marek's disease is a viral neoplastic disease of chickens caused by Marek's disease virus (MDV). Gene expression patterns have been investigated at different MDV infection stages, but there is limited research about the late tumor transformation phase. In this experiment, 44K Agilent chicken genome-wide expression microarrays were used to profile differential expression in tumorous spleens (TS) from severely morbid chickens and apparently normal spleens from survivors (SS) after MDV infection and expression in noninfected spleens (NS) from controls. There were 4,317 differentially expressed (DE) genes in TS versus NS. However, no DE genes were detected in SS versus NS, suggesting that maintenance of, or return to, homeostasis of gene activity in survivor spleens. Downregulated genes in tumorous spleens mainly enriched in the cytokine-cytokine receptor interaction pathway, and commonly investigated genes in Marek's disease study, IL6, IL18, IFNA, and IFNG were nondifferentially expressed, which indicates host inflammatory response was impaired. The IL10 and TNFRSF8 genes were upregulated in tumorous spleens. We speculated that IL10 might be exploited by MDV to escape from host immune surveillance, as reported for Epstein-Barr virus, which stimulated T cells secreting IL10 to subvert immune response. Previous study reported that transcription from TNFRSF8 promoter could be enhanced by MDV oncogene Meq. In this study, the increased expression of TNFRSF8 indicated interaction between MDV and TNFRSF8, which might facilitate pathogenesis and tumor transformation. The expression of many members in IGF system was changed in tumorous compared with noninfected spleens. The downregulation of IGFBP7 was considered to be associated with MD lymphoma transformation. Gene expression change of multiple regulatory pathways indicated their involvements in facilitating tumor transformation.

Robustness of a rhythmic circuit to short- and long-term temperature changes.

Recent computational and experimental work has shown that similar network performance can result from variable sets of synaptic and intrinsic properties. Because temperature is a global perturbation that differentially influences every biological process within the nervous system, one might therefore expect that individual animals would respond differently to temperature. Nonetheless, the phase relationships of the pyloric rhythm of the stomatogastric ganglion (STG) of the crab, Cancer borealis, are remarkably invariant between 7 and 23°C (Tang et al., 2010). Here, we report that, when isolated STG preparations were exposed to more extreme temperature ranges, their networks became nonrhythmic, or "crashed", in a reversible fashion. Animals were acclimated for at least 3 weeks at 7, 11, or 19°C. When networks from the acclimated animals were perturbed by acute physiologically relevant temperature ramps (11-23°C), the network frequency and phase relationships were independent of the acclimation group. At high acute temperatures (>23°C), circuits from the cold-acclimated animals produced less-regular pyloric rhythms than those from warm-acclimated animals. At high acute temperatures, phase relationships between pyloric neurons were more variable from animal to animal than at moderate acute temperatures, suggesting that individual differences across animals in intrinsic circuit parameters are revealed at high temperatures. This shows that individual and variable neuronal circuits can behave similarly in normal conditions, but their behavior may diverge when confronted with extreme external perturbations.

Effects of dietary vitamin E type and level on lipopolysaccharide-induced cytokine mRNA expression in broiler chicks.

Vitamin E modulates the immune response, in part by reducing inflammation. The bacterial component lipopolysaccharide (LPS) can induce an inflammatory response in chickens. The objective of this study was to evaluate immunomodulatory effects of dietary type and level of vitamin E on response of broilers to LPS. One-day-old broiler males (n=96) were placed in a vitamin E-type (synthetic, natural) × vitamin E level (22, 220 IU/kg)×LPS (LPS, saline) block design. At 22 d, LPS (or saline) was injected subcutaneously. Spleens were harvested for RNA isolation at 3 and 24 h postinjection. Relative levels of RNA expression were measured for the immune-related genes: avian ß defensin 10 (AvBD10), interleukin 6 (IL6), interferon-γ (IFN-γ), inducible nitric oxide synthase (iNOS), interleukin 10 and transforming growth factor- ß1 (TGF-ß1). Avian ß defensin 10 and iNOS are innate antimicrobial proteins. Interleukin 6 and IFN-γ are pro-inflammatory cytokines, whereas interleukin 10 and transforming growth factor-ß1 are anti-inflammatory cytokines. There were significantly higher splenic levels of IL6, IFN-γ, iNOS, and IL10 RNA expression at 3 h postinjection in chickens receiving LPS than in chickens 24 h post-LPS injection or saline-injected birds at either time. These data suggest that LPS induced an immune response that was regulated by both pro- and anti-inflammatory cytokines. Birds fed natural-type (versus synthetic) vitamin E had a significantly lower LPS-induced inflammatory response, as indicated by lower IL6 RNA expression levels, suggesting a protective effect from natural-type vitamin E when a chicken encounters a bacterial component.