Project description:Marek’s disease virus (MDV) is an oncovirus causing tumor disease known as Marek’s disease (MD) in chicken. Breeding of chickens genetically resistant to MD is considered a vital augment to better control MD. To find the mechanism underlying the genetic resistance to MD, a genomic structural variation, copy number variation (CNV), was examined in inbred MD-resistant and -susceptible chicken lines by using the comparative genomic hybridization (CGH) technique. A total of 45 copy number variation regions (CNVRs) were found spanning across 3,297,038 bp in length of the chicken genome in 4 lines of chickens. Ten CNVRs were selectively confirmed with quantitative real-time PCR. The comparison between the resistant and susceptible chicken lines revealed 28 differentially presented CNVRs, which are functionally involved in immune response, cell proliferation in midbrain, G-protein coupled receptor signaling pathway, and protein-glutamine gamma-glutamyltransferase activity. Two CNVRs that are related with MD-resistance and –susceptibility were also found transmitted to descendent recombinant congenic lines that differ in susceptibility to MD. A positive correlation was identified between the CNVRs and gene expression, indicating the importance of gene expression dosage in disease resistance. We also found the overlapping between the CNVR region and the Marek’s disease trait related quantitative trait loci (QTLs). In conclusion, our data provided additional information elucidating one of possible mechanisms underlying of genetic resistance to MD. The findings may eventually lead to better strategies for genetic improvement of resistance to MD in poultry. L63: highly resistant to MD; L72: highly susceptible to MD; RCS-L: moderate resistant to MD; RCS-M: moderate susceptible to MD
Project description:Chromosomal structural variation can cause alterations in gene dosage and gene regulation between genomes. Structural variants producing a change in the number of copies of a genomic region are termed copy number variants (CNVs). CNVs have been demonstrated to have causative effects on both Mendelian and complex traits, including susceptibility to infectious diseases. We are interested in mapping CNVs to domesticated chicken breeds to help determine structural variation between genomes that influences economically important traits. For this study, Fayoumi, Leghorn, Line A broiler and Line B broiler chicken were chosen. Fayoumi and Leghorn chickens were selected as these two breeds harbor different responses certain pathogens like Avian Influenza Virus and coccidiosis; Broiler Line A and Line B indivduals were chosen as they harbor different intestinal colonization loads to the bacterium Campylobacter jejuni. Campylobacter genetic Line A and genetic Line B are from a commercial producer have been previously described as either resistant (Line A) or susceptible (Line B). Highly inbred chicken lines Fayoumi M15.2 (n=6) and Leghorn GHs6 (n=6) and broilers from Line A (n=24 individuals in pools of 4) and Line B (n=24 individuals in pools of 4)were subjected to array Comparative Genomic Hybridization (aCGH). Each sample was normalized to a Red Jungle Fowl reference. CNVs for each individual and between lines were determined. The major goal of this study was to discover and characterize CNVs in chickens to further narrow in on Quantitative Trait Loci (QTLs) affecting disease response. For the test DNA in Fayoumi and Leghorn, samples from 6 inbred Fayoumi and 6 inbred Leghorn individuals were used; For the test DNA in the Campylobacter genetic lines, samples from 24 individual broilers of Line A (in pools of 4) and 24 individual broilers of Line B (in pools of 4) were used. For the reference DNA, Red Jungle Fowl line UCD001 was used from a self-self hybridization.
Project description:Chromosomal structural variation can cause alterations in gene dosage and gene regulation between genomes. Structural variants producing a change in the number of copies of a genomic region are termed copy number variants (CNVs). CNVs have been demonstrated to have causative effects on both Mendelian and complex traits, including susceptibility to infectious diseases. We are interested in mapping CNVs to domesticated chicken breeds to help determine structural variation between genomes that influences economically important traits. For this study, Fayoumi, Leghorn, Line A broiler and Line B broiler chicken were chosen. Fayoumi and Leghorn chickens were selected as these two breeds harbor different responses certain pathogens like Avian Influenza Virus and coccidiosis; Broiler Line A and Line B indivduals were chosen as they harbor different intestinal colonization loads to the bacterium Campylobacter jejuni. Campylobacter genetic Line A and genetic Line B are from a commercial producer have been previously described as either resistant (Line A) or susceptible (Line B). Highly inbred chicken lines Fayoumi M15.2 (n=6) and Leghorn GHs6 (n=6) and broilers from Line A (n=24 individuals in pools of 4) and Line B (n=24 individuals in pools of 4)were subjected to array Comparative Genomic Hybridization (aCGH). Each sample was normalized to a Red Jungle Fowl reference. CNVs for each individual and between lines were determined. The major goal of this study was to discover and characterize CNVs in chickens to further narrow in on Quantitative Trait Loci (QTLs) affecting disease response.
Project description:Marek’s disease (MD) is an economically significant disease in chickens caused by the highly oncogenic Marek’s disease virus (MDV). Understanding the genes and biological pathways that confer MD genetic resistance should lead towards the development of more disease resistant commercial poultry flocks or improved MD vaccines. MDV Meq, a bZIP transcription factor, is largely attributed for viral oncogenicity though only a few host target genes have been described, which has impeded our understanding of MDV-induced tumorigenesis. Given the importance of Meq in MDV-induced pathogenesis, we explored the role of Meq in genetic resistance to MDV. Using global transcriptome analysis to compare the host response between birds challenge with either wild type MDV or a recombinant lacking Meq, we identified a number of specific genes and pathways associated with either MD resistance. Integrating prior information from ChIP-seq, microarray analysis, and SNPs exhibiting allele-specific expression (ASE) in response to MDV infection from two inbred layer lines that differ greatly in MD genetic resistance, we were able to provide a evidence for 35 genes that SNPs within transcription factor binding sites can affect transcription factor binding and gene expression in an allele-specific manner.