Project description:Background: Mycobacterium bovis is the causative agent of bovine tuberculosis (BTB), a pathological infection with significant economic impact. Recent studies have highlighted the role of functional genomics to better understand the molecular mechanisms governing the host immune response to M. bovis infection. Furthermore, these studies may enable the identification of novel transcriptional markers of BTB that can augment current diagnostic tests and surveillance programmes. In the present study, we have analysed the transcriptome of peripheral blood leukocytes (PBL) from eight M. bovis-infected and eight control non-infected age-matched and sex-matched Holstein-Friesian cattle using the Affymetrix® GeneChip® Bovine Genome Array with features representing more than 23,000 gene transcripts and over 19,000 gene probe sets. Results: Control and infected animals had similar mean white blood cell counts. However, the mean number of lymphocytes was significantly increased in the infected group relative to the control group (P = 0.001), while the mean number of monocytes was significantly decreased in the BTB group (P = 0.002). Hierarchical clustering analysis using gene expression data from all 5,388 detectable mRNA transcripts unambiguously partitioned the animals according to their disease status. In total, 2,960 gene transcripts were differentially expressed (DE) between the infected and control animal groups (adjusted P-value threshold ≤ 0.05); with the number of genes showing decreased relative expression (1,563) exceeding those displaying increased relative expression (1,397). Systems analysis using the Ingenuity Systems Pathway Analysis (IPA) Knowledge Base revealed an over-representation of DE genes involved in the immune response functional category. More specifically, 64.5% of genes in the affects immune response subcategory displayed decreased relative expression levels in the infected animals compared to the control group. Conclusions: This study demonstrates that genome-wide transcriptional profiling of PBL can distinguish active M. bovis-infected animals from control non-infected animals. Furthermore, the results obtained support previous investigations demonstrating that mycobacterial infection is associated with host transcriptional suppression. These data support the use of transcriptomic technologies to enable the identification of robust, reliable transcriptional markers of active M. bovis infection Affymetrix GeneChip® Bovine Genome Arrays were used to examine gene expression of peripheral blood leukocytes from cattle infected with Mycobacterium bovis
Project description:Infection of cattle with Mycobacterium bovis causes severe financial hardship in many countries, in addition to presenting a health risk for humans. As an intracellular pathogen, M. bovis, adapted to survive and thrive within the intramacrophage environment. However, little is known about expression patterns in the macrophage, particularly in the bovine host. In this study, DNA microarray analysis was used to detect genes expressed in Holstein bovine macrophages derived from peripheral blood mononuclear cells infected during four hours with two Argentinean strains of M. bovis, a virulent strain, 04-303 and an attenuated strain, 534. Genes encoding antrax toxin receptor, cell division and apoptosis regulator, ankyrin proteins that are found within the membrane associated cytoskeleton, protein of cell differentiation and regulators of endocytic traffic of membrane were more strongly expressed in infected macrophages.
Project description:Infection of cattle with Mycobacterium bovis causes severe financial hardship in many countries, in addition to presenting a health risk for humans. As an intracellular pathogen, M. bovis, adapted to survive and thrive within the intramacrophage environment. However, little is known about expression patterns in the macrophage, particularly in the bovine host. In this study, DNA microarray analysis was used to detect genes expressed in Holstein bovine macrophages derived from peripheral blood mononuclear cells infected during four hours with two Argentinean strains of M. bovis, a virulent strain, 04-303 and an attenuated strain, 534. Genes encoding antrax toxin receptor, cell division and apoptosis regulator, ankyrin proteins that are found within the membrane associated cytoskeleton, protein of cell differentiation and regulators of endocytic traffic of membrane were more strongly expressed in infected macrophages. Blood from healthy Holstein bovines was taken in sterile conditions and peripheral blood mononuclear cells (PBMC) were separated from heparinized blood. PBMCs were used to prepare ten independent cultures which were incubated at 37C for one week in RPMI 1640 complete medium supplemented with 10% of autologous plasma. Four cultures were infected with viable cells of M. bovis virulent strain 04-303, four with avirulent strain 534 and two were left as uninfected controls. Four hours post infection, the cells were scraped, lysed. RNA was extracted, labeled and hybridized to ten Affymetrix Bovine Genome arrays.
Project description:Mycobacterium bovis causes bovine tuberculosis (bTB), an infectious disease of cattle that represents a zoonotic threat to humans. Research has shown that the peripheral blood (PB) transcriptome is perturbed during bTB disease but the genomic architecture underpinning this transcriptional response remains poorly understood. Here, we analyse PB transcriptomics data from 63 control and 60 confirmed M. bovis infected animals and detect 2,592 differently expressed genes perturbing multiple immune response pathways. Leveraging imputed genome-wide SNP data, we characterise thousands of cis¬-expression quantitative trait loci (eQTLs) and show that the PB transcriptome is substantially impacted by intrapopulation genomic variation during M. bovis infection. Integrating our cis-eQTL data with bTB susceptibility GWAS summary statistics, we perform a transcriptome-wide association study and identify 132 functionally relevant genes (including RGS10, GBP4, TREML2, and RELT) and provide important new omics data for understanding the host response to mycobacterial infections that cause tuberculosis in mammals.
Project description:Background: Mycobacterium bovis is the causative agent of bovine tuberculosis (BTB), a pathological infection with significant economic impact. Recent studies have highlighted the role of functional genomics to better understand the molecular mechanisms governing the host immune response to M. bovis infection. Furthermore, these studies may enable the identification of novel transcriptional markers of BTB that can augment current diagnostic tests and surveillance programmes. In the present study, we have analysed the transcriptome of peripheral blood leukocytes (PBL) from eight M. bovis-infected and eight control non-infected age-matched and sex-matched Holstein-Friesian cattle using the Affymetrix® GeneChip® Bovine Genome Array with features representing more than 23,000 gene transcripts and over 19,000 gene probe sets. Results: Control and infected animals had similar mean white blood cell counts. However, the mean number of lymphocytes was significantly increased in the infected group relative to the control group (P = 0.001), while the mean number of monocytes was significantly decreased in the BTB group (P = 0.002). Hierarchical clustering analysis using gene expression data from all 5,388 detectable mRNA transcripts unambiguously partitioned the animals according to their disease status. In total, 2,960 gene transcripts were differentially expressed (DE) between the infected and control animal groups (adjusted P-value threshold ≤ 0.05); with the number of genes showing decreased relative expression (1,563) exceeding those displaying increased relative expression (1,397). Systems analysis using the Ingenuity Systems Pathway Analysis (IPA) Knowledge Base revealed an over-representation of DE genes involved in the immune response functional category. More specifically, 64.5% of genes in the affects immune response subcategory displayed decreased relative expression levels in the infected animals compared to the control group. Conclusions: This study demonstrates that genome-wide transcriptional profiling of PBL can distinguish active M. bovis-infected animals from control non-infected animals. Furthermore, the results obtained support previous investigations demonstrating that mycobacterial infection is associated with host transcriptional suppression. These data support the use of transcriptomic technologies to enable the identification of robust, reliable transcriptional markers of active M. bovis infection