title: RNAseq reveals hypervirulence-specific host responses to M. tuberculosis infection.
abstract: The distinguishing factors that characterize the host response to infection with virulent Mycobacterium tuberculosis (M.tb) are largely confounding. We present an infection study with 2 genetically closely related M.tb strains that have vastly different pathogenic characteristics. The early host response to infection with these detergent-free cultured strains was analyzed through RNAseq in an attempt to provide information on the subtleties which may ultimately contribute to the virulent phenotype. Murine bone marrow derived macrophages (BMDMs) were infected with either a hyper- (R5527) or hypovirulent (R1507) Beijing M. tuberculosis clinical isolate. RNAseq revealed 69 differentially expressed host genes in BMDMs during comparison of these 2 transcriptomes. Pathway analysis revealed activation of the stress-induced and growth inhibitory Gadd45 signaling pathway in hypervirulent infected BMDMs. Upstream regulators of interferon activation such as and IRF3 and IRF7 were predicted to be upregulated in hypovirulent-infected BMDMs. Additional analysis of the host immune response through ELISA and qPCR included the use of human THP-1 macrophages where a robust proinflammatory response was observed after infection with the hypervirulent strain. RNAseq revealed 2 early-response genes (ier3 and saa3) and 2 host-defense genes (oasl1 and slpi) that were significantly upregulated by the hypervirulent strain. The role of these genes under M.tb infection conditions are largely unknown but here we provide validation of their presence with use of qPCR and Western blot. Further analysis into their biological role during infection with virulent M.tb is required.
authors.affiliation: a SA MRC Center for TB Research , DST/NRF Center of Excellence for Biomedical Tuberculosis Research, Division of Molecular Biology and Human Genetics, Faculty of Medicine and Health Sciences, Stellenbosch University , Tygerberg , South Africa.
authors.forename: Gina
authors.identifier: 0000-0002-4764-4781
authors.initials: G
authors.lastname: Leisching
authors.affiliation: a SA MRC Center for TB Research , DST/NRF Center of Excellence for Biomedical Tuberculosis Research, Division of Molecular Biology and Human Genetics, Faculty of Medicine and Health Sciences, Stellenbosch University , Tygerberg , South Africa.
authors.forename: Ray-Dean
authors.initials: RD
authors.lastname: Pietersen
authors.affiliation: b Central Analytical Facility (CAF) , DNA Sequencing Unit, Stellenbosch University , Stellenbosch , South Africa.
authors.forename: Carel
authors.initials: C
authors.lastname: van Heerden
authors.affiliation: a SA MRC Center for TB Research , DST/NRF Center of Excellence for Biomedical Tuberculosis Research, Division of Molecular Biology and Human Genetics, Faculty of Medicine and Health Sciences, Stellenbosch University , Tygerberg , South Africa.
authors.forename: Paul
authors.initials: P
authors.lastname: van Helden
authors.affiliation: a SA MRC Center for TB Research , DST/NRF Center of Excellence for Biomedical Tuberculosis Research, Division of Molecular Biology and Human Genetics, Faculty of Medicine and Health Sciences, Stellenbosch University , Tygerberg , South Africa.
authors.forename: Ian
authors.initials: I
authors.lastname: Wiid
authors.affiliation: a SA MRC Center for TB Research , DST/NRF Center of Excellence for Biomedical Tuberculosis Research, Division of Molecular Biology and Human Genetics, Faculty of Medicine and Health Sciences, Stellenbosch University , Tygerberg , South Africa.
authors.forename: Bienyameen
authors.initials: B
authors.lastname: Baker
mesh_terms: D000818:Animals; D015153:Blotting, Western; D018797:Cell Cycle Proteins / Q000235:genetics; D020869:Gene Expression Profiling; D059014:High-Throughput Nucleotide Sequencing; D054884:Host-Pathogen Interactions; D006801:Humans; D050838:Interferon Regulatory Factor-3 / Q000235:genetics; D050839:Interferon Regulatory Factor-7 / Q000235:genetics; D008264:Macrophages / Q000382:microbiology; D051379:Mice; D009169:Mycobacterium tuberculosis / Q000235:genetics / Q000276:immunology / Q000472:pathogenicity*; D009687:Nuclear Proteins / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D015398:Signal Transduction; D014376:Tuberculosis / Q000382:microbiology*; D014774:Virulence; D000097642:GADD45 Proteins
chemical_list: D018797:Cell Cycle Proteins; D050838:Interferon Regulatory Factor-3; D050839:Interferon Regulatory Factor-7; D009687:Nuclear Proteins; C499072:Gadd45a protein, mouse; D000097642:GADD45 Proteins; C494233:Irf3 protein, mouse; C494235:Irf7 protein, mouse
keywords: RNAseq; host-response; infection; mycobacterium tuberculosis; virulence