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Cellular factors restricting mouse polyomavirus infection in host cells: Studies of PML protein isoforms
Anderová, Karolína ; Forstová, Jitka (advisor) ; Němečková, Šárka (referee)
Promyelocytic leukaemia nuclear bodies (PML NBs) are multifunctional nuclear spherical structures formed by the PML protein shell and other interaction partners that have been described to be involved in many cellular processes and immune defences. In the antiviral immune response, PML NBs and their components act as direct restriction factors as well as in the regulation of the interferon response. On the other hand, viruses have developed antagonistic mechanisms to resist this inhibition. This work deals with the role of PML NBs in infection with model Murine polyomavirus (MPyV) and focuses on the study of PML protein isoforms. The first aim of the work was to analyse the formation of human (hPML) and mouse (mPML) NBs in a mouse embryonic fibroblast (MEF) model. Subsequently, the localization of hPML and mPML NBs during infection was determined. Close localization with viral replication centres was observed for both PML species. In the next step, the effect of infection or interferon α (IFNα) on mPML protein expression was tested. Infection and treatment with IFNα led to an increase in mPML expression at the level of both gene transcription and protein synthesis. At the same time, the data indicated the largest increase in transcription of the mPML3 isoform. The work also addressed the potential...
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Study of endogenous retroviruses: Insight into the retroviral evolution and virus-host interactions
Hron, Tomáš ; Elleder, Daniel (advisor) ; Kejnovský, Eduard (referee) ; Hirsch, Ivan (referee)
In my doctoral project, I studied the evolution of retroviruses and long-term interactions with their hosts. Retroviruses infect a broad range of species including possibly all vertebrates. They are unique in their ability to efficiently create endogenous retroviruses (ERVs) - viral copies integrated into the host genomes and consequently inherited by successive generations as usual genomic locus. ERVs represent a significant portion of vertebrate genomes and play an important role in a variety of cellular processes and pathologies; however, their sequences are still largely unexplored. The results of my work contributed to the uncovering of ancient evolutionary history of retroviruses. In this regard, I employed the ERV sequences, as they represent "genetic fossils" of viral infections that occurred throughout entire retroviral evolution. By discovery and analysis of ancient ERV lineages, I shed light on the deep history of retroviruses and revealed how the past infections shaped the evolution of vertebrate antiviral defense. In addition to the investigation of retroviral evolution, I also studied process of ongoing endogenization and fixation of newly emerged ERVs in a mammalian host population. In this part of my work, I focused on a unique model of ERV that have been recently invading mule deer genome.
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POSITIVE AND NEGATIVE HOST FACTORS OF AVIAN SARCOMA AND LEUKOSIS VIRUSES
Krchlíková, Veronika ; Elleder, Daniel (advisor) ; Růžek, Daniel (referee) ; Španielová, Hana (referee)
Identification and characterization of the host cell factors that either support or inhibit virus replication constitutes a major direction in virological research. In this work we focus on several such host factors in the context of avian cell. Chicken Tva, cell entry receptor for subgroups A and K of Avian sarcoma and leukosis virus (ASLV), was identified to be orthologous to human receptor for cellular uptake of cobalamin (Cbl). Here, we describe Cbl uptake in chicken cells and its dependency on Tva. Additionally, we characterize in vivo Tva knockout in chicken. Chicken Tvb receptor conferring susceptibility to subgroups B, D and E of ASLV was previously shown to participate in virus-induced cytopathic effects. In this work, we identify a natural ligand of Tvb and investigate its participation in apoptosis. RIG-I-like receptors (RLR) are a key family of cytosolic viral RNA sensors. The activation of these receptors leads to establishment of an antiviral state in the cell. In this study, we describe repeated evolutionary losses of RLR genes in birds: the loss of MDA5 in two avian orders and the loss of RIG-I in multiple species. Tetherin is an antiviral restriction factor blocking the release of newly formed viral particles. We identify tetherin orthologs in avian species and investigate...
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Effect of HBV protein HBx on activation of MEK1/2 signaling and inhibition of type I IFN in hepatoma cell line Huh7
Berehovska, Olena ; Hirsch, Ivan (advisor) ; Zábranský, Aleš (referee)
Hepatitis B virus (HBV) infection is one of the major causes of chronic and cancerous liver disease. Elimination of HBV from chronically infected patients by recombinant interferon α (IFNα) monotherapy shows that the mechanisms of the innate immunity play an important role in suppressing viral infection. However, the mechanisms of recognition of the HBV genome and its escape from the mechanisms of natural immunity are still little known. One of the principal factors enabling the virus to escape from cellular restriction mechanisms is the HBx viral protein. HBx is a 154 amino acid pleiotropic multifunctional protein affecting transcription, signal transduction, cell cycle, protein degradation, apoptosis, and chromosomal stability in the host cell. Previous results from our laboratory have shown that activation of the MEK1/2-ERK signaling pathway in plasmacytoid dendritic cells leads to inhibition of IFNα production. The aim of my work was to determine whether HBx activates the MEK1/2-ERK pathway and thus inhibits IFN type I production also in hepatocytes. For this purpose, I monitored HBx production in the Huh7 hepatoma cell line by transfecting the bicistronic plasmid pHBx- IRES-EGFP and Western blotting. Using the same method, I monitored activation of the MEK1/2-ERK signaling pathway by ERK...
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Intracellular restriction factors of small DNA viruses
Anderová, Karolína ; Forstová, Jitka (advisor) ; Pokrývková, Barbora (referee)
The theme of this work is to summarize knowledge about protein restriction factors, which function in cells infected by small DNA viruses of families Hepadnaviridae, Parvoviridae, Polyomaviridae and Papillomaviridae. Both restriction factors induced by interferon and restriction factors of intrinsic immunity which are constitutively produced in cells are included in this work. At the same time, mechanisms by which viruses overcome the inhibition effects of restriction factors are mentioned. Restriction factors suppressing Hepatitis B virus infection like components of PML nuclear bodies and proteins Smc5/6, SAMHD1, APOBEC, TRIM, ZAP and Tetherin are described. For the representatives of Parvoviridae family, deaminases APOBEC and PML protein were identified as restriction factors. For the infection by polyomaviruses, restriction factors FAM111A and SRSF1 were described. Restriction by PML nuclear bodies and its component Sp100 and proteins APOBEC, IFI16 and IFIT1 is discussed for the Papillomaviridae family. Keywords: small DNA viruses, intracellular DNA sensing, restriction factors, viral antagonistic mechanisms
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Study of endogenous retroviruses: Insight into the retroviral evolution and virus-host interactions
Hron, Tomáš ; Elleder, Daniel (advisor) ; Kejnovský, Eduard (referee) ; Hirsch, Ivan (referee)
In my doctoral project, I studied the evolution of retroviruses and long-term interactions with their hosts. Retroviruses infect a broad range of species including possibly all vertebrates. They are unique in their ability to efficiently create endogenous retroviruses (ERVs) - viral copies integrated into the host genomes and consequently inherited by successive generations as usual genomic locus. ERVs represent a significant portion of vertebrate genomes and play an important role in a variety of cellular processes and pathologies; however, their sequences are still largely unexplored. The results of my work contributed to the uncovering of ancient evolutionary history of retroviruses. In this regard, I employed the ERV sequences, as they represent "genetic fossils" of viral infections that occurred throughout entire retroviral evolution. By discovery and analysis of ancient ERV lineages, I shed light on the deep history of retroviruses and revealed how the past infections shaped the evolution of vertebrate antiviral defense. In addition to the investigation of retroviral evolution, I also studied process of ongoing endogenization and fixation of newly emerged ERVs in a mammalian host population. In this part of my work, I focused on a unique model of ERV that have been recently invading mule deer genome.
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Interaction of hepatitis B virus proteins with mechanisms of innate immunity
Vávrová, Petra ; Hirsch, Ivan (advisor) ; Horníková, Lenka (referee)
Specific aim of this bibliographic research is to elucidate interaction of hepatitis B virus proteins with mechanisms of the innate immunity. The work will specially analyze the role of viral proteins before and after their transport from the infected cell. Because of the central role of cccDNA for virus persistence in human organism, the work will study the effects of restriction factors on its possible destruction and eradication. The research will be focused on the effect of viral proteins during acute, chronic and occult infection.
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Effect of restriction factors on replication of hepatitis B virus
Kunteová, Kateřina ; Hirsch, Ivan (advisor) ; Sýkora, Michal (referee)
Specific aim of this bibliographic research is to elucidate the effects of cellular restriction factors on HBV replication. The work will specially analyze the role of the innate and natural immunity and to compare the effect of analogical or identical restriction factors on HBV and HIV-1 replication. Because of the central role of cccDNA for virus persistence in human organism, the work will study the effects of restriction factors on its possible destruction and eradication and a possible HBV cure. The research will also be focused on the effect of restriction factors during acute, chronic and occult infection. Powered by TCPDF (www.tcpdf.org)
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