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Mouse polyomavirus:The way of virus translocation to the cell nucleus and sensing of viral genomes by sensors of innate immunity
Soldatova, Irina ; Forstová, Jitka (advisor) ; Němečková, Šárka (referee) ; Pichová, Iva (referee)
To understand molecular mechanisms of individual steps of virus infection is a prerequisite for successful design of specific and effective antiviral drugs. Polyomaviruses, replicating in the cell nucleus, travel from plasma membrane to the endoplasmic reticulum (ER) in endosomes. However, it is not clear how they deliver their DNA genomes from ER to the nucleus. In this thesis, we found that partially disassembled virions of the Murine polyomavirus (MPyV) interact with importin β1 at around 6 hours post infection. Mutational disruption of the nuclear localization signal (NLS) of the major capsid protein, VP1, and/or common NLS sequence of the minor capsid proteins VP2 and VP3 did not affect the structure and composition of virions, but it resulted in decreased viral infectivity (up to 80%). Virions are thus released from ER to cytosol and translocate to the nucleus via nucleopores. Mutation analyses of NLSs of individual capsid proteins showed that MPyV virions can utilize VP1 and VP2/VP3 NLSs in concert. However, one functional NLS, either that of VP1 or VP2/3 seems to be sufficient for the delivery of VP1-VP2/3 complexes into the nucleus, although none of these proteins is delivered into the nucleus separately. Thus, the conformation of NLS regions given by the presence of all three capsid...
Sensing of MPyV infection by innate immunity sensors
Rjabčenko, Boris ; Forstová, Jitka (advisor) ; Anděra, Ladislav (referee) ; Mělková, Zora (referee)
Host sensors that recognize pathogen associated molecular patterns and the mechanisms of innate immune response to mouse polyomavirus (MPyV) infection were the main topics of current work. We found that MPyV did not induce interferon (IFN) production during early events of infection, but induced interleukin-6 (IL-6) and other cytokine production without inhibiting virus multiplication. Cytokine microenvironment changed the phenotype of adjacent non infected fibroblasts toward the cancer-associated fibroblast (CAF)-like phenotype. We identified Toll-like receptor 4, a sensor of the innate immunity system, to be responsible for infection dependent IL-6 production. In an effort to determine whether and where virions are released from endosomal compartments into the cytosol, we found that the hydrophobic domains of minor capsid proteins, exposed on the surface of virions after their partial disassembly in the ER, play an important role in effective escape of virions from the lumen part of endoplasmic reticulum into the cytosol, Although naked, partially disassembled virions appear before translocation to the nucleus in the cytosol, viral DNA is not recognized by cytosolic sensors at this phase of infection Sensing of MPyV resulting in IFN production occurs first during viral replication. Mutant virus,...
BK-polyomavirus infection in patients after simultaneous pancreas and kidney transplantation
Mindlová, Martina ; Saudek, František (advisor) ; Forstová, Jitka (referee) ; Reischig, Tomáš (referee)
Introduction. The aim of the study was to introduce a new BKV PCR protocol in our centre and to verify its accuracy as well as to assess the prevalence, risk factors of BK virus replication, course of BKV infection and therapeutic approaches in simultaneous pancreas and kidney (SPK) recipients in order to design a screening protocol. Methods. The results analysed by both Affigene® and Transplantation Virology, Basel PCR protocols were compared. Thereafter 183 SPK patients were examined to assess the prevalence of BK viremia, viruria and BKVN and to identify the risk factors of BKV replication. The cases of retransplantation after a graft loss due to BKVN were retrospectively described. Results. 100 of results were analysed according to the Affigene ® and Transplantation Virology, Basel PCR protocols with the accordance of 95%, Rho = 0,946, 95% CI: 0.920 - 0.963, P<0,0001, Bland-Altman plot analyses: bias Basel PCR protocol/Affigene® BKV trender: -0,1 (mean) *±1.96 SD: -1,6 - 1,3] for both methods. Point-prevalence was assessed in 183 patients; Viruria found in 17,3 %, viremia in 3.8% of patients. High-level viruria >107 copies/mL detected in 3,7% of patiets, high-level virémia >104 in 1,6% of patients simultaneously with high-level viruria. BKVN was found in 0,5% of patients. Diabetes duration...
Virus translocation from cytoplasm to the cell nucleus
Išler, Lukáš ; Forstová, Jitka (advisor) ; Přikryl, David (referee)
Replication cycles of most DNA and some RNA viruses require translocation of these viruses into the host cell nucleus. In this step viruses must cross the nuclear membrane. In the cell cycle interphase, it can be exceeded only by passing through nuclear pores. Individual virus families have developed different strategies to efficiently translocate through the nuclear pore. In this paper, summarizing the knowledge of viral penetration through the nuclear pore, it is shown that in addition to the interaction with transport receptors, viral particles interact directly with some proteins of the nuclear pore complex, called nucleoporins (NUPs). Especially, one group of nucleoporins, so-called FG NUPs, interacts with viral particles. Their sequence contains naturally disordered domains rich in phenylalanine-glycine (FG) repeats which create selective barrier of the nuclear pore complex. These are mainly nucleoporins NUP153, NUP214 and NUP358. Interaction of viral particles with these nucleoporins allow them to cross this barrier and deliver their viral genome to the host cell nucleus. It is therefore an essential step in the early phase of the viral infection cycle. Keywords: cell nucleus, nuclear transport, nuclear pore complex, nucleoporins, virus nuclear entry, NUP153, NUP214, NUP358
Polyomavirus minichromosome structure
Satratzemis, Christos ; Forstová, Jitka (advisor) ; Mělková, Zora (referee)
The polyomavirus genome is present in the host cell as circular double-stranded DNA associated with nucleosomes. Consequently, the expression of polyomavirus genes is affected by the location of nucleosomes on DNA and histone modifications. This thesis reviews the current state of knowledge regarding the polyomavirus minichromosome structure and the effects of nucleosome phasing and histone modifications on polyomaviral replication cycle. In addition, factors conditioning these phenomena are discussed. Drawing on available literature, neither nucleosome phasing nor histone modifications appear to be random. However, not all viral DNA molecules are identical in these respects. Processes such as early and late transcription, replication and encapsidation thus occur only within certain fractions of the set of DNA molecules
Properties and functions of agnoprotein of polyomaviruses
Zosinčuková, Tereza ; Forstová, Jitka (advisor) ; Vinšová, Barbora (referee)
Polyomaviridae family includes small DNA viruses with simple structure and a small genome encoding only a few proteins. These proteins include large T and small T antigens, as well as 2 to 3 structural proteins known as VP1, VP2 and VP3. In addition, some members of the Polyomaviridae family encode in their genome a small non-structural protein called agnoprotein. Among human polyomaviruses, agnoprotein is present in BK polyomavirus and JC polyomavirus. These viruses are the causative agents of some serious diseases in immunocompromised humans and therefore, they are the subject of intensive research. Simian vacuolating virus 40 is another example of a virus which encodes the agnoprotein. Agnoprotein is capable to manipulate its host cell, disrupt vesicle transport and is also crucial for viral replication and transcription. It appears to play an important role in the morphogenesis of virions and/or in their release from the cell. This paper comprehensively summarizes the latest insights into the properties and functions of the agnoprotein BK polyomavirus, JC polyomavirus and SV40 virus, focusing on the production of this protein during infection, its structure, posttranslational modifications, cell localization, interaction partners and the overall importance of this enigmatic protein for the...
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
Replication strategies of newly discovered giant viruses of amoebas
Blaško, Michal ; Forstová, Jitka (advisor) ; Sýkora, Michal (referee)
Giant viruses are a group of viruses with genome composed of double-stranded DNA molecule. They are characterized by the creation of giant viral particles, the size of which varies between 150-1500 nm. Also, their genomes are huge reaching sizes of up to 2,5 Mbp. The viruses replicate either in the cytoplasm or they exploit for their replication both nucleus and cytoplasm. Therefore, they are called, nucleocytoplasmic large DNA viruses (NCLDVs). During their replication cycle, the giant viruses induce the creation of viral factories, which provide morphogenesis of new virions. The aim of this thesis is to summarise current knowledge of selected representatives of the giant viruses, and to describe their replication strategies. Furthemore, this work aims to discuss discoveries made in relation to this particular group if viruses. Thanks to the discovery of giant viruses, another group of small viruses was identified - the so-called virophages (viruses of viruses). Virophages have the ability to take advantage of the giant virus infecting an amoeba to realize their own replication strategy. In some members of the Mimiviridae family there was described a presence of an genome element providing a unique way of immunoprotection of giant viruses from being infected by the Zamilon virophage. Key words:...

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2 Forstová, Jana
2 Forštová, Jana
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