Browsing by Author "Nikolic, Valentina (7102074128)"

Tula hantavirus (TULV) belongs to Bunyaviridae family, with negative sense RNA genome. Segmented nature of hantaviral genome allows for genetic reassortment, but the evidence of homologous recombination also exists. In this study we analyzed TULV sequences isolated in Serbia on different occasions and from different rodent hosts: 1987 strain from Microtus subterraneus and 2007 strain from Microtus arvalis. Phylogenetic analysis of both L and S segment sequences is suggestive of geographically related clustering, as previously shown for majority of hantaviruses. Reconstruction of phylogenetic tree for TULV S segment showed that both sequences from Serbia clustered together with sequences from East Slovakia, which had previously been shown to be recombinants (Kosice strain). Exploratory recombination analysis, supported by phylogenetic and amino acid pattern analysis, revealed the presence of recombination in the S segment sequences from Serbia, resulting in mosaic-like structure of TULV S segment similar to the one of Kosice strain. Although recombination is considered a rare event in molecular evolution of negative strand RNA viruses, obtained molecular data in this study support evidence of recombination in TULV, in geographically distant regions of Europe. © 2013 Elsevier B.V.

Tula hantavirus (TULV) belongs to Bunyaviridae family, with negative sense RNA genome. Segmented nature of hantaviral genome allows for genetic reassortment, but the evidence of homologous recombination also exists. In this study we analyzed TULV sequences isolated in Serbia on different occasions and from different rodent hosts: 1987 strain from Microtus subterraneus and 2007 strain from Microtus arvalis. Phylogenetic analysis of both L and S segment sequences is suggestive of geographically related clustering, as previously shown for majority of hantaviruses. Reconstruction of phylogenetic tree for TULV S segment showed that both sequences from Serbia clustered together with sequences from East Slovakia, which had previously been shown to be recombinants (Kosice strain). Exploratory recombination analysis, supported by phylogenetic and amino acid pattern analysis, revealed the presence of recombination in the S segment sequences from Serbia, resulting in mosaic-like structure of TULV S segment similar to the one of Kosice strain. Although recombination is considered a rare event in molecular evolution of negative strand RNA viruses, obtained molecular data in this study support evidence of recombination in TULV, in geographically distant regions of Europe. © 2013 Elsevier B.V.

We investigated the role of autophagy, a stress-inducible lysosomal self-digestion of cellular components, in modulation of herpes simplex virus type 1 (HSV-1)-triggered death of U251 human glioma cells. HSV-1 caused apoptotic death in U251 cells, characterized by phosphatidylserine externalization, caspase activation and DNA fragmentation. HSV-1-induced apoptosis was associated with the induction of autophagic response, as confirmed by the conversion of cytosolic LC3-I to autophagosome-associated LC3-II, increase in intracellular acidification, presence of autophagic vesicles, and increase in proteolysis of the selective autophagic target p62. HSV-1-triggered autophagy was not associated with the significant increase in the expression of proautophagic protein beclin-1 or downregulation of the major autophagy suppressor mammalian target of rapamycin (mTOR). Moreover, the phosphorylation of mTOR and its direct substrate p70 S6 kinase was augmented by HSV-1 infection, while the mTOR stimulator Akt and inhibitor AMPK-activated protein kinase (AMPK) were accordingly activated and suppressed, respectively. An shRNA-mediated knockdown of the autophagy-essential LC3β, as well as pharmacological inhibition of autophagy with bafilomycin A1 or 3-methyladenine, markedly accelerated apoptotic changes and ensuing cell death in HSV-1-infected glioma cells. These data indicate that AMPK/Akt/mTOR-independent autophagy could prolong survival of HSV-1-infected U251 glioma cells by counteracting the coinciding apoptotic response. © 2013 Institut Pasteur.

We investigated the role of autophagy, a stress-inducible lysosomal self-digestion of cellular components, in modulation of herpes simplex virus type 1 (HSV-1)-triggered death of U251 human glioma cells. HSV-1 caused apoptotic death in U251 cells, characterized by phosphatidylserine externalization, caspase activation and DNA fragmentation. HSV-1-induced apoptosis was associated with the induction of autophagic response, as confirmed by the conversion of cytosolic LC3-I to autophagosome-associated LC3-II, increase in intracellular acidification, presence of autophagic vesicles, and increase in proteolysis of the selective autophagic target p62. HSV-1-triggered autophagy was not associated with the significant increase in the expression of proautophagic protein beclin-1 or downregulation of the major autophagy suppressor mammalian target of rapamycin (mTOR). Moreover, the phosphorylation of mTOR and its direct substrate p70 S6 kinase was augmented by HSV-1 infection, while the mTOR stimulator Akt and inhibitor AMPK-activated protein kinase (AMPK) were accordingly activated and suppressed, respectively. An shRNA-mediated knockdown of the autophagy-essential LC3β, as well as pharmacological inhibition of autophagy with bafilomycin A1 or 3-methyladenine, markedly accelerated apoptotic changes and ensuing cell death in HSV-1-infected glioma cells. These data indicate that AMPK/Akt/mTOR-independent autophagy could prolong survival of HSV-1-infected U251 glioma cells by counteracting the coinciding apoptotic response. © 2013 Institut Pasteur.