En röntgenstudie av kolloidal bentonit

Kärnkraftsproducenterna TVO och Fortum har beslutit att deponera kärnavfall i berggrunden i Olkiluoto. Kärnavfallet kommer att placeras i kopparkanistrar, vilka omringas av en buffert bestående av leran bentonit. Buffertens uppgifter är extremt viktiga för slutförvaringens säkerhet, då bufferten skall skydda kanistrarna från externa kontaminanter och seismiska rörelser samt hindra transporten av radioaktivt material. Bentonitens viktigaste komponent är lermineralen montmorillonit. Montmorillonit består av skivor vilka är en nm tjocka och flera hundratals nm breda. Dessa skivor bildar olika strukturer. I detta arbete studerades montmorillonitpartiklarnas former, samt deras andelar, i kolloidala lösningar. Som lösningsämnen användes olika natrium- och kalciumlösningar, vilka motsvarar möjliga omständigheter i berggrunden i Olkiluoto. Lösningarna studerades med lågvinkelröntgenspridning (SAXS) samt med anpassningar av en teoretisk modell utvecklad av Pizzey et al (2009). Med hjälp av dessa kunde partikelstorlekarna, samt andelarna av de olika partiklarna, bestämmas för varje lösning. I alla lösningar påträffades enskilda bentonitskivor samt bentonitskivor i staplar, d.v.s. varierande lager av bentonit och lösning. Stapelstorlekarna, samt deras andelar, berodde på lösningen. I kalciumlösningarna bildades stora, kompakta staplar. Avståndet mellan skivorna var i dessa c. 1 nm och staplarna kunde bestå av över 10 skivor. Andelen av dessa staplar ökade klart med kalciumkoncentrationen. I natriumlösningarna uppstod staplar bestående endast av två skivor. Avståndet mellan skivorna varierade mellan 6-10 nm beroende på natriumkoncentrationen. I blandningar av både kalcium- och natriumlösningar dominerades växelverkan mellan skivorna av kalciumjonerna, d.v.s. stapelstrukturerna bestod till största delen av den kompaktare strukturen

Zika Virus Non-Structural Protein NS5 Inhibits the RIG-I Pathway and Interferon Lambda 1 Promoter Activation by Targeting IKK Epsilon

The Zika virus (ZIKV) is a member of the Flaviviridae family and an important human pathogen. Most pathogenic viruses encode proteins that interfere with the activation of host innate immune responses. Like other flaviviruses, ZIKV interferes with the expression of interferon (IFN) genes and inhibits IFN-induced antiviral responses. ZIKV infects through epithelial barriers where IFN-lambda 1 is an important antiviral molecule. In this study, we analyzed the effects of ZIKV proteins on the activation of IFN-lambda 1 promoter. All ZIKV proteins were cloned and transiently expressed. ZIKV NS5, but no other ZIKV protein, was able to interfere with the RIG-I signaling pathway. This inhibition took place upstream of interferon regulatory factor 3 (IRF3) resulting in reduced phosphorylation of IRF3 and reduced activation of IFN-lambda 1 promoter. Furthermore, we showed that ZIKV NS5 interacts with the protein kinase IKK epsilon, which is likely critical to the observed inhibition of phosphorylation of IRF3.Peer reviewe

RIG-I signaling Is essential for influenza B virus-induced rapid interferon gene expression

Influenza B virus causes annual epidemics and, along with influenza A virus, accounts for substantial disease and economic burden throughout the world. Influenza B virus infects only humans and some marine mammals and is not responsible for pandemics, possibly due to a very low frequency of reassortment and a lower evolutionary rate than that of influenza A virus. Influenza B virus has been less studied than influenza A virus, and thus, a comparison of influenza A and B virus infection mechanisms may provide new insight into virus-host interactions. Here we analyzed the early events in influenza B virus infection and interferon (IFN) gene expression in human monocyte-derived macrophages and dendritic cells. We show that influenza B virus induces IFN regulatory factor 3 (IRF3) activation and IFN-λ1 gene expression with faster kinetics than does influenza A virus, without a requirement for viral protein synthesis or replication. Influenza B virus-induced activation of IRF3 required the fusion of viral and endosomal membranes, and nuclear accumulation of IRF3 and viral NP occurred concurrently. In comparison, immediate early IRF3 activation was not observed in influenza A virus-infected macrophages. Experiments with RIG-I-, MDA5-, and RIG-I/MDA5-deficient mouse fibroblasts showed that RIG-I is the critical pattern recognition receptor needed for the influenza B virus-induced activation of IRF3. Our results show that innate immune mechanisms are activated immediately after influenza B virus entry through the endocytic pathway, whereas influenza A virus avoids early IRF3 activation and IFN gene induction. IMPORTANCE Recently, a great deal of interest has been paid to identifying the ligands for RIG-I under conditions of natural infection, as many previous studies have been based on transfection of cells with different types of viral or synthetic RNA structures. We shed light on this question by analyzing the earliest step in innate immune recognition of influenza B virus by human macrophages. We show that influenza B virus induces IRF3 activation, leading to IFN gene expression after viral RNPs (vRNPs) are released into the cytosol and are recognized by RIG-I receptor, meaning that the incoming influenza B virus is already able to activate IFN gene expression. In contrast, influenza A (H3N2) virus failed to activate IRF3 at very early times of infection, suggesting that there are differences in innate immune recognition between influenza A and B viruses

Highly Pathogenic H5N1 Influenza A Virus Spreads Efficiently in Human Primary Monocyte-Derived Macrophages and Dendritic Cells

Influenza A viruses cause recurrent epidemics and occasional global pandemics. Wild birds are the natural reservoir of influenza A virus from where the virus can be transmitted to poultry or to mammals including humans. Mortality among humans in the highly pathogenic avian influenza H5N1 virus infection is even 60%. Despite intense research, there are still open questions in the pathogenicity of the H5N1 virus in humans. To characterize the H5N1 virus infection in human monocyte-derived macrophages (M phi s) and dendritic cells (DCs), we used human isolates of highly pathogenic H5N1/2004 and H5N1/1997 and low pathogenic H7N9/2013 avian influenza viruses in comparison with a seasonal H3N2/1989 virus. We noticed that the H5N1 viruses have an overwhelming ability to replicate and spread in primary human immune cell cultures, and even the addition of trypsin did not equalize the infectivity of H7N9 or H3N2 viruses to the level seen with H5N1 virus. H5N1 virus stocks contained more often propagation-competent viruses than the H7N9 or H3N2 viruses. The data also showed that human DCs and M phi s maintain 1,000- and 10,000-fold increase in the production of infectious H5N1 virus, respectively. Both analyzed highly pathogenic H5N1 viruses showed multi-cycle infection in primary human DCs and M phi s, whereas the H3N2 and H7N9 viruses were incapable of spreading in immune cells. Interestingly, H5N1 virus was able to spread extremely efficiently despite the strong induction of antiviral interferon gene expression, which may in part explain the high pathogenicity of H5N1 virus infection in humans

Zika Virus Non-Structural Protein NS5 Inhibits the RIG-I Pathway and Interferon Lambda 1 Promoter Activation by Targeting IKK Epsilon

The Zika virus (ZIKV) is a member of the Flaviviridae family and an important human pathogen. Most pathogenic viruses encode proteins that interfere with the activation of host innate immune responses. Like other flaviviruses, ZIKV interferes with the expression of interferon (IFN) genes and inhibits IFN-induced antiviral responses. ZIKV infects through epithelial barriers where IFN-λ1 is an important antiviral molecule. In this study, we analyzed the effects of ZIKV proteins on the activation of IFN-λ1 promoter. All ZIKV proteins were cloned and transiently expressed. ZIKV NS5, but no other ZIKV protein, was able to interfere with the RIG-I signaling pathway. This inhibition took place upstream of interferon regulatory factor 3 (IRF3) resulting in reduced phosphorylation of IRF3 and reduced activation of IFN-λ1 promoter. Furthermore, we showed that ZIKV NS5 interacts with the protein kinase IKKε, which is likely critical to the observed inhibition of phosphorylation of IRF3

Zika Virus Non-Structural Protein NS5 Inhibits the RIG-I Pathway and Interferon Lambda 1 Promoter Activation by Targeting IKK Epsilon

The Zika virus (ZIKV) is a member of the Flaviviridae family and an important human pathogen. Most pathogenic viruses encode proteins that interfere with the activation of host innate immune responses. Like other flaviviruses, ZIKV interferes with the expression of interferon (IFN) genes and inhibits IFN-induced antiviral responses. ZIKV infects through epithelial barriers where IFN-λ1 is an important antiviral molecule. In this study, we analyzed the effects of ZIKV proteins on the activation of IFN-λ1 promoter. All ZIKV proteins were cloned and transiently expressed. ZIKV NS5, but no other ZIKV protein, was able to interfere with the RIG-I signaling pathway. This inhibition took place upstream of interferon regulatory factor 3 (IRF3) resulting in reduced phosphorylation of IRF3 and reduced activation of IFN-λ1 promoter. Furthermore, we showed that ZIKV NS5 interacts with the protein kinase IKKε, which is likely critical to the observed inhibition of phosphorylation of IRF3

Zika Virus Non-Structural Protein NS5 Inhibits the RIG-I Pathway and Interferon Lambda 1 Promoter Activation by Targeting IKK Epsilon

The Zika virus (ZIKV) is a member of the Flaviviridae family and an important human pathogen. Most pathogenic viruses encode proteins that interfere with the activation of host innate immune responses. Like other flaviviruses, ZIKV interferes with the expression of interferon (IFN) genes and inhibits IFN-induced antiviral responses. ZIKV infects through epithelial barriers where IFN-lambda 1 is an important antiviral molecule. In this study, we analyzed the effects of ZIKV proteins on the activation of IFN-lambda 1 promoter. All ZIKV proteins were cloned and transiently expressed. ZIKV NS5, but no other ZIKV protein, was able to interfere with the RIG-I signaling pathway. This inhibition took place upstream of interferon regulatory factor 3 (IRF3) resulting in reduced phosphorylation of IRF3 and reduced activation of IFN-lambda 1 promoter. Furthermore, we showed that ZIKV NS5 interacts with the protein kinase IKK epsilon, which is likely critical to the observed inhibition of phosphorylation of IRF3

Asian and African lineage Zika viruses show differential replication and innate immune responses in human dendritic cells and macrophages

Zika virus (ZIKV) infections in humans are considered to be mild or subclinical. However, during the recent epidemics in the Pacific Islands and the Americas, the infection was associated with Quillain-Barre syndrome and congenital infections with fetal brain abnormalities, including microcephaly. Thus, more detailed understanding of ZIKV-host cell interactions and regulation of innate immune responses by strains of differential evolutionary origin is required. Here, we characterized the infection and immune responses triggered by two epidemic Asian/American lineage viruses, including an isolate from fetal brains, and a historical, low passage 1947 African lineage virus in human monocyte-derived dendritic cells (DCs) and macrophages. The epidemic Asian/American ZIKV replicated well and induced relatively good antiviral responses in human DCs whereas the African strain replicated less efficiently and induced weaker immune responses. In macrophages both the African and Asian strains showed limited replication and relatively weak cytokine gene expression. Interestingly, in macrophages we observed host protein degradation, especially IRF3 and STAT2, at early phases of infection with both lineage viruses, suggesting an early proteasomal activation in phagocytic cells. Our data indicates that ZIKV evolution has led to significant phenotypic differences in the replication characteristics leading to differential regulation of host innate immune responses

Asian and African lineage Zika viruses show differential replication and innate immune responses in human dendritic cells and macrophages

Zika virus (ZIKV) infections in humans are considered to be mild or subclinical. However, during the recent epidemics in the Pacific Islands and the Americas, the infection was associated with Quillain-Barre syndrome and congenital infections with fetal brain abnormalities, including microcephaly. Thus, more detailed understanding of ZIKV-host cell interactions and regulation of innate immune responses by strains of differential evolutionary origin is required. Here, we characterized the infection and immune responses triggered by two epidemic Asian/American lineage viruses, including an isolate from fetal brains, and a historical, low passage 1947 African lineage virus in human monocyte-derived dendritic cells (DCs) and macrophages. The epidemic Asian/American ZIKV replicated well and induced relatively good antiviral responses in human DCs whereas the African strain replicated less efficiently and induced weaker immune responses. In macrophages both the African and Asian strains showed limited replication and relatively weak cytokine gene expression. Interestingly, in macrophages we observed host protein degradation, especially IRF3 and STAT2, at early phases of infection with both lineage viruses, suggesting an early proteasomal activation in phagocytic cells. Our data indicates that ZIKV evolution has led to significant phenotypic differences in the replication characteristics leading to differential regulation of host innate immune responses.Peer reviewe