Differential use of importin-α isoforms governs cell tropism and host adaptation of influenza virus

Influenza A viruses are a threat to humans due to their ability to cross species barriers, as illustrated by the 2009 H1N1v pandemic and sporadic H5N1 transmissions. Interspecies transmission requires adaptation of the viral polymerase to importin-α, a cellular protein that mediates transport into the nucleus where transcription and replication of the viral genome takes place. In this study, we analysed replication, host specificity and pathogenicity of avian and mammalian influenza viruses, in importin-α-silenced cells and importin-α-knockout mice, to understand the role of individual importin-α isoforms in adaptation. For efficient virus replication, the polymerase subunit PB2 and the nucleoprotein (NP) of avian viruses required importin-α3, whereas PB2 and NP of mammalian viruses showed importin-α7 specificity. H1N1v replication depended on both, importin-α3 and -α7, suggesting ongoing adaptation of this virus. Thus, differences in importin-α specificity are determinants of host range underlining the importance of the nuclear envelope in interspecies transmission

Male offspring born to mildly ZIKV-infected mice are at risk of developing neurocognitive disorders in adulthood

Congenital Zika virus (ZIKV) syndrome may cause fetal microcephaly in -1% of affected newborns. Here, we investigate whether the majority of clinically inapparent newborns might suffer from long-term health impairments not readily visible at birth. Infection of immunocompetent pregnant mice with high-dose ZIKV caused severe offspring phenotypes, such as fetal death, as expected. By contrast, low-dose (LD) maternal ZIKV infection resulted in reduced fetal birth weight but no other obvious phenotypes. Male offspring born to LD ZIKV-infected mothers had increased testosterone (TST) levels and were less likely to survive in utero infection compared to their female littermates. Males also presented an increased number of immature neurons in apical and basal hippocampal dendrites, while female offspring had immature neurons in basal dendrites only. Moreover, male offspring with high but not very high (storm) TST levels were more likely to suffer from learning and memory impairments compared to females. Future studies are required to understand the impact of TST on neuropathological and neurocognitive impairments in later life. In summary, increased sex-specific vigilance is required in countries with high ZIKV prevalence, where impaired neurodevelopment may be camouflaged by a healthy appearance at birth.Peer reviewe

Bildung und Kondensation alkali-, bor- und schwefelhaltiger Phasen in Abgasen aus Glasschmelzwannen- Thermodynamik, Kinetik und Technologie

Evaporation processes generally occurring in glass melting furnaces are undesirable phenomena. Volatile glass components like sodium or boron evaporate from batch and glass melt. Their loss does not only have an effect on glass composition, homogeneity and quality, but also makes flue gas filters behind glass melting tanks indispensable. Although the operation of these filters is often based on long experience and collected empirical data, filter corrosion or slip-through of components can still lead to enormous problems. In boron containing flue gases, the main difficulties during filter operation are the slip-through of the gaseous species (HBO2)n and H3BO3 and the back-reaction of already precipitated filter dust to gaseous species. This study focuses on the thermodynamic and kinetic conditions in flue gases consisting of combustion gases, sodium, boron and sulphur compounds. To identify the reaction mechanisms in flue gases, results from thermodynamic calculations, kinetic experiments and the analysis of industrial filter dust are combined. The obtained data may be used to adjust filter operation in such a way that the above mentioned problems are avoided.In sulphur free flue gases, the possible species are NaBO2, KBO2, Na2B4O7 and H3BO3. In sulphur containing gases Na2SO4, NaHSO4, Na3(HSO4)(SO4) and K3Na(SO4)2 will form. Sodium and potassium borates and sulfates form condensates that can easily be precipitated between 400 and 200 °C. Only if boron has no alkaline reaction partner, can it pass the filters as gaseous species. In this case, boron will condensate as H3BO3. The condensation temperatures of each species depend on the partial pressure of the compound in the flue gas. For a typical partial pressure of PH3BO3 = 1 ∙ 10-4 bar H3BO3 will condensate below 87 °C. The analysis of industrial filter dust in combination with thermodynamic calculations shows, that condensation of compounds from flue gas will occur in the following order:Na2SO4-NaF-CaSO4-NaxByOz-Na2CO3-CaF2-NaOH-CaxByOz-CaCO3-Ca(OH)2The formation of the salts of sulphuric or hydrofluoric acid is preferred. The back-reaction from filter dust results from the reaction of precipitated species with acid components. As the mixing energy of the phases in the row above increases from left to right, SO3, F, B2O3, CO3 and H2O can be disposed by any species positioned left in the row

神岡鉱山深部断層水中のラドン濃度観測による地震前兆現象の研究

平成9年度-平成11年度年度科学研究費補助金 (基盤研究(B)(2)　課題番号09440104) 研究成果報告

Alternative interaction sites in the influenza A virus nucleoprotein mediate viral escape from the importin-alpha 7 mediated nuclear import pathway

Influenza A viruses are able to adapt to restrictive conditions due to their high mutation rates. Importin-alpha 7 is a component of the nuclear import machinery required for avian-mammalian adaptation and replicative fitness in human cells. Here, we elucidate the mechanisms by which influenza A viruses may escape replicative restriction in the absence of importin-alpha 7. To address this question, we assessed viral evolution in mice lacking the importin-alpha 7 gene. We show that three mutations in particular occur with high frequency in the viral nucleoprotein (NP) protein (G102R, M105K and D375N) in a specific structural area upon in vivo adaptation. Moreover, our findings suggest that the adaptive NP mutations mediate viral escape from importin-alpha 7 requirement likely due to the utilization of alternative interaction sites in NP beyond the classical nuclear localization signal. However, viral escape from importin-alpha 7 by mutations in NP is, at least in part, associated with reduced viral replication highlighting the crucial contribution of importin-alpha 7 to replicative fitness in human cells

Mutations in the H7 HA and PB1 genes of avian influenza a viruses increase viral pathogenicity and contact transmission in guinea pigs

ABSTRACTAvian influenza A viruses (AIV) of the H7 subtype continue to evolve posing a pandemic threat. However, molecular markers of H7N7 AIV pathogenicity and transmission in mammals remain poorly understood. In this study, we performed a systematic in vitro and in vivo analysis by comparing an H7N7 highly pathogenic AIV and its ferret adapted variant. Passaging an H7N7 AIV in ferrets led to six mutations in genes encoding the viral polymerase complex and the viral surface proteins. Here, we show that mutations in the H7 hemagglutinin gene cause increased pathogenicity in mice. Contact transmission between guinea pigs required additional mutations in the gene encoding the polymerase subunit PB1. Thus, particular vigilance is required with respect to HA and PB1 mutations as predictive molecular markers to assess the pandemic risk posed by emerging H7 avian influenza viruses

Analysis of IAV Replication and Co-infection Dynamics by a Versatile RNA Viral Genome Labeling Method

Genome delivery to the proper cellular compartment for transcription and replication is a primary goal of viruses. However, methods for analyzing viral genome localization and differentiating genomes with high identity are lacking, making it difficult to investigate entry-related processes and co-examine heterogeneous RNA viral populations. Here, we present an RNA labeling approach for single-cell analysis of RNA viral replication and co-infection dynamics in situ, which uses the versatility of padlock probes. We applied this method to identify influenza A virus (IAV) infections in cells and lung tissue with single-nucleotide specificity and to classify entry and replication stages by gene segment localization. Extending the classification strategy to co-infections of IAVs with single-nucleotide variations, we found that the dependence on intracellular trafficking places a time restriction on secondary co-infections necessary for genome reassortment. Altogether, these data demonstrate how RNA viral genome labeling can help dissect entry and co-infections