1,721,054 research outputs found
Analysis of innate immunity signaling pathways in MDCK cells in an influenza virus vaccine production process
No full textDespite tremendous progress in basic research concerning virus-host cell interaction over the past decade, only little efforts have been undertaken to characterize cell culture-based influenza vaccine production. Since manufacturers have to operate within limited time frames to provide sufficient amounts of vaccine, fast, reliable and robust production processes are of crucial importance. This requires a detailed knowledge of cellular events relevant for influenza A virus replication. For instance, it has for a long time remained unclear what role the activation of host cellular innate immunity plays in influenza vaccine production and what impact signaling has on virus yields. In this work, the activation of a number of signaling cascades crucial for influenza A virus replication (NF-κB, IRF-3, PI3K-Akt, Jak-Stat, Raf/MEK/ERK, PKR/eIF2α) was monitored using phospho-specific antibodies. For two variants of influenza virus A/PuertoRico/8/34 H1N1 that replicate to different final titers it could be shown that these pathways are induced stronger by the variant that replicates less well. These results obtained in high multiplicity of infection experiments could be confirmed under bioprocess conditions and in part also at a varying multiplicity of infection. Current efforts are aimed at clarifying the actual significance of the monitored pathways for virus replication by RNAi technology and by the use of small molecule inhibitors. In the long run, these efforts facilitate the understanding of virus replication in cell culture-based vaccine production and might contribute to the design and optimization of production cell lines. [1, 2] [1] Heynisch B, Frensing T, Heinze K, Seitz C, Genzel Y, Reichl U. Differential activation of host cell signalling pathways through infection with two variants of influenza A/Puerto Rico/8/34 (H1N1) in MDCK cells. Vaccine 2010 Nov 29;28(51):8210-8. [2] Seitz C, Frensing T, Hoper D, Kochs G, Reichl U. High yields of influenza A virus in Madin-Darby canine kidney cells are promoted by an insufficient interferon-induced antiviral state. J Gen Virol Jul;91(Pt 7):1754-63
Analysis of the impact of innate immunity of MDCK cells on virus replication in influenza vaccine production
No full textFor more than half a century influenza vaccines have been produced in embryonated hen’s eggs. While this is still a widely used technique today, there are several drawbacks of this method. These include difficult standardization, chicken protein intolerance, and a fragile supply chain. Therefore, animal cell cultures are becoming increasingly important in influenza vaccine manufacturing. Fast, reliable and robust production processes are essential to manufacturers, as sufficient amounts of vaccine have to be provided within limited time frames. In spite of considerable progress in basic virology over the past decade, there have been only few efforts to characterize cell culture-based influenza vaccine production regarding virus-host cell interaction. For instance, it is largely unknown what role the activation of innate immunity of host cells plays in influenza vaccine production and what impact activation of signaling pathways has on virus yields. In this project, the activation of a number of signaling cascades crucial for influenza A virus replication (NF-κB, IRF-3, PI3K-Akt, Jak-Stat, Raf/MEK/ERK, PKR/eIF2α) was monitored in Madin-Darby Canine Kidney (MDCK) cells using phospho-specific antibodies. Two variants of influenza virus A/PuertoRico/8/34 H1N1 were investigated that replicate to different final titers in cell culture. It could be shown that signaling pathways are induced stronger by the variant that replicates less well. In addition, these results obtained in high multiplicity of infection experiments were confirmed under bioprocess conditions. Current efforts are aimed at clarifying the actual significance of the monitored pathways for virus replication by RNAi technology and by the use of small molecule inhibitors. In the long run, these efforts will facilitate understanding of virus replication in cell culture-based vaccine production and contribute to the design of production cell lines. [1, 2] [1] Heynisch B, Frensing T, Heinze K, Seitz C, Genzel Y, Reichl U. Differential activation of host cell signalling pathways through infection with two variants of influenza A/Puerto Rico/8/34 (H1N1) in MDCK cells. Vaccine 2010 Nov 29;28(51):8210-8. [2] Seitz C, Frensing T, Hoper D, Kochs G, Reichl U. High yields of influenza A virus in Madin-Darby canine kidney cells are promoted by an insufficient interferon-induced antiviral state. J Gen Virol Jul;91(Pt 7):1754-63
Induction of innate immunity signaling pathways in MDCK cells and their relevance in a bioprocess for influenza vaccine production
No full textCell culture based processes are increasingly used for influenza vaccine production. Besides a high demand of seasonal vaccines, pandemic outbreaks challenge existing production capacities. A recurring problem in vaccine manufacturing is the difficulty to grow different seasonal influenza A virus strains to equally high titers. Hence, the cellular production system has to be more thoroughly investigated for further process optimization. Striking differences were found in the replication behavior of two influenza A virus strain variants (A/PR/8/34), supplied by either the National Institute for Biological Standards and Control (NIBSC) or the Robert Koch Institute (RKI). Differences between these two variants regarding proteome alterations, apoptosis induction and survival of infected cells were observed. To elucidate possible causes of these differences the induction of cellular signaling pathways involved in antiviral defense and apoptosis, such as type I interferon (IFN) signaling, was analyzed. Interestingly, all monitored signaling cascades were induced significantly stronger by the PR8-NIBSC variant shown to replicate poorly [1]. However, the inhibition of the IFN system by over-expression of viral antagonistic proteins had no significant impact on final virus titers. On the other hand, stimulation of innate cellular immunity by IFN-containing medium slowed down initial virus replication, but failed to reduce final virus yields. This can partially be ascribed to a lacking antiviral activity of the IFN-induced Mx proteins of the production cell line (Madin-Darby canine kidney) used [2]. Overall, innate immunity seems to be of only minor importance for virus yields of the bioprocess investigated. Nevertheless, observations regarding the induction of cellular signaling pathways allow interpreting alterations in cellular proteome and apoptosis induction previously found. [1] Heynisch B, Frensing T, Heinze K, Seitz C, Genzel Y, Reichl U. Differential activation of host cell signalling pathways through infection with two variants of influenza A/PR/8/34 (H1N1) in MDCK cells. Vaccine (submitted) [2] Seitz C, Frensing T, Hoper D, Kochs G, Reichl U. High yields of influenza A virus in Madin-Darby canine kidney cells are promoted by an insufficient interferon-induced antiviral state. J Gen Virol Jul;91(Pt 7):1754-63
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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