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Hokkaido University Collection of Scholarly and Academic Papers (135.711 recursos)

HUSCAP (Hokkaido University Collection of Scholarly and Academic Papers) contains peer-reviewed journal articles, proceedings, educational resources and any kind of scholarly works of Hokkaido University.

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Mostrando recursos 1 - 20 de 97

  1. TAJIMA'S D AND SITE-SPECIFIC NUCLEOTIDE FREQUENCY IN A POPULATION DURING AN INFECTIOUS DISEASE OUTBREAK

    Omori, Ryosuke; Wu, Jianhong
    Tajima's D measures the difference between two estimates of genetic diversity in a given set of nucleic acid sequences. Here we show how Tajima's D can be calculated/estimated by developing an inductive algorithm for calculating the site-specific nucleotide frequencies from a standard multistrain susceptible-infective-removed (SIR) model (both deterministic and stochastic). We show that these frequencies are fully determined by the mutation rate and the initial condition of the frequencies. We prove that the sign of Tajima's D is independent of the disease population dynamics and that the negative sign does not imply an expansion of the infected population in the...

  2. Influenza A Virus M2 Protein: Roles from Ingress to Egress

    Manzoor, Rashid; Igarashi, Manabu; Takada, Ayato
    Influenza A virus (IAV) matrix protein 2 (M2) is among the smallest bona fide, hence extensively studied, ion channel proteins. The M2 ion channel activity is not only essential for virus replication, but also involved in modulation of cellular homeostasis in a variety of ways. It is also the target for ion channel inhibitors, i.e., anti-influenza drugs. Thus far, several studies have been conducted to elucidate its biophysical characteristics, structure-function relationships of the ion channel, and the M2-host interactome. In this review, we discuss M2 protein synthesis and assembly into an ion channel, its roles in IAV replication, and the...

  3. Valosin-containing protein (VCP/p97) plays a role in the replication of West Nile virus

    Phongphaew, Wallaya; Kobayashi, Shintaro; Sasaki, Michihito; Carr, Michael; Hall, William W.; Orba, Yasuko; Sawa, Hirofumi
    Valosin-containing protein (VCP) is classified as a member of the type II AAA(+) ATPase protein family. VCP functions in several cellular processes, including protein degradation, membrane fusion, vesicular trafficking and disassembly of stress granules. Moreover, VCP is considered to play a role in the replication of several viruses, albeit through different mechanisms. In the present study, we have investigated the role of VCP in West Nile virus (WNV) infection. Endogenous VCP expression was inhibited using either VCP inhibitors or by siRNA knockdown. It could be shown that the inhibition of endogenous VCP expression significantly inhibited WNV infection. The entry assay...

  4. Valosin-containing protein (VCP/p97) plays a role in the replication of West Nile virus

    Phongphaew, Wallaya; Kobayashi, Shintaro; Sasaki, Michihito; Carr, Michael; Hall, William W.; Orba, Yasuko; Sawa, Hirofumi
    Valosin-containing protein (VCP) is classified as a member of the type II AAA(+) ATPase protein family. VCP functions in several cellular processes, including protein degradation, membrane fusion, vesicular trafficking and disassembly of stress granules. Moreover, VCP is considered to play a role in the replication of several viruses, albeit through different mechanisms. In the present study, we have investigated the role of VCP in West Nile virus (WNV) infection. Endogenous VCP expression was inhibited using either VCP inhibitors or by siRNA knockdown. It could be shown that the inhibition of endogenous VCP expression significantly inhibited WNV infection. The entry assay...

  5. Putative endogenous filovirus VP35-like protein potentially functions as an IFN antagonist but not a polymerase cofactor

    Kondoh, Tatsunari; Manzoor, Rashid; Nao, Naganori; Maruyama, Junki; Furuyama, Wakako; Miyamoto, Hiroko; Shigeno, Asako; Kuroda, Makoto; Matsuno, Keita; Fujikura, Daisuke; Kajihara, Masahiro; Yoshida, Reiko; Igarashi, Manabu; Takada, Ayato
    It has been proposed that some non-retroviral RNA virus genes are integrated into vertebrate genomes. Endogenous filovirus-like elements (EFLs) have been discovered in some mammalian genomes. However, their potential roles in ebolavirus infection are unclear. A filovirus VP35-like element (mlEFL35) is found in the little brown bat (Myotis lucifugus) genome. Putative mlEFL35-derived protein (mlEFL35p) contains nearly full-length amino acid sequences corresponding to ebolavirus VP35. Ebola virus VP35 has been shown to bind double-stranded RNA, leading to inhibition of type I interferon (IFN) production, and is also known as a viral polymerase cofactor that is essential for viral RNA transcription/replication. In...

  6. A novel reverse genetics system for production of infectious West Nile virus using homologous recombination in mammalian cells

    Kobayashi, Shintaro; Yoshii, Kentaro; Hirano, Minato; Muto, Memi; Kariwa, Hiroaki
    Reverse genetics systems facilitate investigation of many aspects of the life cycle and pathogenesis of viruses. However, genetic instability in Escherichia coli has hampered development of a reverse genetics system for West Nile virus (WNV). In this study, we developed a novel reverse genetics system for WNV based on homologous recombination in mammalian cells. Introduction of the DNA fragment coding for the WNV structural protein together with a DNA-based replicon resulted in the release of infectious WNV. The growth rate and plague size of the recombinant virus were almost identical to those of the parent WNV. Furthermore, chimeric WNV was...

  7. A novel reverse genetics system for production of infectious West Nile virus using homologous recombination in mammalian cells

    Kobayashi, Shintaro; Yoshii, Kentaro; Hirano, Minato; Muto, Memi; Kariwa, Hiroaki
    Reverse genetics systems facilitate investigation of many aspects of the life cycle and pathogenesis of viruses. However, genetic instability in Escherichia coli has hampered development of a reverse genetics system for West Nile virus (WNV). In this study, we developed a novel reverse genetics system for WNV based on homologous recombination in mammalian cells. Introduction of the DNA fragment coding for the WNV structural protein together with a DNA-based replicon resulted in the release of infectious WNV. The growth rate and plague size of the recombinant virus were almost identical to those of the parent WNV. Furthermore, chimeric WNV was...

  8. Isolation of a simian immunodeficiency virus from a malbrouck (Chlorocebus cynosuros)

    Carr, Michael; Kawaguchi, Akira; Sasaki, Michihito; Gonzalez, Gabriel; Ito, Kimihito; Thomas, Yuka; Hang'ombe, Bernard M.; Mweene, Aaron S.; Zhao, Guoyan; Wang, David; Orba, Yasuko; Ishii, Akihiro; Sawa, Hirofumi
    To investigate the diversity of simian immunodeficiency virus (SIV) among nonhuman primates (NHPs) in Zambia, next-generation sequencing was performed to determine the complete genome sequence of a novel SIV recovered by co-culturing African green monkey (AGM) peripheral blood lymphocytes with human CD4(+) T-cell lines. We report the first described SIV (SIVagmMAL-ZMB) from a malbrouck (Chlorocebus cynosuros). SIVagmMAL-ZMB was detected by real-time PCR analysis of splenic RNA in 3.2% (3/94) of AGMs and was undetectable in baboons (0/105). SIVagmMAL-ZMB possessed < 80% nucleotide sequence identity to known SIV isolates and was located basally to vervet monkey SIV strains in all phylogenies.

  9. Development of an Immunochromatography Assay (QuickNavi-Ebola) to Detect Multiple Species of Ebolaviruses

    Yoshida, Reiko; Muramatsu, Shino; Akita, Hiroshi; Saito, Yuji; Kuwahara, Miwa; Kato, Daisuke; Changula, Katendi; Miyamoto, Hiroko; Kajihara, Masahiro; Manzoor, Rashid; Furuyama, Wakako; Marzi, Andrea; Feldmann, Heinz; Mweene, Aaron; Masumu, Justin; Kapeteshi, Jimmy; Muyembe-Tamfum, Jean-Jacques; Takada, Ayato
    The latest outbreak of Ebola virus disease (EVD) in West Africa has highlighted the urgent need for the development of rapid and reliable diagnostic assays. We used monoclonal antibodies specific to the ebolavirus nucleoprotein to develop an immunochromatography (IC) assay (QuickNavi-Ebola) for rapid diagnosis of EVD. The IC assay was first evaluated with tissue culture supernatants of infected Vero E6 cells and found to be capable of detecting 10(3)-10(4) focus-forming units/mL of ebolaviruses. Using serum samples from experimentally infected nonhuman primates, we confirmed that the assay could detect the viral antigen shortly after disease onset. It was also noted that...

  10. Development of an Immunochromatography Assay (QuickNavi-Ebola) to Detect Multiple Species of Ebolaviruses

    Yoshida, Reiko; Muramatsu, Shino; Akita, Hiroshi; Saito, Yuji; Kuwahara, Miwa; Kato, Daisuke; Changula, Katendi; Miyamoto, Hiroko; Kajihara, Masahiro; Manzoor, Rashid; Furuyama, Wakako; Marzi, Andrea; Feldmann, Heinz; Mweene, Aaron; Masumu, Justin; Kapeteshi, Jimmy; Muyembe-Tamfum, Jean-Jacques; Takada, Ayato
    The latest outbreak of Ebola virus disease (EVD) in West Africa has highlighted the urgent need for the development of rapid and reliable diagnostic assays. We used monoclonal antibodies specific to the ebolavirus nucleoprotein to develop an immunochromatography (IC) assay (QuickNavi-Ebola) for rapid diagnosis of EVD. The IC assay was first evaluated with tissue culture supernatants of infected Vero E6 cells and found to be capable of detecting 10(3)-10(4) focus-forming units/mL of ebolaviruses. Using serum samples from experimentally infected nonhuman primates, we confirmed that the assay could detect the viral antigen shortly after disease onset. It was also noted that...

  11. Multi-reassortant G3P[3] group A rotavirus in a horseshoe bat in Zambia

    Sasaki, Michihito; Orba, Yasuko; Sasaki, Satoko; Gonzalez, Gabriel; Ishii, Akihiro; Hang'ombe, Bernard M.; Mweene, Aaron S.; Ito, Kimihito; Sawa, Hirofumi
    Group A rotavirus is a major cause of diarrhoea in humans, especially in young children. Bats also harbour group A rotaviruses, but the genetic backgrounds of bat rotavirus strains are usually distinct from those of human rotavirus strains. We identified a new strain of group A rotavirus in the intestinal contents of a horseshoe bat in Zambia. Whole genome sequencing revealed that the identified virus, named RVA/Bat-wt/ZMB/LUS12-14/2012/G3P[3], possessed the genotype constellation G3-P[3]-I3-R2-C2-M3-A9-N2-T3-E2-H3. Several genome segments of LUS12-14 were highly similar to those of group A rotaviruses identified from humans, cows and antelopes, indicating interspecies transmission of rotaviruses between bats and...

  12. Multi-reassortant G3P[3] group A rotavirus in a horseshoe bat in Zambia

    Sasaki, Michihito; Orba, Yasuko; Sasaki, Satoko; Gonzalez, Gabriel; Ishii, Akihiro; Hang'ombe, Bernard M.; Mweene, Aaron S.; Ito, Kimihito; Sawa, Hirofumi
    Group A rotavirus is a major cause of diarrhoea in humans, especially in young children. Bats also harbour group A rotaviruses, but the genetic backgrounds of bat rotavirus strains are usually distinct from those of human rotavirus strains. We identified a new strain of group A rotavirus in the intestinal contents of a horseshoe bat in Zambia. Whole genome sequencing revealed that the identified virus, named RVA/Bat-wt/ZMB/LUS12-14/2012/G3P[3], possessed the genotype constellation G3-P[3]-I3-R2-C2-M3-A9-N2-T3-E2-H3. Several genome segments of LUS12-14 were highly similar to those of group A rotaviruses identified from humans, cows and antelopes, indicating interspecies transmission of rotaviruses between bats and...

  13. Impact of mutations in DNA gyrase genes on quinolone resistance in Campylobacter jejuni

    Changkwanyeun, Ruchirada; Yamaguchi, Tomoyuki; Kongsoi, Siriporn; Changkaew, Kanjana; Yokoyama, Kazumasa; Kim, Hyun; Suthienkul, Orasa; Usui, Masaru; Tamura, Yutaka; Nakajima, Chie; Suzuki, Yasuhiko
    Amino acid substitutions providing quinolone resistance to Campyloabcter jejuni have been found in the quinolone resistance-determining region of protein DNA gyrase subunit A (GyrA), with the highest frequency at position 86 followed by position 90. In this study, wild-type and mutant recombinant DNA gyrase subunits were expressed in Escherichia coli and purified using Ni-NTA agarose column chromatography. Soluble 97 kDa GyrA and 87 kDa DNA gyrase subunit B were shown to reconstitute ATP-dependent DNA supercoiling activity. A quinolone-inhibited supercoiling assay demonstrated the roles of Thr86Ile, Thr86Ala, Thr86Lys, Asp90Asn, and Asp90Tyr amino acid substitutions in reducing sensitivity to quinolones. The marked...

  14. Impact of mutations in DNA gyrase genes on quinolone resistance in Campylobacter jejuni

    Changkwanyeun, Ruchirada; Yamaguchi, Tomoyuki; Kongsoi, Siriporn; Changkaew, Kanjana; Yokoyama, Kazumasa; Kim, Hyun; Suthienkul, Orasa; Usui, Masaru; Tamura, Yutaka; Nakajima, Chie; Suzuki, Yasuhiko
    Amino acid substitutions providing quinolone resistance to Campyloabcter jejuni have been found in the quinolone resistance-determining region of protein DNA gyrase subunit A (GyrA), with the highest frequency at position 86 followed by position 90. In this study, wild-type and mutant recombinant DNA gyrase subunits were expressed in Escherichia coli and purified using Ni-NTA agarose column chromatography. Soluble 97 kDa GyrA and 87 kDa DNA gyrase subunit B were shown to reconstitute ATP-dependent DNA supercoiling activity. A quinolone-inhibited supercoiling assay demonstrated the roles of Thr86Ile, Thr86Ala, Thr86Lys, Asp90Asn, and Asp90Tyr amino acid substitutions in reducing sensitivity to quinolones. The marked...

  15. Amino acid substitutions in GyrA affect quinolone susceptibility in Salmonella typhimurium

    Kongsoi, Siriporn; Changkwanyeun, Ruchirada; Yokoyama, Kazumasa; Nakajima, Chie; Changkaew, Kanjana; Suthienkul, Orasa; Suzuki, Yasuhiko
    The prevalence of quinolone-resistant Salmonella has become a public health concern. Amino acid substitutions have generally been found within the quinolone resistance-determining region in subunit A of DNA gyrase (GyrA) of Salmonella Typhimurium. However, direct evidence of the contribution of these substitutions to quinolone resistance remains to be shown. To investigate the significance of amino acid substitutions in S. Typhimurium GyrA to quinolone resistance, we expressed recombinant wild-type (WT) and five mutant DNA gyrases in Escherichia coli and characterized them in vitro. WT and mutant DNA gyrases were reconstituted in vitro by mixing recombinant subunits A and B of DNA...

  16. Amino acid substitutions in GyrA affect quinolone susceptibility in Salmonella typhimurium

    Kongsoi, Siriporn; Changkwanyeun, Ruchirada; Yokoyama, Kazumasa; Nakajima, Chie; Changkaew, Kanjana; Suthienkul, Orasa; Suzuki, Yasuhiko
    The prevalence of quinolone-resistant Salmonella has become a public health concern. Amino acid substitutions have generally been found within the quinolone resistance-determining region in subunit A of DNA gyrase (GyrA) of Salmonella Typhimurium. However, direct evidence of the contribution of these substitutions to quinolone resistance remains to be shown. To investigate the significance of amino acid substitutions in S. Typhimurium GyrA to quinolone resistance, we expressed recombinant wild-type (WT) and five mutant DNA gyrases in Escherichia coli and characterized them in vitro. WT and mutant DNA gyrases were reconstituted in vitro by mixing recombinant subunits A and B of DNA...

  17. Serotyping dengue virus with isothermal amplification and a portable sequencer

    Yamagishi, Junya; Runtuwene, Lucky R.; Hayashida, Kyoko; Mongan, Arthur E.; Lan Anh Nguyen Thi; Linh Nguyen Thuy; Cam Nguyen Nhat; Limkittikul, Kriengsak; Sirivichayakul, Chukiat; Sathirapongsasuti, Nuankanya; Frith, Martin; Makalowski, Wojciech; Eshita, Yuki; Sugano, Sumio; Suzuki, Yutaka
    The recent development of a nanopore-type portable DNA sequencer has changed the way we think about DNA sequencing. We can perform sequencing directly in the field, where we collect the samples. Here, we report the development of a novel method to detect and genotype tropical disease pathogens, using dengue fever as a model. By combining the sequencer with isothermal amplification that only requires a water bath, we were able to amplify and sequence target viral genomes with ease. Starting from a serum sample, the entire procedure could be finished in a single day. The analysis of blood samples collected from...

  18. Serotyping dengue virus with isothermal amplification and a portable sequencer

    Yamagishi, Junya; Runtuwene, Lucky R.; Hayashida, Kyoko; Mongan, Arthur E.; Lan Anh Nguyen Thi; Linh Nguyen Thuy; Cam Nguyen Nhat; Limkittikul, Kriengsak; Sirivichayakul, Chukiat; Sathirapongsasuti, Nuankanya; Frith, Martin; Makalowski, Wojciech; Eshita, Yuki; Sugano, Sumio; Suzuki, Yutaka
    The recent development of a nanopore-type portable DNA sequencer has changed the way we think about DNA sequencing. We can perform sequencing directly in the field, where we collect the samples. Here, we report the development of a novel method to detect and genotype tropical disease pathogens, using dengue fever as a model. By combining the sequencer with isothermal amplification that only requires a water bath, we were able to amplify and sequence target viral genomes with ease. Starting from a serum sample, the entire procedure could be finished in a single day. The analysis of blood samples collected from...

  19. Aureobasidium pullulans produced β-glucan is effective to enhance Kurosengoku soybean extract induced Thrombospondin-1 expression

    Muramatsu, Daisuke; Okabe, Mitsuyasu; Takaoka, Akinori; Kida, Hiroshi; Iwai, Atsushi
    Black yeast, Aureobasidium pullulans is extracellularly produced β-(1,3), (1,6)-D-glucan (β-glucan) under certain conditions. In this study, using Glycine max cv. Kurosengoku (Kurosengoku soybeans), the production of β-glucan through fermentation of A. pullulans was evaluated, and the effects of A. pullulans cultured fluid (AP-CF) containing β-glucan made with Kurosengoku soybeans (kAP-CF) on a human monocyte derived cell line, Mono Mac 6 cells were investigated. Concentration of β-glucan in kAP-CF reached the same level as normal AP-CF. An anti-angiogenic protein, Thrombospondin-1 (THBS1) was effectively induced after the stimulation with kAP-CF for comparison with AP-CF. The THBS1 is also induced after stimulation with...

  20. Fcγ-receptor IIa-mediated Src Signaling Pathway Is Essential for the Antibody-Dependent Enhancement of Ebola Virus Infection

    Furuyama, Wakako; Marzi, Andrea; Carmody, Aaron B.; Maruyama, Junki; Kuroda, Makoto; Miyamoto, Hiroko; Nanbo, Asuka; Manzoor, Rashid; Yoshida, Reiko; Igarashi, Manabu; Feldmann, Heinz; Takada, Ayato
    Antibody-dependent enhancement (ADE) of Ebola virus (EBOV) infection has been demonstrated in vitro, raising concerns about the detrimental potential of some anti-EBOV antibodies. ADE has been described for many viruses and mostly depends on the cross-linking of virus-antibody complexes to cell surface Fc receptors, leading to enhanced infection. However, little is known about the molecular mechanisms underlying this phenomenon. Here we show that Fc gamma-receptor IIa (Fc gamma RIIa)-mediated intracellular signaling through Src family protein tyrosine kinases (PTKs) is required for ADE of EBOV infection. We found that deletion of the Fc gamma RIIa cytoplasmic tail abolished EBOV ADE due...

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