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  1. Article ; Online: Assays for Determining the Sialidase Activity of Influenza Viruses and Monitoring Influenza Virus Susceptibility to Neuraminidase Inhibitors.

    Takashita, Emi

    Methods in molecular biology (Clifton, N.J.)

    2022  Volume 2556, Page(s) 287–302

    Abstract: Three types of assays--colorimetric, fluorescent, and chemiluminescent--are used to determine the sialidase (neuraminidase: NA) activity of influenza viruses. The fluorescent assay is cost-effective and applicable for many laboratories and is, therefore, ...

    Abstract Three types of assays--colorimetric, fluorescent, and chemiluminescent--are used to determine the sialidase (neuraminidase: NA) activity of influenza viruses. The fluorescent assay is cost-effective and applicable for many laboratories and is, therefore, commonly used for global monitoring of the NA inhibitor susceptibility of influenza viruses. Here, I describe, in detail, protocols for the fluorescence-based NA activity assay and the NA inhibition assay, which are used to determine the NA activity and NA inhibitor susceptibility, respectively, of influenza viruses.
    MeSH term(s) Antiviral Agents/pharmacology ; Biological Assay ; Central Nervous System Depressants ; Coloring Agents ; Enzyme Inhibitors/pharmacology ; Neuraminidase ; Orthomyxoviridae
    Chemical Substances Antiviral Agents ; Central Nervous System Depressants ; Coloring Agents ; Enzyme Inhibitors ; Neuraminidase (EC 3.2.1.18)
    Language English
    Publishing date 2022-09-29
    Publishing country United States
    Document type Journal Article
    ISSN 1940-6029
    ISSN (online) 1940-6029
    DOI 10.1007/978-1-0716-2635-1_19
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Influenza Polymerase Inhibitors: Mechanisms of Action and Resistance.

    Takashita, Emi

    Cold Spring Harbor perspectives in medicine

    2021  Volume 11, Issue 5

    Abstract: The influenza virus RNA-dependent RNA polymerase is highly conserved among influenza A, B, C, and D viruses. It comprises three subunits: polymerase basic protein 1 (PB1), polymerase basic protein 2 (PB2), and polymerase acidic protein (PA) in influenza ... ...

    Abstract The influenza virus RNA-dependent RNA polymerase is highly conserved among influenza A, B, C, and D viruses. It comprises three subunits: polymerase basic protein 1 (PB1), polymerase basic protein 2 (PB2), and polymerase acidic protein (PA) in influenza A and B viruses or polymerase 3 protein (P3) in influenza C and D viruses. Because this polymerase is essential for influenza virus replication, it has been considered as a target for antiviral agents. Recently, several polymerase inhibitors that target each subunit have been developed. This review discusses the mechanism of action, antiviral activity, and emergence of resistance to three inhibitors approved for the treatment of influenza or in late-phase clinical trials: the PB1 inhibitor favipiravir, the PB2 inhibitor pimodivir, and the PA inhibitor baloxavir marboxil.
    MeSH term(s) Amides ; Antiviral Agents/therapeutic use ; Dibenzothiepins ; Drug Resistance, Viral ; Humans ; Influenza, Human/genetics ; Influenza, Human/virology ; Morpholines ; Orthomyxoviridae/drug effects ; Pyrazines ; Pyridines ; Pyridones ; Pyrimidines ; Pyrroles ; RNA-Dependent RNA Polymerase/drug effects ; Triazines ; Virus Replication/drug effects
    Chemical Substances Amides ; Antiviral Agents ; Dibenzothiepins ; Morpholines ; Pyrazines ; Pyridines ; Pyridones ; Pyrimidines ; Pyrroles ; Triazines ; baloxavir (4G86Y4JT3F) ; pimodivir (DFC121MXC3) ; RNA-Dependent RNA Polymerase (EC 2.7.7.48) ; favipiravir (EW5GL2X7E0)
    Language English
    Publishing date 2021-05-03
    Publishing country United States
    Document type Journal Article ; Review
    ISSN 2157-1422
    ISSN (online) 2157-1422
    DOI 10.1101/cshperspect.a038687
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article ; Online: Are twindemics occurring?

    Takashita, Emi / Watanabe, Shinji / Hasegawa, Hideki / Kawaoka, Yoshihiro

    Influenza and other respiratory viruses

    2022  Volume 17, Issue 1, Page(s) e13090

    Abstract: The emergence and spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which causes coronavirus disease (COVID-19), prompted worldwide COVID-19 surveillance. To investigate the impact of COVID-19 on influenza activity, we used global ... ...

    Abstract The emergence and spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which causes coronavirus disease (COVID-19), prompted worldwide COVID-19 surveillance. To investigate the impact of COVID-19 on influenza activity, we used global surveillance data collected since 2019 to compare the number of cases positive for COVID-19 and for influenza across 22 representative countries (Australia, Brazil, Canada, China, Egypt, France, Germany, India, Israel, Italy, Japan, Mexico, The Netherlands, The Philippines, Poland, The Republic of Korea, South Africa, Spain, Thailand, The United Kingdom, The United States, and Vietnam). Our results demonstrate alternating prevalence of SARS-CoV-2 and influenza virus.
    MeSH term(s) United States ; Humans ; Influenza, Human/epidemiology ; COVID-19/epidemiology ; SARS-CoV-2 ; France ; Spain
    Language English
    Publishing date 2022-12-25
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 2274538-5
    ISSN 1750-2659 ; 1750-2640
    ISSN (online) 1750-2659
    ISSN 1750-2640
    DOI 10.1111/irv.13090
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article ; Online: Influenza C virus susceptibility to antivirals with different mechanisms of action.

    Chesnokov, Anton / Ivashchenko, Andrei A / Matsuzaki, Yoko / Takashita, Emi / Mishin, Vasiliy P / Ivachtchenko, Alexandre V / Gubareva, Larisa V

    Antimicrobial agents and chemotherapy

    2024  , Page(s) e0172723

    Abstract: Antiviral susceptibility of influenza viruses was assessed using a high-content imaging-based neutralization test. Cap-dependent endonuclease inhibitors, baloxavir and AV5116, were superior to AV5115 against type A viruses, and AV5116 was most effective ... ...

    Abstract Antiviral susceptibility of influenza viruses was assessed using a high-content imaging-based neutralization test. Cap-dependent endonuclease inhibitors, baloxavir and AV5116, were superior to AV5115 against type A viruses, and AV5116 was most effective against PA mutants tested. However, these three inhibitors displayed comparable activity (EC
    Language English
    Publishing date 2024-04-08
    Publishing country United States
    Document type Journal Article
    ZDB-ID 217602-6
    ISSN 1098-6596 ; 0066-4804
    ISSN (online) 1098-6596
    ISSN 0066-4804
    DOI 10.1128/aac.01727-23
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article ; Online: Clinical and Virologic Impacts of Respiratory Viral Co-infections in Children With Influenza.

    Sato, Masatoki / Takashita, Emi / Katayose, Masahiko / Nemoto, Kenji / Sakai, Nobuko / Fujisaki, Seiichiro / Hashimoto, Koichi / Hosoya, Mitsuaki

    The Pediatric infectious disease journal

    2023  Volume 42, Issue 8, Page(s) e268–e273

    Abstract: Background: Advances in multiplex polymerase chain reaction (PCR) methods have enabled the simultaneous detection of multiple respiratory viruses. We aimed to estimate the clinical and virologic impacts of influenza and other respiratory virus co- ... ...

    Abstract Background: Advances in multiplex polymerase chain reaction (PCR) methods have enabled the simultaneous detection of multiple respiratory viruses. We aimed to estimate the clinical and virologic impacts of influenza and other respiratory virus co-infection in children.
    Methods: We enrolled 38 and 35 children diagnosed with influenza and treated with baloxavir marboxil (baloxavir) and oseltamivir, respectively. We performed quantitative reverse transcription-PCR to detect and measure the levels of noninfluenza viruses from 3 nasopharyngeal swab samples collected before and on days 3 and 5 after the initial antiviral dose. We assessed patients' clinical information using questionnaires.
    Results: One or more respiratory viruses other than influenza virus were detected in 26 (35.6%) of 73 children before antiviral treatment. The influenza virus load and clinical characteristics on the day of influenza onset were similar between children with and without virus co-infections. Of the 26 and 32 children without the emergence of the reduced baloxavir and oseltamivir susceptible variants after treatment, 8 (30.8%) and 7 (21.9%) children were dually co-infected with human rhinovirus only, respectively. The level of human rhinovirus RNA on day 0 in these children was less than -3 log 10 that of influenza virus RNA, and the human rhinovirus co-infection had no impact on the disease course either clinically or virologically.
    Conclusions: When multiple respiratory viruses are detected in the same patient, it is necessary to assess clinical symptoms as well as the levels of detected viruses to determine which virus contributes to the development of illness.
    MeSH term(s) Humans ; Child ; Influenza, Human/complications ; Influenza, Human/drug therapy ; Influenza, Human/epidemiology ; Oseltamivir/therapeutic use ; Coinfection/epidemiology ; Coinfection/drug therapy ; Antiviral Agents/therapeutic use ; Viruses ; Virus Diseases
    Chemical Substances baloxavir (4G86Y4JT3F) ; Oseltamivir (20O93L6F9H) ; Antiviral Agents
    Language English
    Publishing date 2023-04-18
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 392481-6
    ISSN 1532-0987 ; 0891-3668
    ISSN (online) 1532-0987
    ISSN 0891-3668
    DOI 10.1097/INF.0000000000003940
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article ; Online: Assessment of the frequency of SARS-CoV-2 Omicron variant escape from RNA-dependent RNA polymerase inhibitors and 3C-like protease inhibitors.

    Takashita, Emi / Fujisaki, Seiichiro / Morita, Hiroko / Nagata, Shiho / Miura, Hideka / Nagashima, Mami / Watanabe, Shinji / Takeda, Makoto / Kawaoka, Yoshihiro / Hasegawa, Hideki

    Antiviral research

    2023  Volume 216, Page(s) 105671

    Abstract: The emergence and spread of antiviral-resistant SARS-CoV-2 is of great concern. In this study, we evaluated the propensity of Omicron variants to escape from RNA-dependent RNA polymerase (RdRP) inhibitors and 3C-like protease (3CLpro) inhibitors. SARS- ... ...

    Abstract The emergence and spread of antiviral-resistant SARS-CoV-2 is of great concern. In this study, we evaluated the propensity of Omicron variants to escape from RNA-dependent RNA polymerase (RdRP) inhibitors and 3C-like protease (3CLpro) inhibitors. SARS-CoV-2 Delta and Omicron variants were serially passaged in vitro in the presence of RdRP inhibitors (remdesivir and molnupiravir) and 3CLpro inhibitors (nirmatrelvir and lufotrelvir) to detect SARS-CoV-2 escape mutants. After five passages with 3CLpro inhibitors, mutant viruses that escaped from 3CLpro inhibitors emerged; however, in the presence of RdRP inhibitors all variants disappeared within 2-4 passages. Our findings suggest that the frequency of SARS-CoV-2 mutant escape from RdRP inhibitors is lower than that from 3CLpro inhibitors. We also found that Delta variants were more likely to acquire amino acid substitutions associated with resistance to 3CLpro inhibitors under the selective pressure of this drug compared with Omicron variants.
    MeSH term(s) Humans ; COVID-19 ; SARS-CoV-2/genetics ; Antiviral Agents/pharmacology ; Leucine ; RNA-Dependent RNA Polymerase/genetics ; Protease Inhibitors/pharmacology
    Chemical Substances Antiviral Agents ; Leucine (GMW67QNF9C) ; RNA-Dependent RNA Polymerase (EC 2.7.7.48) ; Protease Inhibitors
    Language English
    Publishing date 2023-07-13
    Publishing country Netherlands
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 306628-9
    ISSN 1872-9096 ; 0166-3542
    ISSN (online) 1872-9096
    ISSN 0166-3542
    DOI 10.1016/j.antiviral.2023.105671
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  7. Article ; Online: Antiviral Susceptibilities of Distinct Lineages of Influenza C and D Viruses.

    Takashita, Emi / Murakami, Shin / Matsuzaki, Yoko / Fujisaki, Seiichiro / Morita, Hiroko / Nagata, Shiho / Katayama, Misa / Mizuta, Katsumi / Nishimura, Hidekazu / Watanabe, Shinji / Horimoto, Taisuke / Hasegawa, Hideki

    Viruses

    2023  Volume 15, Issue 1

    Abstract: The emergence and spread of antiviral-resistant influenza viruses are of great concern. To minimize the public health risk, it is important to monitor antiviral susceptibilities of influenza viruses. Analyses of the antiviral susceptibilities of ... ...

    Abstract The emergence and spread of antiviral-resistant influenza viruses are of great concern. To minimize the public health risk, it is important to monitor antiviral susceptibilities of influenza viruses. Analyses of the antiviral susceptibilities of influenza A and B viruses have been conducted globally; however, those of influenza C and D viruses are limited. Here, we determined the susceptibilities of influenza C viruses representing all six lineages (C/Taylor, C/Yamagata, C/Sao Paulo, C/Aichi, C/Kanagawa, and C/Mississippi) and influenza D viruses representing four lineages (D/OK, D/660, D/Yama2016, and D/Yama2019) to RNA polymerase inhibitors (baloxavir and favipiravir) by using a focus reduction assay. All viruses tested were susceptible to both drugs. We then performed a genetic analysis to check for amino acid substitutions associated with baloxavir and favipiravir resistance and found that none of the viruses tested possessed these substitutions. Use of the focus reduction assay with the genotypic assay has proven valuable for monitoring the antiviral susceptibilities of influenza C and D viruses as well as influenza A and B viruses. Antiviral susceptibility monitoring of all influenza virus types should continue in order to assess the public health risks posed by these viruses.
    MeSH term(s) Humans ; Influenza, Human/drug therapy ; Antiviral Agents/pharmacology ; Antiviral Agents/therapeutic use ; Brazil ; Orthomyxoviridae ; Drug Resistance, Viral/genetics
    Chemical Substances Antiviral Agents ; baloxavir (4G86Y4JT3F) ; favipiravir (EW5GL2X7E0)
    Language English
    Publishing date 2023-01-15
    Publishing country Switzerland
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 2516098-9
    ISSN 1999-4915 ; 1999-4915
    ISSN (online) 1999-4915
    ISSN 1999-4915
    DOI 10.3390/v15010244
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  8. Article ; Online: Establishment of Reference Reagents for Single-Radial-Immunodiffusion Assay on the 2022/23 Seasonal Influenza Vaccine in Japan and Their Quality Validation.

    Shimasaki, Noriko / Kuwahara, Tomoko / Nishijima, Haruna / Nakamura, Kazuya / Sato, Kayoko / Murano, Keiko / Itamura, Shigeyuki / Akahori, Yukiko / Takashita, Emi / Kishida, Noriko / Arita, Tomoko / Nakauchi, Mina / Takeda, Makoto / Hasegawa, Hideki / Ryo, Akihide / Harada, Yuichi

    Japanese journal of infectious diseases

    2023  Volume 77, Issue 2, Page(s) 105–111

    Abstract: Potency tests for influenza vaccines are currently performed using a single-radial immunodiffusion (SRID) assay, which requires a reference antigen and anti-hemagglutinin (HA) serum as reference reagents. Reagents must be newly prepared each time a ... ...

    Abstract Potency tests for influenza vaccines are currently performed using a single-radial immunodiffusion (SRID) assay, which requires a reference antigen and anti-hemagglutinin (HA) serum as reference reagents. Reagents must be newly prepared each time a strain used for vaccine production is modified. Therefore, establishing reference reagents of consistent quality is crucial for conducting vaccine potency tests accurately and precisely. Here, we established reference reagents for the SRID assay to conduct lot release tests of quadrivalent influenza vaccines in Japan during the 2022/23 influenza season. The potency of reference antigens during storage was confirmed. Furthermore, we evaluated the cross-reactivity of each antiserum raised against the HA protein of the 2 lineages of influenza B virus toward different lineages of influenza B virus antigens to select a suitable procedure for the SRID assay for accurate measurement. Finally, the intralaboratory reproducibility of the SRID assay using the established reference reagents was validated, and the SRID reagents had sufficient consistent quality, comparable to that of the reagents used for testing vaccines during previous influenza seasons. Our study contributes to the quality control of influenza vaccines.
    MeSH term(s) Humans ; Influenza Vaccines ; Influenza, Human/prevention & control ; Seasons ; Japan ; Reproducibility of Results ; Hemagglutinin Glycoproteins, Influenza Virus ; Immunodiffusion/methods
    Chemical Substances Influenza Vaccines ; Hemagglutinin Glycoproteins, Influenza Virus
    Language English
    Publishing date 2023-11-30
    Publishing country Japan
    Document type Journal Article
    ZDB-ID 1478383-6
    ISSN 1884-2836 ; 1344-6304
    ISSN (online) 1884-2836
    ISSN 1344-6304
    DOI 10.7883/yoken.JJID.2023.218
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  9. Article ; Online: Detection of Variants With Reduced Baloxavir Marboxil Susceptibility After Treatment of Children With Influenza A During the 2018-2019 Influenza Season.

    Sato, Masatoki / Takashita, Emi / Katayose, Masahiko / Nemoto, Kenji / Sakai, Nobuko / Hashimoto, Koichi / Hosoya, Mitsuaki

    The Journal of infectious diseases

    2020  Volume 222, Issue 1, Page(s) 121–125

    Abstract: During the 2018-2019 influenza seasons, we detected reduced baloxavir marboxil (baloxavir) susceptible variants with I38S or I38T amino acid substitutions on the PA subunit of influenza virus ribonucleic acid polymerase in 7 of 18 baloxavi-treated ... ...

    Abstract During the 2018-2019 influenza seasons, we detected reduced baloxavir marboxil (baloxavir) susceptible variants with I38S or I38T amino acid substitutions on the PA subunit of influenza virus ribonucleic acid polymerase in 7 of 18 baloxavi-treated children and found that virus titer rebounded in some of these children with variants. We also found fever durations to be similar between patients with or without the variants, but the patients with variants shed the virus 3 days longer and took longer to improve clinical symptoms than those without variants. The emergence of these variants should be monitored during future influenza seasons.
    MeSH term(s) Antiviral Agents/therapeutic use ; Child ; Child, Preschool ; Dibenzothiepins/therapeutic use ; Drug Resistance, Viral/drug effects ; Drug Resistance, Viral/genetics ; Female ; Genetic Variation ; Humans ; Infant ; Infant, Newborn ; Influenza A Virus, H3N2 Subtype/drug effects ; Influenza A Virus, H3N2 Subtype/genetics ; Influenza, Human/drug therapy ; Japan/epidemiology ; Male ; Morpholines/therapeutic use ; Pyridones/therapeutic use ; Triazines/therapeutic use
    Chemical Substances Antiviral Agents ; Dibenzothiepins ; Morpholines ; Pyridones ; Triazines ; baloxavir (4G86Y4JT3F)
    Language English
    Publishing date 2020-02-07
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 3019-3
    ISSN 1537-6613 ; 0022-1899
    ISSN (online) 1537-6613
    ISSN 0022-1899
    DOI 10.1093/infdis/jiaa061
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  10. Article ; Online: A community cluster of influenza A(H3N2) virus infection with reduced susceptibility to baloxavir due to a PA E199G substitution in Japan, February to March 2023.

    Takashita, Emi / Fujisaki, Seiichiro / Morita, Hiroko / Nagata, Shiho / Miura, Hideka / Matsuura, Yuki / Yamamoto, Saya / Chiba, Shoko / Inoue, Yumiko / Minami, Iori / Yoshikawa, Sayaka / Yamazaki, Seiko / Kishida, Noriko / Nakamura, Kazuya / Shirakura, Masayuki / Watanabe, Shinji / Hasegawa, Hideki

    Euro surveillance : bulletin Europeen sur les maladies transmissibles = European communicable disease bulletin

    2023  Volume 28, Issue 39

    Abstract: A community cluster of influenza A(H3N2) caused by viruses with an E199G substitution in PA was detected in Nara, Japan, between February and March 2023. The three patients with these mutant viruses had not received antiviral treatment before specimen ... ...

    Abstract A community cluster of influenza A(H3N2) caused by viruses with an E199G substitution in PA was detected in Nara, Japan, between February and March 2023. The three patients with these mutant viruses had not received antiviral treatment before specimen collection but patients in the same hospital had. The sequences of the mutant viruses were closely related, suggesting clonal spread in Nara. They showed reduced susceptibility to baloxavir in vitro; however, the clinical significance of the PA E199G substitution remains unclear.
    MeSH term(s) Humans ; Influenza, Human/drug therapy ; Influenza, Human/epidemiology ; Influenza A Virus, H3N2 Subtype/genetics ; Oxazines/pharmacology ; Pyridines/pharmacology ; Japan ; Thiepins/pharmacology ; Thiepins/therapeutic use ; Antiviral Agents/pharmacology ; Antiviral Agents/therapeutic use ; Drug Resistance, Viral/genetics
    Chemical Substances baloxavir (4G86Y4JT3F) ; Oxazines ; Pyridines ; Thiepins ; Antiviral Agents
    Language English
    Publishing date 2023-09-05
    Publishing country Sweden
    Document type Journal Article
    ZDB-ID 1338803-4
    ISSN 1560-7917 ; 1025-496X
    ISSN (online) 1560-7917
    ISSN 1025-496X
    DOI 10.2807/1560-7917.ES.2023.28.39.2300501
    Database MEDical Literature Analysis and Retrieval System OnLINE

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