Publications by authors named "Kazuya Shirato"

Numerous host factors function as intrinsic antiviral effectors to attenuate viral replication. MARCH8 is an E3 ubiquitin ligase that has been identified as a host restriction factor that inhibits the replication of various viruses. This study elucidated the mechanism by which MARCH8 restricts respiratory syncytial virus (RSV) replication through selective degradation of the viral small hydrophobic (SH) protein.

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Background: Amino acid (AA) substitutions in the fusion protein of respiratory syncytial virus (RSV) and their effects remain unclear. We aimed to analyze AA substitutions in main neutralizing epitopes of the fusion (F) protein.

Methods: We analyzed F protein genes of 236 RSV strains isolated from children hospitalized with RSV infection in Fukushima, Japan (June 2008-February 2023).

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Unlabelled: A critical aspect of the mechanism of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is the protease-mediated activation of the viral spike (S) protein. The type II transmembrane serine protease TMPRSS2 is crucial for SARS-CoV-2 infection in lung epithelial Calu-3 cells and murine airways. However, the importance of TMPRSS2 needs to be re-examined because the ability to utilize TMPRSS2 is significantly reduced in the Omicron variants that spread globally.

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Article Synopsis
  • The isolation of SARS-CoV-2 from patient samples is crucial for accurate COVID-19 diagnosis and studying virus variants.
  • VeroE6 cells modified to overexpress human ACE2 and TMPRSS2 are more effective than standard VeroE6/TMPRSS2 cells, showing a 1.6-fold increase in virus isolation efficiency, especially for samples with low viral loads.
  • Experiments with VSV pseudoviruses indicate that these modified cells enhance infectivity rates, emphasizing the need for selecting optimal cell cultures when studying SARS-CoV-2.
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  • The human parainfluenza virus type 4 (HPIV4) has two subtypes, 4a and 4b, which were analyzed through gene sequences from 48 strains collected between 1966 and 2022.
  • A phylogenetic study revealed that these subtypes separated around 1823, with common ancestors for subtype 4a and 4b existing until approximately 1940 and 1939, respectively.
  • The study indicates that while there are genetic differences among all strains, each subtype maintains genetic conservation with low evolutionary rates and identified potential B-cell epitopes on the virus's fusion protein.
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Unlabelled: Human parainfluenza virus (HPIV) causes respiratory infections, which are exacerbated in children and older people. Correct evaluation of viral characteristics is essential for the study of countermeasures. However, adaptation of viruses to cultured cells during isolation or propagation might select laboratory passage-associated mutations that modify the characteristics of the virus.

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Human metapneumovirus (hMPV) is genetically classified into two major subgroups, A and B, based on attachment glycoprotein (G protein) gene sequences. The A2 subgroup is further separated into three subdivisions, A2a, A2b (A2b1), and A2c (A2b2). Subgroup A2c viruses carrying 180- or 111-nucleotide duplications in the G gene (A2c or A2c ) have been reported in Japan and Spain.

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Article Synopsis
  • * Variations in testing methods and timing, along with multiple positive results for different respiratory viruses, complicate the interpretation of infection status.
  • * A recent study using pediatric specimens suggests that positive real-time PCR tests for multiple agents may indicate the presence of infectious viruses, providing clearer evidence for understanding these infections.
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Human metapneumovirus (hMPV) is a common cause of respiratory infections in children. Many genetic diagnostic assays have been developed, but most detect hMPV regardless of the subgroup. In this study, we developed a real-time RT-PCR assay that can detect and identify the two major subgroups of hMPV (A and B) in one tube.

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Human respiratory syncytial viruses (HRSVs) are divided into subgroups A and B, which are further divided based on the nucleotide sequence of the second hypervariable region (HVR) of the attachment glycoprotein (G) gene. Understanding the molecular diversity of HRSV before and during the coronavirus disease 2019 (COVID-19) pandemic can provide insights into the effects of the pandemic on HRSV dissemination and guide vaccine development. Here, we analyzed HRSVs isolated in Fukushima Prefecture from September 2017 to December 2021.

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Objectives: To establish a point-of-care test for coronavirus disease 2019 (COVID-19), we developed a dry loop-mediated isothermal amplification (LAMP) method to detect severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA.

Methods: We carried out reverse transcription (RT)-LAMP using the Loopamp SARS-CoV-2 Detection kit (Eiken Chemical, Tokyo, Japan). The entire mixture, except for the primers, is dried and immobilized inside the tube lid.

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Middle East respiratory syndrome coronavirus (MERS-CoV) is a zoonotic virus that causes MERS, which is endemic in the Middle East. The absence of human cases in Africa despite the presence of MERS-CoV suggests virological differences between MERS-CoVs in Africa and the Middle East. In fact, in the laboratory, recombinant MERS-CoV carrying the spike (S) protein of Ethiopian isolates exhibits attenuated properties, being more easily neutralized and replicating slower than viruses carrying the S protein of Middle Eastern isolate, EMC.

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The Omicron variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged in late 2021 and gradually overtook the Delta variant, which was the predominant variant at that time. The Omicron variant has been consecutively replaced by related sublineages. The real-time RT-PCR assays developed by the National Institute of Infectious Diseases (NIID), Japan (i.

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Article Synopsis
  • - SARS-CoV-2, including the Omicron variant, can infect cells through various pathways, but recent research highlights a less significant role of the furin/TMPRSS2 pathway for Omicron.
  • - Omicron primarily enters cells by a cathepsin-dependent endocytosis pathway, even though its spike protein is efficiently cleaved.
  • - Studies using TMPRSS2-knockout mice reveal that TMPRSS2 is essential for the infection of SARS-CoV-2 variants, including Omicron, in the airways, emphasizing the need to consider this when studying different variants.
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Article Synopsis
  • - The study reveals that coronaviruses, like SARS-CoV-2 and MERS-CoV, contain many functional hydrophobic alpha-helical peptides (HAHPs) encoded in overlapping sections of their genome, suggesting these may play important roles in the virus.
  • - Researchers analyzed specific HAHPs in the S gene regions of both viruses, finding that some of these peptides inhibited important functions, such as membrane fusion and viral RNA synthesis.
  • - The findings suggest that these HAHPs could serve as regulatory elements in the viral life cycle, which might have implications for understanding and potentially controlling viral propagation.
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The World Health Organization initiated a global surveillance system for respiratory syncytial virus (RSV) in 2015, and the pilot surveillance is ongoing. The real-time RT-PCR RSV assays (Pan-RSV and duplex assays) developed by the United States Centers for Disease Control and Prevention are applied as the standard assays. To introduce these as standard assays in Japan, their practicality was evaluated using 2261 specimens obtained from pediatric inpatients in Japan, which were collected from 2018 to 2021.

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We reported nearly complete genomic sequences of 12 serotypes of human rhinoviruses (HRVs) isolated from pediatric inpatients in Fukushima, Japan using an air-liquid interface culture of human bronchial tracheal epithelial cells. We found that various serotypes of HRV circulated locally and simultaneously from 2018 to 2021.

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  • The study reports on 10 almost complete genomic sequences of human orthorubulavirus 4, known as HPIV4.
  • These viruses were isolated from children in Fukushima, Japan, who were hospitalized with respiratory infections.
  • The researchers used a method involving air-liquid interface cultures of human bronchial and tracheal epithelial cells to obtain these sequences.
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The impact of strengthening preventive measures against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection on the prevalence of respiratory viruses in children was examined. After the SARS-CoV-2 pandemic, the rate of multiple virus detection among hospitalized children decreased. Immediately after the SARS-CoV-2 pandemic, respiratory syncytial and parainfluenza viruses were rarely detected and subsequently reemerged.

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Virus isolates are not only useful for diagnosing infections, e.g., respiratory syncytial virus (RSV), but can also facilitate many aspects of practical viral studies such as analyses of antigenicity and the action mechanisms of antivirals, among others.

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In the ongoing coronavirus diseases 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), real-time RT-PCR based diagnostic assays have been used for the detection of infection, but the positive signal of real-time RT-PCR does not necessarily indicate the infectivity of the patient. Due to the unique replication system of the coronavirus, primer/probe sets targeted nucleocapsid (N) and spike (S) protein detect the abundantly synthesized subgenomic RNAs as well as the virus genome, possibly making the assay unsuitable for estimation of the infectivity of the specimen, although it has an advantage for the diagnostic tests. In this study, the primer/probe set targeting the open reading frame 1a (ORF1a) gene was developed to specifically detect viral genomic RNA.

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Introduction: Seasonal human coronavirus (HCoV)-229E, -NL63, -OC43, and -HKU1 are seasonal coronaviruses that cause colds in humans. However, the clinical characteristics of pediatric inpatients infected with HCoVs are unclear. This study aimed to compare and clarify the epidemiological and clinical features of HCoVs and respiratory syncytial virus (RSV), which commonly causes severe respiratory infections in children.

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We report 13 genomic sequences of human bocavirus 1 isolated from pediatric inpatients in Fukushima, Japan, using an air-liquid interface culture of human bronchial tracheal epithelial cells. This work suggests the endemic circulation of a human bocavirus variant with a unique amino acid signature in Fukushima.

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Various variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) began emerging worldwide from the end of 2020 to the beginning of 2021. The variants GRY/VOC202012/01 (B1.1.

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Soon after the 2019 outbreak of coronavirus disease 2019 in Wuhan, China, a protocol for real-time RT-PCR assay detection of severe acute respiratory syndrome coronavirus (SARS-CoV-2) was established by the National Institute of Infectious Diseases (NIID) in Japan. The protocol used Charité's nucleocapsid (Sarbeco-N) and NIID nucleocapsid (NIID-N2) assays. During the following months, SARS-CoV-2 spread and caused a global pandemic, and various SARS-CoV-2 sequences were registered in public databases, such as the Global Initiative on Sharing All Influenza Data (GISAID).

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