Publications by authors named "Shiho Nagata"

An outbreak of influenza A(H1N1)pdm09 viruses exhibiting cross-resistance to oseltamivir and peramivir occurred in Yokohama, Japan, in September 2024. Among 24 students in a class, 11 were diagnosed with influenza or influenza-like illness, and viruses harbouring the NA H275Y and HA Q210H substitutions were isolated from four. Deep sequencing analysis confirmed the clonal spread of these mutants.

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Article Synopsis
  • * Research on the viruses showed that they were susceptible to various antiviral medications, including remdesivir and oseltamivir, without mutations that could lead to reduced effectiveness of these treatments.
  • * Despite the co-infections, the treated patients did not experience severe symptoms, highlighting the importance of ongoing monitoring of these viruses as they evolve to inform public health strategies.
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Background: Influenza viruses can cause zoonotic infections that pose public health risks. Surveillance of influenza A and B viruses is conducted globally; however, information on influenza C and D viruses is limited. Longitudinal monitoring of influenza C virus in humans has been conducted in several countries, but there has been no long-term monitoring of influenza D virus in humans.

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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.

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  • * In laboratory conditions, Delta and Omicron were exposed to RdRP and 3CLpro inhibitors, revealing that Delta variants mutated to resist 3CLpro inhibitors after five passages, while all variants quickly vanished under RdRP inhibitors.
  • * Results indicate that SARS-CoV-2 is less likely to develop resistance to RdRP inhibitors than to 3CLpro inhibitors, and Delta variants are more prone to acquire resistance compared to Omicron.
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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.

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Article Synopsis
  • - The study explores the potential for reinfection of hamsters previously infected with various SARS-CoV-2 variants, especially the Omicron variant (BA.1), revealing that diverse mutations can occur upon reinfection despite some level of immune response.
  • - Results showed that while viral replication was suppressed in the hamsters' respiratory systems after reinfection, RNA from the virus was still detected, particularly in the upper airways, suggesting that prior infections may not completely prevent reinfection.
  • - Histological analysis indicated no severe disease or acute pneumonia upon reinfection, with only a slight increase in inflammatory markers in the airways, highlighting a relatively mild response compared to initial infections.
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The circulation of avian influenza A viruses in poultry is a public health concern due to the potential transmissibility and severity of these viral infections. Monitoring the susceptibility of these viruses to antivirals is important for developing measures to strengthen the level of preparedness against influenza pandemics. However, drug susceptibility information on these viruses is limited.

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Background: Coronavirus disease (COVID-19), which is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), was first detected in Japan in January 2020 and has spread throughout the country. Previous studies have reported that viral interference among influenza virus, rhinovirus, and other respiratory viruses can affect viral infections at the host and population level.

Methods: To investigate the impact of COVID-19 on influenza and other respiratory virus infections, we analyzed clinical specimens collected from 2244 patients in Japan with respiratory diseases between January 2018 and September 2020.

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The prognosis of chronic myeloid leukemia (CML) has improved dramatically with the introduction of tyrosine kinase inhibitors. Although the use of second-generation tyrosine kinase inhibitors is now available for initial cases, a small number of patients with CML unfortunately still experience progression to the accelerated or blastic phase of the disease. We recently managed a patient with chronic-phase CML, who developed a T315 mutation early in the course of treatment with dasatinib and progressed to the lymphoid blastic phase.

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Mast cells, which express the high-affinity IgE receptor (FcεRI) on their surface, play a crucial role in inducing allergic inflammation. Since mast cells are activated by crosslinking of FcεRI with IgE and allergens, the cell surface expression level of FcεRI is an important factor in determining the sensitivity to allergens. Recently, the involvement of gut microbiota in the prevalence and regulation of allergy has attracted attention but the precise underlying mechanisms are not fully understood.

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Human-to-human transmission of PA I38 mutant influenza A(H3N2) viruses with reduced baloxavir susceptibility has been reported in Japan. In December 2019, we detected a PA E23K mutant A(H1N1)pdm09 virus from a child without baloxavir treatment. The PA E23K mutant virus exhibited reduced baloxavir susceptibility but remained susceptible to neuraminidase inhibitors.

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Influenza virus and respiratory syncytial virus cause acute upper and lower respiratory tract infections, especially in children and the elderly. Early treatment for these infections is thought to be important, so simple and sensitive detection methods are needed for use at clinical sites. Therefore, in this study, real-time reverse transcription loop-mediated isothermal amplification assays with quenching primer for influenza virus and respiratory syncytial virus were developed.

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Human rhinoviruses (RVs) belong to the genus Enterovirus of the family Picornaviridae, and are classified into RV-A, -B, and -C species. Two assays were developed to detect RVs by a real-time fluorescent reverse transcription loop-mediated isothermal amplification method: one was designed based on the 5'-untranslated regions (UTRs) of RV-A and -B, and the other was designed based on the 5'-UTR of RV-C. The competence of both assays for the diagnosis of RV infection was tested using isolated viruses and compared with real-time reverse transcription polymerase chain reaction assays on clinical specimens.

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Protein quality control (PQC) in the heart plays an important role to maintain cellular protein homeostasis. Impairment of PQC may cause the development of heart failure. It is well known that histone deacetylase 6 (HDAC6) is an essential enzyme for regulating the cellular PQC response.

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The H9N2 subtype of avian influenza A viruses (AIV) has spread among domestic poultry and wild birds worldwide. H9N2 AIV is sporadically transmitted to humans from avian species. A total of 42 laboratory-confirmed cases of non-fatal human infection with the Eurasian Y280 and G1 lineages have been reported in China, Hong Kong, Bangladesh and Egypt since 1997.

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From 2005 to July 6, 2018, a total of 435 swine-origin influenza A H3N2 variant virus (H3N2v) infections in humans were reported in the USA. The largest H3N2v outbreak in the USA occurred in 2011-2012. This virus obtained the HA gene from the human seasonal H3N2 influenza A viruses (seasonal H3N2) via human-to-swine transmission in the mid-1990s and was classified as Cluster IV H3N2v.

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The H5 subtype of highly pathogenic avian influenza (H5 HPAI) viruses is a threat to both animal and human public health and has the potential to cause a serious future pandemic in humans. Thus, specific and rapid detection of H5 HPAI viruses is required for infection control in humans. To develop a simple and rapid diagnostic system to detect H5 HPAI viruses with high specificity and sensitivity, we attempted to prepare monoclonal antibodies (mAbs) that specifically recognize linear epitopes in hemagglutinin (HA) of H5 subtype viruses.

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The first human cases of infection with avian influenza A(H7N9) virus were reported in March 2013 in China. The number of confirmed cases continues to increase, although almost all the cases are limited to China. In this study, a one-step real-time RT-PCR assay was developed for detecting the novel A(H7N9) virus.

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