Publications by authors named "Masayuki Saijo"

Progressive multifocal leukoencephalopathy (PML) is a demyelinating disease caused by the JC polyomavirus (JCPyV). Based on the clinical criteria, PML is diagnosed via polymerase chain reaction (PCR) detection of JCPyV DNA in cerebrospinal fluid (CSF) in combination with neurological and imaging findings. Although the utility of CSF JCPyV testing using ultrasensitive PCR assays has been suggested, its potential requires further evaluation.

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Herpes simplex virus type 1 (HSV-1) acyclovir (ACV) resistance is acquired by mutations in the viral thymidine kinase (TK) or DNA polymerase (DNApol) genes. We previously obtained an ACV-resistant clone (HSV-1_VZV_TK_clone α) by sequential passages of HSV-1_VZV-TK, a recombinant virus which lacked its endogenous TK activity and instead expressed the varicella-zoster virus (VZV) TK ectopically. HSV-1_VZV_TK_clone α had been generated using an HSV-1_BAC in the presence of increasing concentrations of ACV.

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Background: Disasters such as earthquakes, terrorism, and pandemics have triggered post-traumatic stress disorder (PTSD), and discrimination against the affected individuals has been linked to the development of PTSD. However, there is limited evidence regarding the association between discrimination against coronavirus disease 2019 (COVID-19) patients and probable PTSD in Japan.

Methods: We conducted a cross-sectional study utilizing a web-based questionnaire targeting individuals who had contracted the severe acute respiratory syndrome-related coronavirus 2 (SARS-CoV-2) infection in Sapporo City.

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At the beginning of the mpox (disease caused by monkey pox) epidemic, there was no platform in Japan to provide appropriate information on emerging and re-emerging infectious diseases (EIDs), and the number of accesses to bioterrorism-related information sites increased rapidly. Even though the interest in mpox was much smaller than in coronavirus infectious disease, emerged in late 2019 (COVID-19), the increase in the number of views were much greater than during the COVID-19 epidemic. This may not be because mpox is bioterrorism-related as an analog of smallpox, but rather because there were no other websites providing information on mpox.

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This study aimed to determine the relationship between specific information source usage and uptake of the coronavirus disease 2019 (COVID-19) vaccine. We analyzed 3348 participants aged 20 to 65 years who were not diagnosed with COVID-19 in a case-control study in Sapporo, Japan. The most prevalent information source on COVID-19 was television (TV; 87.

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Introduction: Severe dengue is thought to be caused by an excessive host immune response.

Methods: To study the pathogenesis of severe dengue, we developed a novel model using LysM Cre mice carrying depleted expression only in subsets of murine myeloid cells.

Results: Although dengue virus (DENV) clinical isolates were not virulent in LysM Cre mice, mouse-adapted DV1-5P7Sp and DV3P12/08P4Bm, which were obtained by passaging the spleen or bone marrow of mice, demonstrated 100% lethality with severe vascular leakage in the liver and small intestine.

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Guanarito virus (GTOV) is the causative agent of Venezuelan hemorrhagic fever. GTOV belongs to the genus , family and has been classified as a Category A bioterrorism agent by the United States Centers for Disease Control and Prevention. Despite being a high-priority agent, vaccines and drugs against Venezuelan hemorrhagic fever are not available.

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Introduction: Severe fever with thrombocytopenia syndrome (SFTS) is a fatal viral disease characterized by high fever, thrombocytopenia, leukopenia, and multi-organ haemorrhage. Disruption of the humoral immune response and decreased lymphocyte numbers are thought to contribute to the disease severity. These findings have been obtained through the analysis of peripheral blood leukocytes in human patients, whereas analysis of lymph nodes has been limited.

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Article Synopsis
  • Nipah virus (NiV) is a dangerous virus causing severe illness in humans with a mortality rate over 40%, primarily transmitted by fruit bats found in Southeast Asia.
  • Researchers developed recombinant vaccinia viruses that express NiV proteins to test their effectiveness at producing immune responses, finding that they successfully induced higher levels of neutralizing antibodies in hamsters than previous vaccine candidates.
  • The study suggests that the LC16m8-based vaccines have promising potential for future clinical use against NiV disease, marking a significant step towards effective prevention methods.
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Heartland virus (HRTV) causes generalized symptoms, severe shock, and multiple organ failure. We previously reported that interferon-α/β receptor knockout (IFNAR) mice infected intraperitoneally with 1 × 10 tissue culture-infective dose (TCID) of HRTV died, while those subcutaneously infected with the same dose of HRTV did not. The pathophysiology of IFNAR mice infected with HRTV and the mechanism underlying the difference in disease severity, which depends on HRTV infection route, were analyzed in this study.

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Zoonotic infection of humans with herpes B virus (BV) causes severe neurological diseases. Acyclovir (ACV) and ganciclovir (GCV), most frequently used as anti-herpes drugs, are recommended for prophylaxis and therapy in human BV infection. In this study, we examined the property of BV thymidine kinase (TK) against anti-herpes drugs using a recombinant herpes simplex virus type 1 (HSV-1) carrying BV TK gene.

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Article Synopsis
  • In 2019, two human patients in Japan were diagnosed with an infection caused by Macacine alphaherpesvirus 1.
  • Both patients were employed at the same company that operated a macaque facility.
  • The virus was identified in the cerebrospinal fluid of both patients, indicating they had the rhesus-genotype B strain.
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Dengue is a major health problem in tropical and subtropical regions. Some patients develop a severe form of dengue, called dengue hemorrhagic fever, which can be fatal. Severe dengue is associated with a transient increase in vascular permeability.

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Intensive immunosuppression has enabled liver transplantation even in recipients with preformed donor-specific antibodies (DSA), an independent risk factor for graft rejection. However, these recipients may also be at high risk of progressive multifocal encephalopathy (PML) due to the comorbid immunosuppressed status. A 58-year-old woman presented with self-limited focal-to-bilateral tonic-clonic seizures 9 months after liver transplantation.

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Manipulating viral genomes is an essential technique in reverse genetics and recombinant vaccine development. A strategy for manipulating large viral genomes involves introducing their entire genome into bacterial artificial chromosomes and employing genetic tools. For sequence manipulation on bacterial artificial chromosomes (bacterial artificial chromosomes recombineering), a well-established method that relies on the strain GS1783, and the template plasmid, pEPKan-S, is often used.

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Progressive multifocal leukoencephalopathy (PML) is a devastating demyelinating disease caused by JC virus (JCV), predominantly affecting patients with impaired cellular immunity. PML is a non-reportable disease with a few exceptions, making national surveillance difficult. In Japan, polymerase chain reaction (PCR) testing for JCV in the cerebrospinal fluid (CSF) is performed at the National Institute of Infectious Diseases to support PML diagnosis.

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We conducted a cross-sectional survey among SARS-CoV-2-positive persons and negative controls in Sapporo, Japan, to clarify symptoms of long COVID. We collected responses from 8,018 participants, 3,694 case-patients and 3,672 controls. We calculated symptom prevalence for case-patients at 2-3, 4-6, 7-9, 10-12, and 13-18 months after illness onset.

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Background: For therapeutic efficacy, molnupiravir and nirmatrelvir-ritonavir must be started to treat patients within 5 days of disease onset to treat patients with novel coronavirus disease 2019 (COVID-19). However, some patients spend more than 5 days from disease onset before reporting to the Public Health Office. This study aimed to clarify the characteristics of patients with reporting delay.

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Chandipura virus (CHPV) is a negative-sense single-stranded RNA virus known to cause fatal encephalitis outbreaks in the Indian subcontinent. The virus displays tropism towards the pediatric population and holds significant public health concerns. Currently, there is no specific, effective therapy for CHPV encephalitis.

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RNA viruses are the etiological agents of many infectious diseases. Since RNA viruses are error-prone during genome replication, rapid, accurate and economical whole RNA viral genome sequence determination is highly demanded. Next-generation sequencing (NGS) techniques perform whole viral genome sequencing due to their high-throughput sequencing capacity.

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Dengue is a febrile illness caused by the dengue virus (DENV) that belongs to the genus Flavivirus in the family Flaviviridae. Cross-reactivity between flaviviruses poses a challenge while interpreting serological test results. In the present study, the cross-reactivity of sera of the patients with dengue, who traveled from Japan to DENV-endemic countries, was analyzed by using an enzyme-linked immunosorbent assay (ELISA) and neutralization test (NT).

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Severe fever with thrombocytopenia syndrome (SFTS) is an emerging tick-borne viral infection caused by a bandavirus in the family of Phenuiviridae, commonly known as SFTS virus (SFTSV). We have previously isolated SFTSV from blood samples of SFTS patients and established an antiviral assay system to identify selective inhibitors of SFTSV in vitro. Using the assay system, the antimalarial agent amodiaquine was identified as a selective inhibitor of SFTSV replication.

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Article Synopsis
  • Japanese encephalitis virus (JEV) is a mosquito-borne virus classified in the Flavivirus family, with five different genotypes (G1-G5) based on genetic variations of its envelope protein.
  • JEV G3 was previously dominant in Japan but was replaced by G1 in the early 1990s; however, G3 re-emerged in 2004 and was found in swine and cows in Kochi Prefecture in 2018.
  • Recent genetic sequencing of JEV isolates shows variations between G3 strains from 2004 and 2018, confirming the presence of both JEV G1 and G3 in the Kochi area.
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The rabies virus is widely distributed and vaccines are an important strategy to prevent its spread. The whole-genome sequences of rabies strains in relation to vaccine development provide essential information to maintain vaccine quality and develop new vaccines. However, the genetic characteristics of the purified chick embryo cell culture rabies vaccine, KM Biologics (PCECV-KMB), developed in Japan in the 1970s, have not been explored.

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Heartland bandavirus (HRTV) is an emerging tick-borne virus that is distributed in the United States and that causes febrile illness with thrombocytopenia and leukocytopenia. It is genetically close to Dabie bandavirus, which is well known as severe fever with thrombocytopenia syndrome (SFTS) virus (SFTSV). The mortality rate of human HRTV infection is approximately 10%; however, neither approved anti-HRTV agents nor vaccines exist.

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