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ARII JunGraduate School of Medicine / Center for Infectious Diseases (CID)Associate Professor
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■ Award- Oct. 2018 日本ウイルス学会, 杉浦奨励賞受賞, 単純ヘルペスウイルスの細胞侵入および粒子形成過程の解明
- Apr. 2017 文部科学省, 科学技術分野の文部科学大臣表彰若手科学者賞, 単純ヘルペスウイルスによる病原性発現機構の研究
- Apr. 2009 日本獣医学会, 獣医学奨励賞, 主要エンベロープ糖タンパク質gBによるヘルペスウイルス病原性発現機構の解明
- Feb. 2025, iScience, 28(2) (2)[Refereed]Scientific journal
- Mar. 2024, Frontiers in Virology, 4[Refereed]
- Nascent nucleocapsids of herpesviruses acquire a primary envelope during their nuclear export by budding through the inner nuclear membrane into the perinuclear space between the inner and outer nuclear membranes. This process is mediated by a conserved viral heterodimeric complex designated the nuclear egress complex, which consists of the nuclear matrix protein and the nuclear membrane protein. In addition to its essential roles during nuclear egress, the nuclear matrix protein has been shown to interact with intracellular signaling pathway molecules including NF-κB and IFN-β to affect viral or cellular gene expression. The human herpesvirus 6A (HHV-6A) U37 gene encodes a nuclear matrix protein, the role of which has not been analyzed. Here, we show that HHV-6A U37 activates the heat shock element promoter and induces the accumulation of the molecular chaperone Hsp90. Mechanistically, HHV-6A U37 interacts with heat shock transcription factor 1 (HSF1) and induces its phosphorylation at Ser-326. We report that pharmacological inhibition of HSF1, Hsp70, or Hsp90 decreases viral protein accumulation and viral replication. Taken together, our results lead us to propose a model in which HHV-6A U37 activates the heat shock response to support viral gene expression and replication. IMPORTANCE Human herpesvirus 6A (HHV-6A) is a dsDNA virus belonging to the Roseolovirus genus within the Betaherpesvirinae subfamily. It is frequently found in patients with neuroinflammatory disease, although its pathogenetic role, if any, awaits elucidation. The heat shock response is important for cell survival under stressful conditions that disrupt homeostasis. Our results indicate that HHV-6A U37 activates the heat shock element promoter and leads to the accumulation of heat shock proteins. Next, we show that the heat shock response is important for viral replication. Overall, our findings provide new insights into the function of HHV-6A U37 in host cell signaling and identify potential cellular targets involved in HHV-6A pathogenesis and replication.Corresponding, Sep. 2023, Journal of virology, 97(9) (9), e0071823, English, International magazine[Refereed]Scientific journal
- BACKGROUND: Omicron variants with immune evasion have emerged, and they continue to mutate rapidly, raising concerns about the weakening of vaccine efficacy, and the very elderly populations are vulnerable to Coronavirus Disease 2019 (COVID-19). Therefore, to investigate the effect of multiple doses of mRNA vaccine for the newly emerged variants on these populations, cross-neutralizing antibody titers were examined against Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) variants, including BQ.1.1 and XBB. METHODS: Blood samples were taken from residents at four long-term care facilities in Hyogo prefecture, Japan (median age, 91 years), after 3rd (n = 67) and 4th (n = 48) mRNA vaccinations, from April to October 2022. A live virus microneutralization assay was performed to determine the neutralizing antibody titers in participants' sera. RESULTS: After 3rd vaccination, cross-neutralizing antibody prevalence against conventional (D614G) virus, Delta, Omicron BA.2, BA.5, BA.2.75, BQ.1.1, and XBB were 100%, 97%, 81%, 51%, 67%, 4%, and 21%, respectively. After 4th vaccination, the antibody positivity rates increased to 100%, 100%, 98%, 79%, 92%, 31%, and 52%, respectively. The 4th vaccination significantly increased cross-neutralizing antibody titers against all tested variants. CONCLUSION: The positivity rates for BQ.1.1 and XBB increased after 4th vaccination, although the titer value was lower than those of BA.5 and BA.2.75. Considering the rapid mutation of viruses and the efficacy of vaccines, it may be necessary to create a system that can develop vaccines suitable for each epidemic in consideration of the epidemic of the virus.Jul. 2023, Journal of infection and public health, 16(7) (7), 1064 - 1072, English, International magazine[Refereed]Scientific journal
- We identified neutralizing monoclonal antibodies against severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) variants (including Omicron variants BA.5 and BA.2.75) from individuals who received two doses of mRNA vaccination after they had been infected with the D614G virus. We named them MO1, MO2, and MO3. Among them, MO1 showed particularly high neutralizing activity against authentic variants: D614G, Delta, BA.1, BA.1.1, BA.2, BA.2.75, and BA.5. Furthermore, MO1 suppressed BA.5 infection in hamsters. A structural analysis revealed that MO1 binds to the conserved epitope of seven variants, including Omicron variants BA.5 and BA.2.75, in the receptor-binding domain of the spike protein. MO1 targets an epitope conserved among Omicron variants BA.1, BA.2, and BA.5 in a unique binding mode. Our findings confirm that D614G-derived vaccination can induce neutralizing antibodies that recognize the epitopes conserved among the SARS-CoV-2 variants. IMPORTANCE Omicron variants of SARS-CoV-2 acquired escape ability from host immunity and authorized antibody therapeutics and thereby have been spreading worldwide. We reported that patients infected with an early SARS-CoV-2 variant, D614G, and who received subsequent two-dose mRNA vaccination have high neutralizing antibody titer against Omicron lineages. It was speculated that the patients have neutralizing antibodies broadly effective against SARS-CoV-2 variants by targeting common epitopes. Here, we explored human monoclonal antibodies from B cells of the patients. One of the monoclonal antibodies, named MO1, showed high potency against broad SARS-CoV-2 variants including BA.2.75 and BA.5 variants. The results prove that monoclonal antibodies that have common neutralizing epitopes among several Omicrons were produced in patients infected with D614G and who received mRNA vaccination.May 2023, Journal of virology, e0028623, English, International magazine[Refereed]Scientific journal
- Nov. 2022, The Journal of infectious diseases, 226(11) (11), 2041 - 2042, English, International magazine[Refereed]Scientific journal
- The stimulus-induced cAMP response element (CRE)-binding protein (CREB) family of transcription factors bind to CREs to regulate diverse cellular responses, including proliferation, survival, and differentiation. Human herpesvirus 6A (HHV-6A), which belongs to the Betaherpesvirinae subfamily, is a lymphotropic herpesvirus frequently found in patients with neuroinflammatory diseases. Previous reports implicated the importance of CREs in the HHV-6A life cycle, although the effects of the binding of transcription factors to CREs in viral replication have not been fully elucidated. In this study, we analyzed the role of the CREB family of transcription factors during HHV-6A replication. We found that HHV-6A infection enhanced phosphorylation of the CREB family members CREB1 and activating transcription factor 1 (ATF1). Knockout (KO) of CREB1 or ATF1 enhanced viral gene expression and viral replication. The increase in viral yields in supernatants from ATF1-KO cells was greater than that in supernatants from CREB1-KO cells. Transcriptome sequencing (RNA-seq) analysis showed that sensors of the innate immune system were downregulated in ATF1-KO cells, and mRNAs of beta interferon (IFN-β) and IFN-regulated genes were reduced in these cells infected with HHV-6A. IFN-β treatment of ATF1-KO cells reduced progeny viral yields significantly, suggesting that the enhancement of viral replication was caused by a reduction of IFN-β. Taken together, our results suggest that ATF1 is activated during HHV-6A infection and restricts viral replication via IFN-β induction. IMPORTANCE Human herpesvirus 6A (HHV-6A) is a ubiquitous herpesvirus implicated in Alzheimer's disease, although its role in its pathogenesis has not been confirmed. Here, we showed that the transcription factor ATF1 restricts HHV-6A replication, mediated by IFN-β induction. Our study provides new insights into the role of ATF1 in innate viral immunity and reveals the importance of IFN-β for regulation of HHV-6A replication, which possibly impairs HHV-6A pathogenesis.Oct. 2022, Journal of virology, 96(19) (19), e0126422, English, International magazine[Refereed]Scientific journal
- Abstract The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variant omicron is now under investigation. We evaluated cross-neutralizing activity against omicron in coronavirus disease 2019 (COVID-19) convalescent patients (n = 23) who had received 2 doses of an mRNA vaccination (BNT162b2 or mRNA-1273). Intriguingly, after the second vaccination, the neutralizing antibody titers of subjects against SARS-CoV-2 variants, including omicron, all became seropositive, and significant fold-increases (21.1–52.0) were seen regardless of the disease severity. Our findings thus demonstrate that 2 doses of mRNA vaccination to SARS-CoV-2 convalescent patients can induce cross-neutralizing activity against omicron.Oxford University Press (OUP), May 2022, The Journal of Infectious Diseases, 226(8) (8), 1391 - 1395[Refereed]Scientific journal
- Importance: Although 2 and 3 doses of vaccine have been implemented against the SARS-CoV-2 pandemic, the level of immunity achieved by these additional vaccinations remains unclear. Objective: To investigate the induction of neutralizing antibodies against the SARS-CoV-2 Omicron variant after 2 and 3 doses of the BNT162b2 messenger RNA (mRNA) vaccine among recipients of different ages. Design, Setting, and Participants: A cohort study was conducted from June 1, 2021, to January 12, 2022, among 82 physicians at Kobe University Hospital who had received 2 doses of the BNT162b2 mRNA vaccine. Main Outcomes and Measures: The rates of positive test results and the titers of neutralizing antibodies against the Omicron variant after 2 and 3 doses of the vaccine were compared with those against other variants and compared among 3 age groups (≤38 years [younger age group], 39-58 years [intermediate age group], and ≥59 years [older age group]). Results: A total of 82 physicians (71 men [87%]; median age, 44 years [IQR, 33-58 years]) participated; 31 (38%) were in the younger age group, 32 (39%) were in the intermediate age group, and 19 (23%) were in the older age group. At 2 months after 2 doses of the vaccine, 23 participants (28%) had neutralizing antibodies against the Omicron variant, with a titer of 1.3 (95% CI, 1.2-1.4), which was 11.8-fold (95% CI, 9.9-13.9) lower than the titer against the D614G variant and the lowest among the variants tested. Although the titer of the neutralizing antibody against the Delta variant tended to be low among the older age group (2.9 [95% CI, 2.0-4.1]), the titers of the neutralizing antibody against the Omicron variant were low among all age groups (younger age group, 1.3 [95% CI, 1.1-1.6]; intermediate age group, 1.3 (95% CI, [95% CI, 1.1-1.5]; and older age group, 1.2 [95% CI, 1.0-1.4]). At 7 months after 2 doses of the vaccine, 5 participants (6%) had the neutralizing antibody against the Omicron variant, but after the booster (third dose) vaccination, all 72 participants who received the booster had the neutralizing antibody, and the titer was 41 (95% CI, 34-49), much higher than that at 7 months after 2 doses of the vaccine (1.0 [95% CI, 1.0-1.1]). This increase in titers was observed regardless of age groups; the titers were 44 (95% CI, 32-59) among the younger age group, 44 (95% CI, 32-59) among the intermediate age group, and 30 (95% CI, 22-41) among the older age group. Conclusions and Relevance: In this cohort study of 82 Japanese participants, 2 doses of the BNT162b2 mRNA vaccine did not induce sufficient neutralizing antibody against the Omicron variant. However, booster vaccination was associated with induction of a high level of neutralizing antibodies against the Omicron variant, irrespective of the recipient's age.May 2022, JAMA network open, 5(5) (5), e2210780, English, International magazine[Refereed]Scientific journal
- Oxford University Press (OUP), Apr. 2022, The Journal of Infectious Diseases, 226(8) (8), 1481 - 1483[Refereed]Scientific journal
- This study developed a system consisting of two rounds of screening cellular proteins involved in the nuclear egress of herpes simplex virus 1 (HSV-1). Using this system, we first screened cellular proteins that interacted with the HSV-1 nuclear egress complex (NEC) consisting of UL34 and UL31 in HSV-1-infected cells, which are critical for the nuclear egress of HSV-1, by tandem affinity purification coupled with mass spectrometry-based proteomics technology. Next, we performed CRISPR/Cas9-based screening of live HSV-1-infected reporter cells under fluorescence microscopy using single guide RNAs targeting the cellular proteins identified in the first proteomic screening to detect the mislocalization of the lamin-associated protein emerin, which is a phenotype for defects in HSV-1 nuclear egress. This study focused on a cellular orphan transporter SLC35E1, one of the cellular proteins identified by the screening system. Knockout of SLC35E1 reduced HSV-1 replication and induced membranous invaginations containing perinuclear enveloped virions (PEVs) adjacent to the nuclear membrane (NM), aberrant accumulation of PEVs in the perinuclear space between the inner and outer NMs and the invagination structures, and mislocalization of the NEC. These effects were similar to those of previously reported mutation(s) in HSV-1 proteins and depletion of cellular proteins that are important for HSV-1 de-envelopment, one of the steps required for HSV-1 nuclear egress. Our newly established screening system enabled us to identify a novel cellular protein required for efficient HSV-1 de-envelopment. IMPORTANCE The identification of cellular protein(s) that interact with viral effector proteins and function in important viral procedures is necessary for enhancing our understanding of the mechanics of various viral processes. In this study, we established a new system consisting of interactome screening for the herpes simplex virus 1 (HSV-1) nuclear egress complex (NEC), followed by loss-of-function screening to target the identified putative NEC-interacting cellular proteins to detect a defect in HSV-1 nuclear egress. This newly established system identified SLC35E1, an orphan transporter, as a novel cellular protein required for efficient HSV-1 de-envelopment, providing an insight into the mechanisms involved in this viral procedure.Apr. 2022, Journal of virology, 96(10) (10), e0030622, English, International magazine[Refereed]Scientific journal
- Herpesvirus UL34 homologs contain conserved amino-terminal domains that mediate vesicle formation through interactions with UL31 homologs during primary envelopment. UL34 homologs also comprise other domains adjacent to their membrane-anchoring regions, which differ in length, are variable in herpesviruses, and do not form distinguished secondary structures.Lead, American Society for Microbiology, Jan. 2022, Journal of Virology, 96(2) (2), e0170421.[Refereed]Scientific journal
- Background: Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is the virus responsible for the Coronavirus Disease 2019 (COVID-19) pandemic. The emergence of variants of concern (VOCs) has become one of the most pressing issues in public health. To control VOCs, it is important to know which COVID-19 convalescent sera have cross-neutralizing activity against VOCs and how long the sera maintain this protective activity. Methods: Sera of patients infected with SARS-CoV-2 from March 2020 to January 2021 and admitted to Hyogo Prefectural Kakogawa Medical Center were selected. Blood was drawn from patients at 1-3, 3-6, and 6-8 months post onset. Then, a virus neutralization assay against SARS-CoV-2 variants (D614G mutation as conventional strain; B.1.1.7, P.1, and B.1.351 as VOCs) was performed using authentic viruses. Results: We assessed 97 sera from 42 patients. Sera from 28 patients showed neutralizing activity that was sustained for 3-8 months post onset. The neutralizing antibody titer against D614G significantly decreased in sera of 6-8 months post onset compared to those of 1-3 months post onset. However, the neutralizing antibody titers against the three VOCs were not significantly different among 1-3, 3-6, and 6-8 months post onset. Discussion: Our results indicate that neutralizing antibodies that recognize the common epitope for several variants may be maintained for a long time, while neutralizing antibodies having specific epitopes for a variant, produced in large quantities immediately after infection, may decrease quite rapidly.2022, Frontiers in immunology, 13, 773652 - 773652, English, International magazine[Refereed]Scientific journal
- Continuous appearance of SARS-CoV-2 variants and mass vaccination have been intricately influencing on the COVID-19 situation. To elucidate the current status in Japan, we analyzed totally 2,000 sera in August (n = 1,000) and December (n = 1,000) 2021 collected from individuals who underwent a health check-up. The anti-N seropositive rate were 2.1% and 3.9% in August and December 2021, respectively, demonstrating a Delta variant endemic during that time; it was approximately twofold higher than the rate based on the PCR-based diagnosis. The anti-S seropositive rate was 38.7% in August and it reached 90.8% in December, in concordance with the vaccination rate in Japan. In the December cohort, 78.7% of the sera showed neutralizing activity against the Delta variant, whereas that against the Omicron was much lower at 36.6%. These analyses revealed that effective immunity against the Delta variant was established in December 2021, however, prompt three-dose vaccination is needed to overcome Omicron's outbreak.2022, PloS one, 17(4) (4), e0266270, English, International magazine[Refereed]Scientific journal
- Human herpesvirus 6A (HHV-6A) is frequently found in patients with neuro-inflammation, although its role in the pathogenesis of this disease has not been elucidated. Most viral infections activate the NF-κB pathway, which causes the transactivation of various genes, including those encoding proinflammatory cytokines.American Society for Microbiology, Nov. 2021, Journal of Virology, 95(23) (23)[Refereed]Scientific journal
- Background: As of March 2021, Japan is facing a fourth wave of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. To prevent further spread of infection, sera cross-neutralizing activity of patients previously infected with conventional SARS-CoV-2 against novel variants is important but has not been firmly established. Methods: We investigated the neutralizing potency of 81 coronavirus disease 2019 (COVID-19) patients' sera from the first to fourth waves of the pandemic against SARS-CoV-2 D614G, B.1.1.7, P.1, and B.1.351 variants using their authentic viruses. Results: Most sera had neutralizing activity against all variants, showing similar activity against B.1.1.7 and D614G, but lower activity especially against B.1.351. In the fourth wave, sera-neutralizing activity against B.1.1.7 was significantly higher than that against any other variants, including D614G. The sera-neutralizing activity in less severe patients was lower than that of more severe patients for all variants. Conclusions: The cross-neutralizing activity of convalescent sera was effective against all variants but was potentially weaker for B.1.351. The high neutralizing activity specific to B.1.1.7 in the fourth wave suggests that mutations in the virus might cause conformational change of its spike protein, which affects immune recognition of D614G. Our results indicate that individuals who recover from COVID-19 could be protected from the severity caused by infection with newly emerging variants.Oct. 2021, Open forum infectious diseases, 8(10) (10), ofab430, English, International magazine[Refereed]Scientific journal
- Cold Spring Harbor Laboratory, Sep. 2021, MedRxiv
Abstract The situation of the COVID-19 pandemic in Japan is drastically changing in the 2nd year, 2021, due to the appearance of SARS-CoV-2 variants of concern and the roll-out of mass vaccination. In addition to PCR diagnosis, periodic seroepidemiologic surveillance is important to analyze the epidemic situation. In this study, we analyzed the rate of seropositivity for the SARS-CoV-2 N and S antigens in Hyogo prefecture, Japan in August 2021. Sera collected from people who received a health check-up in a clinic of the Hyogo Prefecture Health Promotion Association were subjected to analysis of reactivity to the SARS-CoV-2 N and S antigens by electrochemiluminescence immunoassay (ECLIA) and enzyme-linked immunosorbent assay (ELISA), respectively. For a total 1,000 sera, the positive rates to N and S antigens were 2.1% and 38.7%, respectively. The infectious rate estimated by serological analysis based on the presence of the anti-N antibody was 2.5-fold higher than the value reported based on PCR-based analysis, and it increased five-fold compared to the rate determined by our previous seroepidemiologic study in October, 2020. The anti-S positive rate was almost consistent with the vaccination rate in this area. The observed high anti-S antibody level in the seropositive population may indicate that the mass vaccination in Japan is being performed smoothly at this time point, although the infectious rate has also increased. - Herpes simplex virus 1 (HSV-1) replicates its genome and packages it into capsids within the nucleus. HSV-1 has evolved a complex mechanism of nuclear egress whereby nascent capsids bud on the inner nuclear membrane to form perinuclear virions that subsequently fuse with the outer nuclear membrane, releasing capsids into the cytosol. The viral-encoded nuclear egress complex (NEC) plays a crucial role in this vesicle-mediated nucleocytoplasmic transport. Nevertheless, similar system mediates the movement of other cellular macromolecular complexes in normal cells. Therefore, HSV-1 may utilize viral proteins to hijack the cellular machinery in order to facilitate capsid transport. However, little is known about the molecular mechanisms underlying this phenomenon. This review summarizes our current understanding of the cellular and viral factors involved in the nuclear egress of HSV-1 capsids.Apr. 2021, Viruses, 13(5) (5), English, International magazine[Refereed]Scientific journal
- Glycoprotein Q2 (gQ2), an essential gene for virus propagation, forms a heterodimer with gQ1. The gQ1/gQ2 complex has a critical role in receptor recognition in the gH/gL/gQ1/gQ2 complex (a tetramer).American Society for Microbiology, Feb. 2021, Journal of Virology, 95(5) (5)[Refereed]
- Patients with coronavirus disease 2019 (COVID-19) exhibit a wide clinical spectrum ranging from mild respiratory symptoms to critical and fatal diseases, and older individuals are known to be more severely affected. The underlying mechanism of this phenomenon is unknown. A neutralizing antibody against viruses is known to be important to eliminate the virus. In addition, this antibody is induced at high levels in patients with severe COVID-19, followed by a termination of virus replication. Severe COVID-19 patients exhibit high levels of cytokines/chemokines, even after the disappearance of the virus. This indicates that cytokines/chemokines play significant roles in disease severity. These findings also suggest that antiviral therapy (monoclonal antibody and/or convalescent plasma therapy) should be administered early to eliminate the virus, followed by steroid treatment after viral genome disappearance, especially in patients with severe symptoms.Jan. 2021, JMA journal, 4(1) (1), 1 - 7, English, Domestic magazine[Refereed]Scientific journal
- Introduction: The coronavirus disease 2019 (COVID-19) pandemic is spreading rapidly all over the world. The Japanese government lifted the state of emergency, announced in April 2020, on May 25, but there are still sporadic clusters. Asymptomatic patients who can transmit severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) cause some of these clusters. It is thus urgent to investigate the seroprevalence of antibodies against SARS-CoV-2 and their neutralizing activity. We conducted a cross-sectional study of >10,000 samples at hospitals in Hyogo Prefecture, Japan. Methods: Between August 6 and October 1, 2020, we collected samples of residual blood from the patients who visited or were admitted to five hospitals and a foundation in Hyogo. We tested the samples for antibodies against SARS-CoV-2 by electrochemiluminescence immunoassay (ECLIA) and chemiluminescent enzyme immunoassay (CLEIA). Sera that were positive by ECLIA or CLEIA were analyzed by an immunochromatographic (IC) test and neutralizing activity assay. Results: We tested 10,377 samples from patients aged between 0 and 99 years old; 27 cases (0.26%) were positive on the ECLIA, and 51 cases (0.49%) were positive on CLEIA. In the 14 cases that tested positive on both ECLIA and CLEIA, the positive rates on the IC test and for neutralizing activity were high (85% and 92%, respectively). In 50 cases (0.48%) that were positive by either ECLIA or CLEIA, the corresponding rates were low (20% and 6%, respectively). The positive rate of neutralizing antibody was 0.15%. Conclusions: These results indicate that most Hyogo Prefecture residents still do not have antibodies and should avoid the risk of incurring a SARS-CoV-2 infection. Two or more antibody tests should be required for seroepidemiological studies of the antibody for SARS-CoV-2, and a neutralizing activity assay is also essential.Lead, Jan. 2021, JMA journal, 4(1) (1), 41 - 49, English, Domestic magazine[Refereed]Scientific journal
- Most COVID-19 patients experience asymptomatic/mild symptoms, but some suffer critical symptoms requiring intensive care. It is important to determine how asymptomatic/mild patients react to SARS-CoV-2 infection and suppress virus spread. Innate immunity is important for evasion from the first virus attack, and it may play an important role in the pathogenesis in these patients. We measured serum cytokine levels of 95 COVID-19 patients during the infection's acute phase and are first to report that significantly higher IL-12 and IL-2 levels were induced in asymptomatic/mild patients versus those in the moderate/severe patients, indicating these cytokines' key roles in asymptomatic/mild infections' pathogenesis.Jan. 2021, The Journal of infectious diseases, 223(7) (7), 1145 - 1149, English, International magazine[Refereed]Scientific journal
- Viral cell-to-cell spread, a method employed by several viral families for entrance via cell junctions, is highly relevant to the pathogenesis of various viral infections. Cell-to-cell spread of herpes simplex virus 1 (HSV-1) is known to depend greatly on envelope glycoprotein E (gE). However, the molecular mechanism by which gE acts in HSV-1 cell-to-cell spread and the mechanisms of cell-to-cell spread by other herpesviruses remain poorly understood. Here, we describe our identification of prohibitin-1 as a novel gE-interacting host cell protein. The ectopic expression of prohibitin-1 increased gE-dependent HSV-1 cell-to-cell spread. As observed with the gE-null mutation, the decreased expression or pharmacological inhibition of prohibitin-1 reduced HSV-1 cell-to-cell spread without affecting the yield of virus progeny. Similar effects were produced by pharmacological inhibition of the mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) pathway, wherein prohibitin-1 acts as a protein scaffold and is required for induction of this pathway. Furthermore, artificial activation of the MAPK/ERK pathway restored HSV-1 cell-to-cell spread impaired by the gE-null mutation. Notably, pharmacological inhibition of prohibitins or the MAPK/ERK pathway reduced viral cell-to-cell spread of representative members in all herpesvirus subfamilies. Our results suggest that prohibitin-1 contributes to gE-dependent HSV-1 cell-to-cell spread via the MAPK/ERK pathway and that this mechanism is conserved throughout the Herpesviridae, whereas gE is only conserved in the Alphaherpesvirinae subfamily.Importance Herpesviruses are ubiquitous pathogens of various animals, including humans. These viruses primarily pass through cell junctions to spread to uninfected cells. This method of cell-to-cell spread is an important pathogenic characteristic of these viruses. Here, we show that the host cell protein prohibitin-1 contributes to HSV-1 cell-to-cell spread via the downstream intracellular signaling cascade, the MAPK/ERK pathway. We also demonstrate that the role of the prohibitin-1-mediated MAPK/ERK pathway in viral cell-to-cell spread is conserved in representative members of every herpesvirus subfamily. This study has revealed a common molecular mechanism of the cell-to-cell spread of herpesviruses.Lead, Nov. 2020, Journal of virology, 95(3) (3), English, International magazine[Refereed]Scientific journal
- Hutchinson-Gilford progeria syndrome (HGPS) is a premature aging disorder, caused by mutation in the gene encoding lamin A/C, which produces a truncated protein called progerin. In cells from HGPS patients, progerin accumulates at the nuclear membrane (NM), where it causes NM deformations. In this study, we investigated whether progerin-induced NM deformation involved ESCRT-III, a protein complex that remodels nuclear and cytoplasmic membranes. The ESCRT-III protein CHMP4B was recruited to sites of aberrant NM proliferation in human cells ectopically expressing progerin and in patient-derived HGPS fibroblasts. Derepression of NM deformation in these cells was observed following depletion of CHMP4B or an ESCRT-III adaptor, ALIX. Treatment with rapamycin (which induce autophagic clearance of progerin and reverse progerin-induced cellular phenotypes) down-regulated progerin-induced NM deformation, whereas treatment with bafilomycin A1 (an inhibitor of autophagy and lysosome-based degradation) or CHMP4B depletion antagonized the effects of rapamycin. These results indicate that the ALIX-mediated ESCRT-III pathway plays a suppressive role in progerin-induced NM deformation and suggest that autophagy down-regulates progerin-induced NM deformation in a manner dependent on ESCRT-III machinery.Lead, Nov. 2020, Scientific reports, 10(1) (1), 18877 - 18877, English, International magazine[Refereed]Scientific journal
- Glycerophospholipids are major components of cell membranes. Phosphatidylethanolamine (PE) is a glycerophospholipid and is involved in multiple cellular processes, such as membrane fusion, cell cycle, autophagy and apoptosis. In this study, we investigated the role of PE biosynthesis in herpes simplex virus 1 (HSV-1) infection by knocking out the host cell gene encoding phosphate cytidylyltransferase 2, ethanolamine (Pcyt2), which is a key rate-limiting enzyme in one of the two major pathways for PE biosynthesis. Pcyt2 knockout reduced HSV-1 replication and caused an accumulation of unenveloped and partially enveloped nucleocapsids in the cytoplasm of an HSV-1-infected cell culture. A similar phenotype was observed by treating infected cells with meclizine, which is an inhibitor of Pcyt2. In addition, treatment of HSV-1-infected mice with meclizine significantly reduced HSV-1 replication in the mouse brains and improved their survival. These results indicated that PE biosynthesis mediated by Pcyt2 was required for efficient HSV-1 envelopment in the cytoplasm of infected cells and for viral replication and pathogenicity in vivo. The results also identified the PE biosynthetic pathway as a possible novel target for antiviral therapy of HSV-associated diseases and raised an interesting possibility for meclizine repositioning for treatment of these diseases, since it is an over-the-counter drug used for decades against nausea and vertigo in motion sickness.IMPORTANCEGlycerophospholipids in cell membranes and virus envelopes often affects viral entry and budding. However, the role of glycerophospholipids in herpesvirus infected cells on membrane-associated events in viral replication has not been reported thus far. In this study, we have presented data showing that cellular phosphatidylethanolamine (PE) biosynthesis mediated by Pcyt2 is important for HSV-1 envelopment in the cytoplasm as well as for viral replication and pathogenicity in vivo. This is the first report showing the importance of PE biosynthesis in herpesvirus infections. Our results showed that inhibition of Pcyt2, a key cell enzyme for PE synthesis, significantly inhibited HSV-1 replication and pathogenicity in mice. This suggested that the PE biosynthetic pathway, as well as the HSV-1 virion maturation pathway, can be targets for the development of novel anti-HSV drugs.Lead, Sep. 2020, Journal of virology, 94(24) (24), English, International magazine[Refereed]Scientific journal
- Identification of the complete set of translated genes of viruses is important to understand viral replication and pathogenesis as well as for therapeutic approaches to control viral infection. Here, we use chemical proteomics, integrating bio-orthogonal non-canonical amino acid tagging and high-resolution mass spectrometry, to characterize the newly synthesized herpes simplex virus 1 (HSV-1) proteome in infected cells. In these infected cells, host cellular protein synthesis is shut-off, increasing the chance to preferentially detect viral proteomes. We identify nine previously cryptic orphan protein coding sequences whose translated products are expressed in HSV-1-infected cells. Functional characterization of one identified protein, designated piUL49, shows that it is critical for HSV-1 neurovirulence in vivo by regulating the activity of virally encoded dUTPase, a key enzyme that maintains accurate DNA replication. Our results demonstrate that cryptic orphan protein coding genes of HSV-1, and probably other large DNA viruses, remain to be identified.Sep. 2020, Nature communications, 11(1) (1), 4894 - 4894, English, International magazine[Refereed]Scientific journal
- Human herpesvirus 6A (HHV-6A) is a member of the genus Roseolovirus and the subfamily Betaherpesvirinae. It is similar to human herpesvirus 7 (HHV-7) and human cytomegalovirus (HCMV). HHV-6A encodes a 41-kDa nuclear phosphoprotein, U27, which acts as a processivity factor in the replication of the viral DNA. HHV-6A U27 has 43% amino acid sequence homology with HCMV UL44, which is important for DNA replication. A previous study on HHV-6A U27 revealed that it greatly increases the in vitro DNA synthesis activity of HHV-6A DNA polymerase. However, the role of U27 during the HHV-6A virus replication process remains unclear. In the present study, we constructed a U27-deficient HHV-6A mutant (HHV-6ABACU27mut) with a frameshift insertion at the U27 gene using an HHV-6A bacterial artificial chromosome (BAC) system. Viral reconstitution from the mutant BAC DNA was not detected, in contrast to the wild type and the revertant from the U27 mutant. This suggests that U27 plays a critical role in the life cycle of HHV-6A. This article is protected by copyright. All rights reserved.Aug. 2020, Microbiology and immunology, 64(10) (10), 703 - 711, English, International magazine[Refereed]Scientific journal
- Lead, Oxford University Press (OUP), May 2020, Clinical Infectious Diseases, 72(4) (4), 723 - 724[Refereed]Scientific journal
- Lead, Nov. 2019, Journal of virology, 93(21) (21), English, International magazine[Refereed]Scientific journal
- Lead, Jul. 2019, Journal of virology, 93(14) (14), English, International magazine[Refereed]Scientific journal
- 2019, Uirusu, 69(1) (1), 73 - 82, Japanese, Domestic magazine[Refereed]Scientific journal
- Oct. 2018, Nature immunology, 19(10) (10), 1071 - 1082, English, International magazine[Refereed]Scientific journal
- Sep. 2018, Journal of virology, 92(18) (18), English, International magazine[Refereed]Scientific journal
- Sep. 2018, Journal of virology, 92(17) (17), English, International magazine[Refereed]Scientific journal
- Vesicle-mediated nucleocytoplasmic transport is a nuclear pore-independent mechanism for the nuclear export of macromolecular complexes, but the molecular basis for this transport remains largely unknown. Here we show that endosomal sorting complex required for transport-III (ESCRT-III) is recruited to the inner nuclear membrane (INM) during the nuclear export of herpes simplex virus 1 (HSV-1). Scission during HSV-1 budding through the INM is prevented by depletion of ESCRT-III proteins. Interestingly, in uninfected human cells, the depletion of ESCRT-III proteins induces aberrant INM proliferation. Our results show that HSV-1 expropriates the ESCRT-III machinery in infected cells for scission of the INM to produce vesicles containing progeny virus nucleocapsids. In uninfected cells, ESCRT-III regulates INM integrity by downregulating excess INM.Lead, Aug. 2018, Nature communications, 9(1) (1), 3379 - 3379, English, International magazine[Refereed]Scientific journal
- Feb. 2018, Cell host & microbe, 23(2) (2), 254 - 265, English, International magazine[Refereed]Scientific journal
- 2018, Advances in experimental medicine and biology, 1045, 3 - 21, English, International magazine[Refereed]Scientific journal
- Oct. 2017, The Journal of clinical investigation, 127(10) (10), 3784 - 3795, English, International magazine[Refereed]Scientific journal
- Sep. 2017, Journal of virology, 91(18) (18), English, International magazine[Refereed]Scientific journal
- Jun. 2017, Journal of virology, 91(12) (12), English, International magazine[Refereed]Scientific journal
- Lead, Nov. 2016, Journal of virology, 90(22) (22), 10170 - 10181, English, International magazine[Refereed]Scientific journal
- Oct. 2016, Journal of virology, 90(19) (19), 8754 - 67, English, International magazine[Refereed]Scientific journal
- Aug. 2016, Journal of virology, 90(15) (15), 6738 - 6745, English, International magazine[Refereed]Scientific journal
- Jun. 2016, Journal of virology, 90(12) (12), 5622 - 5635, English, International magazine[Refereed]Scientific journal
- Mar. 2016, The Journal of veterinary medical science, 78(3) (3), 405 - 10, English, Domestic magazine[Refereed]Scientific journal
- Jan. 2016, Journal of virology, 90(6) (6), 3173 - 86, English, International magazine[Refereed]Scientific journal
- Jan. 2016, Journal of virology, 90(1) (1), 457 - 73, English, International magazine[Refereed]Scientific journal
- 2016, Biological & pharmaceutical bulletin, 39(11) (11), 1897 - 1902, English, Domestic magazine[Refereed]Scientific journal
- Sep. 2015, Journal of virology, 89(17) (17), 8982 - 98, English, International magazine[Refereed]Scientific journal
- Aug. 2015, Journal of Virology, 89(15) (15), 7799 - 7812
- Jun. 2015, Microbiology and immunology, 59(6) (6), 331 - 7, English, International magazine[Refereed]Scientific journal
- Jun. 2015, Journal of virology, 89(11) (11), 6141 - 7, English, International magazine[Refereed]Scientific journal
- Lead, Feb. 2015, Journal of virology, 89(3) (3), 1879 - 88, English, International magazine[Refereed]Scientific journal
- Jan. 2015, eLife, 4, English, International magazine[Refereed]Scientific journal
- Jan. 2015, Journal of virology, 89(1) (1), 241 - 8, English, International magazine[Refereed]Scientific journal
- Sep. 2014, Journal of virology, 88(18) (18), 10624 - 34, English, International magazine[Refereed]Scientific journal
- Jul. 2014, Journal of virology, 88(13) (13), 7445 - 54, English, International magazine[Refereed]Scientific journal
- Jul. 2014, Journal of virology, 88(14) (14), 7776 - 85, English, International magazine[Refereed]Scientific journal
- May 2014, Journal of virology, 88(9) (9), 4657 - 67, English, International magazine[Refereed]Scientific journal
- Feb. 2014, Journal of virology, 88(4) (4), 2359 - 64, English, International magazine[Refereed]Scientific journal
- Jan. 2014, Microbiology and immunology, 58(1) (1), 31 - 7, English, International magazine[Refereed]Scientific journal
- 2013, PloS one, 8(8) (8), e72050, English, International magazine[Refereed]Scientific journal
- Dec. 2012, The Journal of biological chemistry, 287(52) (52), 43910 - 26, English, International magazine[Refereed]Scientific journal
- Transient transfection of small interfering RNA (siRNA) provides a powerful approach for studying cellular protein functions, particularly when the target protein can be re-expressed from an exogenous siRNA-resistant construct in order to rescue the knockdown phenotype, confirm siRNA target specificity, and support mutational analyses. Rescue experiments often fail, however, when siRNA-resistant constructs are expressed at suboptimal levels. Here, we describe an ensemble of mammalian protein expression vectors with CMV promoters of differing strengths. Using CHMP2A rescue of HIV-1 budding, we show that these vectors can combine high-transfection efficiencies with tunable protein expression levels to optimize the rescue of cellular phenotypes induced by siRNA transfection.Lead, Aug. 2012, BioTechniques, 0(0) (0), 1 - 5, English, International magazine[Refereed]Scientific journal
- Sep. 2011, Journal of virology, 85(18) (18), 9599 - 613, English, International magazine[Refereed]Scientific journal
- May 2011, Journal of virology, 85(10) (10), 5003 - 15, English, International magazine[Refereed]Scientific journal
- Lead, Oct. 2010, Nature, 467(7317) (7317), 859 - 62, English, International magazine[Refereed]Scientific journal
- Lead, Oct. 2010, Journal of virology, 84(20) (20), 10773 - 83, English, International magazine[Refereed]Scientific journal
- Feb. 2010, Antiviral research, 85(2) (2), 389 - 95, English, International magazine[Refereed]Scientific journal
- Jan. 2010, Journal of virology, 84(1) (1), 153 - 62, English, International magazine[Refereed]Scientific journal
- Dec. 2009, Journal of virology, 83(24) (24), 13042 - 5, English, International magazine[Refereed]Scientific journal
- Nov. 2009, Journal of virology, 83(22) (22), 11624 - 34, English, International magazine[Refereed]Scientific journal
- Lead, Aug. 2009, Microbiology and immunology, 53(8) (8), 433 - 41, English, International magazine[Refereed]Scientific journal
- Lead, May 2009, Journal of virology, 83(9) (9), 4520 - 7, English, International magazine[Refereed]Scientific journal
- Mar. 2009, Microbiology and immunology, 53(3) (3), 155 - 61, English, International magazine[Refereed]Scientific journal
- Lead, Jan. 2009, Journal of virology, 83(1) (1), 250 - 61, English, International magazine[Refereed]Scientific journal
- 2009, Archives of virology, 154(5) (5), 833 - 42, English, International magazine[Refereed]Scientific journal
- Mar. 2008, Cell, 132(6) (6), 935 - 44, English, International magazine[Refereed]Scientific journal
- Lead, Apr. 2006, Microbes and infection, 8(4) (4), 1054 - 63, English, International magazine[Refereed]Scientific journal
- 2016, 日本免疫学会総会・学術集会記録, 45(Proceedings) (Proceedings)Fatty acid synthesis pathway is required for TLR3 response through mTORC2 activity
- 2016, 日本分子生物学会年会プログラム・要旨集(Web), 39thTLR3応答におけるmTORの機能解析
- 2015, 日本免疫学会総会・学術集会記録, 44(Proceedings) (Proceedings)The role of mTOR in TLR3 responses to Herpes Simplex Virus infection
- Nov. 2008, GLYCOBIOLOGY, 18(11) (11), 1000 - 1000, EnglishCrucial Role of O-Glycosylation on Glycoprotein B in Herpes Simplex Virus I InfectionSummary international conference
- Contributor, ヘルペスウイルス治療薬開発を目指したウイルス粒子形成機構の解析 50:206-210, 春恒社, Oct. 2022臨床とウイルス
- Contributor, 組換え多価ワクチンベクターとしての水痘生ワクチンの可能性 279: 1021-1025, Dec. 2021医学のあゆみ 第一土曜特集「ワクチン設計のサイエンス」
- Contributor, HHV-6 149:1246, 日本医師会, Oct. 2020日本医師会雑誌
- Contributor, 単純ヘルペスウイルスとその感染受容体, 日本臨床ウイルス学会, Mar. 2019臨床とウイルス
- Contributor, 新しい抗ヘルペスウイルス戦略の構築を目指した戦略的基礎研究, 文永堂, Jun. 2018獣医畜産新報 特集 最先端微生物学研究に基づいた疾病対策の試み
- Contributor, ウイルスとヒトとの共生関係, ニューサイエンス社, Dec. 2017月刊細胞
- Contributor, 単純ヘルペスウイルスの潜伏感染ーどのように宿主体内で生き残り再活性化するのか？, 羊土社, Oct. 2015実験医学 増刊「感染症ーいま何が起きているのか」
- 東京大学・医科学研究所・学友会セミナー, Dec. 2023抗ウイルス因子APOBEC3とヘルペスウイルスとの攻防[Invited]
- 第75回細胞生物学会大会・シンポジウム“「細胞外キャリア」の多様性とその形成機構”, Jun. 2023ウイルス粒子形成に伴うオルガネラの再構築[Invited]
- 第65回日本脂質生化学会・シンポジウム“生体膜脂質組成が規定するタンパク質動態・生理機能”, Jun. 2023ウイルス粒子形成の足場としての脂質の機能[Invited]
- 第63回日本臨床ウイルス学会 日本ウイルス学会共催セミナー「ヘルペスウイルス感染症」, Jun. 2022ヘルペスウイルス治療薬開発を目指したウイルス粒子形成機構の解析[Invited]
- 第92回 日本生化学会シンポジウム・病原体と宿主が交差するオルガネラ・ゾーン, Sep. 2019単純ヘルペスウイルスによる核膜の再構築[Invited]
- 京都大学・ウイルス研究所・ウイルス研究の潮流シリーズセミナー, Jul. 2019単純ヘルペスウイルスによる核膜通過の分子機構[Invited]
- 第66回ウイルス学会 杉浦奨励賞特別講演, Oct. 2018, EnglishMolecular mechanisms of entry and egress of herpes simplex virus 1[Invited]
- Molecular Virology course in the institute of Virology, Freie Universität Berlin, Jul. 2017, EnglishThe interplay between HSV-1 and cellular membranes[Invited]
- 第14回ウイルス学キャンプin湯河原, Jun. 2015単純ヘルペスウイルスと宿主細胞膜との相互作用[Invited]
- 第62回ウイルス学会学術集会, Nov. 2014ラパトアセッション DNAウイルス[Invited]
- 東京大学・医科学研究所 若手研究者シンポジウム「最先端基礎研究が開く新しい医療」, Nov. 2013単純ヘルペスウイルスと宿主レセプターとの関わり[Invited]
- 第61回ウイルス学会学術集会ミニシンポジウム「ウイルスエントリー」, Nov. 2013Non-Muscle Myosin Heavy Chain IIBは、HSV-1の侵入を仲介するco-receptorである[Invited]
- 理研セミナー, Oct. 2013AngiomotinはHIV出芽を促進する[Invited]
- 日本学術振興会, 科学研究費助成事業, 挑戦的研究(萌芽), 神戸大学, 30 Jun. 2023 - 31 Mar. 2025ゲノム編集を標的とした革新的抗ウイルス・抗ガン戦略の構築
- 日本学術振興会, 科学研究費助成事業 基盤研究(B), 基盤研究(B), 神戸大学, 01 Apr. 2020 - 31 Mar. 2023ヘルペスウイルスの細胞指向性を規定する分子機構の解明ヒトを宿主とするヘルペスウイルスは9種存在が知られているが、いずれもヒトに終生続く潜伏感染を成立させることができる。潜伏したヘルペスウイルスは、ストレスや免疫抑制など伴って再活性化され、病態を繰り返すことが知られている。9種のヒトヘルペスウイルスには、多くの遺伝子が保存され、ゲノム複製や粒子形成といった基本的な増殖機構は、ほぼ同じであるにも関わらず、それぞれの病態や症状が認められる部位はウイルスごとに異なる。これらのヘルペスウイルスの指向性がどのように決定され、それぞれの特徴的な病態を引き起こす原因となっているのかは全くわかっていない。本研究は、このようなヘルペスウイルスが、どのように異なる細胞を“好む”のか、その分子機構を解明することを目指している。本年度は、単純ヘルペスウイルス（HSV）増殖を増強する因子としてPHB1を、さらに粒子形成を担う機構としPE産生系を新たに同定した。本研究により、医学上重要なヘルペスウイルスの病態発現機構の理解と、その治療法開発が促進されると考えられる。
- Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research on Innovative Areas (Research in a proposed research area), Grant-in-Aid for Scientific Research on Innovative Areas (Research in a proposed research area), The University of Tokyo, 01 Apr. 2019 - 31 Mar. 2021ユビキチンテクノロジーの創出によるウイルス出芽の解剖
- Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research on Innovative Areas (Research in a proposed research area), Grant-in-Aid for Scientific Research on Innovative Areas (Research in a proposed research area), The University of Tokyo, 01 Apr. 2019 - 31 Mar. 2021生死を分ける脳炎発火点の解明
- Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C), Grant-in-Aid for Scientific Research (C), The University of Tokyo, 01 Apr. 2017 - 31 Mar. 2020HSV細胞間伝播の分子機構単純ヘルペスウイルス（HSV）は、ヒトに脳炎、性器ヘルペス、眼疾患、新生児ヘルペスといった多様な疾患を引き起こす医学上重要なウイルスの一つである。関連する医療費はアメリカ合衆国で年間30億ドルと試算されるなど、公衆衛生上大きな問題となっており生体内におけるHSVの病態をより深く理解する必要があると考えられる。伝統的にウイルス学では、感染細胞から培養液に放出されたウイルスを“ウイルス液”として実験に用いてきた。HSVの場合、このcell freeのウイルスによって引き起こされる感染とは全く異なる感染様式として、ウイルス粒子が細胞外に放出されず直接隣の細胞に感染する方法（細胞間伝播）が存在することが知られている。HSVの場合、生体内においてはほとんどcell freeのウイルスが検出されず、主に細胞間伝播していると考えられている。細胞間伝播は、薬剤や抗体のアクセスに抵抗するため、抗ウイルス戦略上無視できない。このように細胞間伝播の重要性は明らかである一方で、cell freeのウイルスによる感染と比較して、その複雑さからあまり研究はされていない。HSVがコードするgEが細胞間伝播に必要であるが、その具体的な意義は不明である。 平成30年度は、gEと相互作用し、HSVによる細胞間伝播を促進する宿主因子と、当該因子が関与する細胞内シグナルに注目して解析を行った。この細胞内シグナルは、HSVの細胞間伝播に貢献しており、また当該因子は、HSV以外のヘルペスウイルスにおいても細胞間感染に関与している可能性が示唆された。
- Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Exploratory Research, Grant-in-Aid for Challenging Exploratory Research, The University of Tokyo, Apr. 2015 - Mar. 2018Identification of receptor for cell-to-cell infection of HSVWe investigated the mechanism of HSV cell-to-cell infection and identified new cellular factor which promotes cell-to-cell infection of HSV. This protein was interacted with viral gE, which is kwon to be important for cell-to-cell infection. Moreover, this protein was required for gE-dependent cell-to-cell infection. Thus, understanding of molecular mechanism of cell-to-cell infection of HSV may indicate new prophylactic and therapeutic approaches for the development of antiherpetic drugs.
- Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (A), Grant-in-Aid for Young Scientists (A), The University of Tokyo, Apr. 2014 - Mar. 2018Studies on entry and nuclear egress of Herpes Simplex VirusWe investigated the mechanism by which HSV passes though cellular membranes. We successfully identified several viral or cellular factors which promote passage through cellular membranes of HSV. As these steps are essential for viral life cycle, our results may indicate new prophylactic and therapeutic approaches for the development of antiherpetic drugs.
- Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Research Activity start-up, Grant-in-Aid for Research Activity start-up, The University of Tokyo, 30 Aug. 2013 - 31 Mar. 2015単純ヘルペスウイルスによる非筋ミオシンII利用のメカニズムと意義単純ヘルペスウイルス（HSV）はさまざまな疾患の原因となるが、その予防や完治を行う方法が確立されておらず、先進国においても重大な感染症の一つといえる。これまで申請者らは、Non-muscle myosin(NM)-IIAが、HSVによる細胞侵入過程において重要な役割を持ち、抗ヘルペスウイルス予防薬の魅力的なターゲットであることを示してきた。 NM-IIAはHSVの初感染および再起感染において重要なターゲットである上皮細胞に強く発現しているが、一方ではNM-IIAの発現が低い、ないしほとんどない細胞も存在する。特にHSVは神経細胞において潜伏し、また神経細胞での増殖は致死的な脳炎の原因として知られているが、神経細胞においてはM-IIAの発現が低いことが知られていた。そこで研究代表者らは、NM-IIAと相同性を持ち、神経細胞において強く発現することが知られているNM-IIBに注目し、HSVとNM-IIBとの関係を解析した。アフリカミドリザル由来のCos細胞は、NM-IIAを発現せず、NM-IIBを発現することが知られており、HSVに感受性のある細胞である。Cos細胞へのHSV侵入時において、NM-IIBはHSVの細胞侵入に必須の糖タンパク質gBと結合していた。さらにCos細胞へのHSV侵入およびHSV糖タンパク質による膜融合はNM-IIBを阻害することで低下した。またHSVへの感受性の低い細胞であるIC21へのNM-IIBの過剰発現は、HSV感受性を増加させることができた。すなわち、HSVはNM-IIBを介して細胞に侵入することができることが明らかになった。これらの結果は、J Virol. 2015 Feb;89(3):1879-88.において公表されている。
- Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for JSPS Fellows, Grant-in-Aid for JSPS Fellows, The University of Tokyo, 2007 - 2009ヘルペスウイルスの宿主特異性決定機構の解明多くのアルファヘルペスウイルスはさまざまな細胞種に感染可能であるが、イヌヘルペスウイルス、ネコヘルペスウイルスはそれぞれイヌ由来細胞、ネコ由来細胞でしか増殖することができない。この厳密な宿主域を規定する原因を探索するため、最終的にはこれらのウイルスゲノムを自在に組換えられるシステムの確立をまず試みた。イヌヘルペスウイルスについてはすでに組換え系が確立しており、論文発表しているが、さらに本年度は、ネコヘルペスウイルスゲノムの大腸菌への保持と、組換えウイルスの作成系を確立した。(Microbiol Immunol.2009) アルファヘルペスウイルスが細胞に侵入するときに必須である糖タンパクはgD、gB、gH、gLの4種類である。これまでは唯一細胞側の受容体が同定されているgDを中心に研究がなされてきた。しかし我々のグループでは、共同研究者とともに、gBと結合する新しいHSV-1のレセプターとしてPILRαを同定した(Satoh T, Arii J and et.al.Cell 2008)。 本研究課題において、ブタのアルファヘルペスウイルスであるオーエスキー病ウイルスがPILRαを用いることを明らかにした。一方HSV-1に極めて近縁なHSV-2はPILRαを用いることができず、新たにPILRαがHSV-1とHSV-2の病態の差に寄与している可能性が考えられた。 また、ヘルペスウイルスは細胞膜表面でのfusionあるいはendocytosisを介して細胞に侵入する。二つのルートは完璧に細胞腫に依存しており、どのように選択されているかは不明であった。CHO細胞や、CHOにgD receptorを発現させた場合はHSv-1はendocytosisを介して侵入することが知られていた。しかし、新しく同定したPILRαを発現させたCHOへの侵入はfusionを介していた。すなわち、CHOへの侵入経路がPILRαの発現によって変化することが明らかとなり、二つの侵入経路を決定する因子の一つがgBのレセプターである可能性が示唆された。この結果は最も権威のあるウイルス学雑誌Journal of Virologyに採用され、editorが選ぶspotlightとして巻頭において紹介された。 さらに、PILRαを用いることができない組換えウイルスを作製し、マウスへの感染実験に供することで、実際に生体内において、PILRαがヘルペスウイルスの増殖や病態に重要な役割を担っていることを初めて明らかにした。(投稿準備中)