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Yusuke Yanagi

Publications and source records attributed to Yusuke Yanagi.

32 records · Page 2Linked to original sources
PubMed2004

Dissection of measles virus V protein in relation to its ability to block alpha/beta interferon signal transduction.

Interferon (IFN)-alpha and -beta are the main cytokines for innate immune responses against viral infections. To replicate efficiently in the hosts, viruses have evolved various countermeasures to the IFN response. The V protein of measles virus (MV) has been shown to block IFN-alpha/beta signalling. Here, the wild-type IC-B strain of MV was shown to grow comparably in the presence and absence of IFN-alpha, whereas replication of the Edmonston tag strain recovered from cloned DNA was strongly suppressed in its presence. The V protein of the IC-B strain, but not the Edmonston tag strain, blocked IFN-alpha signalling. The V protein of the Edmonston strain from the ATCC also inhibited IFN-alpha signalling. There were three amino acid differences between the V proteins of the Edmonston ATCC and tag strains, and substitutions of both residues at positions 110 and 272 were required for the Edmonston ATCC V protein to lose IFN-antagonist activity. The P protein of the IC-B strain, which shares the N-terminal 231 aa residues with the V protein, also inhibited IFN-alpha signalling. Indeed, fragments comprising only those 231 residues of the IC-B and Edmonston ATCC V proteins, but not the Edmonston tag V protein, were able to block IFN-alpha signalling. However, the N-terminal region of the Edmonston tag V protein, when attached to the C-terminal region of the Edmonston ATCC V protein, inhibited IFN-alpha signalling. Taken together, our results indicate that both the N- and C-terminal regions contribute to the IFN-antagonist activity of the MV V protein.

Animals↗
PubMed2004

Infection of different cell lines of neural origin with subacute sclerosing panencephalitis (SSPE) virus.

Measles virus is the causative agent of subacute sclerosing panencephalitis (SSPE). The viruses isolated from brain cells of patients with SSPE (called SSPE viruses) are defective in cell-free virus production in vitro. To investigate the cell tropism of three strains of SSPE virus (Osaka-1, Osaka-2, Osaka-3), SSPE virus-infected cell cultures were treated with cytochalasin D to prepare virus-like particles (CD-VLPs). All CD-VLPs formed syncytia after infection in CHO cells expressing CD150 but not in those expressing CD46. In addition, an antibody to CD46 did not block the infection of Vero cells by SSPE CDVLPs. The results were consistent with our previous suggestion that one or more unidentified receptors might be involved in the entry process. Infection with the CD-VLPs from three SSPE strains was further examined in different human cell lines, including those of neural origin, and was found to induce syncytia in epithelial cells (HeLa and 293T) as well as neuroblastoma cells (IMR-32 and SK-N-SH) with varying efficiency. SSPE CD-VLPs also infected glioblastoma cells (A172) and astrocytoma cells (U-251) but syncytial formation was rarely induced. These epithelial and neural cell lines were not permissive for the replication of wild-type MV. Together with our previous observations, these results suggest that the cell entry receptor is the major factor determining the cell tropism of SSPE viruses. Further studies are necessary to identify other viral and/or cellular factors that might be involved in the replication of SSPE virus in specific neural cells and in the brain.

Animals↗
PubMed2003

Neutralising immunogenicity of a polyepitope antigen expressed in a transgenic food plant: a novel antigen to protect against measles.

Transgenic carrot plants were developed expressing a designer polyepitope combining tandem repeats of a protective loop-forming B cell epitope (H386-400) of the measles virus hemagglutinin protein with a human promiscuous, measles-unrelated T cell epitope (tt830-844). Despite the sensitivity of the loop conformation to its molecular environment, proper folding was confirmed by conformation-dependent monoclonal antibodies. The antibodies also reacted with the boiled antigen in Western blot. Immunisation of mice peritoneally with carrot plant extracts induced high titers of antibodies that crossreacted strongly with the virus. Furthermore, the sera neutralised field isolates of different geographic origins and genotypes in a modified plaque reduction neutralisation assay performed on CD150-transfected Vero cells. These results demonstrate that transgenic carrot plants can serve as an efficient expression system to produce highly immunogenic, randomly assembled polyepitope antigens. The combined features of the selected epitopes and the potential of the plant expression system may pave the way towards new vaccines against measles.

Amino Acid Sequence↗
PubMed2003

Caspase-dependent apoptosis in fulminant hepatic failure induced by herpes simplex virus in mice.

BACKGROUND/AIMS: Herpes simplex virus (HSV) is known to induce fulminant hepatic failure. The aim of this study is to clarify the molecular basis of liver injury in HSV-induced hepatitis. METHODS: Immunocompetent mice were inoculated with HSV or ultraviolet-inactivated HSV (UV-HSV) intravenously. Extent of liver injury was evaluated by changes of serum enzymes and histopathology. Apoptosis was assessed by DNA fragmentation and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL). Immunohistochemistry for caspase-3 and Fas ligand was performed. Reverse transcriptase-polymerase chain reaction for Fas ligand was also performed. RESULTS: All mice died of rapid and massive liver cell death after HSV infection, whereas no change was observed in mice after UV-HSV inoculation. The extent of viral replication and DNA fragmentation correlated well with the severity of liver injury. Caspase-3 was activated in the liver after HSV infection, but not UV-HSV. Positive reaction for TUNEL was observed not only in HSV-antigen positive cells but also in HSV-antigen negative cells. Fas ligand was induced in the liver infected with HSV, but not with UV-HSV. CONCLUSIONS: Caspase-dependent apoptosis is involved in HSV-associated liver injury. Not only viral replication but also non-viral factor such as Fas ligand may facilitate rapid development of this disease.

Animals↗
PubMed2003

Receptor use by vesicular stomatitis virus pseudotypes with glycoproteins of defective variants of measles virus isolated from brains of patients with subacute sclerosing panencephalitis.

The vaccine or Vero cell-adapted strains of measles virus (MV) have been reported to use CD46 as a cell entry receptor, while lymphotropic MVs preferentially use the signalling lymphocyte activation molecule (SLAM or CD150). In contrast to the virus obtained from patients with acute measles, little is known about the receptor that is used by defective variants of MV isolated from patients with subacute sclerosing panencephalitis (SSPE). The receptor-binding properties of SSPE strains of MV were analysed using vesicular stomatitis virus pseudotypes expressing the envelope glycoproteins of SSPE strains of MV. Such pseudotype viruses could use SLAM but not CD46 for entry. The pseudotype viruses with SSPE envelope glycoproteins could enter Vero cells, which do not express SLAM. In addition, their entry was not blocked by the monoclonal antibody to CD46, pointing to another entry receptor for SSPE strains on Vero cells. Furthermore, the unknown receptor(s), distinct from SLAM and CD46, may be present on cell lines derived from lymphoid and neural cells. Biochemical characterization of the receptor present on Vero cells and SK-N-SH neuroblastoma cells was consistent with a glycoprotein. Identification of additional entry receptors for MV will provide new insights into the mechanism of spread of MV in the central nervous system and possible reasons for differences between MVs isolated from patients with acute measles and SSPE.

Animals↗
PubMed2003

Histidine at position 61 and its adjacent amino acid residues are critical for the ability of SLAM (CD150) to act as a cellular receptor for measles virus.

Signalling lymphocyte activation molecule (SLAM, also known as CD150), a membrane glycoprotein involved in lymphocyte activation, has two extracellular immunoglobulin superfamily domains, V and C2. It has been shown previously that human SLAM is a cellular receptor for measles virus (MV) and that its V domain is necessary and sufficient for receptor function. Although mouse SLAM has functional and structural similarity to human SLAM, it hardly acts as a receptor for MV. By producing human/mouse chimeric molecules and assessing their receptor function with a vesicular stomatitis virus pseudotype assay, the region at amino acid positions 58-67 was found to be critically responsible for the difference in MV receptor function between human and mouse SLAMs. Exchange of this region allowed mouse SLAM to act as a receptor for MV, almost comparable to human SLAM. Among three amino acid differences (positions 60, 61 and 63) in this region, histidine 61 present in human SLAM was most significant, but combined substitutions with this residue and one or both of isoleucine 60 and valine 63 increased further the receptor activity of mouse SLAM. On the other hand, converse substitution at position 61 compromised receptor function of human SLAM. Thus, histidine 61 and its adjacent residues at positions 60 and 63 are critical for SLAM to act as a receptor for MV. Notably, the pseudotype assay indicated that residues at these three positions are also critical for the function of SLAM as a receptor for canine distemper virus.

Animals↗
PubMed2003

Efficient isolation of wild strains of canine distemper virus in Vero cells expressing canine SLAM (CD150) and their adaptability to marmoset B95a cells.

We have previously shown that canine signaling lymphocyte activation molecule (SLAM; also known as CD150) acts as a cellular receptor for canine distemper virus (CDV). In this study, we established Vero cells stably expressing canine SLAM (Vero.DogSLAMtag cells). Viruses were isolated in Vero.DogSLAMtag cells one day after inoculation with spleen samples from five out of seven dogs with distemper. By contrast, virus isolation with reportedly sensitive marmoset B95a cells was only successful from three diseased animals at 7 to 10 days after inoculation, and no virus was recovered from any dogs when Vero cells were used for isolation. The CDV strain isolated in Vero.DogSLAMtag cells did not cause cytopathic effects in B95a and human SLAM-expressing Vero cells, whereas the strain isolated in B95a cells from the same dog did so in canine or human SLAM-expressing Vero cells as well as B95a cells. There were two amino acid differences in the hemagglutinin sequence between these strains. Cell fusion analysis after expression of envelope proteins and vesicular stomatitis virus pseudotype assay showed that their hemagglutinins were responsible for the difference in cell tropism between them. Site-directed mutagenesis indicated that glutamic acid to lysine substitution at position 530 of the hemagglutinin was required for the adaptation to the usage of marmoset SLAM. Our results indicate that Vero cells stably expressing canine SLAM are highly sensitive to CDV in clinical specimens and that only a single amino acid substitution in the hemagglutinin can allow the virus to adapt to marmoset SLAM.

Adaptation, Physiological↗
PubMed2002

The morbillivirus receptor SLAM (CD150).

Morbilliviruses are highly contagious pathogens that cause some of the most devastating viral diseases of humans and animals, including measles virus (MV), canine distemper virus (CDV), and rinderpest virus (RPV). They replicate mainly in lymphoid organs throughout the body and cause severe immunosuppression accompanied with lymphopenia. We have recently shown that human, canine, and bovine signaling lymphocyte activation molecules (SLAMs; also known as CD150) act as cellular receptors for MV, CDV, and RPV, respectively. In these three morbilliviruses, all strains examined were shown to use SLAMs of their respective host species, and laboratory strains passaged on SLAM-negative cells were found to use, besides SLAM, alternative receptors, such as human CD46 for the Edmonston strain of MV. The use of SLAM as a receptor may be a property common to most, if not all, of the members of morbilliviruses. Human SLAM is a membrane glycoprotein selectively expressed on the cells of the immune system (immature thymocytes, activated lymphocytes, activated monocytes, and mature dendritic cells) and seems to mediate lymphocyte activation and to control interferon-gamma production. The destruction and/or impairment of infected SLAM-positive cells may be a mechanism for the immunosuppression induced by morbilliviruses, but other mechanisms may be also involved.

Amino Acid Sequence↗
PubMed2002

Restriction of measles virus RNA synthesis by a mouse host cell line: trans-complementation by polymerase components or a human cellular factor(s).

The mouse epithelial MODE-K cell line expressing human CD46 or CD150 cellular receptors was found to be nonpermissive for measles virus (MV) replication. The virus binding and membrane fusion steps were unimpaired, but only very limited amounts of virus protein and RNA synthesized were detected after the infection. In a minigenome chloramphenicol acetyltransferase assay, MODE-K cells were as able as the permissive HeLa cells in supporting MV polymerase activity. The restriction phenotype of MODE-K cells could be alleviated by providing, in trans, either N-P-L or N-P functional protein complexes but not by P-L complexes or individual N, P, and L proteins. Several human x mouse (HeLa x MODE-K) somatic hybrid clones expressing human CD46 were isolated and found to be either nonpermissive or permissive according to their human chromosomal contents. The MV-restricted phenotype exhibited by the MODE-K cell line suggests that a cellular factor(s) can control MV transcription, possibly by stabilizing the incoming virus polymerase templates.

Animals↗
PubMed2002

SLAM (CD150)-independent measles virus entry as revealed by recombinant virus expressing green fluorescent protein.

Wild-type measles virus (MV) strains use human signaling lymphocyte activation molecule (SLAM) as a cellular receptor, while vaccine strains such as the Edmonston strain can use both SLAM and CD46 as receptors. Although the expression of SLAM is restricted to cells of the immune system (lymphocytes, dendritic cells, and monocytes), histopathological studies with humans and experimentally infected monkeys have shown that MV also infects SLAM-negative cells, including epithelial, endothelial, and neuronal cells. In an attempt to explain these findings, we produced the enhanced green fluorescent protein (EGFP)-expressing recombinant MV (IC323-EGFP) based on the wild-type IC-B strain. IC323-EGFP showed almost the same growth kinetics as the parental recombinant MV and produced large syncytia exhibiting green autofluorescence in SLAM-positive cells. Interestingly, all SLAM-negative cell lines examined also showed green autofluorescence after infection with IC323-EGFP, although the virus hardly spread from the originally infected individual cells and thus did not induce syncytia. When the number of EGFP-expressing cells after infection was taken as an indicator, the infectivities of IC323-EGFP for SLAM-negative cells were 2 to 3 logs lower than those for SLAM-positive cells. Anti-MV hemagglutinin antibody or fusion block peptide, but not anti-CD46 antibody, blocked IC323-EGFP infection of SLAM-negative cells. This infection occurred under conditions in which entry via endocytosis was inhibited. These results indicate that MV can infect a variety of cells, albeit with a low efficiency, by using an as yet unidentified receptor(s) other than SLAM or CD46, in part explaining the observed MV infection of SLAM-negative cells in vivo.

Animals↗
PubMed2001

Induction of the measles virus receptor SLAM (CD150) on monocytes.

Wild-type strains of measles virus (MV) isolated in B95a cells use the signalling lymphocyte activation molecule (SLAM; also known as CD150) as a cellular receptor, whereas the Edmonston strain and its derivative vaccine strains can use both SLAM and the ubiquitously expressed CD46 as receptors. Among the major target cells for MV, lymphocytes and dendritic cells are known to express SLAM after activation, but monocytes have been reported to be SLAM-negative. In this study, SLAM expression on monocytes was examined under different conditions. When freshly isolated from the peripheral blood, monocytes did not express SLAM on the cell surface. However, monocytes became SLAM-positive after incubation with phytohaemagglutinin, bacterial lipopolysaccharide or MV. Anti-SLAM monoclonal antibodies efficiently blocked infection of activated monocytes with a wild-type strain of MV. These results indicate that SLAM is readily induced and acts as a monocyte receptor for MV.

Antigens, CD↗
PubMed2001

Analysis of the molecules involved in human T-cell leukaemia virus type 1 entry by a vesicular stomatitis virus pseudotype bearing its envelope glycoproteins.

Cellular entry of human T-cell leukaemia virus type 1 (HTLV-1) was studied by a quantitative assay system using vesicular stomatitis virus (VSV) pseudotypes in which a recombinant VSV (VSVDeltaG*) containing the gene for green fluorescent protein instead of the VSV G protein gene was complemented with viral envelope glycoproteins in trans. Most of the cell lines tested showed susceptibility to VSVDeltaG* complemented with either HTLV-1 envelope glycoproteins (VSVDeltaG*-Env) or VSV G protein (VSVDeltaG*-G), but not to VSVDeltaG* alone, indicating that cell-free HTLV-1 could infect many cell types from several species. High concentration pronase treatment of cells reduced their susceptibility to VSVDeltaG*-Env, while trypsin treatment, apparently, did not. Treatment of the cells with sodium periodate, heparinase, heparitinase, phospholipase A2 or phospholipase C reduced the susceptibility of cells to VSVDeltaG*-Env, but not to VSVDeltaG* complemented with measles virus (Edmonston strain) H and F proteins (VSVDeltaG*-EdHF), which was used as a control. Purified phosphatidylcholine also inhibited the infectivity of VSVDeltaG*-Env, but not VSVDeltaG*-G. These findings indicated that, in addition to cell surface proteins, glycosaminoglycans and phospholipids play an important role in the process of cell-free HTLV-1 entry.

Animals↗