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S Kusagawa

Publications and source records attributed to S Kusagawa.

33 records · Page 2Linked to original sources
PubMed1996

Identification of the sequences responsible for nuclear targeting of the V protein of human parainfluenza virus type 2.

In human parainfluenza virus type 2 (hPIV-2)-infected cells, anti-phosphoprotein (P)-specific monoclonal antibody (MAb) densely stained the perinuclear regions of infected cells throughout infection, indicating that the P protein was localized exclusively in the cell cytoplasm. By contrast, antigens recognized by MAbs directed against the P-V-common domain of hPIV-2 were located predominantly in the cytoplasm, but in some hPIV-2-infected cells they were also found in the nuclei, suggesting that a fraction of hPIV-2 V protein is localized there. hPIV-2 V protein expressed from a cDNA clone was localized in the nuclei of transfected cells. By using indirect immunofluorescence analyses, we examined the intracellular localization of various sequentially deleted V proteins, to determine the nuclear localization signals (NLS) of the V protein. Two noncontiguous regions in the V protein were required for nuclear localization and retention, since deletion of these regions [region I (aa 1-46) and region II (aa 175-196)] resulted in cytoplasmic localization. Both regions resulted in nuclear localization independently. A nucleoplasmin-like NLS was identified in region II but no consensus targeting sequence could be found in region I. When NP protein was co-expressed with V protein or the N-terminal fragment (aa 1-46) of V protein, a fraction of the NP protein was translocated into cell nuclei.

Amino Acid Sequence↗
PubMed1995

A cell fusion-inhibiting monoclonal antibody binds to the presumed stalk domain of the human parainfluenza type 2 virus hemagglutinin-neuraminidase protein.

Previously, we obtained a neutralizing monoclonal antibody directed against the hemagglutinin-neuraminidase (HN) protein of human parainfluenza type 2 virus (PIV2), which was able to prevent cell fusion without affecting the hemagglutinating and neuraminidase activities. In this study, four escape mutants of PIV2 have been obtained under pressure of the monoclonal antibody. Intriguingly, the HN protein of each mutant proved to have two amino acid substitutions, one of which is at 83Asn or 91Lys, and another one is at 150Leu, 160Ala, or 186Met. One mutant designated F13, which has substitutions at 83Asn and 186Met in the HN protein, could not cause cell fusion in HeLa cells despite its multiple replication, while the other mutants formed typical syncytial cells. The deduced amino acid sequence of F13 fusion (F) protein proved to be identical to that of wild-type F protein, and furthermore, protein expression analyses have revealed that the low-fusion phenotype of F13 was due to its mutated HN protein, whose antigenicity to the monoclonal antibody was abolished by the single mutation at 83Asn. These observations have suggested that the principal epitope for the monoclonal antibody resides in the presumed stalk domain of the HN protein, which may play an important role in promoting cell fusion.

Amino Acid Sequence↗
PubMed1995

Sequence analyses of human parainfluenza virus type 4A and type 4B fusion proteins.

cDNAs encoding human parainfluenza virus type 4A and type 4B (hPIV-4A and -4B) fusion (F) proteins were cloned and sequenced. The predicted amino acid sequences of the F proteins had similar characteristic traits to those reported for the F proteins of other paramyxoviruses. They were more closely related to the F proteins of simian virus 5 (SV5), mumps virus (MuV), hPIV-2 and Newcastle disease virus (NDV) than to the F proteins of hPIV-1, hPIV-3, Sendai virus (SV) and measles virus (MV). In addition, hPIV-4A, hPIV-4B, SV5 and MuV shared a common feature of genomic organization: there was a small ORF between the F and haemagglutinin-neuraminidase (HN)-coding sequences, implying a common ancestry.

Amino Acid Sequence↗
PubMed1994

HN proteins of human parainfluenza type 4A virus expressed in cell lines transfected with a cloned cDNA have an ability to induce interferon in mouse spleen cells.

Primary monkey kidney cells infected with human parainfluenza type 4A virus (HPIV-4A) were treated with various concentrations of formaldehyde. Formaldehyde (0.275%) treatment completely blocked virus production. However, when mouse spleen cells were cocultured with the fixed virus-infected cells, interferon was produced in the culture fluid. On the other hand, when mouse spleen cells were incubated with the fixed virus-infected cells in the presence of anti-HPIV-4A antiserum or a mixture of anti-HN protein monoclonal antibodies, interferon activity could scarcely be detected in the culture fluid. These findings indicated that the fixed virus-infected cells had an ability to induce interferon in mouse spleen cells and that the HN protein was related to interferon induction. Subsequently, a recombinant plasmid was constructed by inserting the cDNA of the HN gene of HPIV-4A into a pcDL-SR alpha expression vector. Mouse spleen cells produced interferon when cocultured with COS7 cells transfected with the recombinant plasmid, but did not when cocultured with COS7 cells transfected with the vector alone. Furthermore, we established HeLa cells constitutively expressing HPIV-4A HN (HeLa-4aHN cells) or F protein (HeLa-4aF cells). Type I (alpha/beta) interferon was detected in culture fluids of mouse spleen cells with HeLa-4aHN cells, but was not detected in those with HeLa-4aF cells. Therefore, it was concluded that the HN glycoproteins on the cell surface were sufficient for interferon induction to occur.

Animals↗
PubMed1994

The character of endogenous retrovirus in pancreatic beta-cells of NOD mice.

The character of retrovirus type C in NOD mouse pancreatic-beta-cells was investigated. First, the in vitro response of retrovirus type C to glucose stimulation was examined. When the pancreatic islets of control NON mice were observed with an electron microscopy retrovirus types C could not be detected in the beta-cells with or without glucose stimulation. Retrovirus type C particles and intracisternal type A particles (IAPs) in NOD mouse pancreatic beta-cells increased by glucose stimulation, but the increase in retrovirus type C differed from that of IAPs. The clusters of retrovirus type C were found in some beta-cells, whereas IAPs were scattered in beta-cells. Next, we investigated the expression of retrovirus type C transcript in NOD mouse pancreatic islets. From polymerase chain reaction analysis using two primers of retrovirus type C designed from a conserved U3 region, a major product was found to be endogenous polytropic retrovirus (Pmv). The subcloned PCR probe and oligonucleotide probes specific for Pmv and modified polytropic retrovirus were used for Northern blot analysis. Pancreatic islets from NOD and NON mice (control mice) contained 8.4-kb and 3.0-kb Pmv transcripts. The quantity of transcripts of Pmv in NOD mouse pancreatic beta-cells were the same as that in NON mice. The transcript level of islets was much higher than those of thymus and liver. The appearance of retrovirus type C particles in beta-cells of NOD mice may involve the mechanisms by which diabetes is generated in NOD mice.

Animals↗
PubMed1993

Antigenic and molecular properties of Murayama virus isolated from cynomolgus monkeys: the virus is closely related to avian paramyxovirus type 2.

A new virus that belonged to a member of paramyxovirus was isolated from cynomolgus monkeys showing respiratory disorders about 20 years ago and was named Murayama virus (MrV). Interestingly, it showed no serological relationship with the mammalian paramyxoviruses tested. On the other hand, it was related to Yucaipa (YuV) and Bangor virus (BaV) belonging to avian paramyxovirus type 2 (PMV2). In analysis using anti-MrV monoclonal antibodies, MrV showed the closest relationship with YuV, and furthermore some conserved epitopes were found among avian paramyxovirus, MrV, YuV, BaV, and Newcastle disease virus (NDV). Subsequently, the nucleotide sequences of the F and HN genes of MrV were determined. In comparison with the deduced amino acid sequence of MrV and other paramyxoviruses, MrV showed the highest homology with NDV and higher similarity to HPIV2 group rather than to HPIV1 group. The present study clearly indicates that MrV belongs to PMV2 adapting to monkeys.

Amino Acid Sequence↗
PubMed1993

Sequence determination of the P gene of simian virus 41: presence of irregular deletions near the RNA-editing sites of paramyxoviruses.

The complete nucleotide sequence of the P gene of simian virus 41 (SV41) was determined. The gene was found to be 1406 nucleotides long and to contain a relatively small open reading frame encoding a cysteine-rich V protein with a calculated M(r) of 24076. We have demonstrated that RNA-editing events occur in SV41 P gene transcripts and that the ratio of edited mRNAs to faithfully copied mRNA (P-mRNA:V-mRNA) is about 1:5 at either 24 or 40 h post-infection. The mRNA with two G insertions was capable of encoding a P protein of 395 amino acids with a predicted M(r) of 41,992. A kinetic study of P and V proteins by Western blot analysis showed that in virus-infected cells the amounts of both proteins were almost equal although the V-mRNA was considerably more abundant than the P-mRNA. Alignment of the SV41 P and V proteins with those of nine other paramyxoviruses demonstrated that irregular gaps were present around the RNA-editing sites.

Amino Acid Sequence↗
PubMed1992

Molecular evolution of human paramyxoviruses. Nucleotide sequence analyses of the human parainfluenza type 1 virus NP and M protein genes and construction of phylogenetic trees for all the human paramyxoviruses.

The nucleotide sequences of the NP and M genes of human parainfluenza type 1 virus (HPIV-1) were determined. The NP gene was 1677 nucleotides long excluding polyadenylic acid. The NP gene contained a single large open reading frame (ORF), which encoded a polypeptide of 524 amino acids with a calculated molecular weight of 57,736. The M gene 1173 nucleotides long excluding the poly(A) tract and the sequence also contained a single large ORF which encoded a polypeptide of 348 amino acid with a molecular weight of 38,445, which was inconsistent with 28 kDa previously determined by SDS-PAGE. We aligned the deduced HPIV-1 NP and M protein sequences with 12 and 13 other paramyxoviruses, respectively, suggesting that a common tertiary structure was found in the NPs or Ms of HPIV-1, Sendai virus (SV), HPIV-3 and BPIV-3 and that other common structure was also maintained in these proteins of HPIV-2, SV 41 and 5, MuV, HPIV-4. Phylogenetic trees were constructed for the NP and M proteins of all the paramyxoviruses of which nucleotide sequences had been previously reported. Paramyxoviruses could be subdivided into two groups, i.e., PIV-1 group and PIV-2 group; the former group is composed of HPIV-1, SV, HPIV-3 and BPIV-3, and the latter group consists of HPIV-2, SV 41, SV 5, MuV, HPIV-4 A and HPIV-4 B.

Amino Acid Sequence↗
PubMed1992

Nucleotide sequence analysis of the simian virus 41 gene encoding the large (L) protein and construction of a phylogenetic tree for the L proteins of paramyxoviruses.

The complete nucleotide sequence of the simian virus 41 (SV41) large (L) protein gene was determined. The L gene spanned 6883 nucleotides including a putative trailer RNA, and the L mRNA contained a single large open reading frame encoding a polypeptide of 2269 amino acids. Dot-matrix comparisons under stringent conditions identified domains highly conserved among paramyxoviruses. Domain 3 is the most highly conserved, and has been hypothesized to be the RNA polymerase active site. A phylogenetic tree was constructed from the sequences of the L proteins of seven paramyxoviruses. SV41 was most closely related to human parainfluenza virus type 2 (HPIV-2), and SV41, HPIV-2 and SV5 form a subgroup. The intergenic sequences at the nucleocapsid protein-phosphoprotein and haemagglutinin-neuraminidase-L protein gene junctions, and the 5' trailer sequence of SV41 were also determined, and it was shown that the first 13 nucleotides of the 5' trailer sequence are complementary to those of the 3' leader sequence. The intergenic, and gene-start and -end sequences of SV41, HPIV-2 and SV5 are shown.

Amino Acid Sequence↗
PubMed1992

Sequence analysis of the large (L) protein of simian virus 5.

The complete nucleotide sequence of the large (L) protein gene of simian virus 5 (SV5) was determined from cDNA of the genomic RNA and mRNA, and found to be 6804 bases in length, exclusive of a poly(A) tract. The sequence contained an open reading frame of 6765 nucleotides encoding 2255 amino acids. Results of dot matrix comparisons of the L protein of SV5 with those of human parainfluenza type 3 virus and Sendai virus indicated that there are five conserved domains, and that each domain contains characteristic sequence(s). The L protein of SV5 was detected in purified virions using antiserum directed against an oligopeptide corresponding to the N-terminal region.

Amino Acid Sequence↗
PubMed1992

Antigenic diversity of human parainfluenza virus type 1 isolates and their immunological relationship with Sendai virus revealed by using monoclonal antibodies.

Fifty-six monoclonal antibodies (MAbs) directed against human parainfluenza virus type 1 (hPIV-1) were prepared in order to identify the structural proteins of hPIV-1, to examine the immunological relationship between hPIV-1 and Sendai virus (SV), and to determine the antigenic diversity of clinical isolates of hPIV-1. In addition, 41 MAbs characterized previously and directed against SV were used for immunological comparison of SV and hPIV-1 isolates. Of the MAbs against hPIV-1, two reacted with phospho (P) protein, 11 with nucleocapsid protein (NP), 24 with haemagglutinin-neuraminidase (HN) protein and 19 with fusion (F) protein. With the aid of MAbs against hPIV-1 and those against SV showing cross-reactivity with hPIV-1, the structural proteins of hPIV-1 were identified; p83, p56, p34, gp74 and gp60 of hPIV-1 were identified as the P, NP, M, HN and F proteins, respectively. The MAbs against the P protein and NP of hPIV-1 showed limited cross-reactivity with SV, whereas they had high reactivity with clinical isolates of hPIV-1. Interestingly, one MAb against the NP of hPIV-1 lacked reactivity with clinical isolates which were isolated in the 1970s and 1980s. The MAbs against the HN of hPIV-1 also exhibited quite limited reactivity with SV and the clinical isolates; two groups of HN-specific MAbs showed almost no reactivity with the clinical isolates from the 1970s and 1980s, similarly to the NP-specific MAb. However, anti-HN MAbs belonging to the two groups showing specific activities (neuraminidase inhibition and haemolysis inhibition) reacted with almost all clinical isolates. On the other hand, although anti-F protein MAbs had limited reactivity with SV, they showed reactivity with almost all hPIV-1 isolates. The MAbs against the P, NP, M, HN and F proteins of SV also showed limited cross-reactivity with the clinical hPIV-1 isolates, and this reactivity was independent of the time and place of isolation, except for that of the F protein. These results confirm that although hPIV-1 is related to SV, it is antigenically distinct from it.

Antibodies, Monoclonal↗
PubMed1992

Fusion regulation proteins on the cell surface: isolation and characterization of monoclonal antibodies which enhance giant polykaryocyte formation in Newcastle disease virus-infected cell lines of human origin.

Newcastle disease virus (NDV)-infected HeLa and FL cells showed small polykaryocytes at about 24 h postinfection, while the addition of anti-FL-cell rabbit, rat, or mouse serum to the NDV-infected cells gave rise to giant polykaryocytes at 15 h postinfection. We isolated three monoclonal antibodies (MAbs) (4-5-1, 6-1-13, and 7-2-1) capable of enhancing giant polykaryocyte formation in NDV-infected HeLa cells. These MAbs immunoprecipitated gp80 or gp135, which were detected mainly on the surface of HeLa cells. A functionally intact F protein was essential for antibody-enhanced cell fusion, and hemagglutinating (receptor-binding) activity of HN protein was involved in the fusion at an early stage; that is, the MAbs enhanced NDV-mediated syncytium formation. These molecules were considered to have the ability to regulate NDV-mediated cell fusion and thus were designated fusion regulation protein (FRP)-1 (gp80) and FRP-2 (gp135). Anti-FRP MAbs enhanced the susceptibility of cells to fusion activity of NDV. Anti-FRP-1 MAbs reacted with a molecule on the surface of every cell derived from humans and monkeys but showed no cross-reactivity with mouse or hamster cells. FRP-2 could be detected in limited cell lines of human origin.

Animals↗
PubMedDate not supplied

Characterization of Bangor virus proteins by using monoclonal antibodies.

A new virus was isolated from a finch in quarantine in Northern Ireland in 1973. The virus had the morphological characteristics of a paramyxovirus, and was named Bangor virus (BaV). In order to identify the structural proteins of BaV and to investigate the biological characterization of the virus, 28 monoclonal antibodies (mAbs) directed against BaV were prepared. Eight of these mAbs reacted with the nucleocapsid protein (NP), 10 with hemagglutinin-neuraminidase (HN) protein, and 10 with fusion (F) protein. With the aid of these mAbs, the structural proteins of BaV were determined, namely, p52, gp74, gp63, and gp51 were identified as the NP, HN, F0, and F1 proteins, respectively. The biological activities of the mAbs directed against the envelope glycoproteins of BaV were examined. Intriguingly, it was found in the neutralization assay that four mAbs directed against the HN protein of BaV can enhance the fusion of HeLa cells infected with BaV, showing the presence of a potential third function of the HN protein that affects the fusion activity of the F protein. Furthermore, all of the anti-F protein mAbs showed neutralizing activity.

Animals↗