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T Hyypiä

Publications and source records attributed to T Hyypiä.

At least 19 recordsLinked to original sources
PubMed2002

Release of soluble ICAM-5, a neuronal adhesion molecule, in acute encephalitis.

BACKGROUND: Intercellular adhesion molecule (ICAM)-5 (telencephalin) is an adhesion molecule in telencephalic neurons of the mammalian brain that binds to the leukocyte integrin CD11a/CD18. The authors observed that human cerebral neurons also expressed ICAM-5 and that ICAM-5--mediated neuron--leukocyte binding in cultured hippocampal neurons. This led the authors to examine ICAM-5 expression during clinical CNS inflammation. METHODS: The authors found, by immunoblotting, a 115-kDa soluble form of ICAM-5 (sICAM-5) cleaved from the membrane-bound (130 kDa) ICAM-5, and established an ELISA assay to measure it. CSF samples of patients with acute encephalitis and MS were studied. RESULTS: sICAM-5 was increased in encephalitis (320 plus minus 107 ng/mL; n = 25), as compared with patients with MS (128 plus minus 10 ng/mL; n = 16) and control subjects without CNS disease (137 plus minus 6 ng/mL; n = 42) (p < 0.001). The concentration of sICAM-5 correlated with the performance in the immediate recall task (p = 0.013) and with the leukocyte count in the CSF (p = 0.02), especially in cases caused by herpes simplex virus (HSV) (r = 0.94; p = 0.002). CONCLUSIONS: sICAM-5 is cleaved from CNS into CSF during acute encephalitis, and it may mediate leukocyte--neuron interactions. sICAM-5 release from cerebral neurons may actively regulate immune responses and leukocyte adhesion during microbial neuroinvasion in humans during encephalitis.

Acute Disease↗
PubMed2002

Measles virus enhances the expression of cellular immediate-early genes and DNA-binding of transcription factor AP-1 in lung epithelial A549 cells.

In this work we investigated the effect of measles virus (MV) infection on the expression of immediate-early genes junB, c-jun and c-fos mRNA as well as AP-1 DNA-binding activity in the lung epithelial-like adenocarcinoma cell line A549. The transcription factor AP-1, which is a group of dimeric complexes of the Fos and Jun family proteins, is an important regulator in many cellular responses to different extracellular stimuli. Membrane cofactor protein CD46, which acts as a receptor for laboratory-adapted and vaccine strains of MV, has been reported to associate with beta1 integrin molecules, which are known to trigger signaling events and activate immediate-early genes. The expression of junB and c-jun mRNA was rapidly induced by MV. It was observed already at 1 h postinfection and detected again at the later phase of infection. Moreover, the expression of c-fos mRNA seemed to be weak and transient. The early induction was apparently associated with MV binding and CD46 clustering, whereas the later induction coincided with virus replication. MV infection also enhanced the activation of AP-1 DNA-binding. Our results suggest that changes in the expression of immediate-early genes and in the activation of AP-1 DNA-binding may have an important role in many cellular events detected in MV-infected cells.

Antigens, CD↗
PubMed2001

Measles virus activates NF-kappa B and STAT transcription factors and production of IFN-alpha/beta and IL-6 in the human lung epithelial cell line A549.

Epithelial cells of the respiratory tract are the primary targets of measles virus (MV) infection. In this work we have studied the effect of MV infection on the activation of transcription factors nuclear factor (NF)-kappa B and signal transducer and activator of transcription (STAT) and the production of cytokines in the lung epithelial A549 cell line. NF-kappa B and STAT activation were induced by MV in A549 cells as analyzed by electrophoretic mobility shift assay. NF-kappa B activation was rapid and it was not inhibited by the protein synthesis inhibitor cycloheximide, suggesting that MV directly activates NF-kappa B. In contrast, Stat1, Stat3, and interferon-stimulated gene factor 3 (ISGF3) DNA binding was induced by MV infection with delayed kinetics compared to NF-kappa B activation. MV infection also resulted in an efficient interferon (IFN)-alpha/beta and interleukin-6 production. Cycloheximide and neutralizing anti-IFN-alpha/beta antibodies inhibited MV-induced activation of Stat1, Stat3, and ISGF3 DNA binding in A549 cells. In conclusion, the results suggest that MV infection activates transcription factors involved in the initiation of innate immune responses in epithelial cells by two different mechanisms: directly by leading to NF-kappa B activation and indirectly via IFN-alpha/beta leading to STAT activation.

Animals↗
PubMed2001

Entry of human parechovirus 1.

Human parechovirus 1 (HPEV-1) is a prototype member of parechoviruses, a recently established picornavirus genus. Although there is preliminary evidence that HPEV-1 recognizes alpha(V) integrins as cellular receptors, our understanding of early events during HPEV-1 infection is still very limited. The aim of this study was to clarify the entry mechanisms of HPEV-1, including the attachment of the virus onto the host cell surface and subsequent internalization. In blocking experiments with monoclonal antibodies against different receptor candidates, antibodies against alpha(V) and beta(3) integrin subunits, in particular in combination, appeared to be the most efficient ones in preventing the HPEV-1 infection. To find out whether HPEV-1 uses clathrin-coated vesicles or other routes for the entry into the host cell, we carried out double-labeling experiments of virus-infected cells with anti-HPEV-1 antibodies and antibodies against known markers of the clathrin and the caveolin routes. At the early phase of infection (5 min postinfection [p.i.]) HPEV-1 colocalized with EEA1 (early endosomes), and later, after 30 min p.i., it colocalized with mannose-6-phosphate receptor (late endosomes), whereas no colocalization with caveolin-1 was observed. The data indicate that HPEV-1 utilizes the clathrin-dependent endocytic pathway for entry into the host cells. Interestingly, endocytosed HPEV-1 capsid proteins were observed in the endoplasmic reticulum and cis-Golgi network 30 to 60 min p.i. Depolymerization of microtubules with nocodazole inhibited translocation of the virus to the late endosomes but did not block HPEV-1 replication, suggesting that the RNA genome may be released early during the entry process.

Antigens, CD↗
PubMed2001

Parechoviruses, a novel group of human picornaviruses.

Parechoviruses are a recently established group of human viral pathogens. At the time of their first isolation, parechoviruses were classified among the enterovirus genus in the picornavirus family, but based on their different biological properties they were separated into their own genus. The type member is human parechovirus 1 (HPEV1), which frequently infects humans, in particular small children. The parechovirus genus also includes HPEV2 and the Ljungan virus, which was recently isolated from rodents, is a candidate for the group. Seroepidemiological studies have shown that the prevalence of HPEV1 antibodies is surprisingly high, exceeding 95% in adult populations. According to present data, HPEV1 causes mainly gastrointestinal and respiratory infections; however, severe disease conditions, such as myocarditis and encephalitis, have also been reported. HPEV2 infections appear to be rare, and it is currently not known whether the Ljungan virus can infect humans.

Adult↗
PubMed2000

Effects of echovirus 1 infection on cellular gene expression.

To obtain a view of the influence of enterovirus infection on host cell gene expression, multiple cellular mRNA levels were first investigated during echovirus 1 (EV1) infection in HOS palpha2AW cells using cDNA array analysis. Visible cytopathic effect and partial shut-off of host cell protein synthesis were observed 6-10 h after the EV1 infection. Simultaneously, approximately 2% of the investigated genes, among them immediate-early response genes and genes involved in apoptotic pathways and cell growth regulation, were activated over twofold and less than 0.5% of genes were downregulated. For comparison, the cellular effects of coxsackievirus B4 and poliovirus 1 infections were studied in HeLa-Ohio cells by cDNA arrays. Gene activation patterns detected in the host cells during the infection by the three enteroviruses were only partially similar.

Animals↗
PubMed2000

Molecular epidemiology and evolution of coxsackievirus A9.

Genetic relationships between 35 clinical isolates of coxsackievirus A9 (CAV9), collected during the last five decades from different geographical regions, were investigated by partial sequencing. Analysis of a 150 nucleotide sequence at the VP1/2A junction region identified 12 CAV9 genotypes. While most of the strains within each genotype showed geographical clustering, the analysis also provided evidence for long-range importation of virus strains. Phylogenetic analysis of a longer region around the VP1/2A junction (approximately 390 nucleotides) revealed that the designated genotypes actually represented phylogenetic lineages. The phylogenetic grouping pattern of the isolates in the analysis of the VP4/VP2 region was similar to that obtained in the VP1/2A region whereas analysis of the 3D region indicated a strikingly different grouping, which suggests that recombination events may occur in the region encoding the nonstructural proteins. Analysis of the deduced amino acid sequences of the VP1 polypeptide demonstrated that the RGD (arginine-glycine-aspartic acid) motif, implicated in the interaction of the virus with integrin, was fully conserved among the isolates.

Amino Acid Motifs↗
PubMed2000

Antigenic properties of human parechovirus 1.

Human parechoviruses 1 and 2 (HPEV1 and HPEV2, respectively), formerly known as echoviruses 22 and 23, have been assigned to a novel picornavirus genus on the basis of their distinct molecular and biological properties. To study the immunological characteristics of HPEV1 capsid proteins, antigenic analysis was carried out by a peptide scanning technique, which can be used to identify the immunogenic peptide sequences of a protein. Partially overlapping peptides, representing the capsid of HPEV1, were synthesized using a 12 aa window in a three residue shift and reactivity of rabbit and murine HPEV1 antisera against these peptides were tested. Using this method, an antigenic site in the VP0 polypeptide, recognized by both rabbit and murine antisera, was identified. The sequence of this region was conserved among HPEV1 clinical isolates obtained from Finland and the United States. Antiserum against this peptide region showed neutralizing activity against HPEV1 in cell culture. Because the C-terminal region of HPEV1 VP1 contains a functional RGD motif, the antigenicity of this region was also tested. By using the corresponding peptide antiserum, neutralization of HPEV1 was observed. Cross-neutralization between HPEV1 and coxsackievirus A9, an enterovirus with a similar RGD motif in VP1, was also detected.

Amino Acid Sequence↗
PubMed2000

Enterovirus RNA in serum is a risk factor for beta-cell autoimmunity and clinical type 1 diabetes: a prospective study. Childhood Diabetes in Finland (DiMe) Study Group.

Recent prospective studies have documented serologically an increased frequency of enterovirus infections in prediabetic children, indicating that these infections may initiate and accelerate the beta-cell damaging process several years before the clinical manifestation of type 1 diabetes. The aim of the present study was to establish whether these serological findings would be supported by the detection of enterovirus RNA in a unique prospective series of sera collected from prediabetic children 0-10 years before the manifestation of clinical type 1 diabetes. Reverse transcription followed by polymerase chain reaction employing highly conserved primers among enteroviruses were used to amplify enteroviral sequences. Viral RNA was found in 22% (11/49) of follow-up samples from prediabetic children but in only 2% (2/105) of those from controls (OR 14.9, P < 0.001). Persisting RNA positivity was not observed in any of these children. The presence of enterovirus RNA was associated with concomitant increases in the levels of autoantibodies against islet cells (OR 21.7, P < 0.01) and glutamic acid decarboxylase (OR 15.4, P < 0.05), but not in the levels of antibodies against insulin or the tyrosine phosphatase-like IA-2 protein. In contrast to the prediabetic children, those with newly diagnosed type 1 diabetes were negative for enterovirus RNA. The results thus complement previous serological data, suggesting that enterovirus infections are an important risk factor underlying type 1 diabetes and associated with the induction of beta-cell autoimmunity even years before symptoms appear.

Adolescent↗
PubMed1999

The crystal structure of coxsackievirus A9: new insights into the uncoating mechanisms of enteroviruses.

BACKGROUND: Coxsackievirus A9 (CAV9), a human pathogen causing symptoms ranging from common colds to fatal infections of the central nervous system, is an icosahedral single-stranded RNA virus that belongs to the genus Enterovirus of the family Picornaviridae. One of the four capsid proteins, VP1, includes the arginine-glycine-aspartate (RGD) motif within its C-terminal extension. This region binds to integrin alpha v beta 3, the only receptor for CAV9 to be conclusively identified to date. RESULTS: The crystal structure of CAV9 in complex with the antiviral compound WIN 51711 has been solved to 2.9 A resolution. The structures of the four capsid proteins, VP1 to VP4, resemble those of other picornaviruses. The antiviral compound is bound in the VP1 hydrophobic pocket, and it is possible that the pocket entrance contains a second WIN 51711 molecule. Continuous electron density for the VP1 N terminus provides a complete picture of the structure close to the fivefold axis. The VP1 C-terminal portion is on the outer surface of the virus and becomes disordered five-residues N-terminal to the RGD motif. CONCLUSIONS: The RGD motif is exposed and flexible in common with other known integrin ligands. Although CAV9 resembles coxsackie B viruses (CBVs), several substitutions in the areas implicated in CBV receptor attachment suggest it may recognise a different receptor. The structure along the fivefold axis provides new information on the uncoating mechanism of enteroviruses. CAV9 might bind a larger natural pocket factor than other picornaviruses, an observation of particular relevance to the design of new antiviral compounds.

Amino Acid Sequence↗
PubMed1999

A new picornavirus isolated from bank voles (Clethrionomys glareolus).

A previously unknown picornavirus was isolated from bank voles (Clethrionomys glareolus). Electron microscopy images and sequence data of the prototype isolate, named Ljungan virus, showed that it is a picornavirus. The amino acid sequences of predicted Ljungan virus capsid proteins VP2 and VP3 were closely related to the human pathogen echovirus 22 (approximately 70% similarity). A partial 5' noncoding region sequence of Ljungan virus showed the highest degree of relatedness to cardioviruses. Two additional isolates were serologically and molecularly related to the prototype.

Amino Acid Sequence↗
PubMed1999

Molecular detection and typing of human picornaviruses.

Picornaviruses include several important clinical pathogens which cause diseases varying from common cold to poliomyelitis and hepatitis. Introduction of RT-PCR methods for the detection of these viruses has significantly facilitated the diagnosis of picornavirus infections and elucidated their etiological role in clinical illnesses. Partial sequence analysis of the genomes has been used for typing of the viruses and in studies of molecular epidemiology of picornaviruses. These molecular approaches are likely to become the most predominant techniques for the diagnosis and epidemiological analysis, particularly in the enterovirus infections.

Genome, Viral↗
PubMed1999

Depletion of alphaV integrins from osteosarcoma cells by intracellular antibody expression induces bone differentiation marker genes and suppresses gelatinase (MMP-2) synthesis.

Integrin heterodimers sharing the common alphaV subunit are receptors for adhesion glycoproteins such as vitronectin and fibronectin. They are suggested to play an essential role in cell anchoring, differentiation, and survival. Here, we describe the construction of an expression plasmid coding for an intracellular single-chain antibody against alphaV integrin subunit. Saos-2 osteosarcoma cells transfected with this DNA construct showed an approximately 70-100% decrease in the cell surface expression of alphaVbeta3 and alphaVbeta5 integrins as shown by flow cytometry. Intracellular antibody expression had no effect on the mRNA levels of alphaV integrin. Pulse chase experiments of metabolically labeled integrins showed that the translation of precursor alphaV integrin subunit was not affected. However, the maturation of alphaV integrins as glycoproteins was slow suggesting that the transport from endoplasmic reticulum to Golgi complex was partially prevented. Depletion of alphaV integrins from Saos-2 cells led to a decreased ability to spread on fibronectin and vitronectin. Furthermore, the expression of osteoblast differentiation marker genes, alkaline phosphatase and osteopontin, was induced and concomitantly the expression of matrix metalloproteinase-2 decreased. Thus, alphaV integrins seem to be important regulators of osteosarcoma cell phenotypes. Our data also indicate that the expression of intracellular antibodies is an effective strategy to study the significance of specific integrins for cell phenotype and differentiation.

Alkaline Phosphatase↗
PubMed1999

Evidence of recombination among enteroviruses.

Human enteroviruses consist of more than 60 serotypes, reflecting a wide range of evolutionary divergence. They have been genetically classified into four clusters on the basis of sequence homology in the coding region of the single-stranded RNA genome. To explore further the genetic relationships between human enteroviruses and to characterize the evolutionary mechanisms responsible for variation, previously sequenced genomes were subjected to detailed comparison. Bootstrap and genetic similarity analyses were used to systematically scan the alignments of complete genomic sequences. Bootstrap analysis provided evidence from an early recombination event at the junction of the 5' noncoding and coding regions of the progenitors of the current clusters. Analysis within the genetic clusters indicated that enterovirus prototype strains include intraspecies recombinants. Recombination breakpoints were detected in all genomic regions except the capsid protein coding region. Our results suggest that recombination is a significant and relatively frequent mechanism in the evolution of enterovirus genomes.

Enterovirus↗
PubMed1999

Parechoviruses.

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5' Untranslated Regions↗