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T Hyypiä

Publications and source records attributed to T Hyypiä.

At least 19 recordsLinked to original sources
PubMed1992

A distinct picornavirus group identified by sequence analysis.

Although echovirus 22 is presently classified as a member of the enterovirus group in the family of picornaviruses, it has been reported to have exceptional biological properties when compared with other representatives of the group. We have determined the complete nucleotide sequence of the echovirus 22 (Harris strain) genome, which appears to be significantly different from all the other studied picornaviruses. However, the organization of the genome [7339 nucleotides, excluding the poly(A) tract] is similar to that of previously sequenced picornaviruses. This genome includes a 5' untranslated region, relatively well-conserved when compared with aphtho- and cardioviruses, followed by an open reading frame coding for a 2180-amino acid-long polyprotein. The amino termini of capsid polypeptides VP1 and VP3 were determined by direct sequencing, and the other proteolytic cleavage sites in the polyprotein were predicted by comparison with other picornavirus proteins. The amino acid identities of echovirus 22 polypeptides with the corresponding proteins of other picornaviruses are in the 14-35% range, similar to those percentages seen when representatives of the five picornavirus groups (entero-, rhino-, cardio-, aphtho-, and hepatoviruses) are compared. Our results suggest that echovirus 22 belongs to an independent group of picornaviruses.

Amino Acid Sequence↗
PubMed1992

Mumps and Coxsackie B3 virus infection of human fetal pancreatic islet-like cell clusters.

Islet-like cell clusters (ICCs) prepared from human fetal pancreases were infected with mumps or coxsackie B3 virus. Double-labeled antibody technique showed that the viruses infected both insulin-secreting and other pancreatic cells and that secretion of immunoreactive insulin into the culture medium of the mumps virus-infected cells had already ceased on day 7. The mumps virus-infected ICC clusters produced virus for 14 days, and the mumps virus antigen was detected in the ICCs through the whole 22-day observation period. The coxsackie B3 virus-infected ICCs contained cells highly positive for viral antigen during the first 2 days after infection, and the infectious virus was detected in the culture medium for 22 days. This in vitro model indicates that mumps and coxsackie B3 viruses infect human fetal pancreatic endocrine cells and are able to alter beta-cell function. Coxsackie B3 virus infection in ICCs is lytical and seems to lead to rapid cell destruction, but long-lasting, restricted mumps virus infection in human fetal pancreatic ICCs offers an interesting model to study the effects of viral infection in the endocrine pancreas and beta cell.

Cells, Cultured↗
PubMed1992

The nucleotide sequences of wild-type coxsackievirus A9 strains imply that an RGD motif in VP1 is functionally significant.

We have shown previously that, compared to other enteroviruses, the coxsackievirus A9 (CAV-9) prototype strain, Griggs, contains a C-terminal extension to the capsid protein VP1 and that within this extension there is an RGD (arginine-glycine-aspartic acid) motif. To determine whether these features are found in other CAV-9 strains and therefore analyse whether they are likely to be functionally important, we have determined the nucleotide sequence of the appropriate region from five strains, isolated over a 25 year period. The results indicate that there is considerable diversity between the strains and there is little correlation between nucleotide sequence identity and date of isolation. All isolates exhibit the VP1 extension and although its amino acid sequence is otherwise variable, the RGD motif is common to all. This conservation of sequence, within a region which can otherwise vary, implies that the RGD sequence must be functionally significant. The VP1 extension shows similarity to sequences found in foot-and-mouth-disease virus strains and to part of the precursor of the cellular protein, human transforming growth factor beta, and the possible significance of these observations is discussed.

Amino Acid Sequence↗
PubMed1992

Effect of interferon-alpha on measles virus replication in human peripheral blood mononuclear cells.

We analyzed the effect of exogenous human leukocyte interferon (IFN)-alpha on measles virus (MV) replication in human peripheral blood mononuclear cells (PBMC). The release of infectious virus was progressively reduced by increasing concentrations of IFN-alpha, and blocked with an IFN-alpha concentration of 1000 U/ml. In order to detect a possible target of this inhibitory effect, viral transcription and translation events were analyzed. The synthesis of MV mRNAs was reduced, but not blocked, in the presence of IFN-alpha. However, this effect was not specific on the viral RNAs, but due to a general inhibition of RNA synthesis in IFN-treated PBMC. The expression of viral polypeptides was also inhibited in a dose-dependent manner by exogenous IFN-alpha, but a low level of protein synthesis was detected by both Western blotting and immunofluorescence techniques, even with the maximum amount of IFN-alpha used (1000 U/ml). These findings account for a partial maintenance of the viral replicative cycle, even when the production of infectious virus is blocked. Moreover, the effect of IFN-alpha is not specifically targeted on the virus macromolecular synthesis.

Base Sequence↗
PubMed1991

Inclusion body myositis and paramyxoviruses.

Inclusion body myositis (IBM) is a distinct type of muscle disease. The characteristic electron microscopic findings, intranuclear or intracytoplasmic inclusions composed of microtubular filaments, morphologically resemble paramyxovirus nucleocapsids. These findings and the reported immunoreactivity of the inclusions with mumps virus antibodies have suggested that inclusion body myositis is a chronic virus infection. We analyzed skeletal muscle specimens from three patients with characteristic light microscopic features and electron microscopically verified inclusions of IBM by immunocytochemistry using antibodies raised against members of the paramyxovirus group, and by in situ hybridization with a cRNA probe representing the mumps virus nucleocapsid gene. The specificity of the reactions was demonstrated with infected and uninfected cultured cells. No immunocytochemical staining or hybridization signal was observed in biopsy specimens from IBM patients. These findings speak against a paramyxovirus etiology of IBM.

Aged↗
PubMed1991

Early signal transduction in measles virus-infected lymphocytes is unaltered, but second messengers activate virus replication.

In order to understand measles virus-lymphocyte interactions, we have started to analyze factors and events which regulate measles virus infection in peripheral blood mononuclear cells (PBMC). We analyzed the initiation of cell proliferation, induced by phytohemagglutinin, in infected and control PBMC by measuring intracellular free Ca2+ by using fura-2. Measles virus-infected and control PBMC responded similarly with an increase in the amount of cytosolic free Ca2+, indicating that the early activation events are not affected and are not involved in immunosuppression. The activation signals, Ca2+ and protein kinase C, induced specifically and independently by Ca ionophore A23187 or 12-O-tetradecanoylphorbol-13-acetate (TPA), changed the restricted measles virus infection to a productive one. The combination of TPA and A23187 was the most potent activator of measles virus replication. TPA and A23187 operate through different activation mechanisms, and it is evident that measles virus replication depends on the activation of cellular signal pathways. Depletion of adherent cells enhanced virus replication, especially at the early stage of infection, indicating the inhibitory role of monocytes. Monocytes were strongly infected, but they supported complete measles virus replication only at a very low level, and virus replication could not be enhanced with TPA and/or A23187.

Adult↗
PubMed1991

RGD-dependent entry of coxsackievirus A9 into host cells and its bypass after cleavage of VP1 protein by intestinal proteases.

The recently reported nucleotide sequence of coxsackievirus A9 (CAV-9) showed that unlike other enteroviruses, CAV-9 has an insertion of about 17 amino acids at the C-terminal end of VP1 (K. H. Chang, P. Auvinen, T. Hyypiä, and G. Stanway, J. Gen. Virol. 70:3269-3280, 1989). This sequence includes the RGD (arginine-glycine-aspartic acid) motif which is known to be important in certain protein-protein interactions. We studied the inhibitory effect of RGD-containing peptides in the attachment of CAV-9 to African green monkey kidney cells. A peptide corresponding to the RRGDM sequence derived from the inserted segment of CAV-9 was found to block virus attachment effectively, and the inhibition was dose dependent. Substitution of glutamic acid for the homologous aspartic acid completely abolished the inhibitory effect, indicating great specificity of the action. During replication in the gut, all enteroviruses are exposed to host proteolytic enzymes. Exposure of CAV-9 to purified trypsin or human intestinal fluid resulted in selective cleavage of the VP1 capsid protein. Intact and trypsin-cleaved VP1 proteins gave identical N-terminal sequences, indicating that cleavage of VP1 takes place near the C terminus. Attachment of proteolytically cleaved infectious CAV-9 to green monkey kidney cells was not prevented by RGD-containing peptides, indicating that cleaved CAV-9 is able to bypass RGD-dependent entry. The altered receptor specificity of proteolytically cleaved viruses may have important consequences in the pathogenesis of enteric infections.

Amino Acid Sequence↗
PubMed1990

Identification of rhinoviruses by cDNA probes.

We have used nucleic acid hybridization for the detection and grouping of human rhinoviruses (HRV) according to their genetic relationships. Fifteen rhinovirus reference strains, seventy-one clinical isolates and four enteroviruses were propagated in cell cultures, spotted onto membrane filters and hybridized with radioactively labelled cDNA probes covering different parts of the genomes of HRV-1B, HRV-2, HRV-14, HRV-85 and HRV-89. When the rhinovirus and enterovirus reference strains were tested, the 5' probe of HRV-2 hybridized with thirteen of the fifteen HRV reference strains, with poliovirus type 3 and with ECHO virus 11. The HRV-14 5' probe reacted with eleven HRV reference strains and with all the enteroviruses studied. Sixty-nine of the 71 clinical isolates were recognised by the HRV-2 5' probe, whereas the HRV-14 probe from the same part of the genome hybridized with 54 field isolates. One of the two isolates that remained negative with the HRV-2 5' probe was detected with the HRV-2 probe that derived from the P2 region of the genome, and the other isolate was not detected by any of the probes. Probes from other parts than the 5' end of the genome were generally more specific, and clusters could be formed based on the reactivity of the HRV strains with these probes.

DNA Probes↗
PubMed1990

Echoviruses include genetically distinct serotypes.

We have studied the genetic relationships of echoviruses using nucleotide sequencing and hybridization analysis. The nucleotide sequence of the echovirus 11 (EV11) P2 and P3 regions, which encode the nonstructural proteins, was shown to resemble closely those of coxsackie B viruses (CBV) and coxsackievirus A9 (CAV9). EV11, CBV and CAV9 have a similar organization in the 3' non-coding region when compared to polioviruses and CAV21. In contrast, the 3' end of EV22 shares only minimal sequence homology with other sequenced enteroviruses, and the 3' non-coding region has a unique secondary structure. Thirty-three echovirus reference strains were tested by nucleic acid hybridization using cDNA probes from the genomes of EV6, 11, 18 and 22. It was shown that a great majority of the strains belongs to the same subgroup as serotypes 6, 11 and 18, whereas EV22 and EV23 are genetically not closely related to this major subgroup.

Amino Acid Sequence↗
PubMed1990

Rapid quantitation of DNA spot hybridization by flatbed scintillation counting.

The flatbed scintillation counting system (Betaplate) was used for quantitative measurement of the radioactive hybridization signal in detection of adenovirus and papillomavirus DNA in clinical specimens. In this method, 96 samples on a nylon membrane can be handled as a single entity throughout the hybridization and counting procedure. The technique is sensitive, rapid, and convenient in routine use when compared with conventionally applied methods for the numerical analysis of hybridization results. The assay principle allows simultaneous testing of large numbers of specimens.

Adenoviridae Infections↗
PubMed1990

Mumps, enteroviruses, and human acute pancreatitis.

The presence of mumps virus and enterovirus RNA was studied by in situ hybridization in 15 surgical biopsy specimens from patients with acute pancreatitis. 35S-Labeled cRNA probes, detecting the 5' end of the poliovirus type 3, a 1.1-kb fragment of the polymerase gene region of coxsackievirus B3, and mumps virus mRNA, encoding the nucleocapsid protein, were used. The controls consisted of mumps virus-infected and uninfected cultured cells, normal human and mouse pancreatic tissue, and mouse tissue from experimental coxsackievirus B3-induced pancreatitis. No specific hybridization signal was observed in any of the acute pancreatitis cases. It is concluded that neither mumps virus nor enteroviruses tested were present in pancreatic tissue of advanced human acute pancreatitis.

Acute Disease↗
PubMed1990

In situ detection of enterovirus genomes in mouse myocardial tissue by ribonucleic acid probes.

We have applied a sensitive in situ hybridization method for the detection of coxsackievirus RNA in myocardial tissue. Two radioactive cRNA probes were used: an RNA transcript representing the 5' end of poliovirus 3 which recognizes a highly conserved region among enteroviruses and an RNA transcript of a 1.1 kb fragment from the polymerase gene region of coxsackievirus B3. The reactivity of these probes was tested by dot-blot hybridization against a panel of enteroviruses. Formaldehyde-fixed and paraffin-embedded tissue of experimentally coxsackievirus B3 infected mice was analyzed for the localization of virus RNA. Both the probes gave signals in mouse myocardial cells, disseminated evenly in the heart tissue 7 days postinfection. At this time point, hybridization-positive cells and inflammatory reaction were mainly found in different areas that may be due to the inability of the immune system to recognize the infected cells before cytolysis. The samples were still positive when fixed 52 hours postmortem indicating that virus RNA is in a relatively stable form in the cells.

Animals↗
PubMed1989

Genetic diversity of enterovirus subgroups.

Enterovirus serotypes were studied using nucleic acid hybridization and nucleotide sequence analysis. A great majority of enteroviruses could be roughly divided into two larger subgroups the first consisting of poliovirus and certain coxsackievirus A serotypes. The second subgroup included coxsackie B viruses, most ECHO viruses, enterovirus 71 and representatives of coxsackie A viruses. Enterovirus 70 showed low homology to the viruses in both groups. Interestingly, ECHO virus 22 failed to react with any of the hybridization probes indicating a relatively distant relationship. The close relationship between coxsackie B and ECHO viruses as well as between polio and certain coxsackie A viruses was also evident when nucleotide sequences of the 3' end noncoding parts were compared.

Base Sequence↗
PubMed1989

Production of viral antibodies in vitro by CSF cells from mumps meningitis and multiple sclerosis patients.

Cerebrospinal fluid (CSF) cells from 4 mumps meningitis and 11 multiple sclerosis (MS) patients were cultured in vitro for 7 days with and without pokeweed mitogen (PWM) stimulation. The cells produced varying amounts of IgG without stimulation and no significant increase of IgG synthesis was observed after PWM stimulation. Antibodies against mumps, measles, rubella, herpes simplex, and adeno viruses were measured in the supernatants of the cultures by a sensitive enzyme immunoassay. In the mumps meningitis patients, the largest amount of antibody was against mumps virus but low amounts of antibodies with other specificities were also synthesized by CSF cells of one patient. The most commonly detected specificities in MS patients were against measles and rubella viruses, whereas antibodies against adeno and mumps viruses were detected in only one CSF cell supernatant. No antibodies produced against herpes simplex virus in vitro were detected in any of the supernatants. The amounts of viral antibodies produced in vitro and intrathecally were only partially correlated.

Antibodies, Viral↗
PubMed1989

Identification of human picornaviruses by nucleic acid probes.

Human picornaviruses include rhinoviruses and enteroviruses which are responsible for both common and severe clinical diseases. Rhinoviruses are a frequent cause of respiratory infections while members of enterovirus subgroups, polio, coxsackie and ECHO viruses are often responsible for infections of the central nervous system, myocarditis, myositis etc. Human picornaviruses consist of nearly two hundred serotypes and therefore their specific identification after virus isolation, or the diagnosis based on the detection of immune response in patients, is problematic and does not usually provide virological diagnosis at the acute phase of illness. New methods for detection of picornavirus genomic RNA together with increasing knowledge of the nucleotide sequences of this virus group offer interesting possibilities for diagnostic procedures. Spot hybridization, in situ hybridization and enzymatic amplification of specific sequences have successfully been used for this purpose. Probes covering the 5' non-coding part of the genome, and also sequences derived from the region coding for non-structural proteins, can be used as broadly reacting reagents in picornavirus detection. Specific sequences are mainly found in the capsid protein region of the genome. cDNA probes and synthetic oligonucleotides are useful in rapid identification of picornaviruses after amplification in cell cultures and in epidemiological analysis. The biochemical amplification methods may enable recognition of picornaviruses directly in clinical samples in the near future. In situ hybridization methods have been of special interest because they can be used to reveal the presence of enterovirus genomes in biopsy specimens from e.g. affected heart muscle in patients with myocarditis and cardiomyopathy.

Animals↗