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V ter Meulen

Publications and source records attributed to V ter Meulen.

At least 73 records · Page 4Linked to original sources
PubMed1997

CD46 expression does not overcome the intracellular block of measles virus replication in transgenic rats.

The study of measles pathogenesis and the testing of improved vaccine candidates is hampered by the lack of a small animal model which is susceptible to infection by the intranasal route. With the identification of CD46 as a measles virus (MV) receptor, it was feasible to generate transgenic rats to overcome this problem. Although there was widespread expression of CD46 in the transgenic Sprague-Dawley rats, no measles-like disease could be induced after various routes of infection. The expressed transgenic protein was functionally intact since it mediated MV fusion and was downregulated by contact with MV hemagglutinin. In vitro studies revealed that CD46-expressing rat fibroblasts take up MV but do not allow viral replication, which explains the nonpermissiveness of the transgenic rats for in vivo infection.

Animals↗
PubMed1997

Regulation of glutathione and cell toxicity following exposure to neurotropic substances and human immunodeficiency virus-1 in vitro.

The aim of the present study was to assess the toxic potential of drugs of abuse and other neuropharmacological agents in the pathogenesis of AIDS dementia complex (ADC), the neurological complication of AIDS. Neuroblastoma and glioblastoma cell lines expressing the dopamine transporter, as well as primary macrophages exposed to human immunodeficiency virus-1 (HIV-1), were used to investigate the possibility of any synergistic effect between the mode of toxicity of such substances and virus exposure. The drugs of abuse used in our experiments were cocaine and morphine, which exert their action, among others, on the dopaminergic system. Effects were compared to treatment with dopamine itself and a typical dopaminergic drug used pharmaceutically, selegiline. In macrophage cultures, glutathione (GSH) was upregulated strongly after treatment with dopamine, morphine or selegiline, and this effect was enhanced when cells were pre-exposed to virus. This upregulation is discussed as a compensatory reaction to an oxidative signal. When hydrogen peroxide plus iron sulfate was used as a strong oxidant in macrophages, GSH concentrations decreased as a result of cell injury. Cell numbers remained constant in all treatment groups. In contrast, in both neuroblastoma and glioblastoma cell lines, the modulation of GSH concentrations by neurotropic substances was accompanied by significant cell loss, which was exacerbated by HIV-1 pretreatment. Selegiline did not change cell numbers when incubated alone. However, when incubated following treatment with HIV-1 cell death was highly significant. Ascorbic acid (AA), included as antioxidant, totally restored cell loss in cultures treated with dopamine. However, no effect was observed in combined treatment of AA and morphine or selegiline. The results demonstrate a synergistic role in cellular toxicity due to neurotropic substances and HIV-1, and suggest that neuropharmacological agents may contribute to the pathogenesis of ADC.

AIDS Dementia Complex↗
PubMed1996

Interaction of measles virus glycoproteins with the surface of uninfected peripheral blood lymphocytes induces immunosuppression in vitro.

A marked suppression of immune function has long been recognized as a major cause of the high morbidity and mortality rate associated with acute measles. As a hallmark of measles virus (MV)-induced immunosuppression, peripheral blood lymphocytes (PBLs) isolated from patients exhibit a significantly reduced capacity to proliferate in response to mitogens, allogens, or recall antigens. In an in vitro system we show that proliferation of naive PBLs [responder cells (RCs)] in response to a variety of stimuli was significantly impaired after cocultivation with MV-infected, UV-irradiated autologous PBLs [presenter cells (PCs]. We further observed that a 50% reduction in proliferation of RCs could still be observed when the ratio of PC to RC was 1:100. The effect was completely abolished after physical separation of the two populations, which suggests that soluble factors were not involved. Proliferative inhibition of the RCs was observed after short cocultivation with MV-infected cells, which indicates that surface contact between one or more viral proteins and the RC population was required. We identified that the complex of both MV glycoproteins, F and H, is critically involved in triggering MV-induced suppression of mitogen-dependent proliferation, since the effect was not observed (i) using a recombinant MV in which F and H were replaced with vesicular stomatitis virus G or (ii) when either of these proteins was expressed alone. Coexpression of F and H, however, lead to a significant proliferative inhibition in the RC population. Our data indicate that a small number of MV-infected PBLs can induce a general nonresponsiveness in uninfected PBLs by surface contact, which may, in turn, account for the general suppression of immune responses observed in patients with acute measles.

Animals↗
PubMed1996

U-373 MG glioblastoma and IMR-32 neuroblastoma cell lines express the dopamine and vesicular monoamine transporters.

The U-373 MG glioblastoma and the IMR-32 neuroblastoma cell lines were found to express the dopamine (DA) and vesicular monoamine transporters, using reverse transcriptase-polymerase chain reaction (RT-PCR). To further characterize the DA transporter, [3H]GBR-12935 binding and [3H]DA uptake studies were performed. Specific binding of [3H]GBR-12935 to U-373 MG and IMR-32 cells is saturable as saturation experiments indicated. Scatchard analysis revealed two binding sites on U-373 MG as well as on IMR-32 cells. The high-affinity sites exhibited a KD of 2.95 and 0.42 nM and a Bmax of 6.4 and 0.83 fmol/mg protein for U-373 MG and IMR-32 cells, respectively. The low-affinity sites exhibited a KD of 144 and 251 nM and a Bmax of 37.5 and 119 fmol/mg protein for the same cells, respectively. The high-affinity binding of both types of cells probably represents the "classic" DA uptake site identified in other studies from human and rat striatal membranes or synaptosomes, while the low-affinity binding may represent a mazindol-insensitive binding site (the "piperazine acceptor site"). [3H]DA uptake was 0.55 +/- 0.16 and 1.08 +/- 0.33 pmol/mg protein for U-373 MG and IMR-32 cells, respectively. Since the DA transporter has been implicated as an important site for drugs and toxins, the above-mentioned cell lines may be a useful tool in the study of the mechanism of action of DA transporter modulating substances.

Animals↗
PubMed1996

The effect of simian immunodeficiency virus infection in vitro and in vivo on the cytokine production of isolated microglia and peripheral macrophages from rhesus monkey.

Microglia are the major target for human immunodeficiency virus (HIV) infection within the central nervous system. Because only a few cells are productively infected, it has been suggested that an aberrant cytokine production by this cell population may be an indirect mechanism leading to the development of neurological disorders in HIV-infected patients. Therefore we decided to study the secretion pattern of several interleukins (IL) by microglial cells and peripheral blood macrophages isolated from uninfected and simian immunodeficiency virus (SIV)-infected Rhesus monkeys. We found that uninfected, unstimulated primate microglia produce more IL-6 and less TNF alpha than peripheral blood macrophages, but generate comparable levels of IL-1 beta and IL-8. After infection with SIV in vitro, synthesis of all cytokines tested is increased compared to uninfected cultures and to peripheral blood macrophages. Microglia isolated from infected animals produce more IL-8 and TNF alpha than the uninfected cultures and display a strongly increased capacity to secrete TNF alpha upon stimulation with lipopolysaccharide. In addition, production of IL-6 by in vivo-infected microglia increases with time in culture to very high levels despite the fact that only a few cells contained replicating virus. These findings clearly show that the cytokine production of microglia is impaired after SIV infection both in vitro and in vivo and that a low level of viral replication is sufficient for these alterations to occur. In conclusion, the results of this study further support a possible role of cytokines in the pathogenesis of neuro-AIDS.

Animals↗
PubMed1996

Expression of the human MxA protein is associated with hyperphosphorylation of VSV P protein in human neural Cells.

Constitutive expression of the type I interferon-inducible human cytoplasmic MxA protein has been shown to interfere with primary transcription of vesicular stomatitis virus (VSV) in tissue culture cells. As phosphorylation of the VSV P protein has been linked to its ability to stimulate viral transcription, we analyzed the phosphorylation status of this protein in human brain cells (U-87) stably transfected with MxA. We observed a general increase in cellular kinase activity in the presence of MxA, affecting both cellular proteins and VSV P protein. Phosphorylation of the latter was up to threefold higher both in vivo and in vitro. In vitro phosphorylation of recombinant VSV P protein could be enhanced in MxA-negative cell extracts after exogenous addition of recombinant His-MxA. Biochemical evidence and phosphorylation of a mutant P protein lacking the recognized casein kinase II (CKII) sites suggested that hyperphosphorylation of VSV P protein was not due to a stimulation of CKII. We thus propose that expression of MxA in human brain cells is associated with the stimulation of a cellular kinase that is active in phosphorylating both cellular target proteins and VSV P protein.

Casein Kinase II↗
PubMed1996

Receptor (CD46) modulation and complement-mediated lysis of uninfected cells after contact with measles virus-infected cells.

Recently, it has been observed that the infection of human target cells with certain measles virus (MV) strains leads to the downregulation of the major MV receptor CD46. Here we report that CD46 downregulation can be rapidly induced in uninfected cells after surface contact with MV particles or MV-infected cells. Receptor modulation is detectable after 30 min of cocultivation of uninfected cells with MV-infected cells and is complete after 2 to 4 h, a time after which newly synthesized MV hemagglutinin (MV-H) cannot be detected in freshly infected target cells. This contact-mediated receptor modulation is also induced by recombinant MV-H expressed by vaccinia virus and is inhibitable with antibodies against CD46 and MV-H. By titrating the effect with MV Edmonston strain-infected cells, a significant contact-mediated CD46 modulation was detectable up to a ratio of 1 infected to 64 uninfected cells. As a result of CD46 downregulation, an increased susceptibility of uninfected cells for complement-mediated lysis was observed. This phenomenon, however, is MV strain dependent, as observed for the downregulation of CD46 after MV infection. These data suggest that in acute measles or following measles vaccination, uninfected cells might also be destroyed by complement after contacting an MV-infected cell.

Animals↗
PubMed1995

Receptor usage and differential downregulation of CD46 by measles virus wild-type and vaccine strains.

Recently, two cell surface molecules, CD46 and moesin, have been found to be functionally associated with measles virus (MV) infectivity of cells. We investigated the receptor usage of MV wild-type, subacute sclerosing panencephalitis, and vaccine strains and their effect on the down-regulation of CD46 after infection. We found that the infection of human cell lines with all 19 MV strains tested was inhibitable with antibodies against CD46. In contrast, not all strains of MV led to the downregulation of CD46 following infection. The group of CD46 non-downregulating strains comprised four lymphotropic wild-type isolates designated AB, DF, DL, and WTF. Since the downregulation of CD46 is caused by interaction with newly synthesized MV hemagglutinin (MV-H), we tested the capability of recombinant MV-H proteins to downregulate CD46. Recombinant MV-H proteins of MV strains Edmonston, Halle, and CM led to the down-regulation of CD46, whereas those of DL and WTF did not. This observed differential downregulation by different MV strains has profound consequences, since lack of CD46 on the cell surface leads to susceptibility of cells to complement lysis. These results suggest that lymphotropic wild-type strains of MV which do not downregulate CD46 may have an advantage for replication in vivo. The relatively weak immune response against attenuated vaccine strains of MV compared with wild-type strains might be related to this phenomenon.

Animals↗
PubMed1995

A comparison of nucleotide sequences of measles virus L genes derived from wild-type viruses and SSPE brain tissues.

The nucleotide sequences of the large protein (L) gene derived from two wild-type measles viruses (MV) and two SSPE brain-derived viruses have been determined. All sequences have single large open reading frames encoding 2183 amino acid residues. The deduced L proteins are well conserved and the proposed functional domains which have been identified for rhabdo- and paramyxoviruses are completely conserved in all strains. The degree of variability of L proteins is the lowest of all structural proteins of MV, reflecting its role in virus reproduction and persistence. Biased hypermutation was not observed in the L genes derived from SSPE brain tissue. None of the nucleotide changes can be associated with the attenuated phenotype of the Edmonston vaccine viruses.

Amino Acid Sequence↗
PubMed1995

Measles virus-induced down-regulation of CD46 is associated with enhanced sensitivity to complement-mediated lysis of infected cells.

CD46, the major component of the measles virus (MV) receptor complex and a member of the regulators of complement activity (RCA) gene cluster, is down-regulated in MV-infected cells. We investigated whether the reduction of surface CD46 correlates with enhanced sensitivity of lymphoid and monocytic cells to lysis by activated complement. On human U937 cells, acutely or persistently infected with MV-Edmonston (ED) vaccine strain, infection-dependent down-regulation of CD46 confers sensitivity to activated complement, regardless of the pathway of activation and the specificity of the activating antibodies. Interestingly, down-regulation of CD46 alone is sufficient to confer susceptibility of cells to complement lysis despite the continued surface expression of other RCA proteins such as CD35 and CD55. In primary cultures, both peripheral blood lymphocytes and macrophages are efficiently lysed in the presence of complement activated via the alternative pathway after MV infection. In contrast to the MV-ED infection, infection of cells with the lymphotropic MV wild-type strain WTF does not down-regulate CD46. Cells infected with MV-WTF do not exhibit enhanced susceptibility to complement lysis. These data suggest that MV strains similar to WTF that do not down-regulate CD46 may have an enhanced potential for replication and dissemination within the human host, whereas complement-mediated elimination of cells infected with CD46-down-regulating strains of MV, such as ED, may limit the spread of MV infection, and could thus represent an attenuating factor for MV.

Antigens, CD↗
PubMed1995

Detection of human coronavirus 229E-specific antibodies using recombinant fusion proteins.

Human coronaviruses are known to be a common cause of respiratory infections in man. However, the diagnosis of human coronavirus infections is not carried out routinely, primarily because the isolation and propagation of these viruses in tissue culture is difficult and time consuming. The aim of this study was to evaluate the use of recombinant, bacterial expressed proteins in the serodiagnosis of coronavirus infections. Two proteins were examined: the human coronavirus 229E nucleocapsid protein (N), expressed as a fusion protein in the vector pUR and the coronavirus 229E surface glycoprotein (S), expressed as a fusion protein in the vector pROS. The recombinant proteins were used as antigens in Western blot (WB) assays to detect the 229E-specific IgG antibodies and the results were compared with a standard serological method, indirect immunofluorescence. Serum samples of 51 paediatric patients, suffering from acute respiratory illness, and 10 adults, voluntarily infected with human coronavirus, were tested. The serum samples of the adult group had coronavirus-specific IgG antibodies in both test systems. In contrast, only 8/51 sera of the paediatric group were positive for coronavirus-specific IgG by both WB and IF and 20/51 sera were positive by WB, but not by IF. The overall incidence of human coronavirus infections in the paediatric age group was 55% evaluated by WB analysis and 16% evaluated by IF. This study shows that recombinant human coronavirus 229E proteins are suitable reagents for the epidemiological screening of coronavirus 229E infections.

Adult↗
PubMed1995

Pathogenetic aspects of measles virus infections.

In this review we briefly summarise virological and immunological aspects of acute and persistent measles virus (MV) infections as found in man and further investigated in animal models and tissue culture. Several mechanisms contributing to MV persistence are discussed. Recent findings, especially the analysis of CD46 and moesin as receptor acting molecules for MV, correlate well with the tropism of MV and open new fields for the investigation of MV associated immunosuppression and central nervous system (CNS) complications.

Animals↗
PubMed1995

Recombinant bacille Calmette-Guérin priming against measles.

Live attenuated measles virus (MV) vaccines are ineffective in young infants because of neutralization by maternal antibody. An immunization strategy that may permit priming for T cell memory for MV in infants at or shortly after birth uses recombinant bacille Calmette-Guérin expressing the full-length MV nucleocapsid (N) protein (rBCG::N). C3H/He mice immunized with rBCG::N developed T cell responses and ELISA antibodies to the N protein and low levels of neutralizing antibody after intracranial infection with MV strain CAM/R40. There was considerable reduction in the virus titer recovered from brain homogenates, a decrease in the incidence and severity of histologic encephalitis, and a decrease in mortality in rBCG::N-printed C3H/He mice compared with control mice. Given the limitations of existing live attenuated MV vaccines, these results encourage the further testing of rBCG::N vaccines in primate models.

Animals↗
PubMed1995

Temporal and geographical distribution of measles virus genotypes.

The nucleotide sequence encoding the C terminus of the nucleocapsid protein of measles virus (MV) is the most variable in the genome. The sequence of this region is reported for 21 new MV strains and for virus RNA obtained from cases of subacute panencephalitis (SSPE) tissue. The nucleotide sequence of a total of 65 MV strains has been analysed using the CLUSTAL program to determine the relationships between the strains. An unrooted tree shows that eight different genotypes can be discerned amongst the sequences analysed so far. The data show that the C-terminal coding sequence of the nucleocapsid gene, although highly variable between strains, is stable in a given strain and does not appear to diverge in tissue culture. It therefore provides a good 'signature' sequence for specific genotypes. The sequence of this region can be used to discriminate new imported viruses from old 'endemic' strains of MV in a geographical area. The different genotypes are not geographically restricted although some appear to be the mainly 'endemic' types in large areas of the world. In global terms there appears to be at least four cocirculating genotypes of MV. The low level of divergence in the Edmonston lineage group isolated before 1970 indicates that some isolates are probably laboratory contaminants. This applies to some SSPE isolates such as the Hallé, Mantooth and Horta-Barbosa strains as well as some wild-type isolates from that period.

Amino Acid Sequence↗
PubMed1995

Moesin, and not the murine functional homologue (Crry/p65) of human membrane cofactor protein (CD46), is involved in the entry of measles virus (strain Edmonston) into susceptible murine cell lines.

Membrane cofactor protein (CD46) has been firmly established as the major high affinity receptor for measles virus (MV). In addition, another protein, moesin, has been shown to be linked with the susceptibility of human cells to MV infection. Murine cells are largely resistant to MV infection, although a number of cell types can be productively infected. As murine cells do not express CD46 an additional mechanism for the uptake of MV is likely. Murine cells possess a functional homologue of CD46 (Crry/p65) in addition to murine moesin, which has nucleotide and amino acid homology to human moesin. We report that anti-moesin monoclonal antibodies 119 and 38/87 reduce the number of infectious centres attributed to MV in murine cell lines NS20Y and L929, whereas polyclonal antisera specific for Crry/p65 and CD46 had no effect on MV infection of these cells. We suggest that moesin may be important in the non-CD46-mediated uptake of MV strain Edmonston by susceptible murine cell lines.

Animals↗
PubMed1995

Differential downregulation of CD46 by measles virus strains.

Recently, we found that several lymphotropic wild-type isolates of measles virus (MV) did not lead to the downregulation of CD46 following infection. We hypothesized that either the site of virus isolation, e.g., throat swab versus peripheral blood mononuclear cells, or the cell type used for the isolation may exert selective pressure on a mixed population of viruses, resulting in isolates with the differential properties observed. This hypothesis has been tested by simultaneously isolating MV from a throat swab and peripheral blood mononuclear cells from a single patient by cultivation on B95 and Vero cells. We report that neither the source of MV nor the cell type used for isolation directly influenced the capacity for CD46 modulation of these MV isolates.

Animals↗