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Biomedical subjects

A Rhodes-Feuillette

Publications and source records attributed to A Rhodes-Feuillette.

36 records · Page 2Linked to original sources
PubMed1983

Circulating interferon in cytomegalovirus infected bone-marrow-transplant recipients and in infants with congenital cytomegalovirus disease.

In a study concerning five CMV-infected bone-marrow-transplant recipients, five congenital CMV diseases and appropriate controls, presence of high levels of circulating interferon (IFN) was demonstrated exclusively during the course of CMV disease. This interferon was predominantly "immune" or gamma interferon (gamma-IFN). These results suggest that during CMV disease the interferon compartment of the immune response is modified.

Adult↗
PubMed1983

Effect of human interferon on type D retroviruses multiplication in chronically infected cell lines.

A study was made on the effect of human interferon (HuIFN) on the synthesis and release of type D viruses (MPMV and SMRV) by chronically infected human lines. Interferon at concentrations of 50 IU/ml lead to an inhibition of the extracellular virus production by about 50%-80% as measured by virus-associated reverse transcriptase activity, by metabolic labeling of the virus with (3H) uridine or (3H) amino acids, or by electron microscopy counting of particles. The profiles of intracellular viral proteins, as visualized by radioimmunoprecipitation and electrophoresis, were not different in control or IFN-treated cells and the yield of intracellular protein p27 stayed unchanged or was slightly increased. Electron microscopy of thin sections taken from the control and IFN-treated cells revealed no difference in any subcellular structures including that of the viruses. However, electron microscopic examination of IFN-treated cells showed an increased number of either budding particles and intracytoplasmic precursors (two- to five-fold) or mature virus particles (four- to ten-fold) on the cell surface of the IFN-treated cells. These results indicate that IFN inhibits further developments of MPMV and SMRV replication as was described for type C and B retroviruses.

Animals↗
PubMed1983

Characterization of RNase H activity associated with reverse transcriptase in simian foamy virus type 1.

Spumavirinae or foamy viruses have been shown to have a characteristic RNA-dependent DNA polymerase activity. We demonstrate here the existence of an RNase H activity that copurifies with the 81-kilodalton monomeric polypeptide, which carries the RNA-dependent DNA polymerase activity of simian foamy virus type 1. RNase H degrades RNA hybrid substrates; however, it does not solubilize single-stranded RNAs. Inactivation assays with heat, high levels of bivalent cations, ethidium bromide, and sodium fluoride suggest that the RNase H catalytic site could be topologically independent from the DNA polymerase catalytic site.

Animals↗
PubMed1982

Reverse transcriptase from simian foamy virus serotype 1: purification and characterization.

Chromatography on heparin-Sepharose, known for its affinity for nucleotide-binding polypeptides, was used to purify the viral RNA-dependent DNA polymerase (reverse transcriptase) from the core polypeptides of simian foamy virus type 1. This procedure allowed the recovery of highly purified enzyme with a high specific activity. The average molecular weight of this monomeric enzyme is 81,000 and is thus comparable to that found for other known primate retroviruses. Reverse transcriptase activity of simian foamy virus type 1 requires a ribonucleotide template as a primer or otherwise a DNA with 3'-OH ends. Other optimal conditions of activity are reviewed. Heat inactivation studies led to the concept of an enzyme with two loci, one specific for the substrate and the other for the template-primer.

Hot Temperature↗
PubMed1981

Biochemical characterization of simian foamy virus type i.

Simian syncitium-forming ("foamy") virus type I (SFV1) was characterized biochemically. RNA was extracted from purified virus either with 0.1 per cent SDS or by the standard phenol-chloroform method. By both techniques a main component of 65-70S was found. Denaturation of the 65-70S RNA by heat resulted in a shift of the sedimentation coefficient mainly to a 30-35S component. Electrophoresis on a composite polyacrylamide gel demonstrated the existence of three minor RNA's: 8S, 5S and 4S respectively. PAGE-SDS analysis of disrupted purified virions enabled the separate migration of five viral proteins and the identification of two main proteins: a 30 kd polypeptide and a 70 kd polypeptide.

Animals↗
PubMed1981

Study of a human heteroploid cell line cryptically infected by a murine oncornavirus.

This report concerns the establishment of a human cell line cryptically infected by a murine leukemia virus (MuLV). This cell line, named J112, is characterized by the presence of genetic viral information in a majority of cells as demonstrated by immunological and virological methods, and by the absence of detectable viral activity in the supernatant culture fluids. Nevertheless, electron microscopy demonstrated the presence of a small number of particles which have the morphology of immature type C particles. We discuss the importance of this experimental model in relationship with non-producing (NP) infections of human cells by oncogenic retroviruses.

Cell Line↗
PubMed1979

Effect of interferon on chronic infection of human cells by xenotropic type-C viruses.

Different preparations of human interferon inhibit virus production in human cells chronically infected by a variety of type-C xenotropic viruses. Some of these viruses have been incriminated in the development of leukemia in primates. The characteristics of blocking of viral multiplication are similar to those described for the effect of mouse interferon on ecotropic viruses. The amount of free virus in culture supernatants is strongly decreased while intracellular protein p30 stays unchanged or is slightly increased. On the other hand, the inhibitory effect is reversible. The withdrawal of interferon results in a rapid increase in virus production as detectable in supernatant fluids. In the light of these results it is suggested that human interferon might be useful in the treatment of some blood malignancies suspected of being related to infection with xenotropic type-C viruses.

Animals↗
PubMed1979

Isolation and characterization of a new simian foamy virus serotype from lymphocytes of a Papio cynocephalus baboon.

A new type of syncytium-forming (foamy) virus was isolated from peripheral lymphocytes of a Papio cynocephalus baboon after cocultivation with a rhesus monkey cell line. The isolate was characterized by cytopathogenic effect, host range, electron microscopy, reverse transcriptase activity and physical and chemical properties. Seroneutralization tests indicate that the new isolate is antigenically distinct from the other nine known simian foamy virus serotypes.

Animals↗
PubMed1979

Effect of levamisole on interferon production by PHA-stimulated human leukocyte cultures.

Mononuclear leukocytes of 10 normal blood donors were cultured in vitro and treated with phytohemagglutinin (PHA-P) and/or levamisole. Interferon-like activity was investigated in the supernatant fluids of the cultures, using VSV as challenge virus. In most of the cases the PHA-stimulated interferon-like activity was slightly but significantly enhanced by levamisole. The antiviral activity produced in the supernatant fluids was characterized as interferon since it was trypsin sensitive, species specific and inhibited by specific antiserum. This interferon has the characteristic sensitivity to PH2 of immune interferon.

Cells, Cultured↗
PubMedDate not supplied

Effects of human recombinant alpha and gamma and of highly purified natural beta interferons on simian Spumavirinae prototype (simian foamy virus 1) multiplication in human cells.

The present study demonstrates the inhibitory effect of human recombinant interferons (r-Hu-IFN) alpha and gamma, and that of highly purified natural human interferon beta on the replication of simian foamy virus type 1 (SFV1) in human AV3-cell cultures. All IFN led to strong inhibition of the SFV1 cytopathic effect. Electron microscopy showed a 70 to 95% decrease in viral particles. Significant inhibition of virus-associated reverse transcriptase activity was found in supernatant fluids of infected IFN-treated cultures. Metabolic labelling of the virus confirmed the inhibition of extracellular release of SFV1. PAGE analysis of immunoprecipitates indicated a reduction in viral-specific protein bands. Altogether, these results indicate that the mechanism of inhibition of Spumavirinae infection by interferon differs from that described for the other Retroviridae, and particularly for types B, C and D viruses. Our data is of therapeutic interest since Spumavirinae have been linked to pathological processes such as de Quervain thyroiditis.

Cell Line↗
PubMedDate not supplied

In vitro studies on interferon-inducing capacity and sensitivity to IFN of human foamy virus.

We demonstrate in this article that human foamy virus (HFV) fails to induce interferon (IFN) production in two different human tissue culture cell lines: U373-MG and AV3. We also show the effect of human alpha-, beta- and gamma IFN on the multiplication cycle of HFV. Treatment of cells with 100 IU/ml of any IFN led to strong inhibition of an HFV-induced cytopathic effect. This effect was associated with a significant diminution of reverse transcriptase activity in supernatant fluids of IFN-treated infected cultures, and a substantial decrease in viral particle production, as detected by electron microscopy. All these effects were accompanied by strong inhibition of both viral proteins and RNA synthesis, as well as almost total disappearance of free and integrated proviral DNA. In light of our data, human IFN action on HFV seems to be mediated by a mechanism which differs from that observed in the case of other retroviruses (type C and D for instance); however, it evokes that described for HIV.

Animals↗
PubMedDate not supplied

[Production of circulating interferon in human malaria].

The presence of an interferon-like activity inhibiting the cytopathic effect of vesicular stomatitis virus was studied in 216 sera from 100 patients with P. falciparum (67 cases), P. vivax (16), P. ovale (13), P. malariae (4) infections. 87% of patients were found positive on one or more occasions. The prevalence of interferon-like activity was similar in all 4 species. Titers varied between 20 to 320 U/ml and were found to be higher in Europeans experiencing a primary attack of malaria (mean = 72 U/ml) than in subjects from hyperendemic areas of West Africa (mean = 37 U/ml). In patients followed-up either a delayed positivity or an increase of interferon-like activity was found in 60% of cases. High titers were observed up to the 3rd month. The viral inhibitory activity met all criteria for defining interferon. Seroneutralization assays using anti-alpha and anti-gamma interferon antibodies showed in 5 patients that human malaria was associated with the presence of a gamma interferon.

Africa, Western↗
PubMedDate not supplied

Effects of serotonin and melanin on in vitro HIV-1 infection.

In this article, we describe the effect of indoleamines: serotonin (5-HT) and synthetic soluble melanin, on the multiplication of HIV-1 in T4 lymphocytic cell lines. The results show that viral production is increased when infected CEM-11 cells are incubated with 5-HT (10(-7) M and 10(-8) M) for 72 hours, whereas at higher doses (10(-3) M and 10(-4) M), there is an inhibition of viral multiplication. As well, when infected CEM cells were cultured in the presence of 5-HT at 10(-4) M, during 15 days, virus production, syncytia formation and cytolytic effect were drastically inhibited. Melanin also inhibits HIV-1 cytopathic effect on MT-2 cells, without cell toxicity, at concentrations of 0.2-10 micrograms/ml. Syncytium formation and cell lysis were also blocked by melanin at concentrations of 0.1 to 10 micrograms/ml, when uninfected MT-2 cells were mixed with HIV-1 chronically infected CEM-11 cells.

Antiviral Agents↗