[Scientific research in France. Structures and research career]. / La investigación científica en Francia. Estructuras y carrera del investigador.

In France, scientific research has always been considered an important activity. The aim of this article is to present data with reference to French research, mainly research in Medical and Biological Sciences. This includes a description of the Research Career in the two main institutions, CNRS (National Research Center) and INSERM (National Institute of Health and Medical Research). Investment in science is substantial in France originating both from the Scientific Institutions of the State and from a large number of Private Organizations. France is the second European country, after Germany, as far as the number of national and private investigators is concerned. CNRS covers all the dominions of science, including Natural Sciences, Mathematics, Biology and Medical Sciences. One of its main structures is undoubtedly its National Committee of Research which is responsible for the evaluation of the laboratories and research projects, of the incorporation of investigators in the Research Career and of their promotion. This Committee includes, among others, members of the Research Career elected among themselves. In parallel, INSERM is centered in both basic and applied Medical Research, and is supervised by a Scientific Committee and eleven specialized Commissions. In both institutions, the Research Career incorporates investigators as civil servants after very competitive examinations; their performance is evaluated by specialized committees as well as by national and international experts.

La investigación científica en Francia. Estructuras y carrera del investigador / [Scientific research in France. Structures and research career]

In France, scientific research has always been considered an important activity. The aim of this article is to present data with reference to French research, mainly research in Medical and Biological Sciences. This includes a description of the Research Career in the two main institutions, CNRS (National Research Center) and INSERM (National Institute of Health and Medical Research). Investment in science is substantial in France originating both from the Scientific Institutions of the State and from a large number of Private Organizations. France is the second European country, after Germany, as far as the number of national and private investigators is concerned. CNRS covers all the dominions of science, including Natural Sciences, Mathematics, Biology and Medical Sciences. One of its main structures is undoubtedly its National Committee of Research which is responsible for the evaluation of the laboratories and research projects, of the incorporation of investigators in the Research Career and of their promotion. This Committee includes, among others, members of the Research Career elected among themselves. In parallel, INSERM is centered in both basic and applied Medical Research, and is supervised by a Scientific Committee and eleven specialized Commissions. In both institutions, the Research Career incorporates investigators as civil servants after very competitive examinations; their performance is evaluated by specialized committees as well as by national and international experts.

La investigación científica en Francia. Estructuras y carrera del investigador. / [Scientific research in France. Structures and research career]

In France, scientific research has always been considered an important activity. The aim of this article is to present data with reference to French research, mainly research in Medical and Biological Sciences. This includes a description of the Research Career in the two main institutions, CNRS (National Research Center) and INSERM (National Institute of Health and Medical Research). Investment in science is substantial in France originating both from the Scientific Institutions of the State and from a large number of Private Organizations. France is the second European country, after Germany, as far as the number of national and private investigators is concerned. CNRS covers all the dominions of science, including Natural Sciences, Mathematics, Biology and Medical Sciences. One of its main structures is undoubtedly its National Committee of Research which is responsible for the evaluation of the laboratories and research projects, of the incorporation of investigators in the Research Career and of their promotion. This Committee includes, among others, members of the Research Career elected among themselves. In parallel, INSERM is centered in both basic and applied Medical Research, and is supervised by a Scientific Committee and eleven specialized Commissions. In both institutions, the Research Career incorporates investigators as civil servants after very competitive examinations; their performance is evaluated by specialized committees as well as by national and international experts.

Study of human foamy virus proviral integration in chronically infected murine cells.

This report describes integration sites of human foamy virus (HFV) in chronically infected BALB/c murine cells that we isolated by inverse PCR and characterized. We show that integration of HFV proviral genome mainly occurs in highly repetitive and/or transcriptionally active regions and leads to the formation of a 4-bp cellular direct repeat sequence at each provirus extremity. As non-random deletions were previously described in the HFV be/1 transactivator gene as well as in the long terminal repeats (LTRs), these regions were verified in integrated HFV. The analysis reveals that, in the studied chronic state, the defective interfering virus (delta HFV) is the main integrated proviral form and is always associated with a small LTR. Our results show that HFV can use a classic retroviral integration process to enter the host cell genome and stress the importance of delta HFV and the short LTRs in the establishment of the chronic state of infection.

Mycosis fungoides and Sezary syndrome are not associated with HTLV-I infection: an international study.

Association between mycosis fungoides (MF), its leukaemic variant Sezary syndrome (SS) and the human T-cell lymphotropic virus type-I (HTLV-I) has been controversial, with the reported incidence of infection varying between 0% and nearly 100%. We studied 127 patients (85 MF, 28 SS, five Sezary cell leukaemia, four lymphomatoid papulosis, and five unspecified cutaneous T-cell lymphomas (CTCL)) originating from Europe (France, Spain, U.K., Portugal) or from U.S.A. (California) for the presence of HTLV-I infection markers. HTLV-I and -II serology were performed on 78 patients using standard immunological methods. Reverse transcriptase (RT) assay was also performed in 26 cases using an RT-PCR-based method of high sensitivity. Molecular analyses were performed on 215 DNA samples (121 from fresh PBMCs, 26 from PBMCs after short-term culture and 68 from skin lesions) by PCR amplification using HTLV-I and -II gag, pol, env, pX and LTR specific primers. Immunological tests were negative except for two sera which were indeterminate. PCR with all HTLV-I and -II primer pairs showed negative results in all 215 samples investigated. No RT activity was detected in short-term PBMC cultures of any of the 26 cases studied. The results of this large study from five different countries clearly indicate that MF and SS are not associated with HTLV-I infection.

Long-term persistent infection of domestic rabbits by the human foamy virus.

Human foamy virus (HFV) belongs to the spumaretrovirus group of the Retroviridae taxonomic family. Attempts to associate HFV or other foamy viruses to a specific pathology still remain unsuccessful. However, viral gene expression as well as tissue-specific tropism in an in vivo context remain poorly analyzed. To address this issue, we have infected domestic rabbits with a single dose of HFV and followed them at the biological and molecular levels for 5 years. No apparent pathology was detectable in the infected animals which have developed a strong immunological response against major viral proteins. We found that HFV provirus in blood cells and several organs persisted predominantly in its defective form, delta HFV, suggesting that in vivo viral persistence could be related to homologous interference as was recently shown in vitro. This animal model might be useful for studying the in vivo targets of HFV and should also be convenient for testing therapeutic effects of antiretroviral drugs.

Nuclear targeting of incoming human foamy virus Gag proteins involves a centriolar step.

The pathways used in the transport of retroviral genomes to the nucleus are poorly identified. Analyzing the intracellular localization of incoming foamy viruses, we have found that the Gag antigens and the viral genome accumulate in a distinct perinuclear domain identified as the centrosome. Colchicine treatment completely abolished pericentriolar targeting of human foamy virus (HFV) proteins, suggesting a role for microtubules in the transport of the incoming viral proteins to the centrioles. Finally, we demonstrate that, similarly to human immunodeficiency virus DNA, HFV DNA can enter the nucleus of G1/S-phase-arrested cells, although no viral gene expression can be observed. Recent observations have demonstrated that foamy viruses have several features not shared by other retroviruses. The intracellular route of the incoming Gag antigens may constitute a new specificity of this class of viruses.

Inhibition of the in vitro infectivity and cytopathic effect of human foamy virus by dideoxynucleosides.

Human foamy virus (HFV) is a human retrovirus that has not been clearly associated with human disease. In this study, we tested the capacity of nucleoside derivatives to inhibit the infectivity and cytopathic effect of HFV in T-lymphoblastoid cells in vitro. H9 cells showed a dramatic cytopathic effect 3 weeks after exposure to HFV. At this time, viral infection was demonstrated by detection of viral antigens by immunofluorescence staining, release of reverse transcriptase activity (RT) in the supernatant, detection of typical viral particles by electron microscopy, and presence of proviral DNA by Southern blot analysis. H9 cells were pretreated with dideoxycytidine (ddC), dideoxyinosine (ddI), or azidothymidine (AZT) at various concentrations before HFV infection. ddC could not completely suppress viral replication at low concentrations, and inhibited cell proliferation at higher concentrations. ddI partially inhibited the formation of giant cells at 10 microM, with 95% inhibition of RT in the supernatant. AZT induced a complete inhibition of cytopathic effect at concentrations > or = 1 microM, with more than 95% inhibition of RT in the supernatant. Moreover, the synthesis of proviral DNA was completely suppressed by 10 microM AZT. These results show that AZT and ddI can inhibit HFV replication in vitro.

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.

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.

Human T-cell-leukemia virus type I in post-transfusional spastic paraparesis: complete proviral sequence from uncultured blood cells.

Human T-cell-leukemia virus type I (HTLV-I) is the causative agent of adult T-cell leukemia/lymphoma (ATL) and tropical spastic paraparesis/HTLV-I-associated myelopathy (TSP/HAM). The different disease outcome may be attributable to subtle mutations leading to modification of viral tropism or infectivity. Initial attempts found a very high level of sequence conservation among all HTLV-I strains. However, only one complete proviral DNA sequence is reported from a TSP/HAM patient, with a provirus derived from immortalized lymphocytes, which might be expected to be a leukemogenic variant rather than a neurotropic one. We cloned and sequenced a complete HTLV-I provirus (HTLV-IBoi) derived from the uncultured lymphocytes of a sub-acute post-transfusional TSP/HAM patient with clonal integration of HTLV-I. HTLV-IBoi proviral genome is 9033 bp long, and its overall genetic organization is similar to that of the prototype HTLV-I(ATK), without major deletions or insertions. No premature termination codon was found in the 4 open reading frames of the pX region. Divergence at the nucleotide level of HTLV-IBoi from the reported full-length HTLV-I varies from 1 to 9.4%, and indicates that it corresponds to a cosmopolitan genotype. This study did not identify specific sequences associated with neurotropic strains.

Involvement of a spliced and defective human foamy virus in the establishment of chronic infection.

Human foamy retrovirus (HFV) is found as two proviruses (HFV and delta HFV) which differ by a splice-induced deletion within the bel1 transactivator gene. The defective delta HFV (which lacks a functional Bel1 but harbors an intronless bet gene) is predominantly found in nonlytic infections in vitro as well as in vivo. Here, we show that infection of cell lines stably transduced by delta HFV DNA with the highly lytic HFV leads to chronic infections characterized by an absence of lysis, a balanced ratio of HFV to delta HFV, and a persistent Bet expression accompanied by a shutoff of structural genes. While this system only partially reflects the natural situation, in which target cells are infected by HFV and delta HFV simultaneously, it strongly suggests that delta HFV is a defective interfering retrovirus. Accordingly, previous or concomitant exposure to delta HFV viruses greatly enhances the formation of lysis-resistant clones in culture after HFV infection. The inability of delta HFV proviruses encoding a mutated bet gene to induce chronic infection suggests a role for Bet in this process. Through a specific, splice-induced, genomic deletion, resulting in a switch from Bel1 to Bet expression, the lytic properties of HFV are progressively lost. Such programmed inactivation of a key gene represents a new regulatory mechanism of gene expression in retroviruses.

Human foamy virus DNA forms and expression in persistently infected Dami megakaryocytic cells.

We have characterized human foamy virus (HFV) proviral DNA and determined HFV expression in a persistent infection model, the Dami megakaryocytic cell line. Molecular studies were performed on parental persistently infected cells (Dami-P), as well as on derived clones (Dami-Cl). We report that in these nonlytic and non-HFV producer cells, viral DNA was found to be integrated into the cellular genome and that the few free proviral forms detected in Dami-P cells were deleted in their 5' LTR. Our molecular analysis indicates the presence of undeleted 5' LTR forms in the integrated provirus within a proviral population mainly composed of deleted forms. In addition, the deletion in the bel1 trans-activator gene, previously described by Saïb et al., was found to be highly predominant. However, in 5-iodo-2'-deoxyuridine treated Dami-Cl cultures, virus production occurred, providing evidence for the presence of complete viral genome. Analysis of HFV expression in Dami-Cl cells, by Northern blot and immunoprecipitation, shows that the most striking difference between cytolytic and persistent HFV infection was the lack of expression of structural viral proteins, in contrast with Bet protein expression, which is maintained. Our data suggest that the Bet protein could be involved in the maintenance of viral persistency and that the persistently infected Dami system provides a suitable model for clarifying its function.

Recent insights into the biology of the human foamy virus.

Human foamy virus (HFV) is a complex retrovirus with structural similarities to HIV and human T cell leukemia virus. There have been considerable advances in understanding the biology of HFV in cell cultures. However, viral behavior in vivo, and even viral detection, are still poorly understood. While HFV-transgenic mice develop neuromuscular disorders, attempts to associate HFV with a specific human disease have given inconclusive results.

[Role of retroviruses in human cancerogenesis]. / Rôle des rétrovirus dans la cancérogenèse humaine.

Retroviruses are viral agents which are natural and experimental inductors of leukemias and solid tumors among numerous animal species. In man, they are implicated as ethiological agents of a specific type of leukemia, adult-T cell leukemia. Thus is for retrovirus HTLV-I. Another retrovirus, HIV, implicated in AIDS is capable of leading to the formation of several types of opportunistic tumors, such as non Hodgkin lymphomas and Kaposi's sarcoma.

Biological and molecular studies on Syrian hamster intracisternal R-type particles.

Retrovirus-like intracisternal R-type particles (IRP) are structures present in Syrian hamster (Mesocricetus auratus) cells cultured in vitro where they appear either spontaneously or under chemical induction conditions. We have tested several chemical inducers and ten different cell lines, looking for the best IRP induction conditions. BHK21 cl. 13 showed the highest inducibility one day after a 24 h treatment with 1 microgram/ml of 5-aza-2'-deoxycytidine. Using detergent treatments and sucrose gradients, we obtained semi-purified IRP cores. A 7.2 kb RNA associated with the core fraction was revealed by hybridization with total Syrian hamster genomic DNA, but not with Syrian hamster intracisternal A particle (IAP) specific probes. This suggests that the IRP genes are distinct from IAP ones.

Functional comparison between HTLV-I envelopes originating from TSP/HAM or ATL cell lines.

The human T-cell leukemia type I (HTLV-I) virus is associated with two different diseases, adult T-cell leukemia (ATL) and tropical spastic paraparesis/HTLV-I-associated myelopathy (TSP/HAM). We have compared the viral envelopes originating from TSP/HAM and ATL patients, using the capacity of infected cells to form syncytia with receptor-expressing cells. We show that like the ATL cell lines, the TSP/HAM ones can form syncytia with a large panel of human target cells, including a variety of hematopoietic cell lines, as well as cell lines of neuroectodermal origin. None of the target cell lines tested was able to discriminate between TSP/HAM- and ATL-infected cell lines. When infected cells of TSP/HAM origin are cocultivated with cells of ATL origins, syncytia are never observed. This interference phenomenon suggests that the viruses expressed by the different cell lines utilize the same receptor.

Unintegrated HTLV-I proviral DNA in cell lines and uncultured peripheral blood mononuclear cells from tropical spastic paraparesis (TSP/HAM) and adult T-cell leukemia (ATL) patients.

Ultrastructural studies on cell cultures derived from TSP/HAM and ATL patients, show the presence of large quantities of HTLV-I viral particles in extracellular spaces and budding at the cytoplasmic membrane. In addition, mature enveloped particles and images of endopinocytosis of virions are seen in the cytoplasm vacuoles suggesting the existence of a reinfection phenomenon. In this context, we decided to investigate some features of the replicative cycle, in particular the synthesis of unintegrated proviral forms. To increase the sensitivity of detection, we applied a procedure which combines the electrophoretic separation of closed circular forms and PCR amplification. By this procedure we produced evidence for the existence of supercoiled HTLV-I DNA in established cell lines from TSP/HAM and ATL and in patients peripheral blood mononuclear cells. These HTLV-I unintegrated proviral forms may play an important role in the physiopathology of HTLV-I associated diseases. Preliminary results of AZT/interferon treatment in ALT patients are largely superior to chemotherapy. The therapeutic effect of AZT, it known inhibitor of reverse transcriptase, may be through its inhibition of the synthesis of HTLV-I unintegrated proviral DNA.