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Biomedical subjects

J C Chermann

Publications and source records attributed to J C Chermann.

At least 91 records · Page 5Linked to original sources
PubMed1990

The env gene variability is not directly related to the high cytopathogenicity of an HIV1 variant.

HIV1-NDK is a Zairian HIV1 isolate which is unique because of its high cytopathic effect on T lymphoblastoid cell lines. Its sequence analysis has indicated 30% divergence with HIV1-LAV/BRU HTLVIII B prototype in the env gene encoding for the envelope glycoprotein gp120. In order to correlate the highly cytopathic properties with the env genetic variability, recombinants between the HIV1 prototype and HIV1-NDK have been constructed, including HIV1-NDK env gene, and their cytopathic phenotypes were analyzed. The viral hybrid containing all HIV1 prototype sequences except a large fragment including the total HIV1-NDK env gene remained at a low cytopathic phenotype. Our results suggest that sequences other than the env gene namely p18 gag, vif, and vpr are required for the high virulence of HIV1-NDK.

Animals↗
PubMed1990

Differences in replication and cytopathogenicity of human immunodeficiency virus type 1 (HIV-1) are not determined by long terminal repeats (LTR).

The growth properties of molecular clones of a highly cytopathic Zairian HIV1-NDK and prototype viruses were compared to correlate genetic variations with biological changes. The cloned HIV1-NDK retained the highly replicating cytopathic phenotype and formed larger syncytia than the prototype. One of the major differences in the alignment of the nucleotide sequence of the HIV1-NDK and HIV1-BRU prototypes was localized in the negative regulatory element (NRE) of the long terminal repeat (LTR). In a chloramphenicol acetyl transferase (CAT) assay, we failed to detect a significant difference between LTR promoter activity of the prototype and HIV1-NDK, suggesting that the LTR of both phenotypes had a similar function. The complete recombinant provirus DNA molecules bearing HIV1 LTR derived from one phenotype and the rest of the genomes from the other phenotype were constructed and transfected. The high cytopathogenicity of both the original and the chimeric viruses was correlated with the high speed of virus replication. Cytopathogenicity, morphology of syncytia, and replication kinetics of the recombinant viruses were determined by the functions coded within an internal part of HIV1 genome, covering the gag to env region, which were, however, not within LTR.

Animals↗
PubMed1990

Differential inhibition of the activities of reverse transcriptase and various cellular DNA polymerases by a traditional Kampo drug, sho-saiko-to.

A traditional Kampo drug, Sho-saiko-to, composed of several herb extracts, differentially inhibited the activities of reverse transcriptase and human cellular DNA polymerase alpha and beta. Reverse transcriptases from murine leukemia virus and human immunodeficiency virus were inhibited by over 80% and 50%, respectively, in the presence of 100 micrograms/ml Sho-saiko-to, whereas DNA polymerase alpha was much less sensitive to inhibition by this drug than were the reverse transcriptases. DNA polymerase gamma was not inhibited by this drug at concentrations of up to 500 micrograms/ml. Only DNA polymerase beta was moderately inhibited by Sho-saiko-to. Thus, it has been shown that the inhibition by Sho-saiko-to is relatively specific for reverse transcriptase and that the drug contains as yet unidentified inhibitory substance(s) for reverse transcriptase.

Animals↗
PubMed1990

An early postinfection signal mediated by monoclonal anti-beta 2 microglobulin antibody is responsible for delayed production of human immunodeficiency virus type 1 in peripheral blood mononuclear cells.

We recently found (C. Devaux, J. Boucraut, G. Poirier, P. Corbeau, F. Rey, M. Benkirane, B. Perarneau, F. Kourilsky, and J.C. Chermann, submitted for publication) a latency in the human immunodeficiency virus (HIV) type 1 cytopathic effect in the human T-cell lymphotropic virus type I immortalized T-cell line MT4 that was mediated by anti-beta 2 microglobulin (beta 2m) monoclonal antibodies (MAb). Here we describe a delay in viral particle production in peripheral blood mononuclear cells (PBMC) that was mediated by three (B1-1G6, B2-62-2, and HC11-151-1) of four anti-beta 2m MAb tested, the nonefficient MAb (C21-48A) being specific for an epitope on beta 2m that was masked by association with the human leukocyte antigen class I heavy chain. Experiments were designed to determine the mechanism of interference. PBMC incubated with anti-beta 2m MAb before viral exposure were not protected from HIV infection. In addition, anti-beta 2m MAb were not efficient in preventing syncytium formation between HIV-infected PBMC and CD4-positive MT4 cells. In contrast, anti-beta 2m MAb treatment of freshly infected PBMC significantly delayed HIV production in these cells. The window of cell sensitivity to anti-beta 2m MAb treatment took place during a very early post-HIV-binding stage. The possible mechanism of anti-beta 2m MAb action is discussed.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Human immunodeficiency virus inhibition by lysed leukocyte ultrafiltrate.

The in vitro effect of partially purified lysed leukocyte ultrafiltrate (LLU) on LAV 1 strain of the human immunodeficiency virus (HIV) was investigated. Decrease of virus production as a function of LLU concentration was observed while the phenotype of cultured lymphocytes has remained unchanged. We observed the same depletion of helper-inducer T-cells in samples treated with LLU as well as in infected controls. LLU did not influence significantly the growth of cultured lymphocytes. Following the effect of LLU on RNA-dependent DNA polymerase, inhibition of the LAV 1 reverse transcriptase by LLU was observed. This inhibition was shown to be LLU dose-dependent, considering its content of proteins and orcinol-reactive material. Kinetic studies revealed that inhibition is reversible and competitive with the substrate (3HTTP) but not with template-primer (poly rA-oligo dT).

Binding, Competitive↗
PubMed1989

Nucleotide sequence of HIV1-NDK: a highly cytopathic strain of the human immunodeficiency virus.

A highly cytopathic strain of HIV1, named HIV1-NDK, has been isolated from a Zaïrian patient affected with AIDS. This isolate is 10(4) times more cytopathic and infectious than the prototype. To correlate the high cytopathic properties of this strain with genetic variations, we have cloned and sequenced the genome of this isolate. The principal feature which could be drawn from the fine analysis of the HIV1-NDK sequence is that the variability is not clustered in one particular region but rather spread out all along the genome. Only minor differences seem to be responsible for the acute biological effect of HIV1-NDK.

Amino Acid Sequence↗
PubMed1989

Soluble IL-2 receptor in AIDS. Correlation of its serum level with the classification of HIV-induced diseases and its characterization.

By using a fluorescence sandwich ELISA, elevated IL-2R levels were detected in the sera from both HIV-infected hemophiliacs and other HIV-infected patients. The serum IL-2R levels were reflective of the classification of HIV-induced diseases by the Centers for Disease Control. Moreover, the IL-2R levels were negatively correlated most prominently with CD4 cell counts, with lymphocyte counts, and with a decrease in the CD4-CD8 ratio but not with either WBC counts or B cell counts. As striking elevations of serum IL-2R were noted in AIDS patients with group IVD infection, the serum IL-2R was purified sequentially by using size-exclusion HPLC, high-pressure chromatofocusing, and H48 affinity HPLC. The isoelectric point values of IL-2R were separated into 4.2 and 3.8, whereas the Mr was determined to be only 45 kDa by immunoprecipitation with H48 antibody followed by SDS-PAGE. However, production of cellular and supernatant IL-2R was not elevated in PBMC of patients with AIDS or in any of the 19 HIV-I- or HIV-II-infected cell line cells. In contrast, PBMC from patients with adult T cell leukemia and cell line cells that expressed human T cell lymphotropic virus -I or -II produced soluble IL-2R, constitutively. The mechanisms by which serum levels of IL-2R might be elevated in HIV-infected patients are discussed in comparison with that in adult T cell leukemia patients.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Inhibition of reverse transcriptase activity by a flavonoid compound, 5,6,7-trihydroxyflavone.

5,6,7-Trihydroxyflavone (baicalein) is a potent inhibitor of the activities of reverse transcriptases from murine leukemia viruses (MLV) (Rauscher and Moloney strains) and human immunodeficiency virus (HIV). Under the reaction conditions specified for each of the MLV- and HIV-reverse transcriptases, both enzyme activities were inhibited by more than 90% in the presence of 2 micrograms/ml baicalein. The mode of the inhibition by baicalein was competitive with respect to the template.primer, (rA)n.(dT)12-18, and noncompetitive to dTTP substrate. Ki value of baicalein for the MLV-reverse transcriptase was determined to be 0.37 microM.

Binding, Competitive↗
PubMed1989

Replication of the human immunodeficiency virus 1 and impaired differentiation of T cells after in vitro infection of bone marrow immature T cells.

HIV-1 infection in vitro of normal bone marrow mononuclear cells (BMMC) depleted of mature T cells was studied. BMMC depleted of either CD3, CD2, or both could replicate HIV-1 irrespective of the presence of macrophages/monocytes. Infected bone marrow cells were shown to differentiate during the culture into CD3+, CD4+, CD8+, and CD1+ cells, whereas noninfected BMMC gave rise to CD3+, CD4+, and CD8+ cells. Moreover, 9-14% of the cells also expressed the viral proteins p24 and gp120 on their surface. Double staining studies revealed that 72 and 83% of the CD4+ cells expressed the gp120 and p24, respectively, suggesting that virus replication occurred in CD4+ cells. T cell colony growth from infected BMMC, either unfractionated or depleted of mature T cells, was impaired in a time-dependent manner, and the differentiation capacity of T cell precursors was abnormal. Colony cells displayed an immature cell phenotype (CD1+ cells) and the viral proteins gp120 and/or p24 could also be detected on CD1+ cells. In addition, pooled colony cells derived from infected CD2- and CD3-depleted BMMC could infect normal mitogen-activated lymphocytes in coculture experiments. These findings strongly suggest that HIV-1 can infect immature bone marrow T cells and be transmitted to the progeny, but the massive viral replication occurs only when the cells differentiate toward CD4+ cells.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1989

Characterization of a reverse transcriptase activity associated with retrovirus-like particles in a Drosophila cell line.

The properties of an endogenous RNA-dependent DNA polymerase (reverse transcriptase) associated with retrovirus-like particles (VLP) in a Drosophila melanogaster cell line were characterized. The enzyme requires a monovalent and a divalent cation, a sulfhydril-reducing agent and the four deoxynucleosides triphosphates for a maximal activity. The reaction was enhanced by a detergent and was sensitive to a DNA-A-free RNA-A indicating that the enzymatic activity was indeed associated with VLP which contain intrinsic RNA. The maximal incorporation of the labelled deoxynucleotide was observed at 25 degrees C in the presence of Mn2+. The enzyme responded well to exogenous template-primers in the similar way to that of retroviral reverse transcriptase and the use of several inhibitors confirms the presence of a real reverse transcriptase activity associated with virus-like particles in drosophila cells.

Animals↗
PubMed1988

Differential inhibition of various mammalian DNA polymerase activities by ammonium 21-tungsto-9-antimoniate (HPA23).

The 21-tungsto-9-antimoniate ammonium salt (HPA23), known as an antiviral agent, has been shown to be a potent inhibitor of both human and murine DNA polymerase alpha and murine DNA polymerase gamma. HPA23 inhibited the activity of DNA polymerase alpha in noncompetitive fashion with respect to either deoxynucleotide substrate or nucleic acid template.primer. The Ki of murine DNA polymerase alpha for HPA23 was determined to be 24 nM. The activity of mouse DNA polymerase gamma also was strongly inhibited by HPA23 (Ki, 20 nM), and the mode of inhibition was competitive with respect to the template.primer, (rA)n.(dT)12-18, and noncompetitive to substrate, dTTP. DNA polymerase beta and terminal deoxynucleotidyltransferase, however, were relatively resistant to inhibition by HPA23. The observed inhibitions by HPA23 seem to be closely related to the polyanionic property of this drug.

Animals↗
PubMed1988

Inactivation and partition of human immunodeficiency virus during Kistler and Nitschmann fractionation of human blood plasma.

We studied the inactivation of the etiologic agent of the acquired immunodeficiency syndrome, human immunodeficiency virus, in the course of the Kistler and Nitschmann cold ethanol fractionation of human blood plasma. By measuring reverse transcriptase activity and viral infectivity, we have shown that the virus load is reduced by a factor of 10(4) during the initial and at least a factor of 10(6) during the subsequent steps of the fractionation procedure. This loss of virus may be observed in the absence or in the presence of antibodies against human immunodeficiency virus and is due to a combination of chemical inactivation, physical partition, and injury caused by repeated freezing and thawing. The laboratory data therefore further confirm epidemiological studies which indicate that immunoglobulin preparations obtained by ethanol fractionation do not transmit human immunodeficiency virus.

Chemical Fractionation↗
PubMed1988

Reverse transcriptase activity (RTA) in lymphocyte cultures of HIV-infected patients receiving short treatments of HPA 23. A biological evaluation.

Ammonium tungsto antimoniate (HPA 23) is a potent inhibitor of nucleic acid polymerases and reverse transcriptases of retroviruses. Its in vivo activity as an HIV inhibitor was previously published. However, its clinical use is limited by pharmacological parameters (short half-life and intravenous administration) and significant side effects (thrombocytopenia). In order to evaluate the place of this drug in the therapeutic strategy of HIV-infected patients, we administered 1.5 mg/kg of HPA 23 in 15 infected patients at various stages of the disease twice a day during 14 days. A significant decrease of reverse transcriptase activity (less than 15% of the initial value) was noticed in 13 patients. This activity remained low at least 6 weeks after the end of the treatment in 8 patients. Thrombocytopenia was the only significant side effect reported and was always transient. This study suggests that HPA 23 can be used as an induction treatment in patients infected by HIV. A maintenance treatment has to be defined, as well as the association to other drugs.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Cellular and molecular mechanisms of antiretroviral effects of HPA23.

HPA23 is an antimonio-tungstate that exhibits numerous antiviral activities both in vivo and in vitro. It has been described as a competitive inhibitor of human immunodeficiency virus (HIV) reverse transcriptase (RT). Patients treated with daily injections of HPA23 show an inhibition of HIV RT activity in cell culture in 60% of the cases. Using biophysical (electronic spin resonance [ESR]), ultrastructural (microspectroscopic analysis), chemical (spectroscopy), and biological (cell culture) assays, HPA23 cellular and molecular mechanisms may be summarized as follows: 1) competitive inhibition of HIV-RT, 2) no or slight effect on cells infected with HIV in culture, 3) interactions with the cell membranes when long incubations are performed, and 4) antiviral activity possibly mediated by immune modulator effect of the drug.

Antimony↗
PubMed1988

Interrelations of lymphocyte subset values, human immunodeficiency virus antibodies, and HIV antigen levels of homosexual males in San Francisco.

Serum and leukocytes from a cohort of homosexual males were analyzed to determine the interrelationships of antibodies to human immunodeficiency virus (HIV), serum HIV antigen levels, and phenotypical differences in lymphocyte subpopulations of HIV antibody-positive (HIV Ab+) and HIV antibody-negative (HIV Ab-) homosexual males. Significant reductions were observed in the percentages of B lymphocytes, CD4+ and CD4+ kappa lambda- T lymphocytes and the CD4+/CD8+ ratios of HIV Ab+ homosexual males in comparison to HIV Ab- homosexual males. Significant increases were observed in the percentages of CD8+, CD8+ CD11b-, CD8+ kappa lambda-, CD8+ DR+, CD8+Leu7+, and Leu7+ lymphocytes of HIV Ab+ study subjects. Statistical analysis revealed that among the immunological variables tested, decreases in the CD4+/CD8+ ratio and in the percentage of CD4+ kappa lambda- lymphocytes showed the strongest associations with HIV-sero-positivity in asymptomatic homosexual males. Only 44 (16.5%) of 267 HIV Ab+ homosexual males had detectable levels of HIV antigen (HIV Ag) in their serum. The percentages of CD4+ or CD4+ kappa lambda- lymphocytes and the CD4+/CD8+ ratios of HIV Ab+ males differed significantly between HIV Ag-positive (HIV Ag+) and--negative (HIV Ag-) homosexual males. These variables, however, did not correlate well with HIV Ag levels,indicating that no clear associations can be drawn between levels of HIV antigen and lymphocyte subset abnormalities of HIV-infected individuals.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Acute and regressive encephalopathy coincident with transient isolation of human immunodeficiency virus from cerebrospinal fluid of a seropositive man.

We observed the development of an acute encephalopathy in a healthy human immunodeficiency virus (HIV) seropositive man. HIV was isolated from cerebrospinal fluid but not from peripheral blood. Signs and symptoms resolved quickly without treatment. This viral isolate could be propagated only in blood cord lymphocytes, but not in peripheral blood T-lymphocytes or in continuous lymphoblastoid cell lines such as CEM. The absence of the virus in the patient's T-lymphocytes or infectivity of the virus for T-lymphocytes may explain the unusual presentation of HIV-associated encephalopathy without immunodeficiency in an asymptomatic carrier. Moreover, it raises the possibility that acute expression of HIV can be controlled by natural host defence mechanisms and that clinical manifestations may be reversible despite the patient's remaining seropositive.

Acquired Immunodeficiency Syndrome↗