PubMed Health⌕ Search

Biomedical subjects

J P Lévy

Publications and source records attributed to J P Lévy.

At least 19 recordsLinked to original sources
PubMed2000

Identification in humans of HPV-16 E6 and E7 protein epitopes recognized by cytolytic T lymphocytes in association with HLA-B18 and determination of the HLA-B18-specific binding motif.

Human papilloma virus type 16 (HPV-16) is the HPV most frequently associated with cervical carcinoma in humans. For the prevention or treatment of cervical carcinoma, the E6 and E7 oncoproteins appear to be good targets for vaccine-induced cytotoxic T lymphocytes (CTL). Lipopeptide vaccination is an efficient way of stimulating cellular responses. However, to synthesize effective lipopeptides, it is necessary to define which epitopes are immunogenic. In this study we first determined that peptide 80 - 88 of the E6 protein was recognized by CTL from a healthy donor in association with the HLA-B18 molecule. We then defined the HLA-B18 anchoring peptide motif by testing the binding of various short peptides with the HLA-B18 molecule and showed that it was related to the HLA-A1-specific peptide motif. Furthermore, in analyzing the potential E7 epitopes susceptible to associating with HLA-B18, we demonstrated that peptide E7 44 - 52 gave the strongest binding. It could also be recognized by CTL from peripheral blood mononuclear cells (PBMC) of the same healthy donor. Finally, with PBMC from a patient with a cervical intraepithelial neoplasia grade 3, we found CTL which recognized the E6 80 - 88 epitope. We have hence identified two peptides encoded by the E6 and E7 proteins which are presented by the HLA-B18 molecule and could be included in a vaccine against HPV-16.

Amino Acid Sequence↗
PubMed2000

Multiepitopic B- and T-cell responses induced in humans by a human immunodeficiency virus type 1 lipopeptide vaccine.

We have attempted to develop an anti-human immunodeficiency virus (HIV) lipopeptide vaccine with several HIV-specific long peptides modified by C-terminal addition of a single palmitoyl chain. A mixture of six lipopeptides derived from regulatory or structural HIV-1 proteins (Nef, Gag, and Env) was prepared. A phase I study was conducted to evaluate immunogenicity and tolerance in lipopeptide vaccination of HIV-1-seronegative volunteers given three injections of either 100, 250, or 500 microg of each lipopeptide, with or without immunoadjuvant (QS21). This report analyzes in detail B- and T-cell responses induced by vaccination. The lipopeptide vaccine elicited strong and multiepitopic B- and T-cell responses. Vaccinated subjects produced specific immunoglobulin G antibodies that recognized the Nef and Gag proteins. After the third injection, helper CD4(+)-T-cell responses as well as specific cytotoxic CD8(+) T cells were also obtained. These CD8(+) T cells were able to recognize naturally processed viral proteins. Finally, specific gamma interferon-secreting CD8(+) T cells were also detected ex vivo.

AIDS Vaccines↗
PubMed1997

Positive role of macaque cytotoxic T lymphocytes during SIV infection: decrease of cellular viremia and increase of asymptomatic clinical period.

We have measured cellular viremia and observed clinical outcome of macaques from two cohorts, the first including 12 macaques infected by SIVmac251 and the second including 12 macaques immunized by lipopeptides and then challenged by SIVmac251. In the first cohort (SIV-infected macaques), 3 patterns of CTL responders were determined: high, low and non-responders. In the macaques belonging to pattern of low and non-responders, cellular viremia, measured by growing the virus from PBMC, was continuously high during the first 6 months after infection, and five macaques developed AIDS within 14.4 +/- 7.7 months. Conversely, in the six high-responder macaques, cellular viremia was constantly low and only one macaque developed AIDS at 19 months, the five others being alive at 24 months. After immunization with lipopeptides, 7/12 macaques showed CTL responses and among these, after SIV challenge, cellular viremia was continually low, and no disease was observed at 22 months of follow-up. Conversely, the five non-responder macaques displayed persistent high viremia and macaques developed AIDS within 12.6 +/- 2.9 months after SIV challenge. These data strongly suggest that the presence of cytotoxic responses is inversely correlated with cellular viremia and correlated with overall survival and thus in an important component of the immune response in vaccinated individuals. It supports the idea that a strengthening of the CTL responses, if possible, might be beneficial in HIV-infected human beings.

Animals↗
PubMed1995

Pimelautide or trimexautide as built-in adjuvants associated with an HIV-1-derived peptide: synthesis and in vivo induction of antibody and virus-specific cytotoxic T-lymphocyte-mediated response.

Covalent association of lipopeptidic immunostimulants is known to improve the immunogenicity of short peptides. In this paper, we describe the synthesis of four analytically pure immunogens, prepared by two different strategies, in which a hexadecameric peptide (V3) derived from the principal neutralizing domain of HIV-1 envelope glycoprotein was associated with two different murein-derived lauroyl-peptides, Pimelautide (RP 44102), or Trimexautide (RP 56142). The in vivo immunogenicity of these compounds was evaluated according to two different criteria: the ability to elicit a cellular-T cytotoxic (CTL response) and the ability to stimulate antibody response. Our studies show that one of our compounds (TrxSucV3) was able to efficiently induce a relevant virus-specific CTL response, while another one (PimSucV3) was able to stimulate a strong antibody response to the linked peptide, or to a co-injected protein. These results suggest that both activities rely on different structure-activity relationships and that such a chemically defined model of peptide vaccines may be used to selectively stimulate subpopulations of immunocompetent cells.

Adjuvants, Immunologic↗
PubMed1995

A natural antisense RNA derived from the HIV-1 env gene encodes a protein which is recognized by circulating antibodies of HIV+ individuals.

A naturally occurring antisense RNA, transcribed in the opposite direction and complementary to the envelope transcript, was identified in various cell lines chronically infected with HIV-1. In T cells, the antisense transcript is constitutively expressed and enhanced by activation with phorbol myristate acetate. The open reading frame corresponding to the antisense transcript, when expressed in vitro, encodes a protein with an apparent molecular mass of 19 kDa. Antibodies against this protein have been detected in several sera of HIV+ individuals and not in any of the noninfected control sera. These results indicate, for the first time, that expression of an antisense open reading frame most likely accompanies the HIV infection cycle in humans.

Base Sequence↗
PubMed1994

Simian immunodeficiency virus as a model for vaccination against HIV. Induction in rhesus macaques of GAG- or NEF-specific cytotoxic T lymphocytes by lipopeptides.

The protection against infection by HIV probably requires the induction of both neutralizing Abs and CTL responses. Vaccination by attenuated HIV is hardly acceptable and the use of viral genes inserted in recombinant living vectors needs further development, especially with respect to safety. The peptidic vaccination is a promising approach but free peptides are usually poorly immunogenic. Because potent immune responses have been obtained in mice with modified peptides such as lipopeptides, we have designed a study to assess the immunogenicity of lipopeptides in nonhuman primates. Seven lipopeptides were synthesized, derived from known immunogenic regions of the simian immunodeficiency virus (SIV) NEF and GAG proteins. Twelve rhesus macaques, randomly chosen and not selected on their MHC basis, were immunized subcutaneously with the seven lipopeptides in IFA. An MHC class I-restricted and CD(8+)-mediated CTL response has been observed in seven macaques directed against one or two of the synthetic immunizing peptides in each case. These CTLs were able to lyse autologous target cells infected with a recombinant vaccinia virus expressing the SIV nef or gag genes, suggesting that they recognized the naturally processed peptides. These activities are detectable in peripheral blood cells for at least 10 mo after the last immunization. Abs against the immunizing peptides have also been observed in all cases. This study demonstrates that lipopeptides can generate cytotoxic and humoral immune responses in a large number of unselected animals and this approach may thus be worth considering in the vaccination against HIV.

AIDS Vaccines↗
PubMed1994

Evaluation of the Coulter MAXM in a children's hospital.

An evaluation of the WBC differential given by the analyzer Coulter MAXM was performed in a children's hospital, in order to establish optimal interpretation of the automated MAXM report in pediatrics. The patient group comprised 419 children of age up to 15 years. Assessment was carried out by comparison of the MAXM results with microscopic examination of blood smears, good correlation being observed between the two methods in non flagged samples and those flagged only with an isolated "Imm Grans/Bands 1" message indicating the presence of band cells. Comparison of the MAXM and optical differentials in normal and abnormal samples was performed according to a standard protocol taking into account both suspect flags and quantitative abnormalities defined in relation to age. In this group of 419 children, there were 20 (4.8%) false positive and 8 (1.9%) false negative reports, the 8 false negative results corresponding to either minor morphological (4) or borderline quantitative abnormalities (4). Overall, the instrument was capable of detecting significant abnormalities in blood samples with a sensitivity of 95.5% and a specificity of 91.7%. Although the review rate was 45.3%, the high efficiency (93.3%) suggested that most blood smear reviews led to the discovery of a morphological and/or quantitative abnormality. Furthermore, the review rate was greater in neonates (< 7 days) and infants (7 days-1 year) but closer to those of adult populations in older children. The Coulter MAXM was thus shown to be appropriate for use in pediatrics, despite a higher frequency of blood smear review than in adults, particularly among patients less than one year old.

Adolescent↗
PubMed1993

Induction of virus-specific cytotoxic T lymphocytes in vivo by liposome-entrapped mRNA.

The induction of anti-influenza cytotoxic T lymphocytes (CTL) in vivo by immunizing mice with liposomes containing messenger RNA (mRNA) encoding the influenza virus nucleoprotein (NP) is described. NP mRNA, obtained by in vitro transcription, was encapsulated into simple cholesterol/phosphatidylcholine/phosphatidylserine liposomes by the detergent removal technique. The dependence of the route of mRNA-liposomes delivery on CTL induction was studied. The CTL induced were identical to those obtained in vivo with infectious virus in terms of specificity, lysing both peptide-sensitized and virus-infected targets. Furthermore, with the same mRNA-liposome preparation, virus-specific CTL responses could be also elicited in mice of three different haplotypes each of them known to present a distinct NP peptide in an MHC-restricted fashion. The relevance of these results in the context of vaccine development is discussed.

Animals↗
PubMed1992

Qualitative and quantitative analysis of human cytotoxic T-lymphocyte responses to HIV-1 proteins.

OBJECTIVE: To study the degree of immunogenicity of each HIV-1 protein. DESIGN: In most viral systems, antiviral cytotoxic T-lymphocytes (CTL) from a given donor preferentially recognize only one or a small number of viral proteins. METHODS: Anti-HIV CTL were generated by in vitro stimulation of peripheral blood mononuclear cells from seropositive donors and tested against multiple HIV-1 proteins or groups of proteins encoded by seven genes (env, gag, pol, nef, rev, tat and vif). Using autologous target cells infected with recombinant vaccinia viruses expressing one of the HIV-1LAI proteins, we compared the cytolytic activities obtained from bulk culture with those found in limiting dilution analysis (LDA). RESULTS: Our results were noteworthy for the following reasons. (1) Each responding donor reacted simultaneously to multiple proteins; this is very unusual in other viral systems. Anti-Gag CTL were detected in most, and anti-Pol in approximately three-quarters, of the patients, together with very high amounts of the corresponding CTL precursors in LDA. CTL against Env and Nef were found in two-thirds of the patients, while Vif- and Rev-specific CTL were less frequent. Finally, Tat was seldom recognized by CTL, but its antigenicity was revealed in LDA. (2) All responding cells revealed in bulk cultures as well as in LDA were CD8+ T-cells, and their in vitro differentiation did not require the help of CD4+ T-cells. (3) Proteins from the HIV-1LAI isolate were recognized with high frequency by CTL from seropositive donors, most certainly being infected by other isolates, which suggests that relatively conserved epitopes are predominant targets of CTL. CONCLUSION: Taken together, these results are encouraging for vaccine purposes, since anti-HIV-1 CTL stimulation is thought to be a requirement for such a vaccine.

AIDS Vaccines↗
PubMed1992

HLA class I binding regions of HIV-1 proteins.

To identify HIV peptides containing HLA class I binding regions, different studies have been performed. These include the detection of interactions between HIV peptides and purified HLA molecules in solid-phase assays, the measurement of HLA molecule assembly in the presence of peptide added to cell lysates, and the detection of inhibition of CTL-mediated cytolysis by competition between peptides on target cells. To date, the HIV epitopes recognized by anti-HIV CTL are from the Env, Gag, Nef, and Pol proteins and they are identified using synthetic peptides of 12 to 20 amino acids. The search for a correlation between known HIV CTL epitopes and the results of HLA/peptide interaction assays reveals that: (1) most of the peptides that are positive in the assembly assay contain a HLA-A2 peptide motif but the correlation between these positive peptides and the CTL epitopes is not obvious; (2) a high proportion of HIV epitopes are included in the peptides positive in solid-phase binding and in inhibition of cytolysis assays, although these tests do not allow us to predict HLA restriction; (3) the HLA-A2 peptide motif is not systematically included in HLA-A2-restricted CTL epitopes, this observation raising the possibility that other sequences are involved in HLA binding.

Alleles↗
PubMed1991

Six epitopes reacting with human cytotoxic CD8+ T cells in the central region of the HIV-1 NEF protein.

In order to identify the target epitopes recognized by specific CTL in the NEF protein of HIV-1, 33 peptides derived from the HIV-BRU sequence were tested with NEF-specific CTL generated from HIV-seropositive donors. Six different epitopes were identified and several points were remarkable: 1) They were all located in two regions of the central part of the NEF protein corresponding to residues 73 to 94 and 113 to 147, respectively. 2) The CTL issued from a single donor could recognize several peptides of the NEF protein. 3) Some of these peptides could be recognized in association with at least two or three different HLA class I molecules. 4) Two different overlapping epitopes were present in a relatively short sequence of 15 amino acids. These results suggest that multiple epitopes corresponding to different HLA restrictions could coexist in a relatively small region of the NEF protein. The implications of these results in vaccine strategies using synthetic peptides bearing CTL epitopes are discussed.

Amino Acid Sequence↗
PubMed1990

Analysis of physical interactions between peptides and HLA molecules and application to the detection of human immunodeficiency virus 1 antigenic peptides.

The physical association of 40 antigenic peptides and purified HLA class I and class II molecules was monitored using a direct peptide binding assay (PBA) in solid phase and an inhibition peptide binding assay (IPBA) in which the competing peptide was present in a soluble phase. We also examined the ability of different peptides to inhibit the lytic activity of human antiviral cytolytic T cells towards cells incubated with the corresponding target peptide. Our results showed that: (a) Binding of a given human T cell-recognized peptide to several HLA class I and class II molecules occurred frequently. Nevertheless, preferential binding of peptides to their respective restriction molecules was also observed. (b) Binding of HLA molecules to peptides recognized by murine T cells occurred less frequently. (c) 11 of 24 (46%) randomly selected HIV-1 peptides contained agretopic residues allowing their binding to HLA molecules. (d) The kinetics of HLA/peptide association depended on the peptide tested and were faster than or similar to those reported for Ia molecules. Dissociation of these complexes was very low. (e) Peptide/HLA molecule binding was dependent on length, number of positive charges, and presence of hydrophobic residue in the peptide. (f) A correlation was demonstrated between a peptide inhibitory effect in the IPBA and its blocking effect in the cytolytic test. Our data indicated that the restriction phenomenon observed in T cell responses was not strictly related to either an elective HLA/peptide association, or a high binding capacity of a peptide to HLA molecules. These data also showed that the PBA and IPBA are appropriate for the detection of agretopic residues within HIV-1 proteins.

Amino Acid Sequence↗
PubMed1990

In vitro human cytotoxic T cell responses against influenza A virus can be induced and selected by synthetic peptides.

Studies on human anti-influenza cytolytic activities have demonstrated that cytotoxic T lymphocytes (CTL) from HLA-B37 individuals react preferentially with the peptide corresponding to residues 335-349 of the nucleoprotein, whereas CTL from HLA-A2 donors recognize peptide 57-68 from the viral matrix as a dominant epitope. We studied the secondary CTL response, obtained from peripheral blood mononuclear cells, of an HLA-A2+,B37+ individual stimulated either by infectious virus or by synthetic peptides. Only an HLA-B37-restricted response was detected after stimulation by the whole virus, showing an immunodominance of this activity over that restricted by HLA-A2. Moreover, human cytotoxic cell lines were successfully obtained after stimulation of peripheral blood mononuclear cells with synthetic peptides. Under these conditions, it was possible to selectively reveal the existence of an HLA-A2-restricted activity directed against the matrix peptide. These results demonstrate that, at least in vitro, it is possible to stimulate a latent repertoire by using synthetic peptides. Nevertheless, we could not induce a response against the matrix or the nucleoprotein peptides in HLA-A2- or B37- individuals, suggesting that a finer selection of synthetic peptides would be necessary for their possible utilization to induce CTL during vaccination.

Amino Acid Sequence↗
PubMed1989

An antigenic peptide of the HIV-1 NEF protein recognized by cytotoxic T lymphocytes of seropositive individuals in association with different HLA-B molecules.

By using target cells that expressed only the regulatory NEF protein of the human immunodeficiency virus (HIV), we were able to identify specific cytolytic T cells (CTL) from most of the seropositive patients tested. This NEF-specific cytolytic activity was mediated by CD8+ lymphocytes. In two different donors, we identified a unique peptide in the NEF protein that could be recognized in association with two different HLA class I molecules. The definition of such a peptide should prove useful in evaluating vaccine strategies.

Amino Acid Sequence↗
PubMed1988

[The oncogenes].

Explore the source record for details and available documents.

Carcinogens↗
PubMed1987

Autoreactive T cell clones of MHC class II specificities are produced during responses against foreign antigens in man.

Although the existence of autoreactive T cells has been widely reported in mice and in guinea pigs, a similar phenomenon is poorly documented in man. Here we report the study of three human autoreactive T cell clones isolated during immunization of HLA-DRw13 donors either against influenza A/Texas virus or against allogeneic cells. These clones are specific for autologous HLA-class II specificities either common to all HLA-DRw13 molecules or restricted to the HLA-DR products specific for the DW19 subtype of HLA-DRw13. They are also cytotoxic and they have the same specificity when tested for lytic activity or in proliferation assays. Furthermore, they are also able to help autologous B cells to polyclonally produce Ig. The possible implication of such clones in regulatory mechanisms involving HLA-class II molecules is discussed.

Adult↗