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Biomedical subjects

D Zagury

Publications and source records attributed to D Zagury.

At least 55 records · Page 3Linked to original sources
PubMed1994

Cytotoxic T lymphocytes specific for HIV-1 gp160 antigen and synthetic P18IIIB peptide in an HLA-A11-immunized individual.

Cytotoxic T cell determinants should be an important component of an anti-human immunodeficiency virus (HIV) vaccine. The epitopes of proteins can be defined with short synthetic peptides for class I-restricted CTLs. An immunodominant CTL epitope from the HIV-1 IIIB envelope protein gp160 comprising 15 amino acids (residues 315-329: RIQRGPGRAFVTIGK) (P18IIIB) has been identified that is recognized by class I MHC molecule H-2d-restricted murine CD8+ CTLs. We have investigated the epitope specificity of anti-HIV-1 CTLs in immunized individuals and we found that the CTL response was restricted by more than one class I MHC molecule, including HLA-A2 and HLA-A3. In the present work, we also show that the response against P18IIIB peptide is restricted by the HLA-A11 molecule in an individual immunized by vaccinia virus expressing gp160 protein. This peptide could thus be recognized in association with different HLA class I allotypes. This work has implications for vaccine strategies, using the P18 peptide.

Amino Acid Sequence↗
PubMed1994

Automat: a novel software system for the systematic search for protein (or DNA) similarities with a notable application to autoimmune diseases and AIDS.

Automat is a novel program which finds exhaustively all the oligopeptide segments shared by a given protein of any size with the proteins of a whole databank. It allows the user to collect statistics on the composition of the sequence studied in reference to the databank used. We present here the rationale and the algorithm underlying this powerful software. Besides its immediate interest for identifying efficiently similarities between proteins (or DNAs), biological applications of this software have already been described in the case of HIV-1 viral proteins, and Automat should prove useful also for studying more generally autoimmune diseases.

Acquired Immunodeficiency Syndrome↗
PubMed1993

Envelope protein and p18(IIIB) peptide recognized by cytotoxic T lymphocytes from humans immunized with human immunodeficiency virus envelope.

Cytotoxic T cells are the main antigen-specific effector cells of the cellular immune system and MHC class I restricted cytotoxic T-lymphocyte (CTL) responses in mice, acting against the HIV-1 envelope protein, are known to be predominantly directed against an amino acid sequence in the third hypervariable domain. We have investigated the epitope specificity of anti-HIV-1 CTL in healthy human volunteers inoculated with a recombinant vaccinia expressing the HIV-1 gp160 envelope gene. Their isolated lymphocytes were stimulated in vitro with autologous HIV-1 infected cells. Our results show that immunization with recombinant virus is able to generate virus-specific CTLs to the HIV-1 gp160 envelope protein and to a 15-residue synthetic peptide corresponding to a highly variable region of the envelope p18(IIIB). The CTL response was restricted by class I MHC molecules HLA-A2 and A3 that commonly occur in the human population.

AIDS Vaccines↗
PubMed1993

Polymerase chain reaction amplified HTLV-I, HIV-1 and HIV-2 DNA fragments in subjects with mixed retroviral infections.

Serum and peripheral blood mononuclear cells from eight patients from the Ivory Coast with positive screening test results for retroviral infections were studied by serology (ELISA, Western blot (WB), synthetic peptide test), cell co-culture, and polymerase chain reaction (PCR). Two HIV-2 infections with indeterminate interpretation on HIV-1 WB were detected, two were clear dual HIV-1/HIV-2 infections, three were ambiguous mixed HIV-1/HIV-2 infections, and one was a triple retroviral infection by HTLV-I, HIV-1 and HIV-2. Four slow/low HIV-1 strains were isolated at the expense of HTLV-I and HIV-2 strains. The ELISA tests were found to be very sensitive. Indeterminate WB interpretations were frequent (HTLV-I, four; HIV-1, three; HIV-2, two). PCR provided clear evidence of multiple retroviral infections in three cases and enabled interpretation of indeterminate WB samples in three cases. One sample presented a puzzling pattern with positive PCR results for HIV-1 and HIV-2 associated with negative or indeterminate serological results. Thus, our data emphasise the need to analyse serological as well as virological markers to gain better insight on mixed retroviral infections, especially in endemic areas such as West Africa.

Base Sequence↗
PubMed1992

One-year follow-up of vaccine therapy in HIV-infected immune-deficient individuals: a new strategy.

Immunization of AIDS/ARC patients with autologous cells expressing HIV antigens, although providing clinical and biological benefits, fails to restore cellular immunity. The latter result is due partly to the antiproliferative effect of HIV-1 on activated T-cells (immune suppression), which leads to blockade of specific immune reactions. To overcome immune suppression, a new vaccine strategy was designed consisting of an immunization against HIV-1 combined with components of the T-cell-suppressive (antiproliferative) network. This new vaccine treatment proved to be innocuous in mice, monkeys, and two non-HIV-infected humans. A Phase I clinical trial was performed in six patients previously under cellular immunotherapy and still presenting a cellular immune defect. Preliminary results confirmed, after a 1-year follow-up of the patients, the safety of the new vaccine, which also partially restored the cellular immune response, including anti-HIV HLA-restricted cell-mediated cytotoxicity, delayed hypersensitivity to recall antigens, and proliferation of T-cells specifically activated by recall antigens.

AIDS Vaccines↗
PubMed1991

Characterization and large production of human monoclonal antibodies against the HIV-1 envelope.

Peripheral blood lymphocytes from a volunteer immunized with a recombinant vaccinia virus VSC-25 expressing the gp160 env protein of HTLV-IIIB strain and from an asymptomatic HIV-infected individual were immortalized by Epstein-Barr (EBV). Clones which secrete human monoclonal antibodies from the two individuals (DZ, IgG1, lambda and C31, IgG1, kappa) were obtained and were stable for more than 2 years. The two monoclonals were directed against the gp160 env protein of HIV, DZ directed against the gp41 and C31 directed against the gp120. C31 was group-specific, whereas DZ was directed against the HTLV-IIIB and HTLV-RF strains. The epitope recognized by DZ was mapped to the carboxy terminus of the gp41, by expression of HIV DNA fragments in a yeast system and peptide analysis. The C31 epitope was not expressed by the yeast library and not present among the peptides which were tested. Monoclonal antibodies had no inhibitory effect in an HIV-induced cell fusion assay, but DZ showed a weak neutralizing activity against the HTLV-IIIB strain. Cloned EBV-transformed cell lines were fused to a murine myeloma, which allowed the heteromyeloma to be cultivated in serum-free medium. The monoclonal antibodies were produced in large quantity in a hollow-fibre reactor at defined culture conditions and purification procedures.

Animals↗
PubMed1990

Variable stringency hybridization of polymerase chain reaction amplified HIV-1 DNA fragments.

DNA isolated from the peripheral blood mononuclear cells of HIV-1 seropositive individuals was used for polymerase chain reaction (PCR) amplification of gag and envelope regions. Eight aliquots of the amplified DNA fragments have been subjected to Southern/dot blot analysis, hybridizing with 32P-labelled-BH10 (HIV-1 strain IIIB) at low stringency. After the filters had been autoradiographed, they were cut so that each hybridized band/dot could be subject to variable stringency washing using various ionic concentrations at a fixed temperature. The filter was reconstructed so that the effect of the variable stringency wash might be visualized following a second exposure to Kodak film. The level of activity for each band/dot was measured by counting the 32P or by densitometry analysis of the photographic record. The results allow a plot to be made of the decrease in bound radioactivity against ionic strength. By comparison with a standard curve obtained for HIV-1 strain IIIB amplified fragments subject to similar hybridization and analysis, an estimation of the degree of nucleotide mismatch relative to the BH10 DNA probe can be obtained. The technique provides a rapid means of characterizing PCR amplified fragments.

DNA, Viral↗
PubMed1990

HGP-30, a synthetic analogue of human immunodeficiency virus (HIV) p17, is a target for cytotoxic lymphocytes in HIV-infected individuals.

Evaluation of the immune response of individuals exposed to human immunodeficiency virus (HIV) is an important component of any plan designed to lead toward the development of an AIDS vaccine. Since the levels of antibodies to HIV p17 and the synthetic p17 peptide HGP-30 correlate with stages of progression to AIDS, studies were initiated to determine whether cytotoxic lymphocytes directed toward target cells pulsed with HGP-30 and radioactive chromium were present in seropositive individuals. The significance of such cells in controlling HIV viral infection has recently been enhanced by reports that HIV p17 is on the surface of infected cells and that an inactivated virus vaccine depleted of viral envelope appears to be effective in controlling expression. The selection of HGP-30 as the p17 peptide to be evaluated in early studies is based on the presence of both T-cell and B-cell epitopes as predicted by computer modeling and mouse studies and the demonstration of in vitro neutralization activity by antibodies to the epitope. By using B-lymphoblastoid cells pulsed with HGP-30 and radioactive chromium as autologous targets and mixed leukocyte culture-expanded peripheral blood lymphocytes as effectors, CD8+ cytotoxic T lymphocytes against HGP-30-coated targets were identified in seropositive individuals. In this report we demonstrate that a synthetic p17 epitope can be a target for major histocompatibility complex-restricted cytotoxic T lymphocytes in HIV-infected individuals.

Cells, Cultured↗
PubMed1990

In vitro characterization of a biologically active molecular clone of HIV-2NIH-Z containing a nef deletion and expressing a full-length transmembrane protein.

We have previously described the cloning and sequencing of a novel stain of human immunodeficiency virus type 2 (HIV-2) called HIV-2NIH-Z. A plasmid clone, pHIV2Z, containing the full-length provirus has now been constructed, and virus particles have been obtained upon transfection into COS-1 and H-9 cells. These particles can infect a number of T-cell lines and exert a cytopathic effect on fresh human and macaque peripheral blood lymphocytes. The cloned virus is biologically and morphologically indistinguishable from its parental uncloned strain as shown by restriction enzyme analysis, electron microscopy, and kinetics of infection. However, as shown by radioimmunoprecipitation assays, the cloned virus-infected cells express a full-length gp41 protein as predicted by the nucleotide sequence, whereas the wild-type parental strain expresses a truncated gp33 protein. Both the parental strain and the cloned virus possess a deletion encompassing the end of the nef gene within the U3 region which apparently does not affect their in vitro cytopathic and replicative capacities.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Use of Old World monkeys for acquired immunodeficiency syndrome research.

Mangabeys, macaques, and baboons persistently infected with human immunodeficiency virus (HIV)-2 NIH-DZ demonstrated no signs of immunodeficiency disease after 6-11 months following seroconversion. Thus Old World monkeys provide an animal model to investigate the effects of passive immunization (anti-HIV-2 antibodies) on HIV infection in primates.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Antigenic peptides recognized by T lymphocytes from AIDS viral envelope-immune humans.

T-lymphocyte immunity is likely to be an important component of the immune defence against the AIDS virus, because helper T cells are necessary for the antibody response as well as the cytotoxic response. We have previously predicted two antigenic sites of the viral envelope protein gp120 likely to be recognized by T lymphocytes, based on their ability to fold as amphipathic helices, and have demonstrated that these are recognized by T cells of mice immunized with gp120 (ref. 1). A peptide corresponding to one of these sites can also be induce immunity in mice to the whole gp120 protein. Because many clinically healthy seropositive blood donors have already lost their T-cell proliferative response to specific antigen, we tested the response to these synthetic peptides of lymphocytes from 14 healthy human volunteers who had been immunized with a recombinant vaccinia virus containing the AIDS viral envelope gene and boosted with a recombinant fragment. Eight of the 14 responded to one peptide, and four to the other peptide, not included in the boost. These antigenic sites recognized by human T cells may be useful components of a vaccine against AIDS. We also found a correlation between boosting with antigen-antibody complexes (compared to free antigen) and higher stimulation indices, suggesting a more effective method of immunization.

Acquired Immunodeficiency Syndrome↗
PubMed1988

A group specific anamnestic immune reaction against HIV-1 induced by a candidate vaccine against AIDS.

The first experimental immunization of humans against the AIDS retrovirus, HIV-1, was started in a series of HIV seronegative, healthy volunteers in November 1986. For the primary vaccination recombinant vaccinia virus (V25) expressing the complete gp160 env protein of the HTLV-IIIB strain of HIV-1 was introduced by scarification. This elicited a weak primary response which we subsequently attempted to enhance by additional immunizations (boosting), using four different immunization protocols. We report here that intravenous injection of paraformaldehyde-fixed autologous cells infected in vitro with V25 (individual D.Z.) gave the best results. This individual received second and third boosts of intramuscular gp160 derived from an HTLV-IIIB clone using the hybrid vaccinia virus/bacteriophage T7 expression system. An anamnestic humoral and cellular immune reaction was achieved for over one year after the original vaccination, with high levels of antibodies to the viral envelope, and neutralizing antibodies against divergent HIV-1 strains such as HTLV-IIIB and HTLV-IIIRF (also called HTLV-III HAT) after the first boost. In addition, group-specific cell-mediated immunity and cell-mediated cytotoxicity against infected T4 cells were obtained after the primary vaccine and enhanced by the boosts. Finally, skin tests showed both immediate and delayed hypersensitivity to gp160 in vivo. Although this protocol is not practical for a large scale vaccine trial, our results show for the first time that an immune state against HIV can be obtained in man.

Acquired Immunodeficiency Syndrome↗