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Biomedical subjects

R A Weiss

Publications and source records attributed to R A Weiss.

At least 235 records · Page 13Linked to original sources
PubMed1989

An engineered poliovirus chimaera elicits broadly reactive HIV-1 neutralizing antibodies.

The Sabin type 1 vaccine strain of poliovirus is probably the safest and most successful live-attenuated vaccine virus used in humans. Its widespread use since the early 1960s has contributed significantly to the virtual eradication of poliomyelitis in developed countries. We have reported previously the construction of an intertypic antigen chimaera of poliovirus, based on the Sabin 1 strain, and proposed that this virus could be modified to express on its surface antigenic determinants from other pathogens. We describe here the construction and characterization of a poliovirus antigen chimaera containing an epitope from the transmembrane glycoprotein (gp41) of human immunodeficiency virus type 1 (HIV-1). In antibody absorption experiments, the virus chimaera inhibited neutralization of HIV-1 by antipeptide monoclonal antibodies specific for the gp41 epitope and significantly reduced the group specific neutralizing activity of HIV-1-positive human sera. Rabbit antisera raised by subcutaneous injection of the polio/HIV chimaera in adjuvant was shown to be specific for HIV-1 gp41 in peptide-binding assays and by western blotting. Moreover, the antisera neutralized a wide range of American and African HIV-1 isolates and also inhibited virus-induced cell fusion. Monoclonal antibodies against the HIV-1 derived regions of the chimaera also neutralized HIV-1. These results establish the potential of using poliovirus for the presentation of foreign antigens and suggest that Sabin 1 poliovirus/HIV chimaeras could offer an approach to the development of an HIV vaccine.

Amino Acid Sequence↗
PubMed1989

Identification of the residues in human CD4 critical for the binding of HIV.

The CD4 molecule is a T cell surface glycoprotein that interacts with high affinity with the envelope glycoprotein of the human immunodeficiency virus, HIV, thus serving as a cellular receptor for this virus. To define the sites on CD4 essential for binding to gp120, we produced several truncated, soluble derivatives of CD4 and a series of 26 substitution mutants. Quantitative binding analyses with the truncated proteins demonstrate that the determinants for high affinity binding lie solely with the first 106 amino acids of CD4 (the V1 domain), a region having significant sequence homology to immunoglobulin variable regions. Analysis of the substitution mutants further defines a discrete binding site within this domain that overlaps a region structurally homologous to the second complementarity-determining region of antibody variable domains. Finally, we demonstrate that the inhibition of virus infection and virus-mediated cell fusion by soluble CD4 proteins depends on their association with gp120 at this binding site.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Soluble CD4 blocks the infectivity of diverse strains of HIV and SIV for T cells and monocytes but not for brain and muscle cells.

The CD4 antigen has been subverted as a receptor by the human and simian immunodeficiency viruses (HIV-1, HIV-2 and SIV). Several groups have reported that recombinant, soluble forms of the CD4 molecule (sCD4) block the infection of T lymphocytes by HIV-1, as CD4 binds the HIV envelope glycoprotein, gp120, with high affinity. We now report that sCD4 blocks diverse strains of HIV-1, HIV-2 and SIV, but is less effective for HIV-2. The blocking effect is apparent even after adsorption of virions to CD4 cells. Soluble CD4 prevents HIV infection of T-lymphocytic and myelomonocytic cell lines, but neither sCD4 nor anti-CD4 antibodies inhibit infection of glioma and rhabdomyosarcoma cell lines.

Antigens, Surface↗
PubMed1989

Human immunodeficiency virus infection studied in CD4-expressing human-murine T-cell hybrids.

Human immunodeficiency virus (HIV) infection was studied by means of CD4-expressing human-murine T-cell hybrids, containing a variable amount of human chromosomes. Fusion of the HPRT- murine cell line BW5147 with human T-cell acute lymphoblastic leukemia or normal human blood cells resulted in a panel of human-murine T-cell hybrids. For this study, we used four hybrids containing all or several human chromosomes, which all expressed the CD4 antigen, as assessed by different anti-CD4 monoclonal antibodies (e.g., OKT4A, Leu-3a, and MT151) and, in addition, a variable number of other human T-cell antigens. For infection, HTLV-IIIB-infected H9 cells, pretreated with mitomycin C, and cell-free concentrated supernatants from these cells were used. In cells of inoculated cultures of the CD4+ T-cell hybrids, no viral antigen could be demonstrated. Culture supernatants of inoculated hybrids, except for an initial rise due to the virus inoculum, never showed reverse transcriptase activity above background. Cocultivation of these cell cultures with H9 cells did not result in detectable virus replication. Cocultivation of CD4-expressing hybrid cells with HIV-infected cells did not result in syncytium formation. Moreover, these hybrids were resistent to infection with vesicular stomatitis virus (VSV)-HIV pseudotypes. These findings imply that expression of the CD4 antigen on the cell surface is not sufficient for productive infection with HIV. The infectivity block observed in these hybrids seems to occur at the level of virus penetration, presumably at the stage of membrane fusion events.

Animals↗
PubMed1989

Characterization of HIV-1 neutralization escape mutants.

Infection by molecularly cloned HIV-1, in the presence of a high-titre neutralizing monoclonal antibody (MAb), resulted in the selection of plaques in MT4 cells releasing HIV resistant to neutralization by the same MAb. The epitope recognized by the MAb was mapped to the V3 neutralization epitope at amino acids 305-321. The HIV-1 variants showed a reduced binding capacity for the selecting MAb as determined by immunofluorescence. Polymerase chain reaction (PCR) amplification of complementary DNA derived from viral RNA, cloning and sequencing identified a base pair (bp) change C----G at position 6663 in variant 110.5/1, predicting a change at amino acid 308 Arg----Gly. No other changes in the epitope were observed by sequencing three other variants. Differential hybridization of PCR amplified viral RNA and DNA, with oligonucleotides specific for the observed bp change or the 'wild type' sequence, indicated that the variants 110.5/1 and 110.5/7 were genotypically mixed for 308Gly/Arg. Subsequent screening of biologically 'recloned' variants 110.5/1 and 110.5/7 identified two subclones homozygous for the 308Gly change. The Arg----Gly change appears to affect the binding of the antibody to the epitope, since the linear peptide substituting 308Gly for 'wild type' 308Arg was 100 times less potent in blocking the neutralization of parental HIV. Amino-acid residue 308 thus appears to be crucial for antibody binding to the epitope. In addition, mutations distant from the monoclonal antibody binding site may also affect neutralization by antibodies recognizing the V3 loop.

Amino Acid Sequence↗
PubMed1989

Evaluation of human and simian immunodeficiency virus plaque and neutralization assays.

A number of CD4+ T cell lines were compared for their ability to act as target cells for human immunodeficiency virus (HIV) infection in syncytium- and plaque-forming assays. MT-4 and C8166 cells were the most sensitive indicator cells for HIV- and simian immunodeficiency virus (SIV)-induced cytopathic effects, and gave rise to macroscopic (MT-4) and microscopic (C8166) plaques. The MT-4 plaque assay was evaluated for the measurement of HIV- and SIV-neutralizing antibodies.

Animals↗
PubMed1989

Inoculation of New World primates with the human immunodeficiency virus.

The susceptibility of common marmosets and cotton-top tamarins to infection by HIV-2 in vivo was tested. One year and 19 months, respectively, post-inoculation, sera taken from three of four animals from each species are reactive for HIV-2 antibodies and HIV-specific nucleotide sequences were demonstrated in short-term cultures of PBL from two cotton-top tamarins. The animals remain in good health.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Mascara and eyelining tattoos: MRI artifacts.

Magnetic resonance imaging (MRI) is very useful in the evaluation of ocular and orbital disease. Heavy metal particles, used in the pigment base of mascara and eyelining tattoos, have a paramagnetic effect that causes alteration of the local magnetic field in adjacent tissues. These changes in normal signal result in distortion of the globes. In some cases, the distortion may mimic actual ocular disease such as a ciliary body melanoma or cyst.

Cosmetics↗
PubMed1988

Human T cell leukemia viruses use a receptor determined by human chromosome 17.

Human T cell leukemia viruses (HTLV-I and HTLV-II) can infect many cell types in vitro. HTLV-I and HTLV-II use the same cell surface receptor, as shown by interference with syncytium formation and with infection by vesicular stomatitis virus (VSV) pseudotypes bearing the HTLV envelope glycoproteins. Human-mouse somatic cell hybrids were used to determine which human chromosome was required to confer susceptibility to VSV(HTLV) infection. The only human chromosome common to all susceptible cell hybrids was chromosome 17, and the receptor gene was localized to 17cen-qter. Antibodies to surface antigens known to be determined by genes on 17q did not block the HTLV receptor.

Animals↗
PubMed1988

Novel HIV systems.

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Acquired Immunodeficiency Syndrome↗
PubMed1988

HIV infection does not require endocytosis of its receptor, CD4.

The T cell surface molecule CD4 interacts with class II MHC molecules on the surface of target cells as well as with the envelope glycoprotein of human immunodeficiency virus (HIV). Internalization of CD4 molecules is observed after exposure of CD4+ T cells to either phorbol esters or appropriate antigen-bearing target cells. To determine whether HIV entry proceeds via receptor-mediated endocytosis or direct viral fusion with the cell membrane, we have constructed two mutants in the cytoplasmic domain of the CD4 protein that severely impair the ability of CD4 molecules to undergo endocytosis. Quantitative infectivity studies reveal that HeLa cell lines expressing wild-type or mutant CD4 molecules are equally susceptible to HIV infection. In addition, HIV binding does not lead to CD4 endocytosis. These studies indicate that although the CD4 molecule can be internalized, HIV entry proceeds via direct fusion of the viral envelope with the cell membrane.

Acquired Immunodeficiency Syndrome↗