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W V Williams

Publications and source records attributed to W V Williams.

At least 91 records · Page 5Linked to original sources
PubMed1992

Synthetic cyclodextrin derivatives inhibit HIV infection in vitro.

The AIDS pandemic has stimulated the search for safe potent antiviral agents. To date, only AZT has been approved as a therapeutic agent for the treatment of HIV infection. It is likely that a large number of antiviral compounds would be necessary to control a life-long infection. We have utilized the rigid structure of the cyclodextrin molecule to determine the minimal components necessary for anti-HIV activity. Utilizing this targeted approach to drug design, we demonstrate the antiviral effects of candidate compounds from the family of cyclodextrins. We report that polysulfated cyclodextrins mediate significant anti-HIV effects which include blocking infectivity and syncytia formation mediated by the HIV viruses. Several other substituted forms of cyclodextrins did not mediate significant antiviral effects. Further results demonstrate that the polysulfated cyclodextrins mediated no specific antiviral effects against already infected human cells. These results demonstrate that the antiviral activities of this class of compounds are centered around early events in the viral life cycle. These in vitro results suggest that such molecules may be of importance in antiretroviral therapeutic regimes.

Antiviral Agents↗
PubMed1992

Vertical transmission of human immunodeficiency virus (HIV) infection. Reactivity of maternal sera with glycoprotein 120 and 41 peptides from HIV type 1.

The observation that approximately 70% of HIV-infected pregnant women do not transmit infection vertically suggests that antibody therapy may be effective in the prevention of transmission of HIV infection from mother to child. Currently, there is an incomplete understanding of the processes involved in vertical transmission of HIV infection. The elucidation of the serological basis of maternal immunity as it relates to protection from vertical transmission is the goal of this study. We have screened 20 maternal sera from HIV+ individuals of known vertical transmission status for reactivity with 31 peptides spanning the entire envelope glycoprotein of HIV-1. Of interest was reactivity to regions outside of the V3 loop of gp120. The findings have been examined in relationship to transmission status, as well as to in vitro anti-HIV-1 biological activity. Our results indicate that lack of vertical transmission is correlated with high viral neutralization activity, but not with antisyncytial activity nor with binding to the V3 peptides examined in this study. Also, the transmission group bound to fewer gp41 peptides when compared with the nontransmission group, suggesting that immune responses to gp41 may be important in preventing transmission. These findings may provide insights into the design of passive immunotherapies.

Adult↗
PubMed1992

Restricted heterogeneity of T cell receptor transcripts in rheumatoid synovium.

RA is characterized by massive proliferation of synovial tissue, accompanying infiltration of the tissue with CD4+ T lymphocytes, and a genetic linkage to the MHC antigen HLA-DR4. Since T cells are restricted by class II MHC molecules such as DR4, this suggests a direct role for these CD4+ cells in pathogenesis. To investigate T cell receptor (TCR) usage in RA, we used oligonucleotide primers specific for each of the major alpha and beta TCR subfamilies to amplify cDNA derived from whole synovium or synovial tissue T cell lines in a family-specific manner. Detection of amplified DNA was facilitated by utilizing oligonucleotide probes derived from the constant regions of the TCRs. The TCR repertoire present in the synovial T cell lines was quite heterogeneous, with an average of 15 alpha chains and 15.8 beta chains detected. When synovial tissue was analyzed, the predominant TCR subfamilies detected tended to be more restricted, with an average of 4.6 alpha chains and 8.6 beta chains detected. This compared with an average of six alpha chains and 12 beta chains in nonrheumatoid synovial samples. The average percentage of synovia positive per TCR beta family was significantly lower for RA versus non-RA specimens (46.1 vs 65.6%, P = 0.034). These findings indicate that while a polyclonal population of T cells is present in RA synovium, the predominant patterns of TCR transcript expression may be somewhat more restricted, suggesting that TCR-based therapy of RA is possible.

Arthritis, Rheumatoid↗
PubMed1992

Binding of type 3 reovirus by a domain of the sigma 1 protein important for hemagglutination leads to infection of murine erythroleukemia cells.

The recognition of cellular receptors by the mammalian reoviruses is an important determinant of cell and tissue tropism exhibited by reovirus strains of different serotypes. To extend our knowledge of the role of reovirus-receptor interactions in reovirus tropism, we determined whether type 1 and type 3 reovirus strains can infect cells derived from erythrocyte precursors. We found that reovirus type 3 Dearing (T3D), but not type 1 Lang, can grow in murine erythroleukemia (MEL) cells. This difference in growth was investigated by using reassortant viruses and we found that the capacity of T3D to infect MEL cells is determined by the viral cell-attachment protein, sigma 1. In experiments using murine monoclonal antibodies (mAbs) that bind to different sigma 1 regions, we show that T3D binding to MEL cells is inhibited by a mAb that identifies a domain important for hemagglutination (HA). We also determined that type 3 strains that can infect murine L cells but do not produce HA do not infect MEL cells. These results suggest that type 3 reovirus binds to and infects erythrocyte precursor cells via a sigma 1 domain important for HA. Moreover, this study suggests that different domains of some viral cell-attachment proteins are used to initiate productive infections of different types of cells.

Animals↗
PubMed1991

Contact residues and predicted structure of the reovirus type 3-receptor interaction.

Sequence similarity between the reovirus type 3 hemagglutinin (HA3) and a anti-idiotypic monoclonal antibody (87.92.6) has been shown to define the site of interaction with a neutralizing (idiotypic) monoclonal antibody (9B.G5) and the cellular receptor for the virus. A synthetic peptide (VL peptide) derived from the anti-idiotypic sequence inhibits viral binding to the receptor. In this study, variants of the VL peptide were utilized to probe specific amino acid residues involved in binding the neutralizing antibody and the receptor. These studies indicate that the--OH groups of several residues are involved in contacting the reovirus type 3 receptor, including Tyr49, Ser50, Ser52, and Thr53 in the anti-idiotypic sequence, corresponding to Tyr326, Ser327, Ser329, and Ser325 in HA3, respectively. In contrast, only Ser50 of the anti-idiotypic sequence, corresponding to Ser327 of HA3, significantly altered neutralizing antibody binding. Additional studies implicate sialic acid as a potential reovirus type 3 receptor on some cells. This includes inhibition of binding of reovirus type 3 and 87.92.6 to L cells by heavily sialylated glycoproteins. Sialic acid was therefore utilized as a candidate receptor to analyze potential interaction schemes with HA3/87.92.6. Sequence similarity to other immunoglobulin structures with similar sequences allowed modeling of the three-dimensional structure of these epitopes. These structures, in combination with peptide studies, allow the development of a model of the interaction of these epitopes with sialic acid, which serves as a reovirus type 3 receptor. These models reveal that similar amino acid residues and side-chain geometries may be utilized by the reovirus type 3 and influenza hemagglutinins in their interactions with cell-surface receptors.

Amino Acid Sequence↗
PubMed1991

Design of bioactive peptides based on antibody hypervariable region structures. Development of conformationally constrained and dimeric peptides with enhanced affinity.

The variable regions of antibody molecules bind antigens with high affinity and specificity. This binding is imparted largely by the hypervariable portions of the variable region. Hypervariable regions typically fold into reverse turn or loop structures. Peptides derived from antibody hypervariable region sequences can bind antigens with similar specificity, albeit with markedly lower affinity. In this study, cyclic and dimeric peptide analogs of an anti-idiotypic/antireceptor antibody hypervariable region were developed. This antibody (87.92.6) binds to reovirus type 3 receptors on cells as well as to a neutralizing anti-reovirus type 3 monoclonal antibody (9B.G5). The cyclic peptides were utilized to probe the optimal conformation for binding to both the receptor and 9B.G5. By dimerizing or constraining the conformation of these peptides, higher affinity binding was produced. By utilizing several different cyclic peptides, the optimal conformation for binding was established. The conformationally optimized cyclic peptide possessed greater than 40-fold higher affinity for the receptor and the idiotype than the linear analog. This study suggests that conformationally constrained and dimeric peptides derived from antibody hypervariable loop sequences can bind antigens (including receptors) with reasonable affinity. hypervariable loop sequences can bind antigens (including

Amino Acid Sequence↗
PubMed1991

Anti-reovirus receptor antibody accelerates expression of the optic nerve oligodendrocyte developmental program.

Previous studies showed that the cell-surface receptor for reovirus serotype 3 (Reo3R) appears at an early stage of oligodendrocyte differentiation and that anti-Reo3R antibodies and Reo3R-binding peptides induce galactocerebroside expression by developing oligodendrocytes. In the present studies, anti-Reo3R antibodies are shown to stimulate additional features of the program of oligodendrocyte development, including the loss of the A2B5 marker and expression of myelin basic protein. In anti-Reo3R antibody-treated cultures, galactocerebroside was expressed by cells having the morphology of immature oligodendrocyte precursors. Reo3R binding did not appear directly to inhibit or stimulate proliferation of glial progenitor cells or to affect their lineage commitment. Cell-surface structures utilized as a receptor by reovirus type 3 appear to play a role in the regulation of the initiation or rate of execution of the oligodendrocyte developmental program.

Animals↗
PubMed1991

Protective humoral immune responses to the human immunodeficiency virus induced in immunized pigs: a possible source of therapeutic immunoglobulin preparations.

The human immunodeficiency virus (HIV-1) induces progressive and fatal disease in infected hosts. Initially the human immune response appears to control HIV infection. This hypothesis is supported by the long latency period observed during HIV infection prior to development of the active disease state. Similarly the observation of fetal protection from HIV infection in some pregnant women who have high titered neutralizing antibody responses to the virus underscores the importance of the humoral response to HIV in limiting infection. Therefore antibody replacement therapy is likely to provide substantial clinical benefits in this and other infected populations. However, currently there is no safe source for human antibodies with the desired protective qualities necessary for passive immune therapies. For a passive immune therapy to be valid it must protect against a diverse collection of viral isolates. Such a task is likely to require a complex mixture of human antibodies or human substitute antibodies which are available in large quantities and target conserved regions of the viral envelope, such that protection from diverse isolates are realized. Porcine products have been used extensively in many human therapeutic replacement regimens. Their use is primarily due to genetic similarity of the two species at the amino acid level which results in a high acceptance of grafted prosthetics and excellent tolerance of repeatedly administered biologicals. Accordingly we have examined the immunoglobulin responses to the Human Immunodeficiency Virus (HIV-1) of the Yorkshire mixed breed pig. Immunized animals developed significant humoral immunity as judged by ELISA, Western blot, radioimmunoprecipitation, flow microfluorimetry as well as in functional assays including neutralization and syncytia inhibition. The high neutralizing activity obtained and the immunological similarity between human and porcine immunoglobulin suggests that further investigation into the use of porcine immunoglobulin as human replacement antibodies for the therapeutic treatment of HIV is warranted.

Animals↗
PubMed1991

Human genes other than CD4 facilitate HIV-1 infection of murine cells.

The human CD4 glycoprotein is a specific receptor for the HIV family of retroviruses. When expressed on human cell lines, this molecule binds virus through direct interactions with the gp 120 viral envelope glycoprotein thus allowing virus infection to occur. Subsequent to binding, conformational changes in the viral envelope glycoproteins are thought to facilitate virus entry into the target cell through direct fusion of the virus with the cell membrane. In contrast to the infection observed in human cell lines, infection of murine cell lines even in the presence of the CD4 receptor does not readily occur. We have examined this species tropism of HIV infection. We report that the inability to infect murine cells is not a function of the receptor for HIV or a suppressive function of the murine cellular background. Human CD4 expression, configuration and down-modulation on the murine background are similar if not identical to expression on the human cell background. Utilizing a panel of interspecific cell hybridomas, we have been able to bypass the barrier to infectivity of human CD4-positive murine cells. We demonstrate that there are at least two different restrictions to infectivity on the mouse background which can be complemented by the human genome. One restriction appears to be an extremely early postbinding function likely to be molecules necessary for viral entry into cells, the second restriction is necessary for high levels of virus production. Our mapping studies suggest that fewer than five human chromosomes are necessary for reconstituting infectivity in the murine background. These results have implications for models of HIV-induced pathogenesis and infectivity.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Expression of the neu gene-encoded protein (P185neu) in human non-small cell carcinomas of the lung.

The neu protooncogene is a recently described transforming gene originally isolated from ethylnitrosourea-induced rat neuroblastomas. We have examined the expression of the neu gene in human non-small cell lung carcinomas using immunoprecipitation and immunohistochemistry. The neu protein product (p185neu) was present in eight of 22 non-small cell carcinoma cell lines derived from human lung tumors. Expression of p185neu was found in all histological subtypes of non-small cell carcinomas including large cell carcinomas, squamous cell carcinomas, and adenocarcinomas. Extension of these data to biopsy specimens of human lung tumors demonstrated that normal ciliated bronchial epithelium of the peripheral airways expressed p185neu at low levels. Neoplastic cells in four of 12 adenocarcinomas and three of five squamous cell carcinomas also expressed p185neu at levels higher than the normal ciliated bronchial epithelium. Together these studies indicate that p185neu expression is a common feature of human lung tumors.

Biopsy↗
PubMed1990

Antibody geometry and form: three-dimensional relationships between anti-idiotypic antibodies and external antigens.

Anti-idiotypes have been developed to mimic a wide variety of antigens in studies of antibody-antigen interactions. Molecular, biochemical and structural analysis of antibody-anti-idiotype pairs presents an excellent model for study of complex protein-protein interactions. An understanding of the ways in which anti-idiotypes mimic antigens and the features determining binding characteristics will facilitate rational design of compounds with biological, enzymatic, pharmaceutical and chemical applications.

Amino Acid Sequence↗
PubMed1990

Ligand binding to the cell surface receptor for reovirus type 3 stimulates galactocerebroside expression by developing oligodendrocytes.

Viruses utilize normal cell surface structures as attachment sites. Interaction of viral components with these structures may alter target cell growth. In the present study, the expression and function of the cell surface receptor for reovirus type 3 (Reo3R) was studied in neonatal rat optic nerve glial cultures. The Reo3R is expressed by mature oligodendrocytes and astrocytes but not by O-2A progenitor cells. It appears at an early stage of oligodendrocyte development, coincident with the O4 marker but prior to galactocerebroside or myelin basic protein. Anti-Reo3R antibodies stimulate the expression of galactocerebroside by developing oligodendrocytes. Divalent Reo3R-binding peptides are similarly active. Maximal stimulation of galactocerebroside expression occurs with treatment as short as 4 hr, consistent with a receptor-mediated process. Cell surface structures used as an attachment site by reovirus type 3 may also play a role in the regulation of oligodendrocyte differentiation.

Amino Acid Sequence↗
PubMed1990

Species tropism of HIV-1 infectivity of interspecific cell hybridomas implies non-CD4 structures are required for cell entry.

Studies have demonstrated that CD4 may be necessary but not sufficient for human immunodeficiency virus (HIV) infection. Murine cell lines constructed to express the human CD4 glycoprotein demonstrate a restriction in their ability to support infection by the HIV-1 retrovirus. Such restrictions may indicate that molecules in addition to CD4 may be necessary for HIV-1 infection. HIV-1 infectivity has been examined in a panel of murine and human cell lines. It has been demonstrated that CD4 expression allows infectivity on a wide range of human cell lines. Some interspecific hybridomas constructed between human and murine cell lines can, when expressing the human CD4 glycoprotein, become infectable in a manner similar to human cell lines. These studies imply that surface molecules, in addition to CD4, are necessary for HIV-1 entry and infectivity. Such molecules will be important for understanding the pathogenesis of HIV-1.

Animals↗
PubMed1989

Immune response to a molecularly defined internal image idiotope.

A monoclonal anti-idiotope termed 87.92.6 mimics the neutralization/cell-attachment site of the reovirus type 3 hemagglutinin (HA3). The second complementarity determining regions of the VH and VL of 87.92.6 share sequence similarity with a determinant on the HA3. We have used synthetic peptides (termed VH, VL, and Reo peptides, respectively) to probe the immunologic significance of this sequence similarity. Antibodies specific for Reo peptide or VL peptide neutralized reovirus type 3 infectivity. Although Reo peptide was an effective immunogen by itself, free VL peptide or VH peptide were unable to elicit antibodies unless they were linked to each other (VH-VL peptide). Immunization with reo peptide, 87.92.6, or the HA3 elicited a specific lymphocyte proliferative response to VH peptide, indicating that VH peptide may bear an important TH determinant. As found previously for 87.92.6, VL peptide elicited a delayed-type hypersensitivity response specific for reovirus type 3. Reovirus type 3 specific cytolytic lymphocytes specifically lysed targets coated with VH-VL peptide, but not VH or VL peptide alone. These results suggest that immune cross-reactivity between an external Ag and an internal image antibody can be understood at the primary structural level. These observations may have important implications for understanding the development of autoantibodies, network interactions, and the regulation of immune responses.

Amino Acid Sequence↗
PubMed1989

A point mutation in the neu oncogene mimics ligand induction of receptor aggregation.

The rat neu gene, which encodes a protein closely related to the epidermal growth factor receptor, is a proto-oncogene that can be converted into an oncogene by a point mutation. Both genes encode proteins with a relative molecular mass of 185,000 but the question of why the neu gene product, p185neu, is oncogenic, whereas the product of c-neu, p185c-neu, is not, remains unanswered. The proteins have several features common to the family of tyrosine kinase growth-factor receptors, including cysteine-rich external domains, a hydrophobic transmembrane region and a cytoplasmic tyrosine kinase domain. The oncogenic p185neu differs from p185c-neu by an amino-acid substitution in the transmembrane region of the glycoprotein: this replacement of valine by glutamic acid at position 664 induces increased intrinsic tyrosine kinase activity which is associated with transformation. Many glycoproteins with charged amino acids in the transmembrane region exist as multimeric complexes at the plasma membrane. We have therefore investigated the association state of both products of the neu gene and show that the oncoprotein p185neu is organized at the plasma membrane primarily in an aggregated form, but that p185c-neu is not. Induction of an aggregated state may mimic aspects of ligand-induced receptor aggregation resulting in enzymatic activation that leads to cellular transformation.

Animals↗