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Biomedical subjects

W E Robinson

Publications and source records attributed to W E Robinson.

At least 55 records · Page 3Linked to original sources
PubMed1990

Effective inactivation of human immunodeficiency virus with chlorhexidine antiseptics containing detergents and alcohol.

The antiseptics 4% chlorhexidine gluconate detergent formulation containing 4% isopropyl alcohol (Hibiclens/Hibiscrub) and 0.5% chlorhexidine gluconate in 70% isopropyl alcohol with emollients (Hibistat/Hibisol) efficiently inactivated human immunodeficiency virus (HIV) produced in cell culture within 15 seconds. These antiseptics were completely effective at 1:100 and 1:5 dilutions, respectively. Therefore, use of these products according to the manufacturer's instructions (i.e. undiluted) for routine disinfection of hands following contact with HIV-contaminated materials, as well as immediate disinfection of abrasions or cuts exposed to HIV, should have significant protective effects.

1-Propanol↗
PubMed1990

Human monoclonal antibodies to the human immunodeficiency virus type 1 (HIV-1) transmembrane glycoprotein gp41 enhance HIV-1 infection in vitro.

Three of 16 human monoclonal antibodies (hu-mAbs) enhanced human immunodeficiency virus type 1 (HIV-1) infection of MT-2 target cells by means of a mechanism that is dependent on complement. Enhanced infections are characterized by an increase in cytopathic effects and antigen synthesis as well as an increase in the production of progeny virus as detected by release of reverse transcriptase activity and infectious virus into the culture medium. Analyses by radioimmunoprecipitation, Western blot, and ELISA using the pENV9 envelope fragment localize the antigenic specificities of these three hu-mAbs to the N-terminal two-thirds of the transmembrane protein gp41. Competitive binding experiments indicate that the hu-mAbs are reactive with immunodominant epitopes of gp41 recognized by sera from essentially all HIV-1-infected subjects. Combination dose-effect experiments demonstrate that these hu-mAbs can act synergistically in vitro to enhance HIV-1 infection. These data demonstrate that hu-mAbs directed against the HIV-1 transmembrane glycoprotein gp41 can enhance HIV-1 infection in vitro. The availability of these reagents allows for the mapping of enhancing epitopes on HIV-1 and provides a means for studying whether deletion of such enhancing epitopes from candidate HIV-1 vaccines might improve the protective immune response to HIV-1 in immunized humans and chimpanzees.

Antibodies, Monoclonal↗
PubMed1990

Differential inhibition of HIV-1 cell binding and HIV-1-induced syncytium formation by low molecular weight sulphated polysaccharides.

Dextran sulphate (MW 5000 and 8000) and a polysulphated glycosaminoglycan (MW 10,000), at concentrations that provided complete protection in a homologous infection assay, failed to block syncytium formation and the resulting cytopathic effect when MT-2 cells were mixed with H9/HIV-1 cells. These substances also had no antiviral activity when added to cells, after virus challenge, at a time when binding and entry were complete. However, a high molecular weight (500,000) dextran sulphate blocked HIV-1 infection at both stages. Thus, the gp120-CD4 interactions mediating HIV-1 binding and HIV-1-induced syncytium formation are differentially affected by this class of polyanionic substances. Furthermore, size may be a determining factor in their potential application as anti-HIV treatment.

Antiviral Agents↗
PubMed1990

Antibody-dependent enhancement of simian immunodeficiency virus (SIV) infection in vitro by plasma from SIV-infected rhesus macaques.

Plasma from two rhesus macaques (Macaca mulatta) experimentally infected with the simian immunodeficiency virus (SIV; isolate SIVmac251) enhanced SIVmac infection of a human CD4+ lymphoblastoid cell line, MT-2. Prechallenge plasma samples from these animals and serum from SIV-negative macaques did not enhance infection. Compared with controls, infection enhancement was characterized by the rapid appearance of syncytium formation (3 to 4 days sooner), reverse transcriptase release (10-fold increase), and cytopathic effect (60% cell killing). Enhancement of activity was dependent on the presence of diluted, fresh SIV-negative macaque serum as a source of complement. A requirement for complement was shown by the absence of enhancement in heat-inactivated serum and by dose-dependent inhibition of enhancement in the presence of polyclonal antibody to monkey complement component C3. Monoclonal antibody to CD4 (OKT4a) blocked enhancement completely, while monoclonal antibody to the human complement component C3d receptor CR2 (OKB7) reduced enhancement by greater than 50%, indicating a requirement for CD4 and CR2 in mediating this phenomenon. SIV infection-enhancing activity appeared in macaques soon after experimental inoculation (28 days). The titer increased over time and peaked just prior to the death of both macaques from opportunistic infections and lymphoma. In vitro SIV infection enhancement is nearly identical to the in vitro complement-mediated, antibody-dependent enhancing (C'-ADE) activity observed in human immunodeficiency virus-positive human sera (Robinson et al., Lancet i:790-794, 1988; Robinson et al., J. Acq. Immun. Def. Synd. 2:33-42, 1989). These observations validate the macaque-SIV model for studies of C'-ADE.

Animals↗
PubMed1990

Antibodies to the primary immunodominant domain of human immunodeficiency virus type 1 (HIV-1) glycoprotein gp41 enhance HIV-1 infection in vitro.

Previous experiments had shown that two human monoclonal antibodies (huMAbs) directed against human immunodeficiency virus type 1 (HIV-1) enhanced HIV-1 infection in vitro (Robinson et al., Proc. Natl. Acad. Sci. USA, 87:3185-3189, 1990). This complement-mediated, antibody-dependent enhancement (C'-ADE) of HIV-1 infection caused 12-fold increases in reverse transcriptase released from MT-2 cells. In the study reported here, it was demonstrated that both of these huMAbs, 86 and V10-9, bound to an immunodominant peptide in gp41 (amino acids 586 to 620). This peptide blocked C'-ADE of HIV-1 infection in vitro regardless of whether huMAb 86 or human polyclonal anti-HIV was used as the source of anti-HIV antibody. Blockade of enhanced infections was characterized by decreases in antigen synthesis, cytopathic effect, and reverse transcriptase release. The ability of the huMAbs to enhance infection was determined to be dependent upon specific peptide reactivity and not dependent upon immunoglobulin subclass, complement fixation, or gross antigen reactivity. Since the peptide to which enhancing antibodies bind is immunodominant and does not bind neutralizing antibodies, it may be worthwhile to investigate deletion of this 35-amino-acid peptide from candidate anti-HIV vaccines.

Amino Acid Sequence↗
PubMed1990

Neutralization and enhancement of in vitro and in vivo HIV and simian immunodeficiency virus infections.

Over the past year significant progress has been made in mapping those regions of the HIV-1 envelope glycoproteins involved in virus neutralization and virus enhancement. These functional, antigenic domains of the gp160 are illustrated in Fig. 1. The role of neutralization in vaccine development is still unresolved, although high-titer antibody to the V3 loop of HIV-1 appears to be correlated with the ability to prevent HIV-1 infection by the homologous strain in chimpanzees. Therefore, the mechanism of type-specific neutralization of HIV appears to be clearly defined. The problem of group-specific neutralization of HIV-1 is still a mystery. Nevertheless, the finding that secondary structure is important for the generation of group-specific neutralizing mAbs and that carbohydrate is an important determinant for group-specific neutralization suggests that non-linear determinants are important. Answers to the question of group-specific neutralization should be available in the next few years. The role of HIV-1-enhancing antibodies in pathogenesis is not well understood. Nevertheless, the ability of patient serum to only enhance the patient's own isolate and not neutralize that isolate suggests that enhancing antibodies are important. Furthermore, the findings that enhancing antibody titers increase in SIV infection and peak immediately prior to the death of the animal suggests that such antibodies may play a role in SIV pathogenesis. With the identification and domain mapping of enhancing hu-mAbs, it should be possible to evaluate directly the role of enhancing domains in HIV and SIV pathogenesis by challenging animals in the presence of pure enhancing antibody. Only when these experiments are performed will it be possible to evaluate what role, if any, enhancing antibodies play in HIV pathogenesis. The above questions, when answered, are likely to provide important insights into lentivirus pathogenesis and help researchers to produce a safe and effective anti-HIV vaccine.

Amino Acid Sequence↗
PubMed1990

Antibody-dependent enhancement of SIV infection: further characterization and cross reactivity between macaque and sooty mangabey isolates.

Plasma from four rhesus macaques (Macaca mulatta), of which two were experimentally infected with the simian immunodeficiency virus (SIV) isolate SIVmac251, one with isolate SIVsmF236, and another with a SIVsmF236 molecular clone, SIVsmH-4, enhanced SIVmac infection of MT-2 cells. In addition to SIV-positive plasma, infection-enhancement required complement, CD4, and CR2. Titers of infection-enhancing antibodies appeared to correlate with disease progression. The MT-2/SIVmac251 system should be useful in future studies of complement-mediated, antibody-dependent enhancement of macaque and sooty mangabey SIV isolates.

Animals↗
PubMed1989

Inhibition of HIV-1 proviral DNA synthesis and RNA accumulation by mismatched dsRNA.

The antiviral activity of mismatched dsRNA of the form poly(I):poly(C12-U)n (Ampligen) against the human immunodeficiency virus type 1 (HIV-1) was investigated by RNA-RNA and RNA-DNA hybridizations. Mismatched dsRNA delayed the appearance of newly transcribed HIV-1 RNA as detected by liquid dot-blot hybridization in cultures of H9 T-lymphoblastoid cells following virus challenge. The appearance of proviral DNA as detected by Southern hybridization following virus challenge in H9 cells was also delayed. Mismatched dsRNA had no effect in syncytium inhibition assays performed by fusing MT-2 cells with H9/HTLV-IIIB cells. These results suggest that the in vitro anti-HIV-1 activity of mismatched dsRNA occurs, at least in part, at an early stage in the viral replication cycle following initial gp120-CD4 binding.

Antiviral Agents↗
PubMed1989

Antibody-independent, complement-mediated enhancement of HIV-1 infection by mannosidase I and II inhibitors.

Human immunodeficiency virus type 1 (HIV-1) infectivity and cytopathic effect require proper maturation of the viral envelope glycoprotein carbohydrate moieties. We have found that fresh human serum enhances the infectivity of HIV-1 in MT-2 cell infection assays when virus is synthesized in the presence of the mannosidase I inhibitor, 1-deoxymannojirimycin, or the mannosidase II inhibitor, swainsonine, but has no enhancing effect on virus synthesized in the presence of the glucosidase I inhibitors, castanospermine and 1-deoxynojirimycin, or the glucosidase II inhibitor, bromoconduritol. Enhanced infections were characterized by cytopathic effect, antigen synthesis and reverse transcriptase release, all which occurred sooner than in control-infected cultures. This enhancement of infection was also observed in C1q-deficient serum but was not observed in serum that was heat-inactivated or depleted of complement components C3 or factor B, thus suggesting a requirement for the alternate pathway of complement.

1-Deoxynojirimycin↗
PubMed1989

Antibody-dependent enhancement of human immunodeficiency virus type 1 (HIV-1) infection in vitro by serum from HIV-1-infected and passively immunized chimpanzees.

Based on recent reports of antibody-dependent enhancement of human immunodeficiency virus type 1 (HIV-1) infection in vitro by serum from HIV-1-infected humans, sera from HIV-1 antibody-positive chimpanzees (Pan troglodytes) was evaluated for enhancing activity in an in vitro infection assay that uses MT-2 cells (a human lymphoblastoid cell line). Although fresh chimpanzee serum was found to have pronounced infection-enhancing properties in the absence of antibody to HIV-1, this effect was abolished by heat inactivation (57 degrees C, 1 hr) or treatment with cobra venom anticomplementary protein. Heat-inactivated, HIV-1 antibody-positive chimpanzee serum could enhance HIV-1 infection of MT-2 cells in vitro when combined with fresh, normal human serum. By serial serum samples from three HIV-1-infected chimpanzees, HIV-1 antibody-positive chimpanzees are shown to develop enhancing antibodies early in infection (2 mo postchallenge), whereas neutralizing antibodies develop later. Over the course of HIV-1 infection, this enhancing activity decreases while neutralizing activity increases, suggesting a possible role for enhancing and neutralizing activities in HIV-1 pathogenesis. The enhancing activity of an IgG fraction used to passively immunize chimpanzees against HIV-1 infection is shown to be present at dilutions as high as 1:65,000, offering an interesting possible reason for the failure of passive immunization to protect chimpanzees from HIV infection. These results suggest that serum from HIV-1-immunized chimpanzees might be tested to determine whether current HIV-1 candidate vaccines induce production of antibodies that mediate antibody-dependent enhancement of HIV-1 infection in this in vitro assay.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Phosphorothioate and cordycepin analogues of 2',5'-oligoadenylate: inhibition of human immunodeficiency virus type 1 reverse transcriptase and infection in vitro.

Natural antiviral activity can be mediated by the interferon-induced synthesis of 2',5'-oligoadenylates (2-5As) and subsequent RNase L activation by these molecules. Analogues of 2-5A that are biologically active and metabolically stable were synthesized and analyzed for antiviral activity against the human immunodeficiency virus type 1 (HIV-1). Replacement of the 3' hydroxyl group of the adenosine moieties of 2-5A with hydrogen atoms (i.e., cordycepin analogues of 2-5A) converted authentic 2-5A trimer into anti-HIV-1 agents in vitro. These cordycepin analogues of 2-5A also inhibited partially purified HIV-1 reverse transcriptase. Introduction of chirality into the 2',5'-phosphodiester internucleotide linkages or 5'-phosphate moieties of the 2-5A molecule (i.e., phosphorothioate analogues of 2-5A) converted authentic 2-5A into more potent inhibitors of HIV-1 reverse transcriptase. However, these phosphorothioate 2-5As demonstrated little or no anti-HIV-1 activity in vitro. Thus, some analogues of 2-5A may form a class of anti-HIV-1 drugs with possible pleiotropic activities that include activation of latent RNase L and inhibition of reverse transcription.

Adenine Nucleotides↗
PubMed1989

In vitro evaluation of mismatched double-stranded RNA (ampligen) for combination therapy in the treatment of acquired immunodeficiency syndrome.

Multiple drug effect analyses with mismatched double-stranded RNA (mismatched dsRNA or Ampligen) as a core drug were performed to identify other agents and mechanisms through which mismatched dsRNA may potentiate effective therapeutic intervention in human immunodeficiency virus (HIV) infection. Antiviral activities were defined by a microtiter infection assay utilizing MT-2 cells as targets and HTLV-III-B produced in H9 cells as a virus source. The scope of agents tested included rIFN-alpha A, rIFN-beta Ser 17, and rIFN-gamma as cytokines; azidothymidine and phosphonoformate (Foscarnet) as inhibitors of reverse transcription; ribavirin as a putative inhibitor of proper HIV mRNA capping; amphotericin B as a lipophile; and castanospermine as a glycoprotein processing (glucosidase I) inhibitor. Separately, each drug demonstrated dose-dependent anti-HIV activity and, when used in combination with mismatched dsRNA, demonstrated synergism. Although mismatched dsRNA was synergistic with all three IFNs for anti-HIV activity in microtiter infection assays, it did not potentiate the transient inhibition of virus production observed for IFN in cultures of H9/HTLV-III-B cells. The results of these studies suggest that the pleiotropic activities of dsRNAs differ from those of IFN and may provide synergism in combination therapy with a wide range of antiviral drugs for the treatment of the acquired immunodeficiency syndrome (AIDS).

Acquired Immunodeficiency Syndrome↗
PubMed1989

Complement-mediated, antibody-dependent enhancement of HIV-1 infection in vitro is characterized by increased protein and RNA syntheses and infectious virus release.

Antibody-dependent enhancement (ADE) of human immunodeficiency virus type 1 (HIV-1) infection in vitro has been described recently and was shown to occur by two mechanisms: either participation of the alternative pathway of complement or to involve an Fc receptor-mediated, complement-independent mechanism. Complement-mediated ADE results in an accelerated cytopathic effect in target cells that can abrogate the protective properties of neutralizing antibodies. This study characterizes the surface antigens of MT-2 cells using flow cytometric analysis and shows that these cells express high levels of both CD4 and complement receptor type 2 (CR2) while several CD4+ cell lines that do not demonstrate complement-mediated ADE lack high levels of complement receptors. Further, utilizing MT-2 cell cultures, it is demonstrated that complement-mediated ADE of HIV-1 infection is conferred by the sera from more than 80% of HIV-1 antibody-positive individuals (N = 85). Complement-mediated ADE of HIV-1 infection causes an acceleration of several parameters indicative of HIV-1 infection in vitro including increased HIV-1 antigen synthesis as detected by indirect immunofluorescence, RNA accumulation as measured by a solution hybridization protocol, reverse transcriptase release, and progeny virus production.

Cell Line↗
PubMed1988

Antibody-dependent enhancement of human immunodeficiency virus type 1 infection.

Two components of human serum enhance human immunodeficiency virus type 1 (HIV-1) infection and mask HIV-1 neutralising antibody activity. The first is heat-stable, unique to HIV-1 seropositive sera, and is removed by protein-A chromatography. The second is heat-labile and ubiquitous; it is found in normal serum and is removed by heating at 60 degrees C for 1 h or by treatment with cobra venom anticomplementary protein. Additionally, complement component C3 deficient serum lacks the labile activity although Clq deficient serum contains the labile factor. The data suggest that the two components are antibody and the alternative pathway of complement fixation. The mechanism of action does not involve an increase in either complement-mediated cytolysis or syncytium formation. The activity has been identified in 11 of 16 patients tested to date.

Antibodies, Viral↗
PubMed1988

Magnetic properties of tunicate blood cells. I. Ascidia nigra.

The magnetic properties of intact and freeze-dried blood cells of the tunicate Ascidia nigra and of model vanadium(III) and (IV) compounds as polycrystalline solids and in aqueous solution have been measured up to 50 kOe with a SQUID susceptometer. Corrections for the samples' diamagnetism were extracted from the temperature dependence of the data without any further assumptions. For vanadium(IV), measured values of the magnetic moment at different values of the applied magnetic field over the temperature range 2-100 K obey a Brillouin function with spin 1/2. For vanadium(III), the magnetic moment data did not obey a Brillouin function and were analyzed in terms of a spin Hamiltonian with S = 1. Measurements on both whole and freeze-dried blood samples give consistent results with vanadium(III) the predominant species. These results are discussed in terms of the mechanisms of vanadium accumulation and the use of vanadium oxidation states as criteria of ascidian taxonomy.

Animals↗
PubMed1988

Natural killer cell infection and inactivation in vitro by the human immunodeficiency virus.

Cytolytic activity of human mononuclear peripheral blood leukocytes from healthy donors, cultured in interleukin-2 conditioned medium, was abrogated by in vitro infection with the lymphadenopathy associated virus (LAV) isolate of the human immunodeficiency virus (HIV). Although viral antigens are not expressed in cultured cells until 14 days postinfection, cytolytic activity was lost as early as 3 days after infection. Loss of cytolytic function was not a result of the release of suppressive factors from either infected cells or uninfected CEM cells since supernatants from neither infected cultures nor CEM cell cultures had any inhibitory effects on the function of uninfected cells. Cultured lymphocytes expressing Leu 11b were also shown to express HIV antigens via immunofluorescence after 14 days in culture. These results suggest that natural killer (NK) cells, as defined by expression of Leu 11b, were infected by HIV in vitro and the loss of lytic function was likely a direct consequence of that infection.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Role of protein N-glycosylation in pathogenesis of human immunodeficiency virus type 1.

Human immunodeficiency virus type 1 (HIV-1), the retrovirus responsible for acquired immunodeficiency syndrome (AIDS), contains two heavily glycosylated envelope proteins, gp120 and gp41, which mediate attachment of virions to glycosylated cell surface receptor molecules (CD4 antigens) and appear to be responsible for syncytium formation and associated cytopathic effects of this virus. A comprehensive study of the effects of N-linked glycoprotein processing inhibitors on HIV-1 replication, infectivity, cytopathicity, target-cell infectibility, syncytium formation, and gp120 electrophoretic mobility was conducted to assess the importance of protein glycosylation in the pathogenesis of HIV-1 in vitro. The electrophoretic mobility of gp120 was decreased when gp120 was synthesized in the presence of castanospermine or 1-deoxynojirimycin (inhibitors of glucosidase I), increased when gp120 was synthesized in the presence of 1-deoxymannojirimycin (mannosidase I) or swainsonine (mannosidase II), and unaffected when gp120 was synthesized in the presence of bromoconduritol (glucosidase II). Inhibition by tunicamycin (lipid-linked oligosaccharide precursor synthesis), castanospermine, 1-deoxynojirimycin, and 1-deoxymannojirimycin attenuated HIV-1 infectivity and blocked HIV-1-induced syncytium formation and cytopathicity, whereas bromoconduritol and swainsonine failed to have such effects. None of the inhibitors interfered with virus replication in acutely infected cells or affected the ability of target cells to form syncytia with untreated HIV-1-infected cells. These results demonstrate that protein N-glycosylation is critical to the pathogenesis of HIV-1 at the levels of viral infectivity and cytopathicity but not at the level of virus replication or of host-cell infectibility.

Acquired Immunodeficiency Syndrome↗