Biomedical subjects

R R Redfield

Publications and source records attributed to R R Redfield.

At least 19 recordsLinked to original sources

PubMed2000

Efficacy testing of recombinant human immunodeficiency virus (HIV) gp160 as a therapeutic vaccine in early-stage HIV-1-infected volunteers. rgp160 Phase II Vaccine Investigators.

A phase II efficacy trial was conducted with recombinant human immunodeficiency virus (HIV) type 1 envelope glycoprotein gp160 (rgp160) in 608 HIV-infected, asymptomatic volunteers with CD4+ cell counts >400 cells/mm3. During a 5-year study, volunteers received a 6-shot primary series of immunizations with either rgp160 or placebo over 6 months, followed by booster immunizations every 2 months. Repeated vaccination with rgp160 was safe and persistently immunogenic. Adequate follow-up and acquisition of endpoints allowed for definitive interpretation of the trial results. There was no evidence that rgp160 has efficacy as a therapeutic vaccine in early-stage HIV infection, as measured at primary endpoints (50% decline in CD4+ cell count or disease progression to Walter Reed stage 4, 5, or 6) or secondary endpoints. A transient improvement was seen in the secondary CD4 endpoint for the vaccination compared with the placebo arm, but this did not translate into improved clinical outcome.

AIDS Vaccines↗

PubMed1999

Antibody-dependent cellular cytotoxicity in HIV type 1-infected patients receiving VaxSyn, a recombinant gp160 envelope vaccine.

Antibody-dependent cellular cytotoxicity (ADCC) activity was measured in 60 human immunodeficiency virus (HIV-1)-infected patients receiving a recombinant gp160 (rgp160) envelope protein of HIV-1(NL4-3) in alum and 64 receiving placebo over a 5-year study period. There was no difference in the percentage of ADCC responders when comparing rgp160-immunized patients (mean, 78.4%) with those receiving placebo alone (mean, 81.5%) at any time point examined. Patients were further divided into progression groups regardless of their vaccine status. ADCC activity was somewhat higher in rapid than in slow-progressing groups, although the number that had detectable ADCC activity was equivalent in each group. ADCC activity of sera from rapid- and slow-progressing groups against primary or laboratory isolate envelopes was similar. This study showed that transcription with rgp160 did not appear to enhance HIV-specific ADCC activity. ADCC activity did not appear to correlate with protection against AIDS in this cohort of HIV-1-infected people.

AIDS Vaccines↗

PubMed1999

Repeated immunization with recombinant gp160 human immunodeficiency virus (HIV) envelope protein in early HIV-1 infection: evaluation of the T cell proliferative response.

This longitudinal study was designed to evaluate cellular immunity in early-stage, asymptomatic human immunodeficiency virus (HIV)-1-infected persons (CD4 cell count,>400/mm3; median, 625/mm3) who were immunized with either recombinant (r) gp160 or placebo every 2 months for 5 years. Proliferative responses were assessed against rgp160, rp24, and a panel of recall antigens and mitogens. Despite good reactivity to recall antigens, at baseline approximately 33% had proliferative responses to gp160, and approximately 42% showed p24 gag responses. There was no statistical difference between vaccine and placebo groups for antigens or mitogens. After 1 year, approximately 73% of the subjects in the vaccine arm had new or boosted responses to gp160, versus approximately 18% in the placebo arm. Statistical significance was maintained throughout the study. Recurrent vaccination with recombinant gp160 was proven to be persistently immunogenic, increasing significantly the ability of HIV-1-infected persons to mount new proliferative responses to the vaccine.

AIDS Vaccines↗

PubMed1998

Correlation between humoral responses to human immunodeficiency virus type 1 envelope and disease progression in early-stage infection.

Human immunodeficiency virus (HIV)-1-infected rapid and slow progressors showed differential humoral responses against HIV envelope peptides and proteins early in infection. Sera from slow progressors reacted more strongly with short envelope peptides modeling gp160NL4-3, predominantly in gp41. Reactivity to six peptides (in constant regions C3, C4, and C5 of gp120 and in gp41) correlated with slower progression. In a novel association, reactivity to three peptides (in constant regions C1 and C3 and variable region V3 of gp120) correlated with faster progression. Envelope peptide reactivity correlated with subsequent course of disease progression as strongly as did reactivity to gag p24. Patients heterozygous for 32-bp deletions in the CCR5 coreceptor reacted more frequently to an epitope in gp41. Rapid progressors had greater gp120 native-to-denatured binding ratios than did slow progressors. While antibody-dependent cellular cytotoxicity against gp120 did not strongly differentiate the groups, slow progressors showed a broader neutralization pattern against 5 primary virus isolates.

Biosensing Techniques↗

PubMed1997

Expansion of restricted cellular immune responses to HIV-1 envelope by vaccination: IL-7 and IL-12 differentially augment cellular proliferative responses to HIV-1.

The failure of immune effector mechanisms to control HIV-1 infection has important consequences for the human host. In a randomized cohort of HIV-infected patients, there was striking in vitro restriction of the proliferative response to HIV-1 envelope protein (Env), gp160; only 34% of patients recognized Env. Therapeutic vaccination with recombinant gp160 or gp120 (rgp160, rgp120) reversed the restriction in vitro, with Env recognition rising to 81%. Peripheral blood mononuclear cells (PBMC) from HIV-infected vaccine recipients, placebo recipients, and seronegative volunteers were cultured with exogenous IL-7 or IL-12 and either tetanus toxoid (TT) or gp160. IL-7 significantly augmented proliferative responses to TT and gp160, whereas IL-12 only affected proliferation to gp160. IL-7, but not IL-12, increased the number of HIV-infected placebo recipients who recognized rgp160. IL-12 had its greatest effect in the induction of rgp160-specific responses from seronegative individuals. The data suggest that these two cytokines have differential activity in the relief of restricted cellular immunity to Env; the predominant effect of IL-7 is in individuals who have been primed by exposure to antigen, while the effect of IL-12 is most evident in seronegative, unprimed individuals. Modification of restricted proliferative responses to Env by vaccination or cytokines in vitro suggests that strategies incorporating IL-7 or IL-12 as adjuvants may selectively boost cellular reactivity to HIV-1.

AIDS Vaccines↗

PubMed1997

Delayed-type hypersensitivity skin testing using third variable loop peptides identifies T lymphocyte epitopes in human immunodeficiency virus-infected persons.

Cellular immune responses to human immunodeficiency virus type 1 (HIV-1) infection, particularly in vivo responses, have been difficult to study in large patient cohorts because of technical impediments. By use of small peptide fragments of the HIV-1 gp120 third variable loop, the CD4 T lymphocyte epitopes of 2 HIV-infected persons were mapped using a cutaneous delayed-type hypersensitivity (DTH) assay. The in vivo DTH responses correlated with epitopes previously identified in vitro using CD4 T lymphocyte lines. The ability to determine CD4 T lymphocyte epitopes in large cohorts of patients using this simple in vivo technique would provide important diagnostic and prognostic data regarding effective immunoregulation of HIV-1. This technique should have broad applicability in HIV vaccine development and in the investigation of other immune-mediated human diseases.

Amino Acid Sequence↗

PubMed1997

Proteosomes, emulsomes, and cholera toxin B improve nasal immunogenicity of human immunodeficiency virus gp160 in mice: induction of serum, intestinal, vaginal, and lung IgA and IgG.

Intranasal immunization of mice with human immunodeficiency virus (HIV) rgp160 complexed to proteosomes improved anti-gp160 serum IgA and IgG titers, increased the number of gp160 peptides recognized, and stimulated anti-gp160 intestinal IgA compared with immunization with uncomplexed rgp160 in saline. These enhanced responses were especially evident when either a bioadhesive nanoemulsion (emulsomes) or cholera toxin B subunit (CTB) was added to the proteosome-rgp160 vaccine. Furthermore, anti-gp160 IgG and IgA in vaginal secretions and fecal extracts were induced after intranasal immunization with proteosome-rgp160 delivered either in saline or with emulsomes. Formulation of uncomplexed rgp160 with emulsomes or CTB also enhanced serum and selected mucosal IgA responses. Induction of serum, vaginal, bronchial, intestinal, and fecal IgA and IgG by intranasal proteosome-rgp160 vaccines delivered in saline or with emulsomes or CTB is encouraging for mucosal vaccine development to help control the spread of HIV transmission and AIDS.

Administration, Intranasal↗

PubMed1996

Transcriptional effects of superinfection in HIV chronically infected T cells: studies in dually infected clones.

We had previously shown that chronically infected ACH-2 cells (HIVLAI) could be superinfected with HIVRF, that the frequency of superinfection increased with time, and that the transcription of the superinfecting virus exceeded that of the host HIVLAI provirus. In contrast, ACH-2 cells superinfected with a nef-substituted neomycin-resistant (proNEO) provirus were not detectable by DNA polymerase chain reaction (PCR) until geneticin (G418) was added, suggesting that the ability to propagate progressively in culture may be HIV strain specific. Clonal populations of ACH-2 superinfected with proNEO did not demonstrate preferential transcription of the superinfecting virus. However, clones of ACH-2 superinfected with HIVRF (ACH2/RF) showed a preponderance of HIVRF transcripts similar to that seen in bulk populations. Induction of the superinfecting virus by phorbol ester (PMA) occurred more rapidly than the hose provirus and did not equalize transcriptional activity. PCR-derived long terminal repeat (LTR) fragments and Tat cDNAs from A3.01 cells acutely infected with HIVRF or from ACH-2 cells were sequenced and tested for transactivation. The HIVLAI LTR was two to three times more Tat-responsive than the HIVRF LTR. TatRF was two to three times more transcriptionally active on either LTR than TatLAI. Demethylation with 5-azacytidine did not significantly affect HIV expression from the HIVLAI host provirus of superinfected ACH2/RF cell clones. These data suggest that the mechanism of preferential transcription in HIVRF superinfected ACH2/RF may be attributed to the Tat/TAR axis and the effect of the specific locus of host proviral integration.

Amino Acid Sequence↗

PubMed1996

Inhibition of HIV replication by sense and antisense rev response elements in HIV-based retroviral vectors.

The life cycle of human immunodeficiency virus type 1 (HIV-1) is critically dependent on the transregulatory proteins Tat and Rev. Tat increases the production of HIV-specific mRNAs by direct binding to the transactivation response (TAR) element located at the 5' end of all HIV transcripts. In contrast, Rev uses a complex RNA stem loop structure, the Rev response element (RRE), which is found in full-length and singly spliced HIV transcripts. Rev is required for the cytoplasmic expression of full-length mRNAs encoding Gag, Pol, and Env structural proteins. The complex intracellular interactions between Tat, Rev, host cell factors, and their respective RNA response elements should be susceptible to interdiction by genetic therapies designed to introduce and express novel genetic information. We show that the expression of antisense RREs inhibited the cytoplasmic expression of RRE containing HIV-1 transcripts. HIV-based retroviral vectors containing either the antisense (-) or sense (+) RREs inhibited HIV replication in transient transfections. The production of full-length HIV mRNA was also decreased significantly by the expression of RREs in either orientation. Interestingly, there was a paradoxic increase in HIV p24 gag production at low levels of inhibitor; this effect may have been the result of encapsidation of RRE-containing HIV-based retroviral vectors. The data suggest that the introduction and inducible expression of RRE-containing, HIV-based retroviral vectors may have therapeutic value in HIV infection.

Animals↗

PubMed1996

CD4+ T-lymphocyte lines developed from HIV-1-seropositive patients recognize different epitopes within the V3 loop.

To define the epitopes present within the V3 loop sequence recognized by five HIV-1 envelope-specific T-cell lines, a panel of V3 LAI peptides bearing sequential truncations from both the N- and C-terminus was synthesized and tested for their ability to induce proliferation. Each individual T-cell line had a different pattern of response against the truncated V3 peptides, demonstrating the presence of a cluster of CD4+ T-cell epitopes within the V3 loop. To assess the ability of these envelope-specific T-cell lines to recognize and proliferate in response to V3 loops of different viral strains, they were tested against a panel of heterologous V3 loop peptides derived from different viral genotypes within and outside of HIV-1 clade B. There was no proliferative response against heterologous V3 loops by any of the lines, demonstrating that recognition of the V3 epitopes is highly strain specific. One of the defined epitopes was shown to elicit a cytotoxic response as well, suggesting the multifaceted role that the CD4+ T cell might play in HIV-1 disease.

Amino Acid Sequence↗

PubMed1996

V3 seroreactivity and sequence variation: tracking the emergence of V3 genotypic variation in HIV-1-infected patients.

OBJECTIVE: To investigate the relationship between V3-specific immune responses and viral quasispecies evolution in 10 HIV-1-seropositive patients enrolled in a phase I trial of recombinant gp160. METHODS: Serologic responses to the HIVLAI V3 loop and autologous V3 loop DNA sequences were sequentially determined over a 3-4-year interval. RESULTS: Six patients either seroconverted or had a > or = 42-fold boost in titer to the V3 reagent associated with an average of 3.2 amino-acid changes in their autologous V3 loops. Four patients with < or = 11-fold change in titer to the V3 loop showed an average of 0.75 amino-acid changes. Attempts to measure autologous V3 loop responses in four patients using a peptide enzyme-linked immunosorbent assay technique did not show a distinct binding preference for autologous versus heterologous V3 loop peptides. Thus, we interpret seroreactivity to the heterologous HIVLAI V3 loop to reflect the broadness of the V3 immune response rather than a direct measure of epitope-specific immune pressure. CONCLUSIONS: These data suggest that the broadness of serologic responses to viral epitopes are reflected in the rate of evolution of their cognate coding sequences and support the view that the immune response to HIV-1 results in the continuous selection of new viral variants during the course of disease.

AIDS Vaccines↗

PubMed1995

Lack of induction of antibodies specific for conserved, discontinuous epitopes of HIV-1 envelope glycoprotein by candidate AIDS vaccines.

We examined the humoral immune response in both HIV-1 infected and uninfected volunteers immunized with candidate HIV-1 recombinant envelope subunit vaccines (Genentech gp120IIIB, MicroGeneSys gp160IIIB, or ImmunoAG gp160IIIB). Immunization of both HIV-1 infected and uninfected volunteers with these immunogens resulted in the induction of Abs preferentially reactive with epitopes accessible on a denatured form of gp120. While sera from HIV-1 uninfected gp120/gp160IIIB vaccinees bound gp120/gp41, which was expressed on the surface of H9 cells infected with HIV-1IIIB, minimal binding to HIV-1MN or HIV-1RF infected cells was obtained. Induction of qualitatively similar immune responses by these immunogens would not have been predicted based on their different tertiary structures. These data indicate a restriction of the immune response to linear, conserved epitopes poorly accessible on both monomeric gp120 and cell-surface expressed oligomeric gp120/gp41 and a lack of Abs specific for conformational epitopes conserved across divergent HIV-1 strains. Poor recognition of HIV-1 envelope tertiary and quaternary structure may explain the restricted neutralization profiles of vaccinee sera against laboratory-adapted strains of HIV-1 and their inability to neutralize primary HIV-1 isolates. Alternate immunogens or reformulations with the capacity to elicit Abs that preferentially bind to natively folded gp120 should be investigated and correlated with their ability to neutralize more diverse laboratory-adapted and primary HIV-1 isolates.

AIDS Vaccines↗

PubMed1995

Humoral responses to linear epitopes on the HIV-1 envelope in seropositive volunteers after vaccine therapy with rgp160.

Humoral responses to the HIV-1 envelope were investigated in 30 human volunteers enrolled in a phase I vaccine therapy trial of rgp160 (LAI/LAV) using two techniques that emphasize detection of antibody response against linear (continuous) epitopes: immunoblotting and PEPSCAN. Seven fusion proteins containing large portions from constant regions 1, 2, 3, and 5, and variable region 3 of gp120 and two regions in the transmembrane protein, gp41, were employed in immunoblots to quantitatively measure immune response as a function of immunization. In addition, the entire gp160 (LAI/LAV) envelope protein was constructed in duplicate sets of 211 overlapping 12-mer peptides to fine-map the changes. Immunoblotting defined significant changes in reactivity to epitopes in constant regions; of 28 volunteers completing the trial, the percentage with reactivity against C1 changed from 62 to 100%; for C2, from 0 to 46%; for C3, from 0 to 82%; and for a constant region in gp41, from 25 to 68%. PEPSCAN on a subset (n = 8) of these volunteers identified new reactivity to epitopes throughout the envelope, concentrated in V1, C3, and C5 in gp120 and several peptides in gp41. Completely immunized patients responded to double the number of linear epitopes compared with two patients receiving alum alone. The results verify that the response to rgp160 is significantly broadened after immunization, providing additional evidence that HIV-1-infected volunteers can expand their antibody repertoire against a protein from a pathogen during chronic infection with that same pathogen. These results expand those previously obtained in this patient cohort, by defining explicitly the immunogenic regions recognized postvaccination and by providing methodology for quantitating those changes.

AIDS Vaccines↗

PubMed1995

Lower extremity lymphedema caused by acquired immune deficiency syndrome-related Kaposi's sarcoma: case report and review of the literature.

A case of severe lymphedema of the lower extremity caused by obstruction by human immunodeficiency virus-associated Kaposi's sarcoma is presented. A review of the signs and symptoms of obstructive lymphedema and Kaposi's sarcoma is provided. Early recognition of this clinical entity may allow use of simple preventative measures and help to avoid this life- and limb-threatening situation.

Acquired Immunodeficiency Syndrome↗

PubMed1995

Establishment and characterization of human immunodeficiency virus type 1 (HIV-1) envelope-specific CD4+ T lymphocyte lines from HIV-1-seropositive patients.

Human immunodeficiency virus type 1 (HIV-1) gp160-, gp120-, and tetanus toxoid-specific CD4+ T lymphocyte lines were developed from 11 HIV-1-seropositive volunteers enrolled in a vaccine therapy trial. Of the 20 HIV-1 envelope-specific T cell lines, 9 were challenged with a panel of overlapping peptides spanning the gp120LAI sequence. The most frequently recognized regions were amino acids 74-105 in the C1 region and 306-328 in the V3 region. When tested against a panel of divergent HIV-1 envelopes, 55% of the envelope-specific lines were able to recognize gp120MN, while only 22% recognized gp120SF2. Cytotoxicity testing with HIV-1 envelope antigen or peptides demonstrated killing by all 3 envelope-specific lines tested. Supernatants from 2 of 9 lines had high titers of p24 gag antigen, which did not seem to interfere with functional properties.

Amino Acid Sequence↗

PubMed1995

Human immunodeficiency virus type 1 cellular RNA load and splicing patterns predict disease progression in a longitudinally studied cohort.

We report the results of a longitudinal study of RNA splicing patterns in 31 early-stage human immunodeficiency virus disease patients with an average follow-up time of 3 years. Eighteen patients showed no evidence for disease progression, whereas 13 patients either showed a > or = 50% reduction in baseline CD4 count or developed opportunistic infections. Levels of unspliced, tat, rev, and nef mRNAs in peripheral blood mononuclear cells were measured by a reverse transcriptase-quantitative, competitive PCR assay. Viral RNA was detected in all patients at all time points. All 13 rapid progressors had viral RNA loads that were > or = 1 log unit greater than those of the slow progressors. In addition, seven of the rapid progressors showed a reduction of more than threefold in the ratio of spliced to unspliced RNA over the 3 years of follow-up. Conversely, two slow progressors with intermediate levels of viral RNA showed no splicing shift. These results confirm earlier observations that viral RNA is uniformly expressed in early-stage patients. We further show that cellular RNA viral load is predictive of disease progression. Importantly, the shift from a predominately spliced or regulatory viral mRNA pattern to a predominately unspliced pattern both is associated with disease progression and adds predictive utility to measurement of either RNA class alone.

AIDS Vaccines↗

PubMed1994

Dissociation rate of antibody-gp120 binding interactions is predictive of V3-mediated neutralization of HIV-1.

mAbs specific for the V3 loop of HIV-1 are capable of neutralizing laboratory strains of HIV-1 in vitro. In this report we use surface plasmon resonance and biosensor technology to demonstrate that the ability of V3-specific mAbs to neutralize HIV-1(MN) correlated with the dissociation rate constant of the homologous mAb-gp120 binding interaction. mAbs capable of binding diverse strains of gp120 with similar association rate constants exhibited marked differences in the dissociation rate. The dissociation rate, and not the association rate, was found to be predictive of the neutralization capacity of the mAb. Furthermore, synthetic peptides corresponding to the V3 loop of HIV-1(IIIB, MN) yielded quantitatively similar binding kinetic profiles abrogating the need for purified recombinant gp120 protein and potentially facilitating the screening of more diverse isolates. Biosensor immobilized V3 peptides were found to mimic their conformational structure in solution. This offers advantages to peptides studied by ELISA where some degree of denaturation and masking of epitopes can occur upon adsorption of peptides to plastic surfaces. The impact of amino acid substitutions within epitopes on subsequent mAb binding was dissected by observing alterations in dissociation rates. The technique provides rapid kinetic analyses of V3 Ab binding interactions with diverse V3 sequences, facilitating the efficient screening and selection of those most likely to possess the broadest and most potent HIV-1 neutralizing potentials.

Amino Acid Sequence↗

PubMed1994

Serum IgA-mediated neutralization of HIV type 1.

The sera of 33 HIV-1-infected individuals, previously shown to neutralize HIV-1MN in vitro, were screened by ELISA for IgA reactivity against rgp120MN and a synthetic V3MN loop peptide. Six were selected for evaluation of the effect of serum IgA from infected individuals on the in vitro infection of susceptible target cells by HIV-1MN. By using protein G immobilized on Sepharose, we depleted the sera of IgG to a level undetectable by nephelometry and viral envelope-specific ELISA. The IgA component of the IgG-depleted serum was affinity purified with immobilized jacalin, a lectin that selectively binds the IgA1 fraction of human Ig. IgG-depleted sera and purified IgA1 serum fractions showing IgA reactivity against rgp120MN and V3MN by ELISA inhibited the in vitro infection of CEM-ss cells by HIV-1MN, but sera depleted of both IgG and IgA1 did not. These data show that, like serum IgG, serum IgA from selected HIV-1-infected individuals is capable of neutralizing HIV-1MN in vitro. The biologic significance of this observation and the identities of serum IgA-recognized HIV-1 neutralization epitopes remain to be determined.

HIV Antibodies↗