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Biomedical subjects

J L Hurwitz

Publications and source records attributed to J L Hurwitz.

At least 19 recordsLinked to original sources
PubMed2002

Antibody and pre- plus post-transplant prednisone treatments support T cell-depleted stem cell engraftment without drug-induced morbidity.

Rigorous T cell depletion methods can now be used to reduce the risk of graft-versus-host disease (GVHD) associated with allogeneic, hematopoietic stem cell transplantation (HSCT). However, full T cell depletion is also associated with a significant risk of graft failure. Here we hypothesize that engraftment failures after T cell-depleted HSCT may be due, in part, to the absence of GVHD prophylaxis. To test this hypothesis, we used a haploidentical mouse model to systematically measure the effects of immunosuppressive drug treatments and anti-T cell antibodies on engraftment. Results showed that engraftment was supported in all animals when hosts were pre-treated with anti-T cell antibodies, but donor chimerism was significantly improved when hosts were also treated with prednisone. Interestingly, when hosts received only pre-HSCT prednisone treatments, engraftment was not improved; when hosts received only post-HSCT prednisone (initiated near the time of irradiation), the animals became extremely ill. Results therefore demonstrated the need for both pre- and post-HSCT prednisone treatments as a means to ensure engraftment without morbidity in all host animals.

Animals↗
PubMed2001

Cutting edge: culture with high doses of viral peptide induces previously unprimed CD8(+) T cells to produce cytokine.

Culturing naive T cells with 50 microM selected HIV-1 envelope peptides for 6 days in the presence of IL-2 drives the emergence of a substantial CD8(+) population that secretes IFN-gamma following short-term stimulation with 1 microM peptide. This response is H-2K(b) restricted, epitope specific, and requires the continuing presence of peptide. The same effect was found for known H-2D(b)-restricted peptides from two influenza virus proteins. The great majority of these influenza-specific CD8(+)IFN-gamma(+) T cells neither stained with the cognate tetramer nor expressed the TCR Vbeta bias that is characteristic of the CD8(+) set expanded in vivo during an infection. Thus, multipoint binding of low affinity TCRs on naive CD8(+) T cells can drive peptide-specific cytokine production. However, at least for two influenza-derived epitopes, the avidity of the TCR-MHC peptide interaction appears to be insufficient to stabilize a tetrameric complex of MHC class I glycoprotein plus peptide on the lymphocyte surface.

Amino Acid Sequence↗
PubMed2001

Structural features of HIV envelope defined by antibody escape mutant analysis.

Two neutralizing antibodies specific for the V3 sequence of HIV envelope were used to generate escape variants from the HTLV(IIIB) founder virus. The full gp120 sequence of each variant was then analyzed to identify mutations responsible for immune escape. As predicted, most escape variants harbored amino acid changes in the V3 crown sequence. However, one variant differed from its founder only within the conserved C2 region. These findings, when analyzed in conjunction with crystallographic data, suggest a new three-dimensional model for HIV envelope folding, in which the V3 loop extends across the CD4-binding face of gp120 to associate with discontinuous C2 residues. This envelope configuration may provide an effective immune defense mechanism for HIV, as the highly variable residues of the V3 loop may shield conserved amino acids pertinent to viral infection.

Amino Acid Sequence↗
PubMed2001

Localization of CD4+ T cell epitope hotspots to exposed strands of HIV envelope glycoprotein suggests structural influences on antigen processing.

The spectrum of immunogenic epitopes presented by the H2-IA(b) MHC class II molecule to CD4(+) T cells has been defined for two different (clade B and clade D) HIV envelope (gp140) glycoproteins. Hybridoma T cell lines were generated from mice immunized by a sequential prime and boost regime with DNA, recombinant vaccinia viruses, and protein. The epitopes recognized by reactive T cell hybridomas then were characterized with overlapping peptides synthesized to span the entire gp140 sequence. Evidence of clonality also was assessed with antibodies to T cell receptor Valpha and Vbeta chains. A total of 80 unique clonotypes were characterized from six individual mice. Immunogenic peptides were identified within only four regions of the HIV envelope. These epitope hotspots comprised relatively short sequences ( approximately 20-80 aa in length) that were generally bordered by regions of heavy glycosylation. Analysis in the context of the gp120 crystal structure showed a pattern of uniform distribution to exposed, nonhelical strands of the protein. A likely explanation is that the physical location of the peptide within the native protein leads to differential antigen processing and consequent epitope selection.

Amino Acid Sequence↗
PubMed2001

Effect of extended immunosuppressive drug treatment on B cell vs T cell reconstitution in pediatric bone marrow transplant recipients.

Allogeneic bone marrow transplantation (BMT) is an effective therapy for a variety of malignancies and blood disorders, but rarely serves as a frontline treatment because of numerous, potential complications. Important and frequent complications relate to the profound immunosuppression that inevitably occurs during the first several months following treatment. To better elucidate and subsequently improve immune reconstitution, we examined T and B cell subsets among 43 pediatric BMT recipients in a retrospective study. We found that the relative numbers of T cells and B cells (T:B ratios) were discordant and highly variable among patients at day approximately 100 after BMT. Further investigation of BMT parameters identified a strong correlation between T:B ratios and immunosuppressive drug treatments, providing an explanation for variable lymphocyte reconstitution profiles. Results suggest that: (1) immunosuppressive therapy inhibits B cell expansion more strongly than T cell expansion following BMT; (2) WBC and absolute lymphocyte counts fail to reveal profound B cell immunodeficiencies in some BMT patients; and (3) routine analyses of T:B ratios serve to identify patients warranting close follow-up and extended supportive immunotherapy.

Adrenal Cortex Hormones↗
PubMed2001

T cell immunotherapeutic populations control viral infections in bone marrow transplant recipients.

Immunotherapies designed to prevent infection serve as an increasingly important adjunct to bone marrow transplantation (BMT). T cell immunotherapies are particularly useful for the control of virus infections, provided that T cell populations are free of graft-vs-host (GVH) activity. In this review, we describe positive and negative selection methods with which donor T cell populations devoid of GVH activity can be prepared for transfer to the immunodeficient BMT recipient. The support of patients with T cell immunotherapies may ultimately revolutionize BMT, elevating the procedure from a salvage to a front-line treatment strategy for otherwise fatal disorders.

Animals↗
PubMed2000

Molecular evidence of ocular Epstein-Barr virus infection.

Ocular manifestations have been attributed to the Epstein-Barr virus (EBV), largely on the basis of seroepidemiologic data. Two patients who developed conjunctival disease as the presenting feature of EBV infection are reported, each confirmed by in situ hybridization of EBV genome in affected tissue biopsy specimens. Recognition of EBV-induced ocular disease as an initial presentation of clinical EBV infection is important to the practitioner because of the ubiquitous nature of this herpesvirus.

Child↗
PubMed2000

Multi-envelope HIV vaccine safety and immunogenicity in small animals and chimpanzees.

A significant obstacle to HIV vaccine development lies in the remarkable diversity of envelope proteins, the major targets of neutralizing antibody. That envelope diversity must be targeted is demonstrated by results from nonhuman primate studies in which single-envelope vaccines have protected against homologous, but rarely against heterologous virus challenges. Similarly, in clinical trials, single-envelope vaccines have failed to prevent break-through infections when challenge viruses were inevitably mismatched with the vaccine. To protect humans from infection by any isolate of HIV, we have prepared vaccine cocktails combining multiple envelopes from distinct viral isolates. We have tested several vehicles for vaccine delivery in small animals and have shown that successive immunizations with envelope, presented first as a DNA recombinant, then as a vaccinia virus (VV) recombinant, and finally as purified protein elicited strong neutralizing antibody responses. We have also tested the VV recombinant vaccine in chimpanzees. Pairs of animals received either single- or multi-envelope VV recombinant vaccines administered by the subcutaneous route. Results showed that the multi-envelope vaccine was safe, immunogenic, and superior to the single-envelope vaccine in eliciting HIV-specific antibody measurable in a standard clinical, immune assay. The promise of this system has led to the initiation of clinical trials, with which the hypothesis that cocktail vaccines will prevent human HIV infections may ultimately be tested.

AIDS Vaccines↗
PubMed1999

A novel vaccine regimen utilizing DNA, vaccinia virus and protein immunizations for HIV-1 envelope presentation.

Recombinant DNA and vaccinia virus (VV) vectors that express envelope (Env) proteins of the human immunodeficiency virus (HIV) have each been prominently utilized in vaccine development. These two vectors (termed DNA-Env and VV-Env) are attractive vaccine candidates due to their abilities to elicit both cytotoxic T-lymphocyte and B-cell responses. Our previous work demonstrated that DNA-Env primed animals, that were relatively unresponsive to DNA-Env boosters, could be immunized with VV-Env to yield more than a 100-fold increase in antibody responses. Here we show: (1) results with an optimized vaccine regimen that primes with DNA-Env, boosts with VV-Env, and re-boosts with purified Env proteins, (2) enhanced responses with 8 rather than 16 week intervals between VV-Env and protein immunizations, and (3) the failure of single Env vaccines to reproducibly elicit responses toward heterologous Env, regardless of the vaccination regimen utilized. Results encourage the use of poly-Env vaccine cocktails administered via DNA/VV/protein regimens in future non-human primate and clinical studies.

AIDS Vaccines↗
PubMed1999

Early activation of TCR alpha gene rearrangement in fetal thymocytes.

We have previously demonstrated that the onset of TCR alpha gene rearrangement is mainly restricted to the J alpha50 gene in fetal day 1delta thymocyte hybridomas. Now, J alpha50 rearrangements from fetal thymocyte hybridomas and from day 15.5 fetal thymus have been isolated and sequenced. We demonstrate that J alpha50 is rearranged to the rearranged Vdelta1 Ddelta2 gene segment. This indicates that the TCR alpha rearrangement process is initiated in fetal thymocytes far earlier than previously thought. These thymocytes have their delta genes still accessible for rearrangement and therefore, are controlled by the TCR delta enhancer (Edelta) (and/or another TCR delta specific cis-acting element). Our results further suggest that both Edelta and the TCR alpha enhancer (Ealpha) are active at the onset of alpha rearrangements or alternatively, the initial activation of the J alpha locus is controlled by Edelta. In addition, Vdelta1 Ddelta2 J alpha50 gene segments are replaced by secondary alpha rearrangements, indicating that thymocytes with the early alpha rearrangement are committed to the alphabeta lineage.

Animals↗
PubMed1998

Profound abnormality of the B/T lymphocyte ratio during chemotherapy for pediatric acute lymphoblastic leukemia.

The fluorescence-activated cell sorter (FACS) was utilized to phenotype lymphocyte compartments in children receiving intensive chemotherapy for acute lymphoblastic leukemia (ALL). Sixteen patients (eight males and eight females) of diverse ages, risks of relapse, and within weeks 7-53 of maintenance/continuation chemotherapy treatment were arbitrarily selected for study. All 16 patients had profound B cell lymphopenia. In contrast, T cell numbers were often normal or marginally low, and accounted for up to 98% of the lymphocyte populations. No abnormality in T cell phenotypes could be demonstrated. Due to the highly skewed B/T lymphocyte ratios in these ALL patients, the absolute white blood cell counts and lymphocyte percentages were not predictive of the underlying B cell lymphopenia. Patients were also tested for serum immunoglobulin levels and most had abnormally low IgG and IgM. None of four patients immunized with the 1996-1997 influenza virus vaccine seroconverted to at least two vaccine antigens as compared to 10 of 10 healthy, age-matched controls. In total, these data highlight for the first time the profound abnormality of the B/T lymphocyte ratio in patients during treatment for ALL, and argue for consideration of B cell-targeted immunotherapy.

Adolescent↗
PubMed1997

Effect of natural HIV-1 envelope V1-V2 sequence diversity on the binding of V3-specific and non-V3-specific antibodies.

In past years, much attention has been paid to the HIV-1 envelope (env) protein variable region 3 (V3), termed the principal neutralizing determinant. HIV-1 vaccines were often designed to target V3, and vaccine efficacy was often measured with V3-based assays. Thus, some disappointment resulted when volunteers in first clinical vaccine trials generated V3-specific antibodies that could not protect against V3-similar viruses. We describe an analysis of V1 and V2 sequence effects on antibody binding to V3 and non-V3 determinants. This study involved the preparation of seven full-length (gp160), chimeric env proteins in a vaccinia virus (VV) expression system. Chimeric proteins displayed different V1-V2 sequences but were otherwise identical. A panel of 12 monoclonal antibodies was then tested for binding activities toward the seven chimeras. Results showed that V1-V2 sequences affected antibody binding to env, both in V3 and non-V3 positions. These data demonstrate the enormous complexity of HIV-1 env protein conformation and antigenic determinants. Respect for the complexity of antibody-antigen interactions encourages the design of sophisticated immunoglobulin and protein cocktails for use in HIV-1 therapies and vaccines, respectively.

Amino Acid Sequence↗
PubMed1997

Screening of HIV-1 Env glycoproteins for the ability to raise neutralizing antibody using DNA immunization and recombinant vaccinia virus boosting.

HIV-1 envelopes from two series of primary isolates (from Swedish patients 5 and 6), from JR-FL and BaL (prototypic monocyte/macrophage tropic viruses) and from HXB-2 (a prototypic T-cell-line-adapted virus), have been screened for their ability to elicit neutralizing antibody to HIV-1. Rabbits were primed by gene gun inoculation with plasmids expressing secreted monomeric (gp120) and oligomeric (gp140) forms of each Env. After four to six DNA immunizations administered over a 1-year period, rabbits were boosted with 10(8) plaque-forming units of a mixture of seven recombinant vaccinia viruses which express chimeric gp140 Envs (primary clade B sequences in a IIIb-related BH10 backbone). Neutralizing antibodies were assayed against two T-cell-line-adapted viruses (MN and IIIb), two non-syncytium-inducing (NSI) and two syncytium-inducing (SI) primary isolates, and two HIV-1-NL4-3-recombinants with patients 5 or 6 Envs (NL4-3/5A, NL4-3/6C). The DNA priming and recombinant vaccinia virus boosting raised low titers of neutralizing antibody in 10 of 19 rabbits. The highest titers of neutralizing activity (approximately 1:150 for MN) were raised in rabbits DNA primed with Envs from Swedish patients 5. These sera cross neutralized IIIb and MN but did not neutralize the primary isolates or the NL4-3 recombinant with the homologous 5A Env. Sera from rabbits primed with the HXB-2 Env DNA were, for the most part, type-specific for neutralization of IIIb. In one of three assays, sera from rabbits primed with plasmids expressing the JR-FL and BaL had possible low titer neutralizing activity for two NSI, but not two SI, primary isolates. Our results highlight the low immunogenic potential of the HIV-1 Env and demonstrate that different Envs have different potentials to raise low titer neutralizing antibody.

AIDS Vaccines↗
PubMed1997

Eliciting HIV-1 envelope-specific antibodies with mixed vaccinia virus recombinants.

Recombinant vaccinia virus (VV) vectors that express the envelope (Env) protein of the human immunodeficiency virus-type 1 (HIV-1) have been previously shown to elicit HIV-specific cytotoxic T-lymphocyte (CTL) and weak antibody responses in non-human primate studies and clinical trials. In first clinical trials, single Env proteins were presented to the immune system by VV recombinants and other vectors, but individuals were not protected against later exposures to heterologous HIV. It is likely that the generation of protective immune responses against diverse HIV will require that vaccines encompass proteins from not just one, but multiple distinct HIV isolates. Here is described the simple construction of numerous new VV, each expressing a unique, truncated, Env protein (VVenv). Mouse experiments were performed to evaluate the ability of these VVenv to elicit immune responses. HIV-1-specific antibodies appeared within one month following one intraperitoneal inoculation of mice with single or mixed VVenv, reaching plateau levels by 4 months. The magnitude of antibody production was poor at the dose of 10(5) p.f.u. VVenv per animal, but improved with increasing doses of VVenv up to 10(7) p.f.u. per animal. The subcutaneous route of VV immunization, previously proven safe in human trials, was also effective for administering VVenv. These results highlight the strengths of recombinant VV constructs as vehicles for the presentation of multiple HIV-1-Env proteins to the naive immune system.

AIDS Vaccines↗
PubMed1997

Intranasal Sendai virus vaccine protects African green monkeys from infection with human parainfluenza virus-type one.

Human parainfluenza virus-type I (hPIV-1) infections are a common cause of "group" and hospitalizations among young children. Here we address the possibility of using the xenotropic Sendai virus [a mouse parainfluenza virus (PIV)] as a vaccine for hPIV-1. Sendai virus was administered to six African green monkeys (Cercopithecus aethiops) by the intranasal (i.n.) route. A long lasting virus-specific antibody response was elicited, both in the serum and nasal cavity. Sendai virus caused no apparent clinical symptoms in the primates, but live virus was detected in the nasal cavity for several days after inoculation. No virus was detected after a second dose of Sendai virus was administered on day 126 after the initial priming. Animals were challenged with hPIV-1 i.n. on day 154. All six vaccinated animals were fully protected from infection while six of six control animals were infected with hPIV-1. The antibody responses induced by Sendai virus immunizations proved to be greater than those induced by hPIV-1. These results demonstrate that unmanipulated Sendai virus is an effective vaccine against hPIV-1 in a primate model and may constitute a practical vaccine for human use.

Administration, Intranasal↗