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V Planelles

Publications and source records attributed to V Planelles.

At least 37 records · Page 2Linked to original sources
PubMed1998

A RANTES-antibody fusion protein retains antigen specificity and chemokine function.

The successful eradication of cancer cells in the setting of minimal residual disease may require targeting of metastatic tumor deposits that evade the immune system. We combined the targeting flexibility and specificity of mAbs with the immune effector function of the chemokine RANTES to target established tumor deposits. We describe the construction of an Ab fusion molecule with variable domains directed against the tumor-associated Ag HER2/neu, linked to sequences encoding the chemokine RANTES (RANTES.her2.IgG3). RANTES is a potent chemoattractant of T cells, NK cells, monocytes, and dendritic cells, and expression of RANTES has been shown to enhance immune responses against tumors in murine models. RANTES.her2.IgG3 fusion protein bound specifically to HER2/neu Ag expressed on EL4 cells and on SKBR3 breast cancer cells as assayed by flow cytometry. RANTES.her2.IgG3 could elicit actin polymerization of THP-1 cells and transendothelial migration of primary T lymphocytes. RANTES.her2.IgG3 prebound to SKBR3 cells also facilitated migration of T cells. RANTES.her2.IgG3 bound specifically to the CCR5 chemokine receptor, as demonstrated by flow cytometry, and inhibited HIV-1 infection via the CCR5 coreceptor. RANTES.her2.IgG3, alone or in combination with other chemokine or cytokine fusion Abs, may be a suitable reagent for recruitment and activation of an expanded repertoire of effector cells to tumor deposits.

Amino Acid Sequence↗
PubMed1998

Coreceptor utilization by human immunodeficiency virus type 1 is not a primary determinant of neutralization sensitivity.

We have examined the relationship between coreceptor utilization and sensitivity to neutralization in a primary isolate of human immunodeficiency virus type 1 and its T-cell line-adapted (TCLA) derivative. We determined that adaptation of the primary-isolate (PI) virus 168P results in the loss of the unique capacity of PI viruses to utilize the CCR5 coreceptor and in the acquisition by the TCLA 168C virus of sensitivity to neutralization by V3-directed monoclonal antibodies (MAbs). In experiments wherein infection by 168P is directed via either the CCR5 or the CXCR4 pathway, we demonstrate that the virus, as well as pseudotyped virions bearing a molecularly cloned 168P envelope protein, remains refractory to neutralization by MAbs 257-D, 268-D, and 50.1 regardless of the coreceptor utilized. This study suggests that coreceptor utilization is not a primary determinant of differential neutralization sensitivity in PI and TCLA viruses.

Animals↗
PubMed1997

Inhibition of HIV-1 replication using a mutated tRNALys-3 primer.

Cellular tRNALys-3 serves as the primer for reverse transcription of human immunodeficiency virus, type 1 (HIV-1). tRNALys-3 interacts directly with HIV-1 reverse transcriptase, is packaged into viral particles and anneals to the primer-binding site (PBS) of the HIV-1 genome to initiate reverse transcription. Therefore, the priming step of reverse transcription is a potential target for antiviral strategies. We have developed a mutant tRNALys-3 derivative with mutations in the PBS-binding region such that priming specificity was re-directed to the highly conserved TAR stem-loop region. This mutant tRNA retains high-affinity binding to HIV-1 reverse transcriptase, viral encapsidation, and is able to prime at both the targeted TAR sequence and at the viral PBS. Constitutive expression of mutant tRNA in T-cells results in marked inhibition of HIV-1 replication, as determined by measurements of viral infectivity, syncytium formation, and p24 production. Inhibition of retroviral replication through interference with the normal process of priming constitutes a new anti-retroviral approach and also provides a novel tool for dissecting molecular aspects of priming.

Base Sequence↗
PubMed1997

Human T-cell leukemia viruses: epidemiology, biology, and pathogenesis.

The human T-cell lymphotropic viruses type I and type II are closely related human retroviruses that have similar biological properties, genetic organization and tropism for T lymphocytes. Along with the simian T-cell lymphoma virus type I, they define the group of retroviruses known as the primate T-cell leukemia/lymphoma viruses. Initially identified in 1980, the human T-cell lymphotropic virus type I has been implicated as the etiologic agent of adult T-cell leukemia/lymphoma and of a degenerative neurologic disorder known as tropical spastic paraparesis or human T-cell lymphotropic virus type I-associated myelopathy. The intriguing link between human T-cell lymphotropic virus type, T-cell malignancy, and a totally unrelated and non-overlapping neurological disorder suggests divergent and unique pathogenetic mechanisms. This review will address the epidemiology, molecular biology, and pathogenesis of human T-cell leukemia viruses.

Adult↗
PubMed1996

Vpr-induced cell cycle arrest is conserved among primate lentiviruses.

We previously reported that expression of human immunodeficiency virus type 1 strain NL4-3 (HIV-1(NL4-3))vpr causes cells to arrest in the G2 phase of the cell cycle. We examined the induction of cell cycle arrest by other HIV-1 isolates and by primary lentiviruses other than HIV-1. We demonstrate that the vpr genes from tissue culture-adapted or primary isolates of HIV-1 are capable of inducing G2 arrest. In addition, we demonstrate that induction of cell cycle arrest is a conserved function of members of two other groups of primate lentiviruses, HIV-2/simian immunodeficiency virus strain sm (SIVsm)/SIVmac and SIVagm. vpr from HIV-1, HIV-2, and SIVmac induced cell cycle arrest when transfected in human (HeLa) and monkey (CV-1) cells. vpx from HIV-2 and SIVmac did not induce detectable cell cycle arrest in either cell type, and SIVagm vpx was capable of inducing arrest in CV-1 but not HeLa cells. These results indicate that induction of cell cycle perturbation is a general property of lentiviruses that infect primates. The conservation of this viral function throughout evolution suggests that it plays a key role in virus-host relationships, and elucidation of its mechanism may reveal important clues about pathology induced by primary lentiviruses.

Alleles↗
PubMed1996

High-efficiency gene transfer into CD34+ cells with a human immunodeficiency virus type 1-based retroviral vector pseudotyped with vesicular stomatitis virus envelope glycoprotein G.

Currently, amphotropic retroviral vectors are widely used for gene transfer into CD34+ hematopoietic progenitor cells. The relatively low levels of transduction efficiency associated with these vectors in human cells is due to low viral titers and limitations in concentrating the virus because of the inherent fragility of retroviral envelopes. Here we show that a human immunodeficiency virus type 1 (HIV-1)-based retroviral vector containing the firefly luciferase reporter gene can be pseudotyped with a broad-host-range vesicular stomatitis virus envelope glycoprotein G (VSV-G). Higher-efficiency gene transfer into CD34+ cells was achieved with a VSV-G-pseudotyped HIV-1 vector than with a vector packaged in an amphotropic envelope. Concentration of virus without loss of viral infectivity permitted a higher multiplicity of infection, with a consequent higher efficiency of gene transfer, reaching 2.8 copies per cell. These vectors also showed remarkable stability during storage at 4 degrees C for a week. In addition, there was no significant loss of titer after freezing and thawing of the stock virus. The ability of VSV-G-pseudotyped retroviral vectors to achieve a severalfold increase in levels of transduction into CD34+ cells will allow high-efficiency gene transfer into hematopoietic progenitor cells for gene therapy purposes. Furthermore, since it has now become possible to infect CD34+ cells with pseudotyped HIV-1 with a high level of efficiency in vitro, many important questions regarding the effect of HIV-1 on lineage-specific differentiation of hematopoietic progenitors can now be addressed.

Animals↗
PubMed1995

The human immunodeficiency virus type 1 vpr gene arrests infected T cells in the G2 + M phase of the cell cycle.

Human immunodeficiency virus type 1 (HIV-1) infection causes profound immunological defects in afflicted patients. Various mechanisms have been proposed to account for the immune dysfunction in AIDS ultimately leading to loss of CD4+ T cells, including HIV-1 envelope-mediated syncytium formation, apoptosis, and cytokine modulation. Here we present results which suggest a novel hypothesis for T-cell dysfunction. We show, using HIV-1 bearing a novel cell surface reporter gene, that infected cells are unable to progress normally through the cell cycle and became arrested in the G2 + M phase. Furthermore, we identify the HIV-1 vpr gene product as being both necessary and sufficient for eliciting this cell cycle arrest. Cell cycle arrest induced by Vpr correlates with an increase in the hyperphosphorylated (inactive) form of the cyclin-dependent serine/threonine kinase CDC2, consistent with an arrest of cells at the boundary of G2 and M.

Acquired Immunodeficiency Syndrome↗
PubMed1995

Genetic analysis of human immunodeficiency virus type 1 integrase and the U3 att site: unusual phenotype of mutants in the zinc finger-like domain.

Retroviral integration is the step which leads to establishment of the provirus, cis- and trans-acting regions of the human immunodeficiency type 1 (HIV-1) retrovirus genome, including the attachment site (att) at the ends of the unintegrated viral DNA and the conserved domains within the integrase (IN) protein, have been identified as being important for integration. We investigated the role of each of these regions in the context of an infectious HIV-1 molecular clone through point mutagenesis of the att site and the zinc finger-like and catalytic domains of IN. The effect of each mutation on integration activity was examined by using a single-step infection system with envelope-pseudotype virus. The relative integration efficiency was estimated by monitoring the levels of viral DNA over time in the infected cells. The integration activities of catalytic domain point mutants and att site deletion mutants were estimated to be 0.5 and 5% of wild-type activity, respectively. However, in contrast with previous in vitro cell-free integration studies, alteration of the highly conserved CA dinucleotide resulted in a mutant which still retained 40% of wild-type integration activity. The relative levels of expression of each mutant, as measured by a luciferase reporter gene, correlated with levels of integration. This observation is consistent with those of previous studies indicating that integration is an obligatory step for retroviral gene expression. Interestingly, we found that three different HIV-1 constructs bearing point mutations in the zinc finger-like domain synthesized much lower levels of viral DNA after infection, suggesting impairment of these mutants before or at the initiation of reverse transcription. Western blot (immunoblot) analysis demonstrated wild-type levels of reverse transcriptase within the mutant virions. In vitro endogenous reverse transcription assays indicated that all three mutants in the zinc finger-like domain had wild-type levels of reverse transcriptase activity. These data indicate that in addition to integration, IN may have an effect on the proper course of events in the viral life cycle that precede integration.

Amino Acid Sequence↗
PubMed1995

Fate of the human immunodeficiency virus type 1 provirus in infected cells: a role for vpr.

We investigated the fate of human immunodeficiency virus type 1 (HIV-1) viral DNA in infected peripheral blood lymphocytes and immortalized T-cell lines by using a replication-defective HIV-1. We observed that integrated HIV-1 DNA and viral gene expression decrease over time. A frameshift mutation in vpr resulted in maintenance of the HIV-1 provirus and stable persistence of viral expression. Transfection of vpr together with the neomycin resistance gene in the absence of other viral genes decreased the formation of geneticin-resistant colonies, indicating either a cytotoxic or a cytostatic effect upon cells. Therefore, maintenance of HIV-1 infection within an infected proliferating population is due to two competing processes, the rate of viral spread and the degree of cell growth inhibition and/or death induced by Vpr.

Animals↗
PubMed1995

A new reporter system for detection of retroviral infection.

We describe a novel reporter molecule, the murine surface antigen Thy-1, useful for immunoselection and detection of retrovirus-mediated transduction by flow cytometry. A cDNA encoding the murine thy-1 gene was isolated, and cell surface expression of its gene product was demonstrated. The Thy-1 glycoprotein was tested as a cell surface reporter molecule in the context of replication-defective and -competent retroviruses. Cells transduced via murine retroviral vectors carrying the thy-1 and the neomycin phosphotransferase genes express Thy-1 glycoprotein on their surfaces. The Thy-1 marker is potentially useful in gene transfer protocols because selection of transduced cells can be achieved by immunoselection with anti-Thy-1 antibodies shortly after infection with the retroviral vector. In addition, a human immunodeficiency virus type 1 (HIV-1) recombinant expressing Thy-1 is described, which is replication-competent and syncytium-inducing in human peripheral blood mononuclear cells (PBMCs) and immortalized CD4-positive cell lines. Cells infected with this HIV-1 recombinant express Thy-1 on their surfaces and can be detected and purified by fluorescence-activated cell sorting (FACS). Because of these properties, retroviruses expressing this genetic marker can be useful for studies in gene therapy and of the retroviral life-cycle.

Animals↗
PubMed1994

Requirement of human immunodeficiency virus type 1 nef for in vivo replication and pathogenicity.

The role of human immunodeficiency virus type 1 (HIV-1) accessory genes in pathogenesis has remained unclear because of the lack of a suitable in vivo model. The most controversial of these genes is nef. We investigated the requirement for Nef for in vivo replication and pathogenicity of two isolates of HIV-1 (HIV-1JR-CSF and HIV-1NL4-3) in human fetal thymus and liver implants in severe combined immunodeficient mice. HIV-1JR-CSF and HIV-1NL4-3 differ in their in vitro phenotypes in that HIV-1JR-CSF does not induce syncytia and is relatively noncytopathic, while HIV-1NL4-3 is highly cytopathic and readily induces syncytia. The nef mutants of both isolates grew with kinetics similar to those of parental virus strains in stimulated peripheral blood lymphocytes but demonstrated attenuated growth properties in vivo. HIV-1NL4-3 induced severe depletion of human thymocytes within 6 weeks of infection, whereas its nef mutant did not. Thus, HIV-1 Nef is required for efficient in vivo viral replication and pathogenicity.

Animals↗
PubMed1993

Immune response of rhesus macaques to recombinant simian immunodeficiency virus gp130 does not protect from challenge infection.

Simian immunodeficiency virus (SIV) infection of rhesus macaques is a model for human immunodeficiency virus (HIV) infection in humans. Inactivated and modified live whole-virus vaccines have provided limited protective immunity against SIV in rhesus macaques. Because of safety concerns in the use of inactivated and live whole-virus vaccines, we evaluated the protective immunity of vaccinia virus recombinants expressing the surface glycoprotein (gp130) of SIVmac and subunit preparations of gp130 expressed in mammalian cells (CHO). Three groups of animals were immunized with recombinant SIV gp130. The first group received SIV gp130 purified from genetically engineered CHO cells (cSIVgp130), the second group was vaccinated with recombinant vaccinia virus expressing SIVmac gp130 (vSIVgp130), and the third group was first primed with vSIVgp130 and then given a booster immunization with cSIVgp130. Although anti-gp130 binding antibodies were elicited in all three groups, neutralizing antibodies were transient or undetectable. None of the immunized animals resisted intravenous challenge with a low dose of cell-free virus. However, the group primed with vSIVgp130 and then boosted with cSIVgp130 had the lowest antigen load (p27) compared with the other groups. The results of these studies suggest that immunization of humans with HIV type 1 surface glycoprotein may not provide protective immunity against virus infection.

Animals↗
PubMed1992

Genetic and biological comparisons of pathogenic and nonpathogenic molecular clones of simian immunodeficiency virus (SIVmac).

Simian immunodeficiency virus (SIV) is a designation for a group of related but unique lentiviruses identified in several primate species. A viral isolate from a rhesus macaque (i.e., SIVmac) causes a fatal AIDS-like disease in experimentally infected macaques, and several infectious molecular clones of this virus have been characterized. This report presents the complete nucleotide sequence of molecularly cloned SIVmac1A11, and comparisons are made with the sequence of molecularly cloned SIVmac239. SIVmac1A11 has delayed replication kinetics in lymphoid cells but replicates as well as uncloned SIVmac in macrophage cultures. Macaques infected with virus from the SIVmac1A11 clone develop antiviral antibodies, but virus does not persist in peripheral blood mononuclear cells and no disease signs are observed. SIVmac239 infects lymphoid cells, shows restricted replication in cultured macrophages, and establishes a persistent infection in animals that leads to a fatal AIDS-like disease. Both viruses are about 98% homologous at the nucleotide sequence level. In SIVmac1A11, the vpr gene as well as the transmembrane domain of env are prematurely truncated, whereas the nef gene of SIVmac239 is prematurely truncated. Sequence differences are also noted in variable region 1 (V1) in the surface domain of the env gene. The potential implications of these and other sequence differences are discussed with respect to the phenotypes of both viruses. This animal model is critically important for investigating the roles of specific viral genes in viral/host interactions that cannot be studied in individuals infected with the human immunodeficiency virus (HIV).

Amino Acid Sequence↗
PubMed1991

Functional and immunological characterization of SIV envelope glycoprotein produced in genetically engineered mammalian cells.

Retroviral envelope glycoproteins interact with cell receptors and are targets for antiviral immune responses in infected hosts. Macaque simian immunodeficiency virus (SIVmac) is a T-lymphocytopathic lentivirus which causes an AIDS-like disease in rhesus macaques. The envelope gene of SIVmac encodes a precursor glycoprotein (gp160) which is cleaved into an external domain (gp130) and a transmembrane domain (gp32). To investigate the functional and immunological properties of the SIV external envelope glycoprotein, we have used genetically engineered mammalian cells to produce recombinant gp130 (rgp130). The rgp130 has the appropriate molecular weight, is glycosylated, and has native conformation as determined by binding to the cell receptor for SIV, the CD4 antigen. Rhesus macaques immunized with purified rgp130 formulated in muramyl dipeptide adjuvant generated high titers of antienvelope antibodies. Antibodies from these macaques were tested for in vitro virus neutralization; very low or undetectable levels of neutralization were observed. In contrast, neutralizing antibodies were readily detected in sera from goats immunized with rgp130. With respect to cell-mediated immunity, proliferative responses to rgp130 were demonstrated in peripheral blood monocyte cells (PBMC) from macaques immunized with the recombinant glycoprotein as well as in PBMC from SIV-infected animals. These results show that rgp130 is functional and immunogenic; the potential of rgp130 for protective immunization remains to be determined.

Animals↗
PubMed1991

Characterization of rhesus macaque B-lymphoblastoid cell lines infected with simian type D retrovirus.

A simian type D retrovirus designated SRV induces a fatal immunosuppressive disease in rhesus macaques. This syndrome shows many clinical similarities to acquired immunodeficiency syndrome (AIDS) in human immunodeficiency virus-infected individuals. To investigate the mechanisms of immune dysfunction in SRV infection, we have focused on the interactions of SRV serotype 1 (SRV-1) with macaque B-lymphoblastoid cell lines (B-LCL). Procedures were optimized for establishing B-LCL by immortalization of macaque B lymphocytes with rhesus Epstein-Barr virus (EBV). These cell lines express B-cell surface markers, secrete immunoglobulins of the IgG or IgM isotypes, and release EBV which transforms monkey B cells. In vitro cultures of B-LCL supported replication of SRV-1. Several B-LCL infected with SRV-1 showed downregulation of major histocompatibility complex (MHC) class II antigen expression whereas levels of MHC class I antigen remained unchanged. Infection of B-LCL with SRV-1 did not alter the level of secreted immunoglobulin. Rhesus EBV was also used to obtain B-LCL from macaques infected with SRV-1; these cell lines were found to release infectious SRV-1. Investigations on the interactions of SRV-1 with B cells will be useful for elucidating mechanisms involved in the immunopathogenesis of primate retroviruses.

Animals↗
PubMedDate not supplied

Apoptosis in AIDS.

Infection with the human immunodeficiency virus type 1 (HIV-1) leads to progressive immunodeficiency and onset of opportunistic infections and neoplasms. The loss of immune competence is associated with declines in both the functionality and the number of CD4+ lymphocytes. Multiple mechanisms have been proposed to explain death and dysfunction of CD4+ T-cells. The mechanisms of HIV-1-mediated cell death which are relevant in vivo are unclear at present. However, in vitro explorations on the cytopathic effects of HIV-1 have yielded a wealth of potential triggering events, and signaling and effector pathways leading to apoptosis. The types of pro- and anti-apoptotic stimuli that have been associated with HIV-1 are multiple and often appear overlapping or even contradictory. This review focuses on the various molecular determinants from HIV-1 that play a role in induction of apoptosis in T-lymphocytes. Special attention is devoted to the viral genes, env, nef, tat and vpr, for which a significant body of literature on apotosis-related effects is available.

Acquired Immunodeficiency Syndrome↗