Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0021051 (immunodeficiency)
 71,517 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The third variable domain (V3) of the human immunodeficiency virus type 1 external envelope contains determinants of cell tropism, cytopathicity, and infectivity and elicits antibodies able to block infectivity in vitro and in vivo. Our study encompassed point-mutational analysis of HXB-2 viruses containing patient-derived V3 regions and expressing a non-syncytium-inducing, low-replicating phenotype in T-cell line SupT1. The mutation within V3 of a serine at position 306 into an also naturally occurring arginine (S to R) required an additional, naturally occurring mutation at position 320 (aspartate to glutamine, D to Q) or 324 (aspartate to asparagine, D to N) for full expression of the syncytium-inducing, high-replicating (SI) phenotype. The naturally occurring mutation of an aspartate into an arginine at position 320 (D to R) was sufficient for production of the SI phenotype. This study proves that introduction of a positively charged amino acid at position 306 or 320, previously shown to be strongly associated with the SI phenotype in field isolates (R.A.M. Fouchier, M. Groenink, N.A. Kootstra, M. Tersmette, H.G. Huisman, F. Miedema, and H. Schuitemaker, J. Virol. 66:3183-3187, 1992), is minimally required for production of SI viruses. In addition, naturally occurring mutations at residue 324 also modulate the virus phenotype.
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PMID:Minimal requirements for the human immunodeficiency virus type 1 V3 domain to support the syncytium-inducing phenotype: analysis by single amino acid substitution. 140 17

An immunotoxin has been made by coupling anti-human immunodeficiency virus (HIV) envelope antibody 907 to ricin A chain (907-RAC). 907 recognizes an epitope within the immunodominant PB-1 loop of gp120. Variant cells were selected by cloning persistently infected H9/human T lymphocyte virus IIIB cells in the presence of the immunotoxin. Clones resistant to 907-RAC arose at a frequency of 0.1-1.0%. Seven clones were selected for intensive analysis. When studied, these clones fell into two distinct groups, members of which appeared to be identical, suggesting that the variation arose before the selection process. In contrast to the parent cells, none of the cloned variants produced infectious HIV. The first set of clones, designated the "E" variants, expressed decreased levels of the HIV envelope on the cell surface. However, levels of intracellular HIV antigens and reverse transcriptase were equal to or greater than that of the parental cell line. Radioimmunoprecipitation demonstrated that the gp160 was truncated to 145 kD (gp120 was normal length), capable of binding to CD4, and, unlike normal gp160, was released in its unprocessed form into the cellular supernatant. Sequence analysis demonstrated that a deletion at codon 687 of the envelope gene resulted in the production of this truncated protein. Ultrastructural analysis of E variants demonstrated some budding forms of virus, but also large numbers of HIV within intracellular vesicles. The second set of variants, the "F" series, produced no HIV antigens, reverse transcriptase, nor was there ultrastructural evidence of virus. However, proviral DNA was present. Virus could not be induced with agents known to activate latent HIV. These cells also lacked cell surface CD4 and could not be infected with HIV. These studies demonstrate that variation in HIV can affect the phenotype of the cells carrying the altered virus, allowing for escape from immunologic destruction. The E variants may serve as prototypes for attenuated HIV, which could be used as a vaccine. We have reconstructed the mutation found in the E variants within the infectious HIV clone HXB-2 and demonstrated that the resulting virus retains its noninfectious phenotype.
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PMID:Variants selected by treatment of human immunodeficiency virus-infected cells with an immunotoxin. 169 55

The inactivation of human immunodeficiency virus (HIV) and cytotoxic properties of ozone-treated serum and serum-supplemented media were examined. The titer of HIV suspensions in human serum was reduced in a dose-dependent manner when treated with total reacted ozone concentrations at a range of 0.5 to 3.5 micrograms/ml-1. Complete inactivation of HIV suspensions was achieved by 4.0 micrograms/ml-1 of ozone in the presence or absence of H-9 cells. In contrast, cellular metabolism, as measured by MTT dye cleavage, and DNA replication, as measured by BUdR incorporation, were enhanced in H-9 cells grown in media treated with quantities of ozone that completely inactivate HIV. The permissively HIV-infected cell line HXB/H-9 was cultured in ozone-treated media for six days with culture supernatants being sampled and assayed on alternate days for HIV p24 core protein. HIV p24 was reduced in all treated cultures compared to control cultures, with an average reduction of 46% [p24].
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PMID:Ozone inactivates HIV at noncytotoxic concentrations. 180 86

The type 1 human immunodeficiency virus (HIV-1) encodes a 27-kDa protein termed Nef (negative factor). Nef has been reported to down-regulate viral gene transcription directed by the HIV-1 long terminal repeat. To assess the possible role of Nef in the initiation or maintenance of viral latency, we prepared two different nef expression vectors (pNEF from the HXB-3 proviral clone; pNEF-2/3 from HXB-2 and HXB-3) and a control vector containing a frameshift mutation in the HXB-3 nef coding sequence (pNEF-fs). Consistent with prior studies, the Nef proteins produced by pNEF and pNEF-2/3 were approximately 27 kDa in size, posttranslationally modified by myristoylation, and primarily associated with cytoplasmic membrane structures. However, in contrast to previous reports, these Nef proteins failed to inhibit transcriptional activity of the HIV-1 long terminal repeat in any of a variety of cell types, including primary human T lymphocytes, Jurkat or YT-1 leukemic T cells, U-937 promonocytic cells, and nonlymphoid COS cells. Furthermore, HXB-3 proviral clones of HIV-1 containing either a wild-type or mutated version of the nef gene replicated in an indistinguishable manner when transfected into COS cells. Our findings suggest that Nef is neither a transcriptional inhibitor nor a negative viral factor under these assay conditions. Rather, we suggest that the primary biological function of this conserved HIV-1 protein has yet to be defined, perhaps reflecting an intrinsic shortcoming in the in vitro experimental systems presently available for the study of HIV-1.
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PMID:Nef protein of human immunodeficiency virus type 1: evidence against its role as a transcriptional inhibitor. 268 84

To study the basis of cellular latency of human immunodeficiency virus (HIV), we have used a recombinant luciferase-encoding HIV (HXB-Luc) to superinfect nonproductively HIV-1-infected human leukemic cell lines. HXB-Luc contains the Photinus pyralis luciferase gene in place of the nef gene and provides a highly sensitive, simple assay for HIV infection and expression. To circumvent any superinfection block in latently infected cells, we also generated viruses pseudotyped with murine leukemia virus amphotropic envelope (HXB-Luc:ampho). The parental uninfected lines, U937 and A3.01, from which the latently infected cell lines U1 and ACH-2, respectively, were derived could be readily infected with pseudotyped or nonpseudotyped reporter viruses. However, superinfection of U1 cells with either HXB-Luc or HXB-Luc:ampho resulted in only low levels of luciferase activity. Like the endogenous provirus, HXB-Luc provirus could be efficiently activated by phorbol ester treatment of HXB-Luc:ampho-superinfected U1 cells. In contrast, superinfection of ACH-2 cells resulted in active expression of the secondarily introduced virus even in unstimulated cells and luciferase production higher than in the parental cell line A3.01. Thus, the proviral latency in U1 cells appears to result from a defect in the cellular environment (a trans effect), whereas the latency in ACH-2 is specific to the integrated provirus and is probably a cis effect due to the site of integration. These results demonstrate distinct modes of proviral latency in these two cell line models and may have implications in our understanding of the regulation and significance of cellular latency in HIV infection.
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PMID:Distinct modes of human immunodeficiency virus type 1 proviral latency revealed by superinfection of nonproductively infected cell lines with recombinant luciferase-encoding viruses. 750 83

The antiviral activities of two substrate-based inhibitors of human immunodeficiency virus type 1 (HIV-1) protease, UK-88,947 and Ro 31-8959, were studied in acute infections. H9 and HeLaCD4-LTR/beta-gal cells were infected either with HIV-1IIIB or a replication-defective virus, HIV-gpt(HXB-2). Both inhibitors were capable of blocking early steps of HIV-1 replication if added to cells prior to infection. Partial inhibition was also obtained by addition of inhibitor at the time of or as late as 15 min after infection. The inhibitors were ineffective if added 30 min postinfection. The inhibitory effects were studied by cDNA analysis with PCR followed by Southern blot hybridization and by infectivity assays allowing quantitation of HIV-1 in a single cycle of replication. When UK-88,947-treated H9 cells were coinfected with HIV-1 and human T-cell leukemia virus type I only the replication of HIV-1 was inhibited, demonstrating viral specificity. Pretreating the infectious virus stocks with the inhibitors also prevented replication, indicating that the inhibitors block the action of the viral protease and not a cellular protease. A panel of primer sets was used to analyze cDNA from cell lysates by PCR amplification at 4 and 18 h postinfection. Four hours after infection, viral specific cDNA was detected with all of the four primer pairs used: R/U5, nef/U3, 5' gag, and long terminal repeat (LTR)/gag. However, after 18 h, only the R/U5 and nef/U3 primer pairs and not the 5' gag or LTR/gag primer pair were able to allow amplification of cDNA. The results suggest a crucial role of HIV-1 protease in the early phase of viral replication. Although it is not clear what early steps are affected by the protease, it is likely that the target is the NC protein, as referred from our previous reports of the in situ cleavage of the nucleocapsid (NC) protein by the viral protease inside lentiviral capsids. The results suggest that it is not the inhibition of initiation and progression of reverse transcription but the stability of full-size unintegrated cDNA which is affected in the presence of protease inhibitors. Alternatively, the cleavage of the NC protein may be required for the proper formation of preintegration complex and/or for its transport to the nucleus.
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PMID:Antiviral activity of human immunodeficiency virus type 1 protease inhibitors in a single cycle of infection: evidence for a role of protease in the early phase. 828 79

Two molecularly cloned viruses, human immunodeficiency virus type 1 (HIV-1)-NL4-3 (NL4-3) and HIV-1-HXB-2 (HXB-2), have been used to study the role of HIV-1 auxiliary genes in the establishment of chronic virus producers. NL4-3 encodes all known HIV-1 proteins, whereas HXB-2 is defective for three auxiliary genes: vpr, vpu, and nef. Studies were done in H9 cells, a T-cell line unusually permissive for the establishment of chronic virus producers. NL4-3 and HXB-2 undergo lytic phases of infection in H9 cultures with HXB-2, but not NL4-3, supporting the efficient establishment of chronic virus producers. Tests of mutant NL4-3 genomes containing various combinations of defective auxiliary genes revealed that both vpr and nef limited the ability of NL4-3 to establish chronic virus producers. Tests of a series of recombinants between NL4-3 and HXB-2 revealed that 5' internal sequences as well as fragments containing defective auxiliary genes affected the establishment of chronic virus producers. Viral envelope sequences and levels of virus production did not correlate with the ability to establish chronic virus producers. These results suggest that complex interactions of viral auxiliary and nonauxiliary gene functions with the host cell determine the ability to establish chronic virus producers.
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PMID:Context-dependent role of human immunodeficiency virus type 1 auxiliary genes in the establishment of chronic virus producers. 841 97

In infants born to mothers infected with the human immunodeficiency virus (HIV), antibody-dependent cellular cytotoxicity (ADCC) or natural killer cytotoxicity (NKC) may either eliminate infection or ameliorate its course. We developed and standardized an assay for cytotoxicity of HIV-infected cells and studied the capacity of leukocytes from healthy neonates and adults to lyse HIV-infected cells by ADCC and NKC. The chosen target cell line, a T cell line infected with the HXB-2 clone of human T-cell lymphotrophic virus-IIIB, displayed stable surface expression of viral antigens over months of continuous culture and allowed simultaneous assessment of NKC and ADCC of effector cell populations. Conditions for optimal ADCC lysis of target cells were defined for unpurified peripheral blood mononuclear cells and purified lymphocytes and monocytes. Polymorphonuclear neutrophils from healthy adults and neonates exhibited low activity in ADCC of HIV-infected targets. Lymphocytes and monocytes from adults were found to differ in antibody dependence, kinetics, and sensitivity to latex inhibition for ADCC-mediated lysis of HIV-infected targets. Peripheral blood mononuclear cells of healthy neonates and adults displayed equivalent capacity to mediate NKC of HIV-infected targets. However, neonates' peripheral blood mononuclear cells were found to be significantly less active than adults' in ADCC lysis of HIV-infected cells. This pattern of diminished ADCC cytotoxicity with intact NKC is the opposite of that seen in HIV-infected adults. Our findings suggest that therapies designed to enhance ADCC effector cell function in the neonate may help interrupt vertical transmission of HIV.
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PMID:Natural killer cytotoxicity and antibody-dependent cellular cytotoxicity of human immunodeficiency virus-infected cells by leukocytes from human neonates and adults. 851 Oct 19

Previously, we described two mutants of the cellular Rev co-factor, eukaryotic initiation factor 5A (eIF-5A M13 and M14), which suppress human immunodeficiency virus type 1 (HIV-1) SF2 replication in clonal T cell lines. This study introduced the notion that it is possible to develop gene therapies against infectious agents on the basis of mutant host factors required for viral replication. In this report, we provide further evidence to support this new paradigm and describe murine leukemia virus (MLV)-based retroviral vectors expressing three different eIF-5A mutants from the viral long terminal repeat (LTR). HIV-1 replication (SF2, HXB-3) was reduced up to 2 orders of magnitude in transduced, polyclonal T cell populations. All eIF-5A mutants also showed antiviral activity (approximately seven-fold reduction) in a chronic HIV-1 infection model. Expression of eIF-5A mutant M13 delta in peripheral blood lymphocytes (PBLs) showed no difference in proliferation and metabolic activity as determined in a 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide (MTT)-assay, suggesting that expression of this type of mutant protein is not associated with cellular toxicity. In summary, these data suggest that gene therapy for HIV-1 infection can be developed on the basis of mutants of the Rev co-factor eIF-5A.
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PMID:Intracellular expression of cellular eIF-5A mutants inhibits HIV-1 replication in human T cells: a feasibility study. 889 78

Different strains of human immunodeficiency virus type 1 (HIV-1) show considerable divergence in genetic content and biological properties. One property that has been closely correlated with clinical prognosis is the ability to induce syncytia formation in susceptible cells. This ability had been correlated with the V3 loop sequence of major envelope glycoprotein, gp120, but recent reports have questioned this connection. We investigated the contributions of different regions of the env gene to syncytia induction using chimeric viruses that contain part of the genome of a strain that lacks this ability (HIV-1(Ba-L)) within the genome of a virus that can form syncytia (HIV-1(HXB-2)). When tested in two cell lines susceptible to both parental viruses, as well as in primary cells, these chimeric viruses demonstrated that the ability to induce syncytia formation was determined by regions of env outside the V3 loop, which encompass residues that contribute to the binding of CD4 by gp120. Further investigation failed to show any difference in the expression of gp120 on the cell surface or cell adhesion molecules by cells infected with SI or NSI variants that would explain the observed differences in the ability to form syncytia. Assays of relative affinity for CD4 indicated that gp120 from SI variants showed a significantly higher affinity for CD4 than gp120 from NSI variants. These observations suggest that areas of the HIV-1 env gene contributing to the CD4 binding site may also contribute to the determination of syncytium-inducing (SI) and non-syncytium-inducing (NSI) phenotypes.
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PMID:Syncytium formation induced by human immunodeficiency virus type 1 isolates correlates with affinity for CD4. 934 72


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