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Query: UMLS:C0019693 (HIV)
 170,526 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Using a polymerase chain reaction-based assay on total cell lysates, we have detected unintegrated human immunodeficiency virus type 1 (HIV-1) DNA in chronically infected T-lymphocytic (ACH-2, J1) and promyelocytic (OM-10.1) cell lines. Treatment with 3'-azido-3'-deoxythymidine (AZT) or soluble CD4 inhibited accumulation of unintegrated viral DNA about 10-fold within 72 h; removal of AZT permitted recovery to pretreatment levels within 72 h. Our results indicate that unintegrated HIV-1 DNA is unstable in these cell lines and originates from a continuous process of reinfection. OM-10.1 cells had relatively high levels of surface CD4 by flow cytometry and high levels of unintegrated viral DNA by polymerase chain reaction. ACH-2 cells had very low levels of both surface CD4 and unintegrated viral DNA. However, J1 cells, with surface CD4 below the level of detection of flow cytometry had a high level of unintegrated viral DNA similar to that of OM-10.1 cells. This implies that the number of CD4 receptors is not rate limiting for reinfection.
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PMID:Unintegrated human immunodeficiency virus type 1 DNA in chronically infected cell lines is not correlated with surface CD4 expression. 201 76

U1 and ACH-2 cells are subclones of HIV-1-infected monocyte/macrophage-like and T lymphocyte cell lines, respectively, which express the HIV-1 genome at very low levels. We have examined whether they might provide a model of HIV-1 latency. The patterns of HIV-1-specific RNA expressed in these cells consisted of singly and multiply spliced RNA species, with little or no full-length genomic RNA. Upon stimulation with agents that activate the HIV-1 long terminal repeat in these cells, a marked rise in the amount of small mRNAs, encoding the viral regulatory proteins, preceded the increase in the unspliced RNA. Thus, U1 and ACH-2 cells maintain HIV-1 in a state equivalent to the early phase of a lytic infection and, after stimulation, recapitulate the events of a single cycle infection of highly susceptible target cells.
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PMID:Cells nonproductively infected with HIV-1 exhibit an aberrant pattern of viral RNA expression: a molecular model for latency. 236 29

A T cell clone (ACH-2) derived from T cells infected with HIV-1 was found to produce HIV-1 in response to stimulation with a monokine-enriched supernatant prepared by culturing human monocyte/macrophages with bacterial LPS (LPS-MO SN). Monokine induction of ACH-2 cells resulted in augmented virus production reflected by an increase in reverse transcriptase activity and in the synthesis of all major viral proteins. Examination of the cells by indirect immunofluorescence revealed that 10 to 15% of uninduced cells constitutively expressed HIV proteins, whereas 100% showed positive immunofluorescence in response to LPS-MO SN. This induction of virus by LPS-MO SN resulted in approximately a 100-fold increase of infectious virus production over uninduced ACH-2 cells. LPS alone could not induce HIV-1 expression, whereas LPS-MO SN resulted in the greatest virus expression. Cell separation studies confirmed the source of the inducing factor(s) to be cells bearing the mature monocyte/macrophage marker, Leu M3. Biochemical fractionation of the LPS-MO SN suggested that one or more factors, having apparent Mr of approximately 45 kDa, were involved in this induction. Absorption of the LPS-MO SN with immunoaffinity gels specific for human TNF-alpha was shown to completely remove the HIV inducing activity for the ACH-2 cell line.
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PMID:Monokine regulation of human immunodeficiency virus-1 expression in a chronically infected human T cell clone. 246 7

Promonocytic (U1) and T lymphocytic (ACH-2) cell lines chronically infected with human immunodeficiency virus type 1 (HIV-1) constitutively express low levels of virus, but expression can be induced by phorbol esters and cytokines. Whereas ACH-2 cells produce infectious virions, U1 cells produce defective, noninfectious particles. Although 3'-azido-3'-deoxythimidine (AZT) prevented acute HIV infection of susceptible cells, it did not prevent the induction of HIV expression in the infected cell lines. In contrast, interferon alpha (IFN-alpha) inhibited the release of reverse transcriptase and viral antigens into the culture supernatant after phorbol ester stimulation of both cell lines. Further, IFN-alpha suppressed the production or release (or both) of whole HIV virions, but had no effect on the amount of cell-associated viral proteins. Also, after phorbol ester stimulation of ACH-2 cells, IFN-alpha reduced the number of infectious viral particles secreted into the culture supernatant, but had no effect on the infectivity of cell-associated virus. These findings lend support to the combined use of antiviral agents that have action at both the early (AZT) and the late (IFN-alpha) stages of HIV replication.
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PMID:Interferon-alpha but not AZT suppresses HIV expression in chronically infected cell lines. 247 Jan 48

Thirty-five patients with active chronic hepatitis B (ACH-B) were evaluated. They were in stable replicative phase (HBeAg +; DNA polymerase and ALT stable in two determinations at least one month apart) and had not been infected by delta virus or HIV-1. Thirty-four patients were heterosexual and no patient was a drug abuser except one. The 23 initial cases were followed up for 15 months without therapy. The subsequent 12 cases were treated with maximal doses of 2.5 megaunits/m2 of lymphoblastoid alpha interferon (IFN-L) daily for two weeks and three times a week during 10 more weeks. While in the controls only two cases (8.69%) lost the DNA-polymerase activity and HBeAg, 5 treated patients (41.66%; p less than 0.05) developed seroconversion to nonreplicative phase. No patient from the control series lost the HBsAg; however, this happened in 2 treated patients (16.66%). These results show that IFN-L is effective in heterosexual patients with ACH-B in replicative phase without delta virus or HIV-I co-infection.
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PMID:[Treatment of chronic hepatitis B with lymphoblastoid alpha interferon]. 261 34

Tumor necrosis factor alpha (TNF-alpha), also known as cachectin, was demonstrated to induce the expression of human immunodeficiency virus (HIV) in a chronically infected T-cell clone (ACH-2). Concentrations of recombinant TNF-alpha as low as 50 pg/ml induced a significant increase over background of HIV expression in the ACH-2 cells as determined by supernatant reverse transcriptase activity. The HIV-inducing effects of TNF-alpha could not be explained by toxic effects on the cells. In addition, both the uninfected parental cell line (A3.01) and the infected ACH-2 cells were shown to have high-affinity receptors for TNF-alpha. Transient-transfection experiments demonstrated that the inductive effects of TNF-alpha were due to specific activation of the HIV long terminal repeat. These studies provide evidence that TNF-alpha may play a role in the mechanisms of pathogenesis of HIV infection.
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PMID:Tumor necrosis factor alpha induces expression of human immunodeficiency virus in a chronically infected T-cell clone. 278 70

Oltipraz (5-pyrazinyl-4-methyl-1,2-dithiole-3-thione), which is undergoing clinical evaluation as an anticarcinogen, also inhibits HIV-1 replication (IC50 approximately equal to 10 microM). The inactivation of RT appears to be a relevant antiviral mechanism since oltipraz blocks viral replication in acutely infected T-cell lines, but is ineffective in chronically infected ACH-2 cells (H. J. Prochaska, W. G. Bornmann, P. Baron, and B. Polsky (1995) Mol. Pharmacol. 48, 15-20). Since a nucleophilic amino acid is a likely target for oltipraz, we assessed whether the conserved cysteine residues of HIV-1 RT (38Cys or 280Cys) were the target(s) for oltipraz, and we synthesized [Me 14C]oltipraz to determine if oltipraz forms a stable adduct with RT. Thus, HIV-2 RT as well as wild-type, 38Cys-->Ser, 280Cys-->Ser, and the Cys-->Ser double mutant of HIV-1 RT were purified from the lysates of transformed Escherichia coli strain DH5 alpha (A. Hizi, M. Shaharabany, R. Tal, and S. H. Hughes (1992) J. Biol. Chem. 267, 1293-1297) via a purification procedure that included (NH4)2SO4 fractionation followed by gel filtration, dye-ligand, and ion-exchange chromatographies. Procion yellow H4R was chosen as the dye-ligand chromatography since it was the most potent and selective inhibitor of RT among seventy reactive dyes that were screened. Mono Q anion-exchange chromatography with diethanolamine (pH 9) resulted in the generation of heterodimeric RT from a predominantly homodimeric enzyme preparation. Because the instability of dilute RT preparations at room temperature rendered the kinetic evaluation of inactivation difficult, we sought to identify conditions that prevent denaturation of these enzymes. High concentrations (25 mM) of MgCl2 had a stabilizing effect. Oltipraz behaved kinetically as an irreversible inhibitor of all RTs purified, and the kinetic constants for the inactivation of these enzymes were not significantly different from wild-type HIV-1 RT (Ki = 17.0 +/- 4.1 microM; k3 = 0.214 +/- 0.051 h-1). In stark contrast, oltipraz neither inhibited nor inactivated the Klenow fragment of DNA polymerase I, whose subdomain structure is similar to the p66 subunit of RT. Wild-type RT was incubated with 60 microM [Me 14C]oltipraz for 4 h and was then subjected to gel filtration chromatography. The [14C] label comigrated with RT with a stoichiometry of binding of 0.88 +/- 0.05 oltipraz per inactivated RT subunit (N = 3 experiments), and the [14C] label remained bound after treatment with 4 M urea.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Inactivation of human immunodeficiency virus type 1 reverse transcriptase by oltipraz: evidence for the formation of a stable adduct. 750 49

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

Recent information has suggested that posttranscriptional mechanisms, whereby human immunodeficiency virus type 1 (HIV-1) RNA exists as multiply spliced transcripts without promoting an accumulation of the larger messages, are responsible for maintaining a stable state of nonproductive viral expression or viral latency. To test the universality of these observations, we compared the patterns of viral RNA splicing and the frequencies of cells actually harboring HIV-1 RNA in four chronically HIV-1-infected cell lines (U1 [promonocytic], ACH-2 [T lymphocytic], OM-10.1 [promyelocytic], and J1.1 [T lymphocytic]). In uninduced U1 and ACH-2 cultures, a high frequency of cells (approximately one in six) contained HIV-1 RNA but mainly as multiply spliced transcripts, again supporting a posttranscriptional mechanism maintaining viral latency. In sharp contrast, only 1 in 50 cells in uninduced OM-10.1 and J1.1 cultures contained HIV-1 RNA, indicating a primary transcriptional mechanism controlling viral expression in these cells. Furthermore, those OM-10.1 and J1.1 cells that did contain viral RNA were in a state of productive HIV-1 expression marked by the presence of both spliced and unspliced transcripts. Even though the total absence of viral RNA in the majority of OM-10.1 and J1.1 cells indicated a state of absolute latency, treatment with tumor necrosis factor alpha induced transcription of HIV-1 RNA in nearly 100% of the cells in all four of the chronically infected cultures. Tumor necrosis factor alpha induction of U1, ACH-2, and OM-10.1 cultures resulted in an initial accumulation of multiply spliced HIV-1 RNA followed by a transition to the larger unspliced viral RNA transcripts. This RNA splice transition was less apparent in the J1.1 cell line. These results demonstrate that host cell-specific transcriptional and posttranscriptional mechanisms are important factors in the control of HIV-1 latency.
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PMID:Human immunodeficiency virus type 1 RNA expression by four chronically infected cell lines indicates multiple mechanisms of latency. 751 Nov 77

Human chorionic gonadotropin (hCG)--a pregnancy-associated immunomodulating hormone--has been recently shown in vitro to suppress reverse transcriptase activity in chronically HIV-infected lymphocytes and monocytes and to block viral transmission resulting from cell-cell contact between virus-carrying lymphocytes and placental trophoblasts. In further pursuit of the query into the mechanism of action, purified alpha and beta subunits of hCG were tested for the inhibition of p24 gag protein synthesis in virus-producing ACH-2 lymphocytes and U1 monocytes. Unlike the alpha subunit, beta-hCG displayed a distinct U-shaped dose response, characteristic of the effect of dimer hCG. Maximum inhibition of viral expression has been achieved at 10-100 ng/ml, the concentration corresponding to blood levels of beta-hCG in pregnant women. The doses that were several logs higher of normal levels seemed to increase viral production in monocytes. The data presented supports our original observations regarding the effect of intact hCG on HIV replication. While the mechanism of action remains to be established, the results suggest that the virus-interfering activity of hCG is determined by hormone-specific beta chain but not by the alpha subunit--shared with the family of glycoprotein hormones from the pituitary--follicle-stimulating hormone, luteinizing hormone and thyrotropin.
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PMID:Anti-HIV effect of beta subunit of human chorionic gonadotropin (beta hCG) in vitro. 753 8


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