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

Mice containing the HIV-1 long terminal repeat (LTR) regulating the expression of firefly luciferase reporter gene were investigated for their use as a model for activation of the LTR. As a limited test of this model, a number of different factors were screened for their ability to affect reporter gene activities in the skin. Reporter gene levels were increased in the skin by topical treatment of dimethylsulfoxide, retinoic acid, phorbol ester, ultraviolet light, and hydrogen peroxide, all of which have previously been shown to cause increased HIV production in cultured human cells. Topically applied arachidonic acid, histamine, ethanol, acetone, and methanol did not increase reporter gene activities. A lack of published reports on activation of HIV-1 in human cells by these agents suggests that they do not activate viral expression in human cells, which corroborates with the findings of this report. Minor forms of skin wounding and intraperitoneally administered psoralen plus ultraviolet light also increased reporter gene activities in skin. Control and test treatments could be performed on the same mouse and repetitive samples could be obtained from each treatment area. These transgenic mice might be useful as predictive models for regulation of the LTR in epidermal or dendritic cells.
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PMID:HIV-1 LTR activation model: evaluation of various agents in skin of transgenic mice. 145 30

We have developed a system in animal cells which allows the quantification of frameshifting determined by specific mRNA sequences. The method is based on the expression of an N-terminally extended firefly luciferase gene which requires frameshifting in order to be translated as a functional enzyme. The systems sensitivity is such that it allows the detection of even low efficiency of frameshifting. Our results show that the HIV-1 frameshift sequence including the 3' located stem-loop structure leads to ribosomal frameshifting at a lower level than that described for in vitro systems when tested in several fibroblastoid cell lines.
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PMID:Test system for determination of HIV-1 frameshifting efficiency in animal cells. 211 13

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

We have developed a vector that allows high and transactivable expression of inserted genes. The vector contains a transcription unit in which the LTR from HIV flanks a multicloning site. The plasmid is based on the EBV p205 plasmid, which allows stable replication in human cells. The ability of the vector to express an exogenous DNA in human cells has been tested using the firefly luciferase gene.
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PMID:An EBV-based vector allowing a high level of LTRHIV-directed expression in human cells. 799 74

Previously it has been demonstrated that the human immunodeficiency virus type 1 (HIV-1) Tat protein mediates induction of the HIV-1 env expression through a TAR-independent manner in heterologous and homologous promoter systems (Kim and Risser, 1993, J. Virol. 67, 239; Kim and Panganiban, 1993, J. Virol. 67, 3739). To further explore the transactivation of HIV-1 env gene, I examined expression of the env, the bacterial CAT, and the firefly luciferase genes from a heterologous promoter, the major immediate-early promoter (MIEP) of murine cytomegalovirus (MCMV). Here we show that Tat augments gene expression from the MCMV MIEP only when linked to the env gene. Surprisingly, in contrast to the expression from an HIV-1 LTR lacking the TAR element, TAR-independent transactivation of env gene expression from MCMV MIEP did not require the full length Tat protein. In addition, deletion of the previously identified cis-acting Tat-responsive element in env did not affect Tat transactivation of the env gene expression. Thus, there are multiple distinct elements that mediate Tat responsiveness in the absence TAR.
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PMID:Requirement of the human immunodeficiency virus type 1 env gene sequence for TAR-independent trans activation by Tat from the major immediate-early promoter of murine cytomegalovirus. 809 34

Epstein-Barr virus (EBV) is a herpesvirus that transforms B-cells (B-LCL) and has undergone intense scrutiny owing to its association with Burkitt's lymphoma, nasopharyngeal carcinoma, and immunoblastic lymphomas. B-LCL have also proven useful in the study of human immunology. We describe a novel system for inducing efficient foreign gene expression in B-LCL using biotinylated adenovirus as an endosome-disrupting agent. Plasmid DNA is coupled to the exterior of viral particles by streptavidin-polylysine chimeric proteins. Up to 67% of B-LCL may be induced to express foreign genes in vitro in transient expression systems, and gene expression lasts for at least 17 days. We have expressed firefly luciferase, beta-galactosidase (beta-gal), chloramphenicol acetyltransferase, HIV gag, and env genes, as well as infectious HIV, and the EBV-specific BZLF gene in B-LCL with this system. In vivo delivery of a beta-gal reporter gene to B-LCL was documented in a SCID mouse model. Potential applications include study of genetic regulation of EBV infection and transformation events, study of potential gene therapies for EBV-related B-cell tumors, and production of antigen-presenting cells for use in immunologic assays. Because of the high percentage of cells transformed and the length of foreign gene expression, the possibility of examining foreign gene expression in transient assays, without selection for clonal populations, exists.
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PMID:Efficient foreign gene expression in Epstein-Barr virus-transformed human B-cells. 829 Dec 40

The protein kinase inhibitor 2-aminopurine (2-AP) greatly stimulated expression in human promonocytes-macrophages of plasmid constructs carrying various reporter genes (chloramphenicol acetyltransferase, lacZ, firefly luciferase [luc], and Salmonella typhimurium histidinol dehydrogenase [his]) driven by the human immunodeficiency virus type 1 (HIV-1) long terminal repeat. Adenine, adenosine, and caffeine were also effective inducers, but other purine or pyrimidine derivatives were ineffective. Experiments with mutant derivatives of the HIV-1 long terminal repeat revealed no specific eukaryotic promoter elements necessary for 2-AP induction but indicated the need for some minimum combination of such elements. Induction of HIV-1-directed gene expression appeared not to require action of the transcription factor NF-kappa B. The mechanism of induction was investigated by using the luc and his genes linked to the HIV-1 long terminal repeat. 2-AP induced marked, steady rises in mRNA accumulation from both transfected and chromosomally integrated HIV-1 constructs but no increases from an endogenous gene encoding gamma-actin or glucose 6-phosphate dehydrogenase. Thus, induction is selective and not an artifact induced by transfecting DNA into cells. In run-on transcription experiments, the rates of transcription initiation of both transfected and integrated copies of the his gene increased about sixfold in cells treated with 2-AP. Thus, while increased initiation accounted for a portion of 2-AP induction, it could not cause the far greater increase in steady-state mRNA levels. 2-AP induction did not change mRNA decay rates and differed from the phorbol ester (phorbol myristate acetate)-induced activation of the protein kinase C-NF-kappa B pathway in its time course and in its requirement for new protein synthesis. Gel retardation assays showed that unlike phorbol myristate acetate induction, 2-AP induction is enhancer independent. Whereas many previous studies have implicated the activation of various protein kinases in gene induction, we here describe a mechanism of gene activation that appears to involve protein kinase inhibition as a component of the induction response.
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PMID:Inducible transcriptional activation of the human immunodeficiency virus long terminal repeat by protein kinase inhibitors. 835 80

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.
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PMID: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. 864 89

2',3'-Dideoxynucleosides (ddN) and their derivatives are currently used as antiretroviral compounds. Their active agents are the corresponding 2',3'-dideoxynucleoside triphosphates (ddNTPs) generated inside the cell by host kinases. Dinucleoside tetraphosphates (Np4Ns) are molecules of interest in metabolic regulation; their synthesis in vitro can be catalyzed by firefly luciferase. The relative synthesis of diadenosine 5',5'''-P1,P4-tetraphosphate or adenosine(5')tetraphospho(5')adenosine (Ap4A) from ATP is about 100-fold faster than that of di-2',3'-dideoxyadenosine 5',5'''-P1,P4-tetraphosphate or 2',3'-dideoxyadenosine (5')tetraphospho (5')-2',3'-dideoxyadenosine (ddAp4ddA) from ddATP. In the presence of ATPgammaS and ddATP the yield of adenosine(5')tetraphospo(5')-2',3'-dideoxyadenosine (Ap4ddA) was similar to that attained for Ap4A in the presence of ATP. The findings of this work indicate that the presence of a 3'-hydroxyl group is essential for the formation of the luciferase-luciferin-AMP complex, and explains the very low yield of ddAp4ddA in the presence of luciferase, luciferin and ddATP. The absence of 3'-hydroxyl groups in ddAp4ddA greatly hindered their hydrolysis by snake venom phosphodiesterase, asymmetrical dinucleoside tetraphosphatase and by a purified membrane preparation from rat liver. The possibility of using di-2',3'-dideoxynucleoside tetraphosphate (ddNp4ddN) or nucleoside(5')tetraphospho(5')-2',3'-dideoxynucleoside (Np4ddN) as a source of the active retroviral agent ddNTP, for example in HIV infection, is outlined.
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PMID:2',3'-dideoxynucleoside triphosphates (ddNTP) and di-2',3'-dideoxynucleoside tetraphosphates (ddNp4ddN) behave differently to the corresponding NTP and Np4N counterparts as substrates of firefly luciferase, dinucleoside tetraphosphatase and phosphodiesterases. 910 13

The mucosal surfaces represent the primary site for transmission of several viruses including HIV. To prevent mucosal transmission and dissemination to the regional lymph nodes, an effective HIV vaccine may need to stimulate immune responses at the genital and rectal mucosa. Optimal induction of mucosal immunity in general requires targeting antigens to the specialized antigen presenting cells of mucosal associated lymphoid tissues. The nasal mucosa may provide a simple, non-invasive route to deliver DNA encoding the introduced gene to stimulate mucosal immunity. As a first step to evaluate the feasibility of this approach, we have investigated as a model system, systemic and mucosal immune responses elicited to firefly luciferase generated by DNA immunization. Incorporating DNA into liposomes with cationic lipids enhanced luciferase expression in nasal tissue, and was associated with induction of a humoral response in serum and vaginal fluids and also a proliferative and cytotoxic T lymphocyte response in the spleen and iliac lymph nodes draining the genital and rectal mucosa.
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PMID:Mucosal immunization with DNA-liposome complexes. 923 23


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