Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0019693 (HIV)
 170,526 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Infectious HIV-1 particles containing replication-defective vectors that express the hygromycin B phosphotransferase gene were generated by transient complementation in COS-1 cells. A defective vector dependent only on trans-complementation with an env gene and a small vector containing a deletion of almost all of the trans region were used to examine pseudotyping of HIV-1 by an amphotropic murine retrovirus. Although pseudotyping by the heterologous envelope glycoprotein occurred with efficiency, no pseudotyping at the RNA level was observed. Genetic complementation was used to rapidly analyze the effect of env mutations in the V3, proteolytic processing site, fusion domain, and cytoplasmic tail on viral infectivity. Mutations decreasing syncytium formation usually also lowered infectivity. However, a mutation in the cytoplasmic tail and a separate mutation adjacent to the fusion domain dramatically decreased viral particle infectivity but did not appreciably decrease envelope glycoprotein-mediated cell-to-cell fusion. These results may indicate that these regions of the transmembrane peptide are necessary for acquisition of envelope glycoprotein by budding virus particles or for virus entry.
 ...
PMID:Analysis of HIV-1 envelope mutants and pseudotyping of replication-defective HIV-1 vectors by genetic complementation. 145 11

Tat-dependent expression of an endogenous lethal or deleterious foreign gene might be useful for abrogating the production of human immunodeficiency virus (HIV) from cells. This type of HIV-induced cellular killing, as well as other approaches to gene therapy for HIV infection, would be facilitated by simple HIV vectors that express introduced genes in a Tat-inducible manner. As part of studies to examine the feasibility of this concept, we constructed HIV-1 vectors that express the hygromycin B phosphotransferase gene (Hygr) in a Tat-dependent manner. Comparison of the efficiency of propagation of each vector indicates that sequences extending into the gag open reading frame are necessary in cis for efficient vector propagation. Southern blot analysis of genomic DNA isolated from vector-infected cells demonstrated that the vectors were capable of being propagated as expected without gross rearrangements or deletions. A fragment of the influenza A virus hemagglutinin (H5 HA) gene, capable of eliciting antibody and cytotoxic T-cell responses, was used as a marker for further characterization of the vector system. A Tat-dependent vector conferring the H5 HA+ phenotype was assayed by indirect immunofluorescence, and cells which contained but did not express the H5 HA gene were isolated. The activation of H5 HA expression following HIV infection of Tat- cells that stably contained but did not express the H5 HA construct was determined to be an efficient process.
 ...
PMID:Human immunodeficiency virus vectors for inducible expression of foreign genes. 156 May 23

Since the recognition of its pivotal role in viral replication, Tat activity has become an interesting target for chemotherapeutic intervention of HIV infection. Here, we report a sensitive and simple colorimetric assay for the screening of Tat inhibitors. We have constructed a plasmid that contains the hygromycin B phosphotransferase gene under the control of the HIV-1 long terminal repeat (LTR) and HIV-1 tat gene constitutively expressed from the cytomegalovirus promoter. This plasmid has been stably transfected to the CD4+ T cell line CEM, which is rendered resistant to hygromycin B through the action of Tat. The inhibitory activity of the anti-Tat drugs was assessed by the extent of cytotoxicity in the presence of hygromycin B as a consequence of the suppressed expression of the hygromycin B phosphotransferase gene. Spectrophotometric quantitation of cell viability was done utilizing 3-(4,5-dimethylthiazol-2-yl)-2,5- diphenyltetrazolium bromide (MTT) dye as the indicator. Using this assay system, we have confirmed that known anti-Tat compound Ro5-3335 and its derivative Ro24-7429 could inhibit Tat-mediated gene expression although their selectivities (anti-Tat activity versus nonselective cytotoxicity) were narrow. Since this method offers the advantage of not handling infectious particles or radioactive materials, it can offer wide applicability as a screening system for anti-Tat compounds.
 ...
PMID:Anti-Tat MTT assay: a novel anti-HIV drug screening system using the viral regulatory network of replication. 857 93

To study Mason-Pfizer monkey virus (MPMV) replication over a single round, virus particles were generated that contain a replication-defective vector encoding a dominant selectable marker, the hygromycin B phosphotransferase (hyg) gene. Genetic complementation with a homologous MPMV envelope glycoprotein (Env-gp) or pseudotyping by several heterologous Env-gps from a variety of viruses resulted in infectious MPMV particles containing the replication-defective RNA. Recently, it has been shown that human immunodeficiency virus type 1 (HIV-1) and simian immunodeficiency virus (SIV) Rev and Rev-responsive element (RRE) functions can be substituted in vitro by a cis-acting sequence, the constitutive transport element (CTE), from simian type D retroviruses like MPMV and simian retrovirus type 1 (SRV-1). To determine whether CTE of MPMV is necessary for MPMV nucleic acid propagation, an MPMV vector that lacked the terminally located CTE was generated. Propagation of this vector was completely abrogated in the absence of CTE, showing the importance of CTE in MPMV replication. Insertion of CTE back into the MPMV genome in the sense orientation rescued replication to wild-type levels. Slot-blot analysis of nuclear versus cytoplasmic RNA fractions revealed that most of the messages were sequestered in the nucleus of cells transfected with the CTE(-) vectors and very little was transported to the cytoplasm. To test whether HIV-1 or SIV RREs could complement CTE function, the HIV-1 or SIV RREs were inserted in the CTE(-) vectors, trans complementation of CTE(-)RRE(+) vectors with Env-and Rev-expression plasmids rescued propagation of the CTE(-) vectors. Computer analysis predicted an RNA secondary structure in MPMV CTE analogous to the HIV-1 and SIV RREs that could form three stable stem loops, the first of which contains a site similar to the Rev-binding domain in the HIV-1 RRE. The presence of a higher-order CTE structure was analyzed by mutational analysis. We conclude that CTE is important in the replication of MPMV and affects the nucleocytoplasmic transport and/or stability of viral messages similar to the Rev/RRE regulatory system of HIV-1 and SIV.
 ...
PMID:Role of Mason-Pfizer monkey virus (MPMV) constitutive transport element (CTE) in the propagation of MPMV vectors by genetic complementation using homologous/heterologous env genes. 887 12