Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.23 (beta-galactosidase)
 14,648 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

With this work we demonstrate that murine leukemia virus (MLV)-based replication-defective retroviral vectors encapsidated with Gibbon ape leukemia virus (GaLV) envelopes are significantly more infectious to bovine embryonic trachea (EBTr) cells than vectors encapsidated with murine xenotropic envelope proteins. In a test of internal promoter activity in an MLV retroviral vector, the rat beta-actin promoter was shown to be better than the herpes simplex virus type 1 thymidine kinase (TK) and human cytomegalovirus (CMV) immediate early promoters for the expression of an E. coli beta-galactosidase marker gene in bovine target cells. By co-culture of bovine blastocysts and virus-producing cells, or by culture of embryos in the medium harvested from virus-producing cells, we transferred the E. coli beta-galactosidase gene into trophoblasts and also into inner cell mass (ICM) cells of a bovine embryo through the infection of the MLV-based replication-defective retroviruses encapsidated with GaLV envelope proteins. The infection was confirmed by the expression of the E. coli beta-galactosidase gene under a beta-actin internal promoter. In addition, co-culture of ICM cells with virus-producing cells resulted in differentiation of ICM cells into embryoid bodies expressing the marker genes.
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PMID:Gene transfer in bovine blastocysts using replication-defective retroviral vectors packaged with Gibbon ape leukemia virus envelopes. 839 Dec 77

The ability to induce proliferation by temporary duct ligation suggested an hypothesis that retrovirus-mediated gene transfer into cells of the biliary tract could be accomplished. The time course of histologic changes, incorporation of 3H-thymidine and immunofluorescent staining with a monoclonal antibody to cytokeratin-19 (a marker for differentiated bile ducts) was studied in male Fischer F344 rats. A recombinant Gibbon ape leukemia virus (GALV), containing a gene encoding Escherichia coli beta-galactosidase was next introduced into 24 hr obstructed bile ducts. Gene transfer was maximal when virus was exposed to the obstructed duct for 12 hr (approximately 0.1%). The majority of X-gal positive cells were in cytokeratin-19 negative peribiliary tissues, which had the appearance of newly forming bile ducts. The data suggest that cells targeted by retroviral infection of the obstructed rat bile duct may be a precursor of mature, fully differentiated biliary epithelium.
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PMID:Targeted retroviral gene transfer into the rat biliary tract. 864 91

The best methods for transducing hematopoietic progenitor cells usually involve either direct co-cultivation with virus-producing cells or human stromal supportive cells. However, these methods cannot be safely or easily applied to clinical use. Therefore, we aimed at improving retrovirus-mediated gene transfer into hematopoietic progenitors derived from cord blood CD34+ cells using viral supernatant to levels achieved at least with direct co-cultivation and under conditions that are suitable for clinical applications. In a first set of experiments, CD34+ cells were infected with supernatant containing amphotropic retroviral particles carrying the nls-lacZ reporter gene and the effects of centrifugation, cell adhesion to fibronectin, and Polybrene on the transduction of both clonogenic progenitors (CFC) and long-term culture initiating cells (LTC-IC) were studied. Transduction efficiency was evaluated on the percentage and total number of progenitors expressing the beta-galactosidase activity. Results show that a 48-hr infection of CD34+ cells with viral supernatant combining centrifugation at 1000 x g for 3 hr followed by adhesion to fibronectin allows transduction levels for both CFC and LTC-IC to be reached that are as good as using direct co-cultivation. In a second set of experiments, CD34+ cells were infected using this optimized protocol with pseudotyped retroviral particles carrying the gibbon ape leukemia virus (GALV) envelope protein. Under these conditions, between 50 and 100% of CFC and LTC-IC were transduced. Thus, we have developed a protocol capable of highly transducing cord blood progenitors under conditions suitable for a therapeutical use.
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PMID:High-level gene transfer to cord blood progenitors using gibbon ape leukemia virus pseudotype retroviral vectors and an improved clinically applicable protocol. 947 82

Gene transfer in regenerating dog liver using high-titer recombinant retroviral vectors carrying the E. coli beta-galactosidase gene was studied. Supernatants containing amphotropic or gibbon ape pseudotyped recombinant retroviruses were infused into a peripheral vein in beagle dogs after partial hepatectomy. The kinetics of liver regeneration were determined in the animals and daily infusions were carried out for 4 or 5 days during the regeneration period. Up to 2.8% of hepatocytes were beta-galactosidase positive at the end of the procedure. However, the number of positive cells declined rapidly and few positive hepatocytes were detected after 3 weeks. PCR demonstrated the disappearance of the provirus. Histologically, inflammatory lesions were observed in the transduced livers. Finally, we demonstrated the presence of a cytotoxic T lymphocyte immune response directed against beta-galactosidase-expressing cells, which could explain the disappearance of the transgene. This work suggests that the efficiency of in vivo gene delivery using high-titer retroviral vectors directly infused into the circulation may be hampered by a cytotoxic immune response against the infected cells.
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PMID:In vivo retrovirus-mediated gene transfer to the liver of dogs results in transient expression and induction of a cytotoxic immune response. 1060 53

The synthetic peptide T-20 (enfuvirtide) represents the first of a new class of antiretroviral compounds to demonstrate in vivo potency by targeting a step in viral entry. T-20 inhibits a conformational change in the human immunodeficiency virus type 1 (HIV-1) transmembrane glycoprotein (gp41) that is required for fusion between HIV-1 and target cell membranes. The initial phase I clinical trial of T-20 treatment for HIV-infected patients thus provided a unique opportunity to evaluate the emergence of resistant virus in vivo to this novel class of antiretroviral agents. All four patients who received an intermediate dose of T-20 (30 mg twice daily) had an initial decline in plasma viral load over the first 10 days but a rising trend by day 14, suggestive of selection for resistant virus. Plasma virus derived from patients enrolled in all dosage groups of the phase I T-20 trial was analyzed by population sequencing before and after treatment. While no mutations were found within a highly conserved 3-amino-acid sequence (GIV) known to be critical for fusion at baseline, after 14 days of therapy, virus from one patient in the 30-mg dose group (30-1) developed a mutation in this motif, specifically an aspartic acid (D) substitution for glycine (G) at position 36. Multiple env clones were derived from the plasma virus of all four patients in the 30-mg dosage group. Sequence analysis of 49 clones derived from the plasma of patient 30-1 on day 14 revealed that 25 clones contained the G36D mutation, while 8 contained the V38A mutation. Dual mutations involving G36D and other residues within the HR1 domain were also identified. In 5 of the 49 env clones, other mutations involving residues 32 (Q32R or Q32H) and 39 (Q39R) were found in combination with G36D. Cloned env sequences derived from the plasma virus of subject 30-3 also had single mutations in the GIV sequence (V38M and I37V) detectable following therapy with T-20. The plasma virus from subjects 30-2 and 30-4 did not contain changes within the GIV sequence. To analyze the biological resistance properties of these mutations, we developed a novel single-cycle HIV-1 entry assay using JC53BL cells which express beta-galactosidase and luciferase under control of the HIV-1 long terminal repeat. Full-length env clones were derived from the plasma virus of patients 30-1 and 30-3 and used to generate pseudotyped virus stocks. The mean 50% inhibition concentrations (IC(50)s) for mutants G36D and V38A (patient 30-1) were 2.3 microg/ml and 11.2 microg/ml, respectively, statistically significant increases of 9.1- and 45-fold, respectively, compared with those of wild-type Env. The IC(50) for the V38 M mutation (patient 30-3) was 7.6 microg/ml, an 8-fold increase compared with that of the wild type. The I37V mutation resulted in an IC(50) 3.2-fold greater than that of the wild type. Envs with double mutations (Q32R plus G36D and Q32H plus G36D) exhibited a level of resistance similar to that of G36D alone. These findings provide the first evidence for the rapid emergence of clinical resistance to a novel class of HIV-1 entry inhibitors and may be relevant to future treatment strategies involving these agents.
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PMID:Emergence of resistant human immunodeficiency virus type 1 in patients receiving fusion inhibitor (T-20) monotherapy. 1201 6