References

Notes: Human immunodeficiency virus (HIV) infection in the monocyte/macrophage (M/M) may be as clinically important as that of the T cells. However, in in vitro experiments, most antiviral activity has been estimated using a human T-cell line, such as MT-4, because of the lack of an appropriate evaluation system with M/M. Although human peripheral blood macrophages have also been used as the target for HIV infection, this procedure is rather cumersome and not reproducible. To overcome this problem, we attempted to establish such an assay system in the present study. One of the subclines of a monocytic cell line, U937, cl.1-14 was obtained by a limiting dilution method. The cl.1-14 cell was much more sensitive for HIV infection than its pareental cell and 60 to 70% of the cells were HIV antigen-positive 8-10 days after infection (MOI=0.1). 937 and cl.1-14 were infected with cell free HIV-1 and the antiviral activity of some compunds was estimated by inhibition of viral antigen expression monitored by an indirect immunofluorescent method....
Reference ID: 3604

Notes: A subclonal cl.1-14 cell was established from a monocytic cell line U937 by a limiting dilution method. The anti-HIV-1 activity of some antiviral compounds was evaluated in HIF-1-infected cl.1-14 cells. The results demonstrated that although AZT was a potent inhibitor of HIV-1 replication in cl.1-14 cells, its 50% effective concentration (EC50) values was 80 times higher than that in HIV-1 infected MT-4 cells; the EC50 of AZT was 0.16uM and 0.002 uM in cl.1-14 and MT 4 cells, respectively. In contrast, the anti-HIV-1 activity of ddA, ddI and ddC in cl.1-14 cells was comparable to that in MT-4 cells. The antiviral activity of nevirapine, dextran sulfate, curdlan sulfate and T22 did not differ significantly between the cl.1-14 and MT-4 cells. The antiviral activity of several compounds in the HIV-1-infected cl.1-14 cells was similar to that in the HIV-1jr-fl-infected human peripheral macrophages. Our results suggest that cl.1-14 cell cultures are very useful for estimating antiviral activity and more advantageous than the use of peripheral blood macrophages.
Reference ID: 4601

Notes: We have identified and analyzed a 27-nucleotide sequence (U5 repressive element, designated as U5RE at the U5 region of the human T-cell leukemia virus type I (HTLV-I) long terminal repeat (LTR) which is required for HTLV-I basal transcriptional repression. The basal promoter strength of constructs that contained deletions in the U5 region of the LTR was analyzed by chloramphenicol acetylatransferase (CAT) assays to 5-fold increase in basal promoter activity when sequences between +277 to +306 were deleted. In vivo competition experiments suggested that enriched fraction that could specifically bind U5RE. This DNA affinity column fraction contained three major detectable proteins on sodium dodecyl sulfate-polyacrylamide gel electrophoresis with silver staining: 110-, 80-, and 70kDa proteins......
Reference ID: 4603

Notes: [Article in Russian] MT-4 cell line is a continuous strain of human T lymphocytes expressing defective noninfective subviral HTLV-1 particles. A fragment of sequence encoding the p24 protein and gene for evnelope protein (env) have been obtained from genomic DNA of this culture by polymerase chain reaction. Both HTLV-1 fragments were cloned in bacterial vectors, and the nucleotide sequence of these regions was determined. The cloned DNA fragment encoding the p24 has only four point nucleotide exchanges. Analysis of the env gene structure revealed that the sequence had several amino acid exchanbes and deleteions (13 bp and 70 bp). PMID:8927062, UI: 96377355
Reference ID: 5009

Notes: The Tax I trans-activator protein of the human T-cell leukemia virus I (HTLV-I) enhances viral gene expression through e nhancer sequences in the viral LTR. These sequences consist of three imperfect 21-bp repeats (TRE-1) and a region between the promoter cen tral and promoter proximal TRE-1 (known as TRE-2). We have previously described the in vivo footprint of the HTLV-I TRE-1s and TRE-2 in two HTLV-I-infected cell lines, MT-2 and MT-4. MT-2 is a high-level producer of virus and shows significant DNA-protein interactions within the TRE-1s and TRE-2. In contrast, the proviral DNA in MT-4 cells is heavily methylated and produces no detectable virus. In this report, we describe the footprints of the TRE-1s and TRE-2 in MT-4 cells that were induced to express high levels of viral proteins by treatment with 5-azacytidine, a potent inhibitor of methylation. The footprints of the TRE-1s in 5-azacytidine-treated MT-4 cells were virtually identical to those observed in MT-2 cells. In contrast, the footprints within the TRE-2 region of 5-azacytidine-treated MT-4 cells did not resemble those in either MT-2 or MT-4 cells. Copyright 2001 Academic Press.
Reference ID: 5406