title: Transient Tat activation of the HIVLAV/Lai-1 LTR by primary HIV-1 phenotypic variants in HeLaT4LTRbeta-gal cells.
abstract: The rapid/high and slow/low phenotypic variants of primary HIV-1 isolates can be distinguished by their differential co-receptor utilization and their ability to productively infect established cell lines. To reveal possible differences in Tat-mediated transactivation, the potential for primary isolate Tat proteins to transactivate the LTR from the laboratory strain HIVLAV/Lai-1 was examined. Using either cell-mediated or PEG-induced fusion of cells infected with primary HIV-1 isolates and HeLaT4LTRbeta-gal cells, it was clear that the Tat protein encoded by all patient isolates efficiently activated transcription from the HIVLAV/Lai-1 LTR. However, infection of HeLaT4LTRbeta-gal cells by primary HIV-1 isolates was transient, suggesting the development of a postpenetration host control of HIV-1 replication at the level of tat activation, a feature not observed for the laboratory-adapted strain HIVIIIB. Although plasmid vectors based on the HIVLAV/Lai-1 LTR remain useful for the development of susceptible established cell lines for titrating primary HIV-1 isolates, the efficacy of such a system would depend upon the stability/duration of Tat activation.
authors.affiliation: Department of Molecular Biology, The Gade Institute, Bergen High Technology Centre, University of Bergen, Norway.
authors.forename: M V
authors.initials: MV
authors.lastname: Nilsen
authors.forename: B
authors.initials: B
authors.lastname: Asjö
authors.forename: M A
authors.initials: MA
authors.lastname: Sommerfelt
mesh_terms: D015704:CD4 Antigens / Q000096:biosynthesis* / Q000235:genetics; D002459:Cell Fusion; D002474:Cell-Free System; D015967:Gene Expression Regulation, Viral; D015696:Gene Products, tat / Q000378:metabolism*; D016325:HIV Long Terminal Repeat; D015497:HIV-1 / Q000235:genetics* / Q000502:physiology; D006367:HeLa Cells; D006801:Humans; D019169:Jurkat Cells; D010641:Phenotype; D015533:Transcriptional Activation; D001616:beta-Galactosidase / Q000096:biosynthesis / Q000235:genetics; D054322:tat Gene Products, Human Immunodeficiency Virus
chemical_list: D015704:CD4 Antigens; D015696:Gene Products, tat; D054322:tat Gene Products, Human Immunodeficiency Virus; D001616:beta-Galactosidase