       Document 0565
 DOCN  M9610565
 TI    Retroviral vector with a CMV-IE/HIV-TAR hybrid LTR gives high basal
       expression levels and is up-regulated by HIV-1 Tat.
 DT    9601
 AU    Robinson D; Elliott JF; Chang LJ; Department of Medical Microbiology and
       Infectious Diseases,; University of Alberta, Edmonton, Canada.
 SO    Gene Ther. 1995 Jun;2(4):269-78. Unique Identifier : AIDSLINE
       MED/96002190
 AB    We have constructed a new retroviral vector by making modifications to
       the commonly used Moloney murine leukemia virus (MoMLV) based vector in
       the long terminal repeat (LTR). The changes include replacement of a
       portion of the U3 region of the MoMLV LTR with a hybrid regulatory
       element consisting of the human cytomegalovirus immediate-early
       enhancer/promoter (CMV-IE) together with the human immunodeficiency
       virus transactivation response element (HIV-TAR). Transfection of
       chloramphenicol acetyl transferase (CAT) reporter constructs into a
       variety of human cell lines showed that the hybrid LTR with the
       CMV-IE/HIV-TAR enhancer/promoter exhibited basal expression levels which
       were 10- to 50-fold higher than those obtained from the wild-type
       MoMLV-LTR enhancer/promoter. Expression from the recombinant LTR was
       further increased in the presence of the HIV-Tat protein, and
       surprisingly, Tat up-regulated transcription from both the HIV and the
       MoMLV TATA boxes. In contrast, a MoMLV enhancer/promoter containing only
       the HIV-TAR element in the LTR did not respond to Tat. When stably
       transfected into an amphotropic packaging cell line, the modified
       retroviral vector containing the hybrid LTR plus an extended packaging
       signal consistently gave higher titres of retrovirus than did the
       parental MoMLV based vector. Higher basal expression levels which can be
       further upregulated by Tat, together with more efficient virion
       production, suggests that the modified vector should be superior for
       anti-HIV gene therapy applications as well as for other more general
       applications in human gene therapy.
 DE    Animal  Base Sequence  Cloning, Molecular  Cytomegalovirus/GENETICS
       Gene Products, tat/BIOSYNTHESIS/GENETICS  *Genes, tat  *Genetic Vectors
       Human  HIV-1/GENETICS  Mice  Molecular Sequence Data  Promoter Regions
       (Genetics)  Recombination, Genetic  *Repetitive Sequences, Nucleic Acid
       Retroviridae/*GENETICS/METABOLISM  RNA Processing, Post-Transcriptional
       Support, Non-U.S. Gov't  Transcription, Genetic  Tumor Cells, Cultured
       *Up-Regulation (Physiology)  JOURNAL ARTICLE

       SOURCE: National Library of Medicine.  NOTICE: This material may be
       protected by Copyright Law (Title 17, U.S.Code).

