Document 0187
 DOCN  M9440187
 TI    Analysis of Tat function in human immunodeficiency virus type 1-infected
       low-level-expression cell lines U1 and ACH-2.
 DT    9404
 AU    Cannon P; Kim SH; Ulich C; Kim S; Department of Biochemistry, University
       of Oxford, United Kingdom.
 SO    J Virol. 1994 Mar;68(3):1993-7. Unique Identifier : AIDSLINE
       MED/94149898
 AB    The U1 and ACH-2 cell lines are subclones of human monocytic and
       T-lymphoid cells, respectively, persistently infected with human
       immunodeficiency virus type 1. These cell lines harbor the viral genome
       but produce only very low levels of viral progeny, which can be
       increased by stimulation with agents such as phorbol ester and
       cytokines. As such, they provide an in vitro model for human
       immunodeficiency virus type 1 latency. In order to examine the basis for
       their latent state, we have analyzed the activity of endogenous Tat
       protein in these cells and investigated the effect on viral replication
       of the addition of exogenous Tat protein. We find that U1 cells seem to
       have levels of Tat protein that are suboptimal for long terminal repeat
       (LTR) transcription, because transcription from a transfected
       LTR-chloramphenicol acetyltransferase plasmid can be enhanced by
       cotransfection of a Tat expression plasmid. Furthermore, viral
       replication can be stimulated in this cell line by incubation with
       purified Tat protein. In contrast, ACH-2 cells are not limited for
       LTR-chloramphenicol acetyltransferase transcription by endogenous levels
       of Tat, and virus production is not increased by the addition of
       exogenous Tat protein. By semiquantitative PCR analysis of viral RNA, we
       have demonstrated that Tat protein caused an increase in human
       immunodeficiency virus RNA expression in U1 cells but had no effect in
       ACH-2 cells. This suggests that a different mechanism underlies the
       latent state in U1 and ACH-2 cells.
 DE    Comparative Study  Gene Products, tat/*PHARMACOLOGY  Human  HIV Core
       Protein p24/BIOSYNTHESIS  HIV-1/*DRUG EFFECTS/GROWTH & DEVELOPMENT
       Monocytes/*MICROBIOLOGY  Polymerase Chain Reaction  Recombinant
       Proteins/PHARMACOLOGY  RNA, Messenger/ANALYSIS  RNA, Viral/ANALYSIS
       Support, Non-U.S. Gov't  Support, U.S. Gov't, P.H.S.
       T-Lymphocytes/*MICROBIOLOGY  Tetradecanoylphorbol Acetate/PHARMACOLOGY
       Transfection  Virus Latency/*DRUG EFFECTS  Virus Replication/DRUG
       EFFECTS  JOURNAL ARTICLE

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       protected by Copyright Law (Title 17, U.S.Code).