home
***
CD-ROM
|
disk
|
FTP
|
other
***
search
/
Shareware Overload Trio 2
/
Shareware Overload Trio Volume 2 (Chestnut CD-ROM).ISO
/
dir26
/
med9407f.zip
/
M9471069.TXT
< prev
next >
Wrap
Text File
|
1994-08-09
|
4KB
|
55 lines
Document 1069
DOCN M9471069
TI Analysis of three distinct stages of replication in human retroviruses.
DT 9409
AU Hammes SR; Duke Univ.
SO Diss Abstr Int [B]; 53(12):6113 1993. Unique Identifier : AIDSLINE
ICDB/94696141
AB The type 1 human immunodeficiency and human T-cell leukemia viruses
(HIV-1 and HTLV-I, respectively) use many mechanisms at various stages
throughout their life cycles to regulate replication. Three of these
processes were examined in detail in order to better understand some of
the complexities of this regulation. The first mechanism studied
involved the regulation of retroviral gene transcription. HIV-1 Nef
protein has been reported to control viral replication by suppressing
gene transcription directed by the HIV-1 LTR. In contrast, these studies
demonstrate that Nef had no effect on transcriptional activity through
the HIV-1 LTR. Furthermore, HIV-1 proviral clones containing either a
wild type or mutated nef gene replicated equally well when transfected
into cells. These findings suggest that, in contrast to previous
reports, Nef is neither a transcriptional inhibitor nor a suppressor of
viral replication. The second regulatory mechanism examined was the
control of retroviral structural protein expression. HTLV-I Rex protein
acts post-transcriptionally to enhance expression of incompletely
spliced viral mRNAs encoding these structural proteins. Rex function
involves its direct interaction with an RNA stem-loop structure located
within the 3' LTR termed the Rex response element (RexRE). This
interaction requires a positively charged arginine-rich domain in Rex
that also serves as a nuclear localization signal. Mutagenesis of this
basic region revealed that, while positive charge alone appears
sufficient for nuclear localization, multiple arginine residues at
specific sites are essential for complete RNA binding and functional
activity of Rex. The final stage of retroviral replication studied was
viral binding to target cells. Little is known about the identity of the
HTLV-I receptor. These studies demonstrated that a direct interaction
between the HTLV-I envelope glycoprotein gp46 and viral receptors on
target cells was necessary for infection. Binding assays using purified
gp46 revealed that HTLV-I receptors were expressed on all mammalian
tumor lines tested, but were absent on non-mammalian cells. Furthermore,
activation of resting primary human T-lymphocytes, which are devoid of
gp46 binding sites, resulted in the induction of HTLV-I receptor
expression. Together, these results suggest that HTLV-I infection may
require T-cell activation, and that HTLV-I receptor expression may
correlate with cellular proliferation. (Full text available from
University Microfilms International, Ann Arbor, MI, as Order No.
AAD93-11846)
DE Gene Products, nef/*GENETICS Genes, pX/*GENETICS HIV Long Terminal
Repeat/GENETICS HTLV-I/*GENETICS/PHYSIOLOGY HTLV-I Infections/GENETICS
Lymphocyte Transformation RNA Splicing Receptors, HIV/METABOLISM
T-Lymphocytes/PHYSIOLOGY Transcription, Genetic *Virus Replication
THESIS
SOURCE: National Library of Medicine. NOTICE: This material may be
protected by Copyright Law (Title 17, U.S.Code).