Volume 271, Number 45,
Issue of November 8, 1996
pp. 28266-28270
©1996 by The American Society for Biochemistry and Molecular Biology, Inc.
Synthesis of Full-length Viral DNA in CD4-positive Membrane
Vesicles Exposed to HIV-1
A MODEL FOR STUDIES OF EARLY STAGES OF THE HIV-1 LIFE CYCLE
(Received for publication, March 12, 1996, and in revised form, August 20, 1996)
Malgorzata
Simm
,
Olga
Pekarskaya
and
David J.
Volsky
From the Molecular Virology Laboratory, St. Luke's-Roosevelt
Hospital Center and College of Physicians & Surgeons, Columbia
University, New York, New York 10019
CD4-positive membrane vesicles (MV) were isolated
under isotonic conditions from human T lymphoblastoid cells MT-2 and
CEM and tested for their ability to support reverse transcription of
viral RNA upon exposure to human immunodeficiency virus, type 1
(HIV-1). MV contained cytoplasms as confirmed by the presence of
mitochondrial DNA but were devoid of chromosomal DNA. Virus binding and
vesicle lysis assays revealed that 4-19% (depending upon virus dose)
of MV-bound HIV-1 entered the vesicles. HIV-1 internalized in MV was
able to initiate and complete viral DNA synthesis as determined by the
detection of products of reverse transcription using polymerase chain
reaction amplification of viral DNA using regions present in early
(strong stop) transcripts and full-length double-stranded molecules.
Viral DNA was undetectable in MV exposed to HIV-1 at 0 °C, in MV
exposed to UV-inactivated virus at 37 °C, or after exposure to
intact virus at 37 °C in the presence of reverse transcriptase
inhibitors 2
,3
-dideoxycytidine and a
tetrahydroimidazo[4,5,1-jk](1,4)-benzodiazepin-2-(1H)-thione
derivative, indicating that viral DNA detected in HIV-1-exposed MV was
synthesized de novo. Kinetic studies revealed that HIV-1
DNA synthesis in MV was very rapid; full-length viral DNA was detected
within 15 min of exposure at 37 °C, and the DNA levels increased
90-fold after 1 h and declined thereafter. Strong stop viral DNA
was 10-fold more abundant than full-length DNA after 1 h at
37 °C, indicating that 10% of input viral genomes are fully
transcribed in MV within this time frame. This system preserves the
critical features of intact CD4-bearing cells to permit studies of
HIV-1 entry, uncoating, and reverse transcription of viral
RNA.