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J. Virol., Feb 1996, 712-720, Vol 70, No. 2
EJ Arts, JP Marois, Z Gu, SF Le Grice and MA Wainberg
We have compared the effects of nucleoside analogs in quiescent and
phytohemagglutinin (PHA)-stimulated peripheral blood mononuclear cells
(PBMC) exposed to human immunodeficiency virus type 1 (HIV-1) with those of
their triphosphorylated derivatives in cell-free HIV-1 reverse
transcription assays. We observed a substantial decrease in synthesis of
early minus-strand proviral DNA products in HIV-1-infected, quiescent PBMC
exposed to each of 3'-azido-3'-deoxythymidine (AZT), 2',3'-dideoxyinosine
(ddI), and 2',3'-dideoxy-3'-thiacytidine (3TC), in comparison with
nontreated, infected controls. In contrast, no such diminution was observed
when PHA-stimulated, HIV-1-infected PBMC were treated with the same drugs.
This result was attributed to previously reported findings that
PHA-stimulated PBMC possessed larger deoxynucleoside triphosphate (dNTP)
pools than quiescent cells did. To further investigate this subject, a
cell-free HIV-1 reverse transcription reaction involving HIV-1 RNA genomic
template, recombinant purified HIV-1 reverse transcriptase, all four dNTPs
and either tRNA3Lys or a deoxyoligonucleotide as primer was used to monitor
chain termi-nation mediated by 2',3'-dideoxynucleoside triphosphates
(ddNTPs) during synthesis of minus-strand strong-stop DNA. Augmented chain
termination was observed with decreasing concentrations of both ddNTP and
dNTP when the ratio of dNTP to ddNTP was fixed. We also found that both the
number and strength of reverse transcription pause sites were increased at
low concentrations of dNTPs and when a deoxyoligonucleotide primer was used
in place of the cognate primer, tRNA3Lys. Preferential incorporation of
ddATP was observed dur-ing reverse transcription opposite a distinct pause
site in a short synthetic RNA template. These results con-firm the notion
that the antiviral activities of ddNTP are dependent on both cellular dNTP
pools and the state of cellular activation. Pausing of HIV-1 reverse
transcriptase during reverse transcription, altered by dNTP concentrations,
may be a mechanism that controls the position and extent of incorporation
of nucleoside analogs.
Copyright © 1996, American Society for Microbiology
Effects of 3'-deoxynucleoside 5'-triphosphate concentrations on chain termination by nucleoside analogs during human immunodeficiency virus type 1 reverse transcription of minus-strand strong-stop DNA
McGill AIDS Centre, Lady Davis Institute, Jewish General Hospital, Montreal, Quebec, Canada.
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