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J. Virol., 11 1997, 8124-8132, Vol 71, No. 11
Z Du, PO Ilyinskii, K Lally, RC Desrosiers and A Engelman
Sequences at the left terminus of U3 in the left long terminal repeat (LTR)
and at the right terminus of U5 in the right LTR are important for
integration of retroviral DNA. In the infectious pathogenic molecular clone
of simian immunodeficiency virus strain mac239 (SIVmac239), 10 of the 12
terminal base pairs form an imperfect inverted repeat structure (5'
TGGAAGGGATTT 3' [nucleotides 1 to 12] and 3' ACGATCCCTAAA 5' [nucleotides
10279 to 10268]). Nineteen different mutant forms of SIVmac239 proviral DNA
with changes at one or more of the positions in each of the
12-terminal-base-pair regions were constructed. Viral replication was
severely or completely compromised with nine of these mutants. Revertants
appeared 40 to 50 days after transfection in two independent experiments
with mutant 7, which contained changes of AGG to TAC at positions 5 to 7 in
U3 and TCC to GAA at positions 10275 to 10273 in U5. Virus produced at
these times from mutant 7 transfection replicated upon reinfection with
only a slight delay when compared to the wild type. Sequence analysis of
the LTR and integrase regions from infected cultures revealed two
predominant changes: G to A at position 10275 in U5 and Glu to Lys at
position 136 in integrase. Derivatives of clone 7 in which these changes
were introduced individually and together were constructed by site-specific
mutagenesis. Each change individually restored replication capacity only
partially. However, the combination of both mutations restored replicative
capacity to that of the original revertants. These results indicate that
changes in integrase can compensate for mutations in the terminal
nucleotides of the SIV LTR. The results further indicate that resistance to
integrase inhibitors may include both integrase and LTR mutations.
Copyright © 1997, American Society for Microbiology
A mutation in integrase can compensate for mutations in the simian immunodeficiency virus att site
New England Regional Primate Research Center, Harvard Medical School, Southborough, Massachusetts 01772, USA.
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