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Journal of Virology, June 2001, p. 5604-5613, Vol. 75, No. 12
AIDS Research Center, National Institute of
Infectious Diseases,1 Department of
Biomolecular Design, School of Pharmaceutical Sciences, Kitasato
University,2 AIDS Clinical Center,
International Medical Center of Japan,3 and
Department of Veterinary Science, National Institute of
Infectious Diseases,4 Tokyo, and Naha
Prefectural Hospital, Okinawa,5 Japan
Received 22 January 2001/Accepted 16 March 2001
A human immunodeficiency virus type 1 (HIV-1) subtype E
(CRF01_AE) variant (99JP-NH3-II) possessing an in-frame 33-nucleotide insertion mutation in the
0022-538X/01/$04.00+0 DOI: 10.1128/JVI.75.12.5604-5613.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.
Augmentation of Human Immunodeficiency Virus Type 1 Subtype E (CRF01_AE) Multiple-Drug Resistance by Insertion of a Foreign
11-Amino-Acid Fragment into the Reverse Transcriptase
3-
4 loop coding region of the reverse transcriptase (RT) gene was isolated from a patient who had not responded to nucleoside analogue RT inhibitors. This virus
exhibited an extremely high level of multiple nucleoside analog
resistance (MNR). Neighbor-joining tree analysis of the
pol sequences indicated that the 99JP-NH3-II variant had
originated from the swarm of drug-sensitive predecessors in the
patient. Population-based sequence analyses of 82 independently cloned
RT segments from the patient suggested that the variants with the
insertion, three or four 3'-azido-3'-deoxythymidine resistance
mutations, and a T69I mutation in combination had strong selective
advantages during chemotherapy. Consistently, in vitro mutagenesis of a
drug-sensitive predecessor virus clone demonstrated that this
mutation set functions cooperatively to confer a high level of MNR
without deleterious effects on viral replication capability. Homology
modeling of the parental RT and its MNR mutant showed that extension of
the
3-
4 loop by an insertion caused
reductions in the distances between the loop and the other subdomains,
narrowing the template-primer binding cleft and
deoxynucleoside triphosphate-binding pocket in a highly flexible
manner. The origin of the insert is elusive, as every effort to find a
homologue has been unsuccessful. Taken together, these data
suggest that (i) HIV-1 tolerates in vivo insertions as long as 33 nucleotides into the highly conserved enzyme gene to survive multiple
anti-HIV-1 inhibitors and (ii) the insertion mutation augments
multiple-drug resistance, possibly by reducing the biochemical
inaccuracy of substrate-enzyme interactions in the active center.
*
Corresponding author. Mailing address: Laboratory of
Molecular Virology and Epidemiology, AIDS Research Center, National
Institute of Infectious Diseases, Toyama 1-23-1, Shinjuku, Tokyo
162-8640, Japan. Phone: (81)-3-52851111. Fax: (81)-3-52851129.
E-mail: hirosato{at}nih.go.jp.
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