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J Virol, August 1998, p. 6629-6636, Vol. 72, No. 8
McGill University AIDS Centre, Lady Davis
Institute-Jewish General Hospital, Montreal, Quebec, Canada H3T
1E2,1 and
Department of Microbiology and
Immunology, McGill University, Montreal, Quebec, Canada H3A
2B42
Received 9 March 1998/Accepted 18 May 1998
The dimerization initiation site (DIS), downstream of the long
terminal repeat within the human immunodeficiency virus type 1 (HIV-1)
genome, can form a stem-loop structure (SL1) that has been shown to be
involved in the packaging of viral RNA. In order to further determine
the role of this region in the virus life cycle, we deleted the 16 nucleotides (nt) at positions +238 to +253 within SL1 to generate a
construct termed BH10-LD3 and showed that this virus was impaired in
viral RNA packaging, viral gene expression, and viral replication.
Long-term culture of these mutated viruses in MT-2 cells, i.e., 18 passages, yielded revertant viruses that possessed infectivities
similar to that of the wild type. Cloning and sequencing showed that
these viruses retained the original 16-nt deletion but possessed two
additional point mutations, which were located within the p2 and NC
regions of the Gag coding region, respectively, and which were
therefore named MP2 and MNC. Site-directed mutagenesis studies revealed that both of these point mutations were necessary to compensate for the
16-nt deletion in BH10-LD3. A construct with both the 16-nt deletion
and the MP2 mutation, i.e., LD3-MP2, produced approximately five times
more viral protein than BH10-LD3, while the MNC mutation, i.e.,
construct LD3-MNC, reversed the defects in viral RNA packaging. We also
deleted nt +261 to +274 within the 3' end of SL1 and showed that the
diminished infectivity of the mutated virus, termed BH10-LD4, could
also be restored by the MP2 and MNC point mutations. Therefore, compensatory mutations within the p2 and NC proteins, distal from deletions within the DIS region of the HIV genome, can restore HIV
replication, viral gene expression, and viral RNA packaging to control
levels.
0022-538X/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
Compensatory Point Mutations in the Human Immunodeficiency Virus
Type 1 Gag Region That Are Distal from Deletion Mutations in the
Dimerization Initiation Site Can Restore Viral Replication
*
Corresponding author. Mailing address: McGill AIDS
Centre, Lady Davis Institute/Jewish General Hospital, 3755 Cote
Ste-Catherine Rd., Montreal, Quebec, Canada H3T 1E2. Phone: (514)
340-8260. Fax: (514) 340-7537. E-mail:
mdwa{at}musica.mcgill.ca.
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