Relative replication fitness of a high-level 3'-azido-3'-deoxythymidine-resistant variant of human immunodeficiency virus type 1 possessing an amino acid deletion at codon 67 and a novel substitution (Thr-->Gly) at codon 69.
The combination of an amino acid deletion at codon 67 (delta 67) and Thr-to-Gly change at codon 69 (T69G) in the reverse transcriptase (RT) of human immunodeficiency virus type 1 (HIV-1) is associated with high-level resistance to multiple RT inhibitors. To determine the relative contributions of the delta 67 and T69G mutations on viral fitness, we performed a series of studies of HIV replication using recombinant variants. A high-level 3'-azido-3'-deoxythymidine (AZT)-resistant variant containing delta 67 plus T69G/K70R/L74I/K103N/T215F/K219Q in RT replicated as efficiently as wild-type virus (Wt). In contrast, the construct without delta 67 exhibited impaired replication (23% of growth of Wt). A competitive fitness study failed to reveal any differences in replication rates between the delta 67+T69G/K70R/L74I/K103N/T215F/+ ++K219Q mutant and Wt. Evaluation of proviral DNA sequences over a 3-year period in a patient harboring the multiresistant HIV revealed that the T69G mutation emerged in the context of a D67N/K70R/T215F/K219Q mutant backbone prior to appearance of the delta 67 deletion. To assess the impact of this stepwise accumulation of mutations on viral replication, a series of recombinant variants was constructed and analyzed for replication competence. The T69G mutation was found to confer 2',3'-dideoxyinosine resistance at the expense of fitness. Subsequently, the development of the delta 67 deletion led to a virus with improved replication and high-level AZT resistance.
Imamichi
T
T
Laboratory of Molecular Retrovirology, Clinical Services Program, SAIC-Frederick, Frederick Cancer Research and Development Center, Frederick, Maryland 21702, USA. timamichi@nih.gov
Berg
S C
SC
Imamichi
H
H
Lopez
J C
JC
Metcalf
J A
JA
Falloon
J
J
Lane
H C
HC
D019380:Anti-HIV Agents / Q000494:pharmacology*; D003062:Codon; D017353:Gene Deletion; D054303:HIV Reverse Transcriptase / Q000235:genetics*; D015497:HIV-1 / Q000187:drug effects* / Q000235:genetics; D006801:Humans; D018894:Reverse Transcriptase Inhibitors / Q000494:pharmacology*; D014779:Virus Replication; D015215:Zidovudine / Q000494:pharmacology*
D019380:Anti-HIV Agents; D003062:Codon; D018894:Reverse Transcriptase Inhibitors; D015215:Zidovudine; D054303:HIV Reverse Transcriptase