title: 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.
abstract: 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.
authors.affiliation: Laboratory of Molecular Retrovirology, Clinical Services Program, SAIC-Frederick, Frederick Cancer Research and Development Center, Frederick, Maryland 21702, USA. timamichi@nih.gov
authors.forename: T
authors.initials: T
authors.lastname: Imamichi
authors.forename: S C
authors.initials: SC
authors.lastname: Berg
authors.forename: H
authors.initials: H
authors.lastname: Imamichi
authors.forename: J C
authors.initials: JC
authors.lastname: Lopez
authors.forename: J A
authors.initials: JA
authors.lastname: Metcalf
authors.forename: J
authors.initials: J
authors.lastname: Falloon
authors.forename: H C
authors.initials: HC
authors.lastname: Lane
mesh_terms: 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*
chemical_list: D019380:Anti-HIV Agents; D003062:Codon; D018894:Reverse Transcriptase Inhibitors; D015215:Zidovudine; D054303:HIV Reverse Transcriptase