AEGiS-13IAC: Emergence of a deletion at codon 67 and a novel mutation at codon 69 (Thr69Gly) in the RT altering drug sensitivity, fitness and evolution of HIV.

13th International AIDS Conference

Durban, South Africa - July 9-July 14, 2000

Emergence of a deletion at codon 67 and a novel mutation at codon 69 (Thr69Gly) in the RT altering drug sensitivity, fitness and evolution of HIV.

Int Conf AIDS 2000 Jul 9-14; 13:(abstract no. TuOrA348)

Imamichi T, Berg S, Imamichi H, Metcalf JA, Falloon J, Lane HC
T. Imamichi, SAIC-Frederick, PO Box B, Bldg. 550, Rm. 126, NCI-FCRDC, Frederick, MD, 21702, United States, Tel.: +1 301 846 1910, Fax: +1 301 846 6762, E-mail: timamichi@nih.gov

Object: The purpose of the present study was to determine the impact of a novel deletion at codon 67 (del67) and a novel substitution at codon 69 (T69G) in replication fitness of these multiple drug resistance forms of HIV.

METHODS: Site-directed mutagenesis were utilized to construct a series of recombinant HIV variants containing defined mutations in RT. Replication competence and resistance profiles of the variants were measured in tissue culture systems. Changes in viral populations in competitive fitness assays were determined by direct DNA sequence of RT-PCR products derived from culture supernatant of sequential passage.

RESULTS: The del67 deletion by itself decreased replication competence by 26±8.6 %. However, addition of six mutations in the RT (T69G/K70R/L74I/K103N/T215F/K219Q) associated with multiple RT inhibitors resistance led to a virus replicated comparable to wild type (Wt). An early isolate obtained in vivo prior to the emergence of the D67 deletion and T69G contained a D67N substitution in association with the AZT resistance motif (K70R/T215F/K219Q). This virus replicated 38±3.5% as well as Wt. Addition of the T69G to the RT resulted in decreased replication (20±5.3 %) and an increase in ddI resistance from an IC50 of 281± 65 nM to 3370 ± 633 nM. Further addition of the D67 to this variant resulted in little change in the fitness and resistance. The addition of L74I and K103N led to a variant with replication activity comparable to Wt (103± 10 % of Wt) and high level of drug resistance to AZT (IC50 = 320000± 15300 nM) and ddI (IC50 = 1450 ± 236 nM).

CONCLUSION: The evolution of multiple drug resistance viruses initially containing the D67 and the T69G in the RT was first characterized by resistance in the setting of compromised replication and later, with the addition of mutations associated with NNRTI resistance, was characterized by replication competence and high level drug resistance.

Keywords: AEGIS, Codon, HIV Infections, Zidovudine, Virus Replication, Mutation, HIV Seropositivity, Evolution, Didanosine, Variation (Genetics), Base Sequence, Drug Resistance, Multiple, genetics, virology
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