Home Search Abstracts Browse Sessions Program Committee View Session E-mail Abstract Author

 

 

Session 24 Oral Abstracts
HIV Drug Resistance: Selection, Persistence, and Impact of Response
Thursday, 10 am - 12:30 pm
Presentation Time: 10:30 am
Auditorium


98
K65R and T215Y Are Not Present on the Same Viral Genome in Plasma Samples with Both Mutations Detected by Population Sequencing
Urvi Parikh*1, D Barnas1, C Bixby1, H Faruki2, and J Mellors1
1Univ of Pittsburgh, PA, USA and 2Lab Corp of America, Research Triangle Park, NC, USA

Background:  The lysine to arginine change at codon 65 in HIV-1 RT (65R) is a multi-nucleoside reverse transcriptase inhibitor- (NRTI)- resistance mutation, reducing susceptibility to all FDA-approved NRTI except zidovudine (AZT). Resistance to AZT is mediated by combinations of thymidine analog mutations (TAM), which include 41L, 67N, 70R, 210W, 215Y/F, and 219Q/E/N. Of the TAM, those at codon 215 are critical for ATP-mediated excision of AZT and other NRTI. Prior virologic and biochemical studies have shown marked phenotypic antagonism between 65R and TAM in site-directed laboratory mutants. We hypothesized, based on this antagonism, that 65R and 215Y/F would not be selected on the same viral genome. We tested this hypothesis by performing single genome sequencing of plasma samples that were found to have both 65R and TAM by standard genotying (population sequencing).

Methods:  We searched the 2003 LabCorp database for the frequency of 65R in combination with 3 or more TAM as determined by population sequencing. Samples with both 65R and 3 or more TAM were analyzed by single genome sequencing.

Results:  Only 19 of 29,505 (0.06%) specimens had both 65R and 3 or more TAM by population sequencing. We analyzed 94 single genomes derived from 7 of these specimens:  9 genomes had both 65R and any TAM; 2 genomes had 65R without TAM; 78 genomes had TAM without 65R; and 5 had neither 65R nor TAM. Of genomes with TAM, 33% (26 of 78) had T215Y and 44% (34 of 78) had T215I. Of the 9 genomes with both 65R and any TAM, 5 of 9 had 41L, 3 of 9 67N, 7 of 9 70R, 2 to 9 210W, 2 to 9 215D, and 7 to 9 219Q/E. But, 65R was never found on the same genome with 215Y/F/I.

Conclusions:  K65R and multiple TAM were rarely detected (< 0.1%) in the same plasma sample by population sequencing. In those samples having both mutations, 65R was not found on the same genome with 215Y/F/I; 65R was rarely present with other TAM. These findings confirm at the genomic level the antagonism and mutual exclusivity of the 65R and the 215Y/F/I pathways of NRTI resistance.

Keywords: K65R; TAMs; NRTI resistance