title: Limited evolution of HIV antiretroviral drug resistance-associated mutations during the performance of drug resistance testing.
abstract: We investigated the evolution of HIV reverse transcriptase (RT)- and protease-associated antiretroviral (ARV) drug resistance mutations during the time taken to perform genotypic drug resistance testing. Thirty treatment-experienced patients who were adherent to therapy and who underwent genotypic drug resistance testing provided blood samples at randomization and when reviewing the test results (baseline). Patients remained on their existing therapy between randomization and baseline. The predominant HIV strains in 10 patients (33%) either lost and/or gained primary RT inhibitor (RTI)- or protease inhibitor (PI)-associated resistance mutations during the testing period. Of the 9 patients with RT mutations, 2 lost, 5 gained, and 2 both lost and gained RTI resistance mutations. One patient gained a significant PI-associated resistance mutation on an existing PI-resistant background. The evolution that occurred in the RT may have altered the effectiveness of subsequent ARV therapy in some patients. Neither viral load at randomization, ARV drug class used at randomization, time between collection of blood samples, duration of current therapy, nor number of ARV drugs used influenced gain or loss of resistance mutations. There was a significant association between duration of previous ARV therapy and gain of RTI-associated resistance mutations ( p =.02), however. In general, our results suggest that patients should continue current therapy until test results are available. A few patients would be expected to gain ARV drug-associated resistance mutations during this time, however.
authors.affiliation: Victorian Infectioud Diseases Reference Laboratory, North Melbourne, Australia. chris.birch@mh.org.au
authors.forename: Chris
authors.initials: C
authors.lastname: Birch
authors.forename: Tracey
authors.initials: T
authors.lastname: Middleton
authors.forename: Gillian
authors.initials: G
authors.lastname: Hales
authors.forename: David
authors.initials: D
authors.lastname: Cooper
authors.forename: Matthew
authors.initials: M
authors.lastname: Law
authors.forename: Suzanne
authors.initials: S
authors.lastname: Crowe
authors.forename: Jennifer
authors.initials: J
authors.lastname: Hoy
authors.forename: Sean
authors.initials: S
authors.lastname: Emery
mesh_terms: D000328:Adult; D019380:Anti-HIV Agents / Q000008:administration & dosage / Q000145:classification / Q000494:pharmacology* / Q000627:therapeutic use; D004334:Drug Administration Schedule; D024921:Drug Resistance, Multiple, Viral; D019143:Evolution, Molecular; D005260:Female; D005838:Genotype; D006678:HIV / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics*; D015658:HIV Infections / Q000188:drug therapy / Q000821:virology*; D016333:HIV Protease / Q000235:genetics; D054303:HIV Reverse Transcriptase / Q000235:genetics; D006801:Humans; D008297:Male; D008875:Middle Aged; D009154:Mutation / Q000235:genetics*; D011897:Random Allocation; D019562:Viral Load
chemical_list: D019380:Anti-HIV Agents; D054303:HIV Reverse Transcriptase; D016333:HIV Protease