15th International HIV Drug Resistance Workshop 13-17 June 2006, Sitges, Spain

REPLICATIVE FITNESS OF A PANEL OF PROTOTYPICAL HIV-1 CONTAINING MULTIPLE NRTI-RESISTANCE MUTATIONS

Antivir Ther. 2006, 11:S48 (abstract no. 40)

J Weber¹, M Mirza¹, O Jegede¹, J Weberova¹, RW Shafer² and ME Quiñones-Mateu^1
1Cleveland Clinic Foundation, Cleveland, OH, USA; ²Stanford University, Stanford, CA, USA

BACKGROUND: Multiple studies have examined the relationship of HIV replicative fitness with drug resistance. However, most of them have used monoinfections (viral growth kinetics or single-cycle assays) to measure viral replication capacity in vitro, which may not be able to discern small (but perhaps clinically significant) differences in HIV replicative fitness. Here, we used a novel system based on EGFP- or DsRed2-tagged viruses to evaluate the effect of common patterns of NRTI-resistant mutations on viral fitness.

METHODS: A well-known panel of twelve prototypical molecular clones containing common patterns of NRTI resistance mutations [1] was used to generate pol-recombinant EGFP- or DsRed2-tagged viruses. These viruses were then used in viral growth kinetics and pairwise growth competition experiments in MT4 cells to estimate their relative replicative fitness.

RESULTS: As expected, since many of these viruses share several mutations in the RT, replication kinetics was not useful to discern small differences in replicative fitness that may exist among them. Thus, we performed a pairwise competition experiment using all 12 viruses expressing either EGFP or DsRed2. These “head-to-head” competitions allowed us to establish a rank of the effects of these RT mutations in HIV-1 replicative fitness. Eight NRTI-resistant viruses showed similar replicative fitness values in the absence of drug pressure. However, three viruses (RT7: 41L, 44D, 67N, 69D, 118I, 210W, 215Y; RT8: 69K, 70G, 75I, 77L, 115Y, 116Y, 151M, 184V; and RT11: 41L, 69SS, 74V, 184V, 210W, 215Y) were consistently more fit than the rest. Interestingly, a virus harbouring the Multi-NRTI resistance 151 complex was the most fit among the twelve recombinant viruses. Moreover, inclusion of lamivudine-, zidovudine- or tenofovir-associated mutations (184V, 70R, or 65R, respectively) to this group of mutations reduced the replicative fitness of this virus significantly.

CONCLUSIONS: We demonstrated that pairwise competitions are necessary to study small differences in the replicative fitness of drug-resistant viruses, which otherwise would remain undetected by using other methodology. In addition, we established relative replicative fitness values for this panel of viruses. This information will prove to be valuable since these viruses are being broadly used as references in the study of novel antiretroviral compounds.

Reference

1. Johnston E, Dupnik KM, Gonzales MJ, et al. Panel of prototypical infectious molecular HIV-1 clones containing multiple nucleoside reverse transcriptase inhibitor resistance mutations. AIDS. 2005 Apr 29;19(7):731-3.

2006-06-13
40

Copyright © 2006 - International Medical Press Ltd.. Reproduction of this abstract (other than one copy for personal reference) must be cleared through the International Medical Press Ltd. 2-4 Idol Lane, London EC3R 5DD UK.