BACKGROUND: Genotypic diversity among HIV-1 subtypes and circulating recombinant forms (CRF) may lead to distinct pathways to drug resistance. This study evaluated subtype-related differences in the development of resistance in culture to tenofovir. METHODS: Genotyping determined nucleotide diversity among subtypes. Representative subtype B, C, CRF1_AE, CRF2_AG, G, and HIV-2 isolates were selected for resistance to tenofovir, lamivudine and didanosine in cell culture. Phenotypic assays determined the effects of the K65R substitution in reverse transcriptase (RT) on drug susceptibility. RESULTS: Subtype C isolates show unique polymorphisms in RT codons 64 (AAG-->AAA), 65 (AAA-->AAG), and 66 (AAA-->AAG), absent in other subtypes. The K65R mutation (AAG-->AGG) arose with tenofovir by week 12 in four subtype C selections. In contrast, no tenofovir resistance arose in four subtype B (> 34-74 weeks), one each of CRF2_AG and G (> 30-33 weeks), and three HIV-2 (> 27-28 weeks) selections. K65R appeared after 55 and 73 weeks in two CRF1_AE selections with tenofovir. In contrast, times to the appearance of M184V with lamivudine pressure (weeks 8-14) did not vary among subtypes. Selective didanosine pressure resulted in the appearance of M184V and L74V after 38 weeks in two of four subtype C selections. The K65R transitions in subtype C and other subtypes (AGG and AGA) conferred similar 6.5-10-fold resistance to tenofovir and five to 25-fold cross-resistance to each of abacavir, lamivudine, and didanosine, while not affecting zidovudine susceptibility. CONCLUSION: Tenofovir -based regimens will need to be carefully monitored in subtype C infections for the possible selection of K65R.
BACKGROUND: Genotypic diversity among HIV-1 subtypes and circulating recombinant forms (CRF) may lead to distinct pathways to drug resistance. This study evaluated subtype-related differences in the development of resistance in culture to tenofovir. METHODS: Genotyping determined nucleotide diversity among subtypes. Representative subtype B, C, CRF1_AE, CRF2_AG, G, and HIV-2 isolates were selected for resistance to tenofovir, lamivudine and didanosine in cell culture. Phenotypic assays determined the effects of the K65R substitution in reverse transcriptase (RT) on drug susceptibility. RESULTS: Subtype C isolates show unique polymorphisms in RT codons 64 (AAG-->AAA), 65 (AAA-->AAG), and 66 (AAA-->AAG), absent in other subtypes. The K65R mutation (AAG-->AGG) arose with tenofovir by week 12 in four subtype C selections. In contrast, no tenofovir resistance arose in four subtype B (> 34-74 weeks), one each of CRF2_AG and G (> 30-33 weeks), and three HIV-2 (> 27-28 weeks) selections. K65R appeared after 55 and 73 weeks in two CRF1_AE selections with tenofovir. In contrast, times to the appearance of M184V with lamivudine pressure (weeks 8-14) did not vary among subtypes. Selective didanosine pressure resulted in the appearance of M184V and L74V after 38 weeks in two of four subtype C selections. The K65R transitions in subtype C and other subtypes (AGG and AGA) conferred similar 6.5-10-fold resistance to tenofovir and five to 25-fold cross-resistance to each of abacavir, lamivudine, and didanosine, while not affecting zidovudine susceptibility. CONCLUSION:Tenofovir -based regimens will need to be carefully monitored in subtype C infections for the possible selection of K65R.
Authors: Eugene L Asahchop; Mark A Wainberg; Richard D Sloan; Cécile L Tremblay Journal: Antimicrob Agents Chemother Date: 2012-06-25 Impact factor: 5.191
Authors: B Chaplin; G Eisen; J Idoko; D Onwujekwe; E Idigbe; I Adewole; W Gashau; S Meloni; A D Sarr; J L Sankalé; E Ekong; R L Murphy; P Kanki Journal: AIDS Res Hum Retroviruses Date: 2010-10-21 Impact factor: 2.205
Authors: Viktor von Wyl; Valentina Cambiano; Michael R Jordan; Silvia Bertagnolio; Alec Miners; Deenan Pillay; Jens Lundgren; Andrew N Phillips Journal: PLoS One Date: 2012-08-08 Impact factor: 3.240
Authors: Krista A Delviks-Frankenberry; Renan B Lengruber; Andre F Santos; Jussara M Silveira; Marcelo A Soares; Mary F Kearney; Frank Maldarelli; Vinay K Pathak Journal: Virology Date: 2012-10-13 Impact factor: 3.616