Amprenavir-resistant HIV-1 exhibits lopinavir cross-resistance and reduced replication capacity

Objectives To evaluate protease inhibitor (PI) cross-resistance and reductions in replication capacity conferred by amprenavir-selected mutations. Methods HIV-1IIIB variants derived from passage in increasing concentrations of amprenavir were studied, as well as 3′Gag/protease recombinants derived from them. These strains progressively accumulated mutations at codons 10, 46, 47, 50 and 84 in the protease as well as a p1/p6 cleavage site mutation at codon 449 in Gag. Their susceptibility (IC50) to various PI and their corresponding replication capacities were evaluated by a single-cycle growth assay and compared with measures using competitive cultures and p24 antigen production. Results Amprenavir susceptibility decreased with increasing numbers of protease mutations. Changes in lopinavir susceptibility paralleled changes in amprenavir susceptibility. Certain amprenavir-selected mutants conferred greater than 10-fold cross-resistance to lopinavir, including PrL10F/M46I/I50V-GagL449F (19-fold) and PrL10F/M46I/I47V/I50V-GagL449F (31-fold). Moreover, one isolate with only two mutations in the protease (L10F/84V) and GagL449F displayed a 7.7-fold increase in lopinavir IC50. Low-level cross-resistance to ritonavir and nelfinavir was also observed. The replication capacity of viruses containing either I84V or I50V was at least 90% lower than the reference virus in the single-cycle assay. The order of relative replication capacity was wild-type > L10F > L10F/I84V > L10F/M46I/I50V > L10F/M46I/I47V/I50V. Conclusion These results indicate that until more comprehensive genotype–phenotype correlations between amprenavir and lopinavir susceptibility are established, phenotypic testing may be preferable to genotyping to detect cross-resistance, and should be considered when switching patients from a failing amprenavir-containing regimen. This study also provides data on the concordance of replication capacity measurements generated using rapid single-cycle growth and competition assays.

[1]  V. Johnson,et al.  Standardized peripheral blood mononuclear cell culture assay for determination of drug susceptibilities of clinical human immunodeficiency virus type 1 isolates. The RV-43 Study Group, the AIDS Clinical Trials Group Virology Committee Resistance Working Group , 1993, Antimicrobial Agents and Chemotherapy.

[2]  D Norbeck,et al.  Characterization of human immunodeficiency virus type 1 variants with increased resistance to a C2-symmetric protease inhibitor , 1994, Journal of virology.

[3]  R. Myers,et al.  In vitro selection and characterization of human immunodeficiency virus type 1 (HIV-1) isolates with reduced sensitivity to hydroxyethylamino sulfonamide inhibitors of HIV-1 aspartyl protease , 1995, Journal of virology.

[4]  E D Blair,et al.  Cross-resistance analysis of human immunodeficiency virus type 1 variants individually selected for resistance to five different protease inhibitors , 1995, Antimicrobial agents and chemotherapy.

[5]  M. Murcko,et al.  Crystal Structure of HIV-1 Protease in Complex with Vx-478, a Potent and Orally Bioavailable Inhibitor of the Enzyme , 1995 .

[6]  B. Sadler,et al.  In vitro antiviral activity of 141W94 (VX-478) in combination with other antiretroviral agents. , 1996, Antiviral research.

[7]  David J. Livingston,et al.  Kinetic Characterization of Human Immunodeficiency Virus Type-1 Protease-resistant Variants* , 1996, The Journal of Biological Chemistry.

[8]  R. Colonno,et al.  Human immunodeficiency virus type 1 viral background plays a major role in development of resistance to protease inhibitors. , 1996, Proceedings of the National Academy of Sciences of the United States of America.

[9]  D. Lamarre,et al.  Second locus involved in human immunodeficiency virus type 1 resistance to protease inhibitors , 1996, Journal of virology.

[10]  G. Satten,et al.  Declining morbidity and mortality among patients with advanced human immunodeficiency virus infection. HIV Outpatient Study Investigators. , 1998, The New England journal of medicine.

[11]  Dale J. Kempf,et al.  In Vitro Selection and Characterization of Human Immunodeficiency Virus Type 1 Variants with Increased Resistance to ABT-378, a Novel Protease Inhibitor , 1998, Journal of Virology.

[12]  M. Markowitz,et al.  Resistance to Human Immunodeficiency Virus Type 1 Protease Inhibitors , 1998, Antimicrobial Agents and Chemotherapy.

[13]  F. Mammano,et al.  Resistance-Associated Loss of Viral Fitness in Human Immunodeficiency Virus Type 1: Phenotypic Analysis of Protease andgag Coevolution in Protease Inhibitor-Treated Patients , 1998, Journal of Virology.

[14]  P. Kissinger,et al.  Declining morbidity and mortality among patients with advanced human immunodeficiency virus infection. , 1998, The New England journal of medicine.

[15]  S. Gulnik,et al.  Protease inhibitors: resistance, cross-resistance, fitness and the choice of initial and salvage therapies. , 1999, AIDS.

[16]  J. Martinez-Picado,et al.  Replicative Fitness of Protease Inhibitor-Resistant Mutants of Human Immunodeficiency Virus Type 1 , 1999, Journal of Virology.

[17]  D. Kuritzkes,et al.  Treatment with amprenavir alone or amprenavir with zidovudine and lamivudine in adults with human immunodeficiency virus infection. AIDS Clinical Trials Group 347 Study Team. , 1999, The Journal of infectious diseases.

[18]  C. Boucher,et al.  Increased fitness of drug resistant HIV-1 protease as a result of acquisition of compensatory mutations during suboptimal therapy. , 1999, AIDS.

[19]  J. Martinez-Picado,et al.  Human Immunodeficiency Virus Type 1 Cloning Vectors for Antiretroviral Resistance Testing , 1999, Journal of Clinical Microbiology.

[20]  K. Hertogs,et al.  Virological and immunological effects of treatment interruptions in HIV-1 infected patients with treatment failure , 2000, AIDS.

[21]  Christos J. Petropoulos,et al.  A Novel Phenotypic Drug Susceptibility Assay for Human Immunodeficiency Virus Type 1 , 2000, Antimicrobial Agents and Chemotherapy.

[22]  R. Myers,et al.  HIV type 1 protease cleavage site mutations and viral fitness: implications for drug susceptibility phenotyping assays. , 2000, AIDS research and human retroviruses.

[23]  J. Martinez-Picado,et al.  Fitness of human immunodeficiency virus type 1 protease inhibitor-selected single mutants. , 2000, Virology.

[24]  B. Schmidt,et al.  Low Level of Cross-Resistance to Amprenavir (141W94) in Samples from Patients Pretreated with Other Protease Inhibitors , 2000, Antimicrobial Agents and Chemotherapy.

[25]  R Hoh,et al.  Virologic and immunologic consequences of discontinuing combination antiretroviral-drug therapy in HIV-infected patients with detectable viremia. , 2001, The New England journal of medicine.

[26]  Indinavir, nevirapine, stavudine, and lamivudine for human immunodeficiency virus-infected, amprenavir-experienced subjects: AIDS Clinical Trials Group protocol 373. , 2001, The Journal of infectious diseases.