scholarly journals Suppression of Viremia and Evolution of Human Immunodeficiency Virus Type 1 Drug Resistance in a Macaque Model for Antiretroviral Therapy

2007 ◽  
Vol 81 (22) ◽  
pp. 12145-12155 ◽  
Author(s):  
Zandrea Ambrose ◽  
Sarah Palmer ◽  
Valerie F. Boltz ◽  
Mary Kearney ◽  
Kay Larsen ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Drug Resistance ◽  
Antiretroviral Therapy ◽  
Reverse Transcriptase ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Immunodeficiency Virus ◽  
The Impact ◽  
Hiv 1

ABSTRACT Antiretroviral therapy (ART) in human immunodeficiency virus type 1 (HIV-1)-infected patients does not clear the infection and can select for drug resistance over time. Not only is drug-resistant HIV-1 a concern for infected individuals on continual therapy, but it is an emerging problem in resource-limited settings where, in efforts to stem mother-to-child-transmission of HIV-1, transient nonnucleoside reverse transcriptase inhibitor (NNRTI) therapy given during labor can select for NNRTI resistance in both mother and child. Questions of HIV-1 persistence and drug resistance are highly amenable to exploration within animals models, where therapy manipulation is less constrained. We examined a pigtail macaque infection model responsive to anti-HIV-1 therapy to study the development of resistance. Pigtail macaques were infected with a pathogenic simian immunodeficiency virus encoding HIV-1 reverse transcriptase (RT-SHIV) to examine the impact of prior exposure to a NNRTI on subsequent ART comprised of a NNRTI and two nucleoside RT inhibitors. K103N resistance-conferring mutations in RT rapidly accumulated in 2/3 infected animals after NNRTI monotherapy and contributed to virologic failure during ART in 1/3 animals. By contrast, ART effectively suppressed RT-SHIV in 5/6 animals. These data indicate that suboptimal therapy facilitates HIV-1 drug resistance and suggest that this model can be used to investigate persisting viral reservoirs.

scholarly journals Exploitation of the Low Fidelity of Human Immunodeficiency Virus Type 1 (HIV-1) Reverse Transcriptase and the Nucleotide Composition Bias in the HIV-1 Genome To Alter the Drug Resistance Development of HIV

2001 ◽  
Vol 75 (13) ◽  
pp. 5772-5777 ◽  
Author(s):  
Jan Balzarini ◽  
Maria-José Camarasa ◽  
Maria-Jesus Pérez-Pérez ◽  
Ana San-Félix ◽  
Sonsoles Velázquez ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Drug Resistance ◽  
Reverse Transcriptase ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Resistance Development ◽  
Nucleotide Bias ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT The RNA genome of the lentivirus human immunodeficiency virus type 1 (HIV-1) is significantly richer in adenine nucleotides than the statistically equal distribution of the four different nucleotides that is expected. This compositional bias may be due to the guanine-to-adenine (G→A) nucleotide hypermutation of the HIV genome, which has been explained by dCTP pool imbalances during reverse transcription. The adenine nucleotide bias together with the poor fidelity of HIV-1 reverse transcriptase markedly enhances the genetic variation of HIV and may be responsible for the rapid emergence of drug-resistant HIV-1 strains. We have now attempted to counteract the normal mutational pattern of HIV-1 in response to anti-HIV-1 drugs by altering the endogenous deoxynucleoside triphosphate pool ratios with antimetabolites in virus-infected cell cultures. We showed that administration of these antimetabolic compounds resulted in an altered drug resistance pattern due to the reversal of the predominant mutational flow of HIV (G→A) to an adenine-to-guanine (A→G) nucleotide pattern in the intact HIV-1-infected lymphocyte cultures. Forcing the virus to change its inherent nucleotide bias may lead to better control of viral drug resistance development.

scholarly journals Immunogenicity of Mutations Induced by Nucleoside Reverse Transcriptase Inhibitors for Human Immunodeficiency Virus Type 1-Specific Cytotoxic T Cells

2000 ◽  
Vol 74 (19) ◽  
pp. 9306-9312 ◽  
Author(s):  
Assia Samri ◽  
Gaby Haas ◽  
Joerg Duntze ◽  
Jean-Marc Bouley ◽  
Vincent Calvez ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Reverse Transcriptase ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Mononuclear Cells ◽  
Immune Therapy ◽  
Immunodeficiency Virus ◽  
The Impact ◽  
Hiv 1

ABSTRACT The impact of drug resistance mutations induced by nucleoside reverse transcriptase (RT) inhibitors (NRTI) on cytotoxic T-lymphocyte (CTL) recognition of human immunodeficiency virus type 1 strain LAI (HIV-1LAI) RT was addressed in 35 treated or untreated patients. Two HIV-1LAI RT regions encompassing mutation M41L, L74V, M184V, and T215Y/F were recognized in 75 and 83% mutated and in 33 and 42% unmutated samples, respectively. A total of 41 new CTL epitopes overlapping these mutations were predicted. Mutations enhanced HLA-binding scores of 17 epitopes, decreased scores of 5, and had no effect in 19. Four predicted epitopes containing mutations 41, 74, and 184 were tested and recognized by CD8 cells from mutated or unmutated samples, with frequencies up to 270 gamma interferon spot-forming cells per 106 peripheral blood mononuclear cells. Therefore, RT mutations induced by NRTI can increase the immunogenicity of RT for CTL and might allow a better immune control of resistant viruses in vivo, suggesting that specific immune therapy might help prevent these mutations.

scholarly journals Resistance to Nucleoside Analog Reverse Transcriptase Inhibitors Mediated by Human Immunodeficiency Virus Type 1 p6 Protein

2001 ◽  
Vol 75 (20) ◽  
pp. 9644-9653 ◽  
Author(s):  
Solange Peters ◽  
Miguel Muñoz ◽  
Sabine Yerly ◽  
Victor Sanchez-Merino ◽  
Cecilio Lopez-Galindez ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Drug Resistance ◽  
Reverse Transcriptase ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Nucleoside Analog ◽  
Viral Protease ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT Resistance of human immunodeficiency virus type 1 (HIV-1) to antiretroviral agents results from target gene mutation within thepol gene, which encodes the viral protease, reverse transcriptase (RT), and integrase. We speculated that mutations in genes other that the drug target could lead to drug resistance. For this purpose, the p1-p6 gag -p6 pol region of HIV-1, placed immediately upstream ofpol, was analyzed. This region has the potential to alter Pol through frameshift regulation (p1), through improved packaging of viral enzymes (p6Gag), or by changes in activation of the viral protease (p6Pol). Duplication of the proline-rich p6Gag PTAP motif, necessary for late viral cycle activities, was identified in plasma virus from 47 of 222 (21.2%) patients treated with nucleoside analog RT inhibitor (NRTI) antiretroviral therapy but was identified very rarely from drug-naı̈ve individuals. Molecular clones carrying a 3-amino-acid duplication, APPAPP (transframe duplication SPTSPT in p6Pol), displayed a delay in protein maturation; however, they packaged a 34% excess of RT and exhibited a marked competitive growth advantage in the presence of NRTIs. This phenotype is reminiscent of the inoculum effect described in bacteriology, where a larger input, or a greater infectivity of an organism with a wild-type antimicrobial target, leads to escape from drug pressure and a higher MIC in vitro. Though the mechanism by which the PTAP region participates in viral maturation is not known, duplication of this proline-rich motif could improve assembly and packaging at membrane locations, resulting in the observed phenotype of increased infectivity and drug resistance.

scholarly journals Development of a New Methodology for Screening of Human Immunodeficiency Virus Type 1 Microbicides Based on Real-Time PCR Quantification

2006 ◽  
Vol 51 (2) ◽  
pp. 638-644 ◽  
Author(s):  
Renato S. Aguiar ◽  
Luciana J. Costa ◽  
Helena S. Pereira ◽  
Rodrigo M. Brindeiro ◽  
Amilcar Tanuri
Keyword(s):  
Human Immunodeficiency Virus ◽  
Reverse Transcriptase ◽  
Real Time ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Real Time Pcr ◽  
Immunodeficiency Virus ◽  
The Impact ◽  
Hiv 1

ABSTRACT Potential topical retrovirucides or vaginal microbicides against human immunodeficiency virus type 1 (HIV-1) include nonnucleoside reverse transcriptase inhibitors (NNRTIs). To be successful, such agents have to be highly active against cell-free virions. In the present study, we developed a new real-time PCR-based assay to measure the natural endogenous reverse transcription (NERT) activity directly on intact HIV-1 particles in the presence of reverse transcriptase (RT) inhibitors. We further evaluated the permeability to nevirapine (NVP) and efavirenz (EFV) and their retention within nascent viral particles. We also demonstrated the NVP and EFV inhibitory effects on NERT activity and the impact of resistance mutations measured directly by this new strategy. Furthermore, the results showed a clear correlation between NERT activity and classical infectivity assays. The 50% inhibitory concentrations (IC50s) of NVP and EFV were demonstrated to be up to 100-fold higher for cell-free than for cell-associated virions, suggesting that cell-free virions are less permeable to these drugs. Our results suggest that NVP and EFV penetrate both the envelope and the capsid of HIV-1 particles and readily inactivate cell-free virions. However, the characteristics of these NNRTIs, such as lower permeability and lower retention during washing procedures, in cell-free virions reduce their efficacies as microbicides. Here, we demonstrate the usefulness of the NERT real-time PCR as an assay for screening novel antiretroviral compounds with unique mechanisms of action.

scholarly journals Drug Resistance Mutations in the Nucleotide Binding Pocket of Human Immunodeficiency Virus Type 1 Reverse Transcriptase Differentially Affect the Phosphorolysis-Dependent Primer Unblocking Activity in the Presence of Stavudine and Zidovudine and Its Inhibition by Efavirenz

2005 ◽  
Vol 49 (1) ◽  
pp. 342-349 ◽  
Author(s):  
Emmanuele Crespan ◽  
Giada A. Locatelli ◽  
Reynel Cancio ◽  
Ulrich Hübscher ◽  
Silvio Spadari ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Drug Resistance ◽  
Reverse Transcriptase ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Nucleotide Binding ◽  
Binding Pocket ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT Human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) derivatives with D113E, Y115F, F116Y, Q151E/N, and M184V mutations were studied for their phosphorolysis-mediated resistance to the nucleoside RT inhibitors (NRTIs) zidovudine and stavudine and for their inhibition by the nonnucleoside analogs (NNRTIs) efavirenz and nevirapine. The results presented here indicate that these single amino acid substitutions within the nucleotide binding pocket of the viral RT can independently affect different enzymatic properties, such as catalytic efficiency, drug binding, and phosphorolytic activity. Moreover, small local alterations of the physicochemical properties of the microenvironment around the active site can have profound effects on some NRTIs while hardly affecting other ones. In conclusion, even though different mutations within the nucleotide binding pocket of HIV-1 RT can result in a common phenotype (i.e., drug resistance), the molecular mechanisms underlying this phenotype can be very different. Moreover, the same mutation can give rise to different phenotypes depending on the nature of the substrates and/or inhibitors.

scholarly journals Increased Multinucleoside Drug Resistance and Decreased Replicative Capacity of a Human Immunodeficiency Virus Type 1 Variant with an 8-Amino-Acid Insert in the Reverse Transcriptase

2005 ◽  
Vol 79 (6) ◽  
pp. 3536-3543 ◽  
Author(s):  
Lia van der Hoek ◽  
Nicole Back ◽  
Maarten F. Jebbink ◽  
Anthony de Ronde ◽  
Margreet Bakker ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Drug Resistance ◽  
Amino Acid ◽  
Reverse Transcriptase ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Antiretroviral Drugs ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT Resistance to antiretroviral drugs is generally conferred by specific amino acid substitutions, rather than insertions or deletions, in reverse transcriptase (RT) of human immunodeficiency virus type 1 (HIV-1). The exception to these findings is the amino acid insertions found in the β3-β4 loop of the RT enzyme in response to treatment with nucleoside reverse transcriptase inhibitors. This insert consists most commonly of two amino acids, but we describe in detail the evolution of a variant with an 8-amino-acid (aa) insert in a patient treated with zidovudine (ZDV) and 2′-3′-dideoxycytidine (ddC). The 24-nucleotide insert is a partial duplication of local sequences but also contains a sequence segment of unknown origin. Extensive sequence analysis of longitudinal patient samples indicated that the HIV-1 population prior to the start of therapy contained not the wild-type amino acid 215T in RT but a mixture with 215D and 215C. Treatment with ZDV and subsequent ZDV-ddC combination therapy resulted in the evolution of an HIV-1 variant with a typical ZDV resistance genotype (41L, 44D, 67N, 69D, 210W, 215Y), which was slowly replaced by the insert-containing variant (41L, 44D, insert at position 69, 70R, 210W, 215Y). The latter variant demonstrated increased resistance to a wide range of drugs, indicating that the 8-aa insert augments nucleoside analogue resistance. The gain in drug resistance of the insert variant came at the expense of a reduction in replication capacity when assayed in the absence of drugs. We compared these data with the resistance and replication properties of 133 insert-containing sequences of different individuals present in the ViroLogic database and found that the size and actual sequence of the insert at position 69 influence the level of resistance to nucleoside analogues.

scholarly journals Extensive Recombination among Human Immunodeficiency Virus Type 1 Quasispecies Makes an Important Contribution to Viral Diversity in Individual Patients

2006 ◽  
Vol 80 (5) ◽  
pp. 2472-2482 ◽  
Author(s):  
Charlotte Charpentier ◽  
Tamara Nora ◽  
Olivier Tenaillon ◽  
François Clavel ◽  
Allan J. Hance
Keyword(s):  
Human Immunodeficiency Virus ◽  
Antiretroviral Therapy ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Viral Diversity ◽  
Resistance Mutations ◽  
Immunodeficiency Virus ◽  
The Impact ◽  
Hiv 1

ABSTRACT Although recombination during human immunodeficiency virus type 1 (HIV-1) replication in vitro and in vivo has been documented, little information is available concerning the extent that recombination contributes to the diversity of HIV-1 quasispecies in the course of infection in individual patents. To investigate the impact of recombination on viral diversity, we developed a technique that permits the isolation of contemporaneous clonal viral populations resulting from single infectious events by plasma-derived viruses, thereby permitting the assessment of recombination throughout the viral genomes, including widely separated loci, from individual patients. A comparison of the genomic sequences of clonal viruses from six patients, including patients failing treatment with antiretroviral therapy, demonstrated strong evidence for extensive recombination. Recombination increased viral diversity through two distinct mechanisms. First, evolutionary bottlenecks appeared to be restricted to minimal segments of the genome required to obtain selective advantage, thereby preserving diversity in adjacent regions. Second, recombination between adjacent gene segments appeared to generate diversity in both pol and env genes. Thus, the shuffling of resistance mutations within the genes coding for the protease and reverse transcriptase, as well as recombination between these regions, could increase the diversity of drug resistance genotypes. These findings demonstrate that recombination in HIV-1 contributes to the diversity of viral quasispecies by restricting evolutionary bottlenecks to gene segments and by generating novel genotypes in pol and env, supporting the idea that recombination may be critical to adaptive evolution of HIV in the face of constantly moving selective pressures, whether exerted by the immune system or antiretroviral therapy.

scholarly journals Influence of Reverse Transcriptase Variants, Drugs, and Vpr on Human Immunodeficiency Virus Type 1 Mutant Frequencies

2003 ◽  
Vol 77 (3) ◽  
pp. 2071-2080 ◽  
Author(s):  
Louis M. Mansky ◽  
Erwann Le Rouzic ◽  
Serge Benichou ◽  
Lisa C. Gajary
Keyword(s):  
Human Immunodeficiency Virus ◽  
Drug Resistance ◽  
Reverse Transcriptase ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Drug Resistant ◽  
Immunodeficiency Virus ◽  
Virus Mutant ◽  
Hiv 1

ABSTRACT The evolution of drug resistance is a major complication of human immunodeficiency virus type 1 (HIV-1) chemotherapy. HIV-1 reverse transcriptase (RT) is a major target of antiretroviral therapy and ultimately the target of drug resistance mutations. Previous studies have indicated that drug-resistant HIV-1 RTs can alter HIV-1 mutant frequencies. In this study, we have tested a panel of HIV-1 RT variants for their ability to influence virus mutant frequencies. The RT variants tested included drug-resistant RT variants as well as other variants analyzed in enzyme fidelity studies with the lacZα gene as a mutation target and/or implicated as being important for enzyme fidelity by structural studies. Combinations of mutations that alone had a statistically significant influence on virus mutant frequencies resulted in different mutant frequency phenotypes. Furthermore, when virus replication occurred in the presence of drugs [e.g., 3′-azido-3′-deoxythymidine, (−)2/,3′-dideoxy-3′-thiacytidine, hydroxyurea, thymidine, or thioguanine] with selected RT variants, virus mutant frequencies increased. Similarly, Vpr variants deficient for binding to the uracil DNA glycosylase repair enzyme were observed to influence HIV-1 virus mutant frequencies when tested alone or in combination with RT variants. In summary, these observations indicate that HIV-1 mutant frequencies can significantly change by single amino acid substitutions in RT and that these effects can be altered by additional mutations in RT, by drugs, and/or by expression of Vpr variants. Such altered virus mutant frequencies could impact HIV-1 dynamics and evolution in small population sizes.

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