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Maphumulo NF, Gordon ML. HIV-1 envelope facilitates the development of protease inhibitor resistance through acquiring mutations associated with viral entry and immune escape. Front Microbiol 2024; 15:1388729. [PMID: 38699474 PMCID: PMC11063367 DOI: 10.3389/fmicb.2024.1388729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2024] [Accepted: 03/27/2024] [Indexed: 05/05/2024] Open
Abstract
Introduction There is increasing evidence supporting a role for HIV-1 envelope in the development of Protease Inhibitor drug resistance, and a recent report from our group suggested that Env mutations co-evolve with Gag-Protease mutations in the pathway to Lopinavir resistance. In this study, we investigated the effect of co-evolving Env mutations on virus function and structure. Methods Co-receptor usage and n-linked glycosylation were investigated using Geno2Pheno as well as tools available at the Los Alamos sequence database. Molecular dynamics simulations were performed using Amber 18 and analyzed using Cpptraj, and molecular interactions were calculated using the Ring server. Results The results showed that under Protease Inhibitor drug selection pressure, the envelope gene modulates viral entry by protecting the virus from antibody recognition through the increased length and number of N-glycosylation sites observed in V1/V2 and to some extent V5. Furthermore, gp120 mutations appear to modulate viral entry through a switch to the CXCR4 coreceptor, induced by higher charge in the V3 region and specific mutations at the coreceptor binding sites. In gp41, S534A formed a hydrogen bond with L602 found in the disulfide loop region between the Heptad Repeat 1 and Heptad Repeat 2 domains and could negatively affect the association of gp120-gp41 during viral entry. Lastly, P724Q/S formed both intermolecular and intramolecular interactions with residues within the Kennedy loop, a known epitope. Discussion In conclusion, the results suggest that mutations in envelope during Protease Inhibitor treatment failure are related to immune escape and that S534A mutants could preferentially use the cell-to-cell route of infection.
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Affiliation(s)
| | - Michele L. Gordon
- Department of Virology, Doris Duke Medical Research Institute, College of Health Sciences, University of KwaZulu-Natala, Durban, South Africa
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2
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Kemp SA, Charles OJ, Derache A, Smidt W, Martin DP, Iwuji C, Adamson J, Govender K, de Oliveira T, Dabis F, Pillay D, Goldstein RA, Gupta RK. HIV-1 Evolutionary Dynamics under Nonsuppressive Antiretroviral Therapy. mBio 2022; 13:e0026922. [PMID: 35446121 PMCID: PMC9239331 DOI: 10.1128/mbio.00269-22] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Accepted: 03/28/2022] [Indexed: 12/19/2022] Open
Abstract
Prolonged virologic failure on 2nd-line protease inhibitor (PI)-based antiretroviral therapy (ART) without emergence of major protease mutations is well recognized and provides an opportunity to study within-host evolution in long-term viremic individuals. Using next-generation sequencing and in silico haplotype reconstruction, we analyzed whole-genome sequences from longitudinal plasma samples of eight chronically infected HIV-1-positive individuals failing 2nd-line regimens from the French National Agency for AIDS and Viral Hepatitis Research (ANRS) 12249 Treatment as Prevention (TasP) trial. On nonsuppressive ART, there were large fluctuations in synonymous and nonsynonymous variant frequencies despite stable viremia. Reconstructed haplotypes provided evidence for selective sweeps during periods of partial adherence, and viral haplotype competition, during periods of low drug exposure. Drug resistance mutations in reverse transcriptase (RT) were used as markers of viral haplotypes in the reservoir, and their distribution over time indicated recombination. We independently observed linkage disequilibrium decay, indicative of recombination. These data highlight dramatic changes in virus population structure that occur during stable viremia under nonsuppressive ART. IMPORTANCE HIV-1 infections are most commonly initiated with a single founder virus and are characterized by extensive inter- and intraparticipant genetic diversity. However, existing literature on HIV-1 intrahost population dynamics is largely limited to untreated infections, predominantly in subtype B-infected individuals. The manuscript characterizes viral population dynamics in long-term viremic treatment-experienced individuals, which has not been previously characterized. These data are particularly relevant for understanding HIV dynamics but can also be applied to other RNA viruses. With this unique data set we propose that the virus is highly unstable, and we have found compelling evidence of HIV-1 within-host viral diversification, recombination, and haplotype competition during nonsuppressive ART.
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Affiliation(s)
- Steven A. Kemp
- Cambridge Institute of Therapeutic Immunology & Infectious Disease (CITIID), University of Cambridge, Cambridge, United Kingdom
| | - Oscar J. Charles
- Division of Infection & Immunity, University College London, London, United Kingdom
| | - Anne Derache
- Africa Health Research Institute, Durban, South Africa
| | - Werner Smidt
- Africa Health Research Institute, Durban, South Africa
| | - Darren P. Martin
- Department of Integrative Biomedical Sciences, University of Cape Town, Cape Town, South Africa
| | - Collins Iwuji
- Africa Health Research Institute, Durban, South Africa
- Research Department of Infection and Population Health, University College London, United Kingdom
| | - John Adamson
- Africa Health Research Institute, Durban, South Africa
| | | | - Tulio de Oliveira
- Africa Health Research Institute, Durban, South Africa
- KRISP - KwaZulu-Natal Research and Innovation Sequencing Platform, UKZN, Durban, South Africa
| | - Francois Dabis
- INSERM U1219-Centre Inserm Bordeaux Population Health, Université de Bordeaux, France
- Université de Bordeaux, ISPED, Centre INSERM U1219-Bordeaux Population Health, France
| | - Deenan Pillay
- Division of Infection & Immunity, University College London, London, United Kingdom
| | - Richard A. Goldstein
- Division of Infection & Immunity, University College London, London, United Kingdom
| | - Ravindra K. Gupta
- Cambridge Institute of Therapeutic Immunology & Infectious Disease (CITIID), University of Cambridge, Cambridge, United Kingdom
- Africa Health Research Institute, Durban, South Africa
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3
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Potential Associations of Mutations within the HIV-1 Env and Gag Genes Conferring Protease Inhibitor (PI) Drug Resistance. MICROBIOLOGY RESEARCH 2021. [DOI: 10.3390/microbiolres12040071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
An increasing number of patients in Africa are experiencing virological failure on a second-line antiretroviral protease inhibitor (PI)-containing regimen, even without resistance-associated mutations in the protease region, suggesting a potential role of other genes in PI resistance. Here, we investigated the prevalence of mutations associated with Lopinavir/Ritonavir (LPV/r) failure in the Envelope gene and the possible coevolution with mutations within the Gag-protease (gag-PR) region. Env and Gag-PR sequences generated from 24 HIV-1 subtype C infected patients failing an LPV/r inclusive treatment regimen and 344 subtype C drug-naïve isolates downloaded from the Los Alamos Database were analyzed. Fisher’s exact test was used to determine the differences in mutation frequency. Bayesian network probability was applied to determine the relationship between mutations occurring within the env and gag-PR regions and LPV/r treatment. Thirty-five mutations in the env region had significantly higher frequencies in LPV/r-treated patients. A combination of Env and Gag-PR mutations was associated with a potential pathway to LPV/r resistance. While Env mutations were not directly associated with LPV/r resistance, they may exert pressure through the Gag and minor PR mutation pathways. Further investigations using site-directed mutagenesis are needed to determine the impact of Env mutations alone and in combination with Gag-PR mutations on viral fitness and LPV/r efficacy.
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4
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Nguyen H, Thorball CW, Fellay J, Böni J, Yerly S, Perreau M, Hirsch HH, Kusejko K, Thurnheer MC, Battegay M, Cavassini M, Kahlert CR, Bernasconi E, Günthard HF, Kouyos RD. Systematic screening of viral and human genetic variation identifies antiretroviral resistance and immune escape link. eLife 2021; 10:67388. [PMID: 34061023 PMCID: PMC8169104 DOI: 10.7554/elife.67388] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Accepted: 05/18/2021] [Indexed: 11/26/2022] Open
Abstract
Background: Considering the remaining threat of drug-resistantmutations (DRMs) to antiretroviral treatment (ART) efficacy, we investigated how the selective pressure of human leukocyte antigen (HLA)-restricted cytotoxic T lymphocytes drives certain DRMs’ emergence and retention. Methods: We systematically screened DRM:HLA class I allele combinations in 3997 ART-naïve Swiss HIV Cohort Study (SHCS) patients. For each pair, a logistic regression model preliminarily tested for an association with the DRM as the outcome. The three HLA:DRM pairs remaining after multiple testing adjustment were analyzed in three ways: cross-sectional logistic regression models to determine any HLA/infection time interaction, survival analyses to examine if HLA type correlated with developing specific DRMs, and via NetMHCpan to find epitope binding evidence of immune escape. Results: Only one pair, RT-E138:HLA-B18, exhibited a significant interaction between infection duration and HLA. The survival analyses predicted two pairs with an increased hazard of developing DRMs: RT-E138:HLA-B18 and RT-V179:HLA-B35. RT-E138:HLA-B18 exhibited the greatest significance in both analyses (interaction term odds ratio [OR] 1.169 [95% confidence interval (CI) 1.075–1.273]; p-value<0.001; survival hazard ratio 12.211 [95% CI 3.523–42.318]; p-value<0.001). The same two pairs were also predicted by netMHCpan to have epitopic binding. Conclusions: We identified DRM:HLA pairs where HLA presence is associated with the presence or emergence of the DRM, indicating that the selective pressure for these mutations alternates direction depending on the presence of these HLA alleles. Funding: Funded by the Swiss National Science Foundation within the framework of the SHCS, and the University of Zurich, University Research Priority Program: Evolution in Action: From Genomes Ecosystems, in Switzerland.
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Affiliation(s)
- Huyen Nguyen
- Division of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland.,Institute of Medical Virology, Swiss National Center for Retroviruses, University of Zurich, Zurich, Switzerland
| | - Christian Wandell Thorball
- School of Life Sciences, École Polytechnique, Fédérale de Lausanne, Switzerland.,Precision Medicine Unit, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
| | - Jacques Fellay
- School of Life Sciences, École Polytechnique, Fédérale de Lausanne, Switzerland.,Precision Medicine Unit, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
| | - Jürg Böni
- Institute of Medical Virology, Swiss National Center for Retroviruses, University of Zurich, Zurich, Switzerland
| | - Sabine Yerly
- Laboratory of Virology, Geneva University Hospital, University of Geneva, Geneva, Switzerland
| | - Matthieu Perreau
- Division of Immunology and Allergy, University Hospital Lausanne, University of Lausanne, Lausanne, Switzerland
| | - Hans H Hirsch
- Transplantation & Clinical Virology, Department of Biomedicine, University of Basel, Basel, Switzerland.,Infectious Diseases and Hospital Epidemiology, Department of Medicine, University Hospital Basel, Basel, Switzerland.,Clinical Virology, Laboratory Medicine, University Hospital Basel, Basel, Switzerland
| | - Katharina Kusejko
- Division of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland.,Institute of Medical Virology, Swiss National Center for Retroviruses, University of Zurich, Zurich, Switzerland
| | - Maria Christine Thurnheer
- University Clinic of Infectious Diseases, University Hospital of Bern, University of Bern, Bern, Switzerland
| | - Manuel Battegay
- Infectious Diseases and Hospital Epidemiology, Department of Medicine, University Hospital Basel, Basel, Switzerland
| | - Matthias Cavassini
- Department of Infectious Diseases, Centre Hospitalier Universitaire Vaudois, University of Lausanne, Lausanne, Switzerland
| | - Christian R Kahlert
- Division of Infectious Diseases and Hospital Epidemiology, Kantonsspital St. Gallen, St. Gallen, Switzerland
| | - Enos Bernasconi
- Division of Infectious Diseases, Regional Hospital, Lugano, Switzerland
| | - Huldrych F Günthard
- Division of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland.,Institute of Medical Virology, Swiss National Center for Retroviruses, University of Zurich, Zurich, Switzerland
| | - Roger D Kouyos
- Division of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland.,Institute of Medical Virology, Swiss National Center for Retroviruses, University of Zurich, Zurich, Switzerland
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5
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Su CTT, Koh DWS, Gan SKE. Reviewing HIV-1 Gag Mutations in Protease Inhibitors Resistance: Insights for Possible Novel Gag Inhibitor Designs. Molecules 2019; 24:molecules24183243. [PMID: 31489889 PMCID: PMC6767625 DOI: 10.3390/molecules24183243] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Revised: 09/03/2019] [Accepted: 09/04/2019] [Indexed: 12/31/2022] Open
Abstract
HIV protease inhibitors against the viral protease are often hampered by drug resistance mutations in protease and in the viral substrate Gag. To overcome this drug resistance and inhibit viral maturation, targeting Gag alongside protease rather than targeting protease alone may be more efficient. In order to successfully inhibit Gag, understanding of its drug resistance mutations and the elicited structural changes on protease binding needs to be investigated. While mutations on Gag have already been mapped to protease inhibitor resistance, there remain many mutations, particularly the non-cleavage mutations, that are not characterized. Through structural studies to unravel how Gag mutations contributes to protease drug resistance synergistically, it is thus possible to glean insights to design novel Gag inhibitors. In this review, we discuss the structural role of both novel and previously reported Gag mutations in PI resistance, and how new Gag inhibitors can be designed.
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Affiliation(s)
- Chinh Tran-To Su
- Antibody & Product Development Lab, Bioinformatics Institute, A*STAR, Singapore 138671, Singapore
| | - Darius Wen-Shuo Koh
- Antibody & Product Development Lab, Bioinformatics Institute, A*STAR, Singapore 138671, Singapore
| | - Samuel Ken-En Gan
- Antibody & Product Development Lab, Bioinformatics Institute, A*STAR, Singapore 138671, Singapore.
- p53 Laboratory, A*STAR, Singapore 138648, Singapore.
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Novel Protease Inhibitors Containing C-5-Modified bis-Tetrahydrofuranylurethane and Aminobenzothiazole as P2 and P2' Ligands That Exert Potent Antiviral Activity against Highly Multidrug-Resistant HIV-1 with a High Genetic Barrier against the Emergence of Drug Resistance. Antimicrob Agents Chemother 2019; 63:AAC.00372-19. [PMID: 31085520 DOI: 10.1128/aac.00372-19] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Accepted: 04/25/2019] [Indexed: 02/08/2023] Open
Abstract
Combination antiretroviral therapy has achieved dramatic reductions in the mortality and morbidity in people with HIV-1 infection. Darunavir (DRV) represents a most efficacious and well-tolerated protease inhibitor (PI) with a high genetic barrier to the emergence of drug-resistant HIV-1. However, highly DRV-resistant variants have been reported in patients receiving long-term DRV-containing regimens. Here, we report three novel HIV-1 PIs (GRL-057-14, GRL-058-14, and GRL-059-14), all of which contain a P2-amino-substituted-bis-tetrahydrofuranylurethane (bis-THF) and a P2'-cyclopropyl-amino-benzothiazole (Cp-Abt). These PIs not only potently inhibit the replication of wild-type HIV-1 (50% effective concentration [EC50], 0.22 nM to 10.4 nM) but also inhibit multi-PI-resistant HIV-1 variants, including highly DRV-resistant HIVDRV R P51 (EC50, 1.6 nM to 30.7 nM). The emergence of HIV-1 variants resistant to the three compounds was much delayed in selection experiments compared to resistance to DRV, using a mixture of 11 highly multi-PI-resistant HIV-1 isolates as a starting HIV-1 population. GRL-057-14 showed the most potent anti-HIV-1 activity and greatest thermal stability with wild-type protease, and potently inhibited HIV-1 protease's proteolytic activity (Ki value, 0.10 nM) among the three PIs. Structural models indicate that the C-5-isopropylamino-bis-THF moiety of GRL-057-14 forms additional polar interactions with the active site of HIV-1 protease. Moreover, GRL-057-14's P1-bis-fluoro-methylbenzene forms strong hydrogen bonding and effective van der Waals interactions. The present data suggest that the combination of C-5-aminoalkyl-bis-THF, P1-bis-fluoro-methylbenzene, and P2'-Cp-Abt confers highly potent activity against wild-type and multi-PI-resistant HIV strains and warrant further development of the three PIs, in particular, that of GRL-057-14, as potential therapeutic for HIV-1 infection and AIDS.
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7
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The N-Terminus of the HIV-1 p6 Gag Protein Regulates Susceptibility to Degradation by IDE. Viruses 2018; 10:v10120710. [PMID: 30545091 PMCID: PMC6316412 DOI: 10.3390/v10120710] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Revised: 12/07/2018] [Accepted: 12/09/2018] [Indexed: 12/14/2022] Open
Abstract
As part of the Pr55Gag polyprotein, p6 fulfills an essential role in the late steps of the replication cycle. However, almost nothing is known about the functions of the mature HIV-1 p6 protein. Recently, we showed that p6 is a bona fide substrate of the insulin-degrading enzyme (IDE), a ubiquitously expressed zinc metalloprotease. This phenomenon appears to be specific for HIV-1, since p6 homologs of HIV-2, SIV and EIAV were IDE-insensitive. Furthermore, abrogation of the IDE-mediated degradation of p6 reduces the replication capacity of HIV-1 in an Env-dependent manner. However, it remained unclear to which extent the IDE mediated degradation is phylogenetically conserved among HIV-1. Here, we describe two HIV-1 isolates with IDE resistant p6 proteins. Sequence comparison allowed deducing one single amino acid regulating IDE sensitivity of p6. Exchanging the N-terminal leucine residue of p6 derived from the IDE sensitive isolate HIV-1NL4-3 with proline enhances its stability, while replacing Pro-1 of p6 from the IDE insensitive isolate SG3 with leucine restores susceptibility towards IDE. Phylogenetic analyses of this natural polymorphism revealed that the N-terminal leucine is characteristic for p6 derived from HIV-1 group M except for subtype A, which predominantly expresses p6 with an N-terminal proline. Consequently, p6 peptides derived from subtype A are not degraded by IDE. Thus, IDE mediated degradation of p6 is specific for HIV-1 group M isolates and not occasionally distributed among HIV-1.
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8
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Coetzer M, Ledingham L, Diero L, Kemboi E, Orido M, Kantor R. Gp41 and Gag amino acids linked to HIV-1 protease inhibitor-based second-line failure in HIV-1 subtype A from Western Kenya. J Int AIDS Soc 2018; 20. [PMID: 29098809 PMCID: PMC5810327 DOI: 10.1002/jia2.25024] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Accepted: 10/05/2017] [Indexed: 12/28/2022] Open
Abstract
Introduction Failure of protease‐inhibitor (PI)‐based second‐line antiretroviral therapy (ART) with medication adherence but no protease drug resistance mutations (DRMs) is not well understood. This study investigated the involvement of gp41 and gag as alternative mechanisms, not captured by conventional resistance testing and particularly relevant in resource‐limited settings where third‐line ART is limited. Methods We evaluated gp41 and gag for unique amino acids in seven subtype A infected Kenyans failing second‐line therapy with no PI resistance yet detectable lopinavir (query dataset), compared to seven similar‐setting patients with PI resistance or undetectable lopinavir and 69 publically available subtype A Kenyan whole‐genomes sequences. Results Three gp41 (607T, 641L, 721I) and four gag (124S, 143V, 339P, 357S) amino acids were significantly more frequent in the query dataset compared to the other datasets, with significantly high co‐occurrence. Conclusion The genotypic analysis of a unique group of HIV‐1 subtype A infected patients, identified seven amino acids that could potentially contribute to a multi‐gene mechanism of PI‐based ART failure in the absence of PI DR mutations.
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Affiliation(s)
- Mia Coetzer
- Division of Infectious Diseases, Brown University, Providence, RI, USA
| | - Lauren Ledingham
- Division of Infectious Diseases, Brown University, Providence, RI, USA
| | - Lameck Diero
- Academic Model Providing Access to Healthcare (AMPATH), Eldoret, Kenya.,Department of Medicine, School of Medicine, College of Health Sciences, Moi University, Eldoret, Kenya
| | - Emmanuel Kemboi
- Academic Model Providing Access to Healthcare (AMPATH), Eldoret, Kenya
| | - Millicent Orido
- Academic Model Providing Access to Healthcare (AMPATH), Eldoret, Kenya
| | - Rami Kantor
- Division of Infectious Diseases, Brown University, Providence, RI, USA
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Manasa J, Varghese V, Pond SLK, Rhee SY, Tzou PL, Fessel WJ, Jang KS, White E, Rögnvaldsson T, Katzenstein DA, Shafer RW. Evolution of gag and gp41 in Patients Receiving Ritonavir-Boosted Protease Inhibitors. Sci Rep 2017; 7:11559. [PMID: 28912582 PMCID: PMC5599673 DOI: 10.1038/s41598-017-11893-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Accepted: 08/31/2017] [Indexed: 11/15/2022] Open
Abstract
Several groups have proposed that genotypic determinants in gag and the gp41 cytoplasmic domain (gp41-CD) reduce protease inhibitor (PI) susceptibility without PI-resistance mutations in protease. However, no gag and gp41-CD mutations definitively responsible for reduced PI susceptibility have been identified in individuals with virological failure (VF) while receiving a boosted PI (PI/r)-containing regimen. To identify gag and gp41 mutations under selective PI pressure, we sequenced gag and/or gp41 in 61 individuals with VF on a PI/r (n = 40) or NNRTI (n = 20) containing regimen. We quantified nonsynonymous and synonymous changes in both genes and identified sites exhibiting signal for directional or diversifying selection. We also used published gag and gp41 polymorphism data to highlight mutations displaying a high selection index, defined as changing from a conserved to an uncommon amino acid. Many amino acid mutations developed in gag and in gp41-CD in both the PI- and NNRTI-treated groups. However, in neither gene, were there discernable differences between the two groups in overall numbers of mutations, mutations displaying evidence of diversifying or directional selection, or mutations with a high selection index. If gag and/or gp41 encode PI-resistance mutations, they may not be confined to consistent mutations at a few sites.
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Affiliation(s)
- Justen Manasa
- Division of Infectious Diseases, Department of Medicine Stanford University, Stanford, CA, USA
| | - Vici Varghese
- Division of Infectious Diseases, Department of Medicine Stanford University, Stanford, CA, USA
| | | | - Soo-Yon Rhee
- Division of Infectious Diseases, Department of Medicine Stanford University, Stanford, CA, USA
| | - Philip L Tzou
- Division of Infectious Diseases, Department of Medicine Stanford University, Stanford, CA, USA
| | - W Jeffrey Fessel
- Department of Internal Medicine, Kaiser Permanente Medical Care Program - Northern California, San Francisco, CA, United States
| | - Karen S Jang
- Division of Infectious Diseases, Department of Medicine Stanford University, Stanford, CA, USA
| | - Elizabeth White
- Division of Infectious Diseases, Department of Medicine Stanford University, Stanford, CA, USA
| | | | - David A Katzenstein
- Division of Infectious Diseases, Department of Medicine Stanford University, Stanford, CA, USA
| | - Robert W Shafer
- Division of Infectious Diseases, Department of Medicine Stanford University, Stanford, CA, USA.
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