1
|
Van Rompay KKA, Trott KA, Jayashankar K, Geng Y, LaBranche CC, Johnson JA, Landucci G, Lipscomb J, Tarara RP, Canfield DR, Heneine W, Forthal DN, Montefiori D, Abel K. Prolonged tenofovir treatment of macaques infected with K65R reverse transcriptase mutants of SIV results in the development of antiviral immune responses that control virus replication after drug withdrawal. Retrovirology 2012; 9:57. [PMID: 22805180 PMCID: PMC3419085 DOI: 10.1186/1742-4690-9-57] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2012] [Accepted: 07/17/2012] [Indexed: 02/01/2023] Open
Abstract
BACKGROUND We reported previously that while prolonged tenofovir monotherapy of macaques infected with virulent simian immunodeficiency virus (SIV) resulted invariably in the emergence of viral mutants with reduced in vitro drug susceptibility and a K65R mutation in reverse transcriptase, some animals controlled virus replication for years. Transient CD8+ cell depletion or short-term tenofovir interruption within 1 to 5 years of treatment demonstrated that a combination of CD8+ cell-mediated immune responses and continued tenofovir therapy was required for sustained suppression of viremia. We report here follow-up data on 5 such animals that received tenofovir for 8 to 14 years. RESULTS Although one animal had a gradual increase in viremia from 3 years onwards, the other 4 tenofovir-treated animals maintained undetectable viremia with occasional viral blips (≤ 300 RNA copies/ml plasma). When tenofovir was withdrawn after 8 to 10 years from three animals with undetectable viremia, the pattern of occasional episodes of low viremia (≤ 3600 RNA/ml plasma) continued throughout the 10-month follow-up period. These animals had low virus levels in lymphoid tissues, and evidence of multiple SIV-specific immune responses. CONCLUSION Under certain conditions (i.e., prolonged antiviral therapy initiated early after infection; viral mutants with reduced drug susceptibility) a virus-host balance characterized by strong immunologic control of virus replication can be achieved. Although further research is needed to translate these findings into clinical applications, these observations provide hope for a functional cure of HIV infection via immunotherapeutic strategies that boost antiviral immunity and reduce the need for continuous antiretroviral therapy.
Collapse
Affiliation(s)
- Koen K A Van Rompay
- California National Primate Research Center, University of California, Davis, CA, 95616, USA
| | - Kristin A Trott
- California National Primate Research Center, University of California, Davis, CA, 95616, USA
| | - Kartika Jayashankar
- California National Primate Research Center, University of California, Davis, CA, 95616, USA
| | - Yongzhi Geng
- California National Primate Research Center, University of California, Davis, CA, 95616, USA
| | | | - Jeffrey A Johnson
- Division of HIV/AIDS Prevention, National Center for HIV, STD and Tuberculosis Prevention, Centers for Disease control and Prevention, Atlanta, GE, 30333, USA
| | - Gary Landucci
- Division of Infectious Diseases, Department of Medicine, University of California, Irvine School of Medicine, Irvine, CA, 92697, USA
| | - Jonathan Lipscomb
- Division of HIV/AIDS Prevention, National Center for HIV, STD and Tuberculosis Prevention, Centers for Disease control and Prevention, Atlanta, GE, 30333, USA
| | - Ross P Tarara
- California National Primate Research Center, University of California, Davis, CA, 95616, USA
| | - Don R Canfield
- California National Primate Research Center, University of California, Davis, CA, 95616, USA
| | - Walid Heneine
- Division of HIV/AIDS Prevention, National Center for HIV, STD and Tuberculosis Prevention, Centers for Disease control and Prevention, Atlanta, GE, 30333, USA
| | - Donald N Forthal
- Division of Infectious Diseases, Department of Medicine, University of California, Irvine School of Medicine, Irvine, CA, 92697, USA
| | | | - Kristina Abel
- Department of Microbiology and Immunology, School of Medicine, University of North Carolina, Chapel Hill, NC, 27599, USA
| |
Collapse
|
2
|
Van Rompay KK. The use of nonhuman primate models of HIV infection for the evaluation of antiviral strategies. AIDS Res Hum Retroviruses 2012; 28:16-35. [PMID: 21902451 DOI: 10.1089/aid.2011.0234] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Several nonhuman primate models are used in HIV/AIDS research. In contrast to natural host models, infection of macaques with virulent simian immunodeficiency virus (SIV) isolates results in a disease (simian AIDS) that closely resembles HIV infection and AIDS. Although there is no perfect animal model, and each of the available models has its limitations, a carefully designed study allows experimental approaches that are not feasible in humans, but that can provide better insights in disease pathogenesis and proof-of-concept of novel intervention strategies. In the early years of the HIV pandemic, nonhuman primate models played a minor role in the development of antiviral strategies. Since then, a better understanding of the disease and the development of better compounds and assays to monitor antiviral effects have increased the usefulness and relevance of these animal models in the preclinical development of HIV vaccines, microbicides, and antiretroviral drugs. Several strategies that were first discovered to have efficacy in nonhuman primate models are now increasingly used in humans. Recent trends include the use of nonhuman primate models to explore strategies that could reduce viral reservoirs and, ultimately, attempt to cure infection. Ongoing comparison of results obtained in nonhuman primate models with those observed in human studies will lead to further validation and improvement of these animal models so they can continue to advance our scientific knowledge and guide clinical trials.
Collapse
Affiliation(s)
- Koen K.A. Van Rompay
- California National Primate Research Center, University of California, Davis, California
| |
Collapse
|
3
|
Gay CL, Cohen MS. Antiretrovirals to prevent HIV infection: pre- and postexposure prophylaxis. Curr Infect Dis Rep 2010; 10:323-31. [PMID: 18765106 DOI: 10.1007/s11908-008-0052-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
More than 3 million people are now receiving antiretroviral therapy (ART) worldwide. Currently, the indications for ART depend primarily on CD4 count, blood viral burden, and clinical signs and symptoms suggesting advanced HIV disease. However, interest is increasing in ART's preventive potential. Postexposure prophylaxis following both occupational and nonoccupational exposure to HIV is the standard-of-care in many settings. Observational and ecologic studies suggest that ART administered to HIV-infected people reduces transmission within serodiscordant couples. Pre-exposure prophylaxis to prevent HIV infection is a potentially safe and intermittent intervention for very high-risk people, and clinical trials to evaluate this preventive strategy are underway. The prevention benefits of ART may begin to affect the decision of when to start therapy and add a much-needed strategy to current HIV prevention efforts.
Collapse
Affiliation(s)
- Cynthia L Gay
- Division of Infectious Disease, University of North Carolina at Chapel Hill, 130 Mason Farm Road, CB #7030, Chapel Hill, NC 27599, USA.
| | | |
Collapse
|
4
|
Van Rompay KKA. Evaluation of antiretrovirals in animal models of HIV infection. Antiviral Res 2009; 85:159-75. [PMID: 19622373 DOI: 10.1016/j.antiviral.2009.07.008] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2009] [Revised: 07/07/2009] [Accepted: 07/13/2009] [Indexed: 01/07/2023]
Abstract
Animal models of HIV infection have played an important role in the development of antiretroviral drugs. Although each animal model has its limitations and never completely mimics HIV infection of humans, a carefully designed study allows experimental approaches that are not feasible in humans, but that can help to better understand disease pathogenesis and to provide proof-of-concept of novel intervention strategies. While rodent and feline models are useful for initial screening, further testing is best done in non-human primate models, such as simian immunodeficiency virus (SIV) infection of macaques, because they share more similarities with HIV infection of humans. In the early years of the HIV pandemic, non-human primate models played a relatively minor role in the antiretroviral drug development process. Since then, a better understanding of the disease and the development of better drugs and assays to monitor antiviral efficacy have increased the usefulness of the animal models. In particular, non-human primate models have provided proof-of-concept for (i) the benefits of chemoprophylaxis and early treatment, (ii) the preclinical efficacy of novel drugs such as tenofovir, (iii) the virulence and clinical significance of drug-resistant viral mutants, and (iv) the role of antiviral immune responses during drug therapy. Ongoing comparison of results obtained in animal models with those observed in human studies will further validate and improve these animal models so they can continue to help advance our scientific knowledge and to guide clinical trials. This article forms part of a special issue of Antiviral Research marking the 25th anniversary of antiretroviral drug discovery and development, Vol 85, issue 1, 2010.
Collapse
Affiliation(s)
- Koen K A Van Rompay
- California National Primate Research Center, University of California, Davis, CA 95616, USA.
| |
Collapse
|
5
|
García-Lerma JG, Otten RA, Qari SH, Jackson E, Cong ME, Masciotra S, Luo W, Kim C, Adams DR, Monsour M, Lipscomb J, Johnson JA, Delinsky D, Schinazi RF, Janssen R, Folks TM, Heneine W. Prevention of rectal SHIV transmission in macaques by daily or intermittent prophylaxis with emtricitabine and tenofovir. PLoS Med 2008; 5:e28. [PMID: 18254653 PMCID: PMC2225435 DOI: 10.1371/journal.pmed.0050028] [Citation(s) in RCA: 272] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/06/2007] [Accepted: 12/18/2007] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND In the absence of an effective vaccine, HIV continues to spread globally, emphasizing the need for novel strategies to limit its transmission. Pre-exposure prophylaxis (PrEP) with antiretroviral drugs could prove to be an effective intervention strategy if highly efficacious and cost-effective PrEP modalities are identified. We evaluated daily and intermittent PrEP regimens of increasing antiviral activity in a macaque model that closely resembles human transmission. METHODS AND FINDINGS We used a repeat-exposure macaque model with 14 weekly rectal virus challenges. Three drug treatments were given once daily, each to a different group of six rhesus macaques. Group 1 was treated subcutaneously with a human-equivalent dose of emtricitabine (FTC), group 2 received orally the human-equivalent dosing of both FTC and tenofovir-disoproxil fumarate (TDF), and group 3 received subcutaneously a similar dosing of FTC and a higher dose of tenofovir. A fourth group of six rhesus macaques (group 4) received intermittently a PrEP regimen similar to group 3 only 2 h before and 24 h after each weekly virus challenge. Results were compared to 18 control macaques that did not receive any drug treatment. The risk of infection in macaques treated in groups 1 and 2 was 3.8- and 7.8-fold lower than in untreated macaques (p = 0.02 and p = 0.008, respectively). All six macaques in group 3 were protected. Breakthrough infections had blunted acute viremias; drug resistance was seen in two of six animals. All six animals in group 4 that received intermittent PrEP were protected. CONCLUSIONS This model suggests that single drugs for daily PrEP can be protective but a combination of antiretroviral drugs may be required to increase the level of protection. Short but potent intermittent PrEP can provide protection comparable to that of daily PrEP in this SHIV/macaque model. These findings support PrEP trials for HIV prevention in humans and identify promising PrEP modalities.
Collapse
Affiliation(s)
- J. Gerardo García-Lerma
- Division of HIV/AIDS Prevention, National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Ron A Otten
- Division of HIV/AIDS Prevention, National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Shoukat H Qari
- Division of HIV/AIDS Prevention, National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Eddie Jackson
- Division of Scientific Resources, National Center for Preparedness, Detection, and Control of Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Mian-er Cong
- Division of HIV/AIDS Prevention, National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Silvina Masciotra
- Division of HIV/AIDS Prevention, National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Wei Luo
- Division of HIV/AIDS Prevention, National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Caryn Kim
- Division of HIV/AIDS Prevention, National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Debra R Adams
- Division of HIV/AIDS Prevention, National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Michael Monsour
- Division of HIV/AIDS Prevention, National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Jonathan Lipscomb
- Division of HIV/AIDS Prevention, National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Jeffrey A Johnson
- Division of HIV/AIDS Prevention, National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - David Delinsky
- Emory University School of Medicine/Veterans Affairs Medical Center, Decatur, Georgia, United States of America
| | - Raymond F Schinazi
- Emory University School of Medicine/Veterans Affairs Medical Center, Decatur, Georgia, United States of America
| | - Robert Janssen
- Division of HIV/AIDS Prevention, National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Thomas M Folks
- Division of HIV/AIDS Prevention, National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Walid Heneine
- Division of HIV/AIDS Prevention, National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| |
Collapse
|
6
|
Kapoor A, Shapiro B, Shafer RW, Shulman N, Rhee SY, Delwart EL. Multiple independent origins of a protease inhibitor resistance mutation in salvage therapy patients. Retrovirology 2008; 5:7. [PMID: 18221530 PMCID: PMC2265302 DOI: 10.1186/1742-4690-5-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2007] [Accepted: 01/25/2008] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Combination anti-viral therapies have reduced treatment failure rates by requiring multiple specific mutations to be selected on the same viral genome to impart high-level drug resistance. To determine if the common protease inhibitor resistance mutation L90M is only selected once or repeatedly on different HIV genetic backbones during the course of failed anti-viral therapies we analyzed a linked region of the viral genome during the evolution of multi-drug resistance. RESULTS Using L90M allele specific PCR we amplified and sequenced gag-pro regions linked to very early L90M containing HIV variants prior to their emergence and detection as dominant viruses in 15 failed salvage therapy patients. The early minority L90M linked sequences were then compared to those of the later L90M viruses that came to dominate the plasma quasispecies. Using Bayesian evolutionary analysis sampling trees the emergence of L90M containing viruses was seen to take place on multiple occasion in 5 patients, only once for 2 patients and an undetermined number of time for the remaining 8 patients. CONCLUSION These results indicate that early L90M mutants can frequently be displaced by viruses carrying independently selected L90M mutations rather than by descendents of the earlier mutants.
Collapse
Affiliation(s)
- Amit Kapoor
- Blood Systems Research Institute, San Francisco, CA 94118, USA
- University of California San Francisco, CA, USA
| | - Beth Shapiro
- Henry Wellcome Ancient Biomolecules Centre, Dept of Zoology, Oxford University, Oxford, UK
| | - Robert W Shafer
- Division of Infectious Diseases, Department of Medicine, Stanford University Medical Center, Stanford, CA, USA
| | - Nancy Shulman
- Division of Infectious Diseases, Department of Medicine, Stanford University Medical Center, Stanford, CA, USA
| | - Soo-Yon Rhee
- Division of Infectious Diseases, Department of Medicine, Stanford University Medical Center, Stanford, CA, USA
| | - Eric L Delwart
- Blood Systems Research Institute, San Francisco, CA 94118, USA
- University of California San Francisco, CA, USA
| |
Collapse
|
7
|
Uberla K, Rosenwirth B, Ten Haaft P, Heeney J, Sutter G, Erfle V. Therapeutic immunization with Modified Vaccinia Virus Ankara (MVA) vaccines in SIV-infected rhesus monkeys undergoing antiretroviral therapy. J Med Primatol 2007; 36:2-9. [PMID: 17359459 DOI: 10.1111/j.1600-0684.2006.00190.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND The long-term benefits of highly active antiretroviral therapy in HIV-infected patients are limited by emergence of drug-resistant variants and side effects. Therefore, we studied the concept of therapeutic immunization in 18 rhesus monkeys infected with a highly pathogenic simian immunodeficiency virus (SIV) swarm. METHODS Monkeys were treated with the reverse transcriptase inhibitor (R)-9-(2-phosphonylmethoxypropyl)adenine (PMPA) for 19 weeks starting 10 days after infection. After suppression of viremia, one group of monkeys was immunized with recombinant modified vaccinia virus Ankara (MVA) vectors expressing gag-pol and env. A second group received MVA vectors expressing the regulatory genes tat, rev and nef, while a third group was not immunized. RESULTS Immunization with gag-pol and env expressing MVA enhanced SIV antibody titers. Following discontinuation of PMPA treatment, a rebound in viral load was observed. However, in three of six monkeys immunized with MVA gag-pol and MVA env, and two of six monkeys immunized MVA expressing regulatory genes set point RNA levels were below or close to a threshold level of 10(4) RNA copies/ml, while only one of six unvaccinated monkeys maintained such low RNA levels. CONCLUSIONS Although a subset of animals seem to benefit from therapeutic immunization with MVA vectors, the difference in set point RNA levels between the groups did not reach statistical significance.
Collapse
Affiliation(s)
- Klaus Uberla
- Department of Molecular and Medical Virology, Ruhr-University Bochum, Bochum, Germany.
| | | | | | | | | | | |
Collapse
|
8
|
Johnson JA, Rompay KKAV, Delwart E, Heneine W. A rapid and sensitive real-time PCR assay for the K65R drug resistance mutation in SIV reverse transcriptase. AIDS Res Hum Retroviruses 2006; 22:912-6. [PMID: 16989618 DOI: 10.1089/aid.2006.22.912] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Macaques infected with simian immunodeficiency virus (SIV) provide a suitable model for assessing the efficacy of antiretroviral (ARV) drug interventions and drug resistance selection associated with treatment. Resistance to the HIV reverse transcriptase inhibitor tenofovir continues to be examined in different treatment strategies in the macaque model. Evaluations of treatment interventions and drug resistance are hampered by the limited sensitivity of conventional population sequencing and the substantial effort involved in testing various tissue compartments in which viruses may reside. Therefore, a sensitive assay that permits simple and rapid testing for drug-resistant viruses would benefit appraisals of ARV treatments using in vivo models. To have this capability, we developed a real-time PCR-based assay for the detection of the SIV K65R reverse transcriptase mutation, a key marker for reduced susceptibility to tenofovir. Evaluations of SIV sequences yielded an assay detection limit mean of 0.4% mutant virus (range = 0.1-2%) in a wild-type background. In testing longitudinal plasma specimens from four SIV-infected macaques that received an active daily regimen of 30 mg/kg of tenofovir subcutaneously, the assay was able to detect K65R-positive viruses in all animals within 1-7 weeks after treatment began. The emerging mutants were initially present at frequencies estimated between 0.4% and 3%, below the detection capability of population sequencing. We propose the SIV K65R real-time PCR assay provides improved sensitivity and simplicity in studying tenofovir resistance in macaque models.
Collapse
Affiliation(s)
- Jeffrey A Johnson
- National Center for HIV, STD, and TB Prevention, Centers for Disease Control and Prevention, Atlanta, Georgia 30303, USA.
| | | | | | | |
Collapse
|
9
|
Taber R, Rajakumar PA, Fuller DH, Trichel AM, Dowling P, Meleason D, Amedee A, Murphey-Corb M. Effects of monotherapy with (R)-9-(2-phosphonylmethoxypropyl)adenine (PMPA) on the evolution of a primary Simian immunodeficiency virus (SIV) isolate. Virology 2006; 354:116-31. [PMID: 16884757 DOI: 10.1016/j.virol.2006.06.025] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2006] [Revised: 05/05/2006] [Accepted: 06/08/2006] [Indexed: 10/24/2022]
Abstract
Determining the impact of antiretroviral therapy on virus evolution could advance the development of improved therapeutics/vaccines against HIV. Toward this goal, we analyzed virus burden, quasispecies complexity, and T cell responses in SIV/DeltaB670-infected rhesus macaques+/-treatment for 7 months with PMPA (2-30 weeks postinfection). Treatment divided the animals into two groups: poor responders (a reduction of < or =1 log) and responders (> or =2 log reduction) in virus burden. Virus evolution in poor responders and untreated controls was characterized by expression of a complex quasispecies that evolved as the disease progressed. This included the universal loss of a viral genotype selected against by in vitro passage in monkey cells and selected for by propagation in human cells. In contrast, a good response to PMPA was characterized by infection with a less complex quasispecies that evolved more slowly. Interestingly, in 2 of the best responders, the human-preferred genotype persisted until the study was discontinued (89 weeks p.i.). Neither virus burden nor the magnitude of the T cell response at 2 weeks postinfection predicted PMPA responsiveness. However, responders expressed a less complex quasispecies than nonresponders prior to treatment. These data suggest a role for intrinsic host factors in treatment responsiveness, and lend support for therapeutic vaccination as an adjunct to effective therapy.
Collapse
Affiliation(s)
- Rachel Taber
- Department of Molecular Genetics and Biochemistry, BSTWR E1240, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA
| | | | | | | | | | | | | | | |
Collapse
|
10
|
Van Rompay KKA, Singh RP, Heneine W, Johnson JA, Montefiori DC, Bischofberger N, Marthas ML. Structured treatment interruptions with tenofovir monotherapy for simian immunodeficiency virus-infected newborn macaques. J Virol 2006; 80:6399-410. [PMID: 16775328 PMCID: PMC1488952 DOI: 10.1128/jvi.02308-05] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2005] [Accepted: 04/17/2006] [Indexed: 11/20/2022] Open
Abstract
We demonstrated previously that prolonged tenofovir treatment of infant macaques, starting early during infection with virulent simian immunodeficiency virus (SIVmac251), can lead to persistently low or undetectable viremia even after the emergence of mutants with reduced in vitro susceptibility to tenofovir as a result of a K65R mutation in reverse transcriptase; this control of viremia was demonstrated to be mediated by the generation of effective antiviral immune responses. To determine whether structured treatment interruptions (STI) can induce similar immunologic control of viremia, eight newborn macaques were infected with highly virulent SIVmac251 and started on a tenofovir STI regimen 5 days later. Treatment was withdrawn permanently at 33 weeks of age. All animals receiving STI fared much better than 22 untreated SIVmac251-infected infant macaques. However, there was a high variability among animals in the viral RNA set point after complete drug withdrawal, and none of the animals was able to achieve long-term immunologic suppression of viremia to persistently low levels. Early immunologic and viral markers in blood (including the detection of the K65R mutation) were not predictive of the viral RNA set point after drug withdrawal. These results, which reflect the complex interactions between drug resistance mutations, viral virulence, and drug- and immune-mediated inhibition of virus replication, highlight the difficulties associated with trying to develop STI regimens with predictable efficacy for clinical practice.
Collapse
Affiliation(s)
- Koen K A Van Rompay
- California National Primate Research Center, University of California, Davis, CA 95616, USA.
| | | | | | | | | | | | | |
Collapse
|
11
|
Bernardin F, Magierowska M, Dandekar S, Van Rompay KKA, Delwart EL. Number of CD4+ and CD8+ T-cell CDR3 clonotypes expanding during acute infection of macaques with simian immunodeficiency virus. Virology 2004; 322:105-17. [PMID: 15063121 DOI: 10.1016/j.virol.2004.01.022] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2003] [Revised: 01/05/2004] [Accepted: 01/20/2004] [Indexed: 10/26/2022]
Abstract
The total number of circulating CD4+ and CD8+ T-cells undergoing clonal expansions following SIV(mac251) infection was determined using a T-cell receptor Vbeta chain (TRBV) third complementarity-determining region (CDR3) DNA heteroduplex tracking assay (HTA). This assay measures the number of newly expanding T-cell clones but not their antigenic specificity. Fewer expanding CD4+ (3-23 per animal) than CD8+ (18-37 per animal) clonotypes were observed during the acute phase of SIV infection. CD8+ T-cell expansions peaked at 4 weeks postinfection (wpi) concomitant with early reductions in viremia. Expanding clone TRBV transcripts ranged in frequency from the limit of detection of 2% to 40% of their TRBV subfamily's transcripts. The number of expanding CD4+ or CD8+ clones correlated with neither peak, subsequent slope, nor steady-state viremia. CDR3 repertoires in CD8-expressing cells in different anatomical compartments were also analyzed. Repertoires were polyclonal in the thymus, oligoclonal in mesenteric lymph nodes, peripheral blood mononuclear cells (PBMC), and spleen, and extremely oligoclonal in intra-epithelial lymphocytes (IEL) and lamina propria lymphocytes (LPL). The lack of correlation between the number of expanding T-cell clonotypes and viremia levels may reflect the highly variable selection pressure imposed on SIV by T-cell responses targeting different epitopes in outbred macaques.
Collapse
|
12
|
Van Rompay KKA, Singh RP, Pahar B, Sodora DL, Wingfield C, Lawson JR, Marthas ML, Bischofberger N. CD8+-cell-mediated suppression of virulent simian immunodeficiency virus during tenofovir treatment. J Virol 2004; 78:5324-37. [PMID: 15113912 PMCID: PMC400346 DOI: 10.1128/jvi.78.10.5324-5337.2004] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
The ability of tenofovir to suppress viremia in simian immunodeficiency virus (SIV)-infected macaques for years despite the presence of virulent viral mutants with reduced in vitro susceptibility is unprecedented in this animal model. In vivo cell depletion experiments demonstrate that tenofovir's ability to suppress viremia during acute and chronic infection is significantly dependent on the presence of CD8+ lymphocytes. Continuous tenofovir treatment was required to maintain low viremia. Although it is unclear whether this immune-mediated suppression of viremia is linked to tenofovir's direct antiviral efficacy or is due to independent immunomodulatory effects, these studies prove the concept that antiviral immune responses can play a crucial role in suppressing viremia during anti-human immunodeficiency virus drug therapy.
Collapse
Affiliation(s)
- Koen K A Van Rompay
- California National Primate Research Center, University of California-Davis, Davis, CA 95616, USA.
| | | | | | | | | | | | | | | |
Collapse
|