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Ismael N, Wilkinson E, Mahumane I, Gemusse H, Giandhari J, Bauhofer A, Vubil A, Mambo P, Singh L, Mabunda N, Bila D, Engelbrecht S, Gudo E, Lessells R, de Oliveira T. Molecular Epidemiology and Trends in HIV-1 Transmitted Drug Resistance in Mozambique 1999–2018. Viruses 2022; 14:v14091992. [PMID: 36146798 PMCID: PMC9505726 DOI: 10.3390/v14091992] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 09/02/2022] [Accepted: 09/05/2022] [Indexed: 11/20/2022] Open
Abstract
HIV drug resistance (HIVDR) can become a public health concern, especially in low- and middle-income countries where genotypic testing for people initiating antiretroviral therapy (ART) is not available. For first-line regimens to remain effective, levels of transmitted drug resistance (TDR) need to be monitored over time. To determine the temporal trends of TDR in Mozambique, a search for studies in PubMed and sequences in GenBank was performed. Only studies covering the pol region that described HIVDR and genetic diversity from treatment naïve patients were included. A dataset from seven published studies and one novel unpublished study conducted between 1999 and 2018 were included. The Calibrated Population Resistance tool (CPR) and REGA HIV-1 Subtyping Tool version 3 for sequences pooled by sampling year were used to determine resistance mutations and subtypes, respectively. The prevalence of HIVDR amongst treatment-naïve individuals increased over time, reaching 14.4% in 2018. The increase was most prominent for non-nucleoside reverse transcriptase inhibitors (NNRTIs), reaching 12.7% in 2018. Subtype C was predominant in all regions, but a higher genetic variability (19% non-subtype C) was observed in the north region of Mozambique. These findings confirm a higher diversity of HIV in the north of the country and an increased prevalence of NNRTI resistance among treatment naïve individuals over time.
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Affiliation(s)
- Nalia Ismael
- Instituto Nacional de Saúde (INS), Estrada Nacional N1, Marracuene 3943, Mozambique
- Division of Medical Virology, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town 8000, South Africa
- Correspondence: (N.I.); (T.d.O.)
| | - Eduan Wilkinson
- Centre for Epidemic Response and Innovation (CERI), School of Data Science and Computational Thinking, Stellenbosch University, Stellenbosch 7602, South Africa
| | - Isabel Mahumane
- Instituto Nacional de Saúde (INS), Estrada Nacional N1, Marracuene 3943, Mozambique
| | - Hernane Gemusse
- Instituto Nacional de Saúde (INS), Estrada Nacional N1, Marracuene 3943, Mozambique
| | - Jennifer Giandhari
- KwaZulu-Natal Research Innovation and Sequencing Platform (KRISP), School of Laboratory Medicine and Medical Sciences, University of KwaZulu-Natal, Durban 4000, South Africa
| | - Adilson Bauhofer
- Instituto Nacional de Saúde (INS), Estrada Nacional N1, Marracuene 3943, Mozambique
| | - Adolfo Vubil
- Instituto Nacional de Saúde (INS), Estrada Nacional N1, Marracuene 3943, Mozambique
| | - Pirolita Mambo
- Instituto Nacional de Saúde (INS), Estrada Nacional N1, Marracuene 3943, Mozambique
| | - Lavanya Singh
- KwaZulu-Natal Research Innovation and Sequencing Platform (KRISP), School of Laboratory Medicine and Medical Sciences, University of KwaZulu-Natal, Durban 4000, South Africa
| | - Nédio Mabunda
- Instituto Nacional de Saúde (INS), Estrada Nacional N1, Marracuene 3943, Mozambique
| | - Dulce Bila
- Elizabeth Glaser Pediatric AIDS Foundation in Mozambique, Avenida Agostinho Neto, Maputo 620, Mozambique
| | - Susan Engelbrecht
- Division of Medical Virology, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town 8000, South Africa
| | - Eduardo Gudo
- Instituto Nacional de Saúde (INS), Estrada Nacional N1, Marracuene 3943, Mozambique
| | - Richard Lessells
- KwaZulu-Natal Research Innovation and Sequencing Platform (KRISP), School of Laboratory Medicine and Medical Sciences, University of KwaZulu-Natal, Durban 4000, South Africa
| | - Túlio de Oliveira
- Centre for Epidemic Response and Innovation (CERI), School of Data Science and Computational Thinking, Stellenbosch University, Stellenbosch 7602, South Africa
- Correspondence: (N.I.); (T.d.O.)
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Baudi I, Iijima S, Chin'ombe N, Mtapuri-Zinyowera S, Murakami S, Isogawa M, Hachiya A, Iwatani Y, Tanaka Y. Molecular epidemiology of co-infection with hepatitis B virus and human immunodeficiency virus (HIV) among adult patients in Harare, Zimbabwe. J Med Virol 2016; 89:257-266. [PMID: 27458715 DOI: 10.1002/jmv.24641] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/23/2016] [Indexed: 12/20/2022]
Abstract
The objective of this study was to determine the prevalence of co-infection with hepatitis B virus (HBV) and human immunodeficiency virus (HIV) and the genetic characteristics of both viruses among pre-HIV-treatment patients in Harare, Zimbabwe. This cross-sectional survey involved 176 remnant plasma samples collected from consenting HIV patients (median age 35 [18-74]) between June and September 2014. HBV seromarkers were determined by high-sensitivity chemiluminescence assays. Molecular evolutionary analyses were conducted on the basal core promoter/precore (BCP/PC) and S regions of HBV, as well as part of the HIV pol region. Of the 176 participants (65.7% female), 19 (10.8%) were positive for HBsAg (median 0.033 IU/ml (IQR 0.01-415). The HBsAg incidence was higher in men than women (P = 0.009). HBsAg-positive subjects had lower median CD4 counts (P = 0.016). HBV DNA was detectable in 12 HBsAg-positive samples (median 3.36 log cp/ml (2.86-4.51), seven being amplified and sequenced. All isolates were subgenotype A1 without HBV drug resistance mutations but each had at least one BCP/PC mutation. PreS deletion mutants and small S antigen variants M133I/T and D144G were identified. Of the 164 HIV isolates successfully genotyped, 163 (99.4%) were HIV-1 subtype C and only one was HIV-1 subtype F1. Sixteen (9.8%) had at least one drug resistance mutation, predominantly non-nucleoside reverse transcriptase inhibitor-related mutations, observed mostly among female participants. This study shows that co-infection with HBV is present among HIV patients enrolling into HIV care in Zimbabwe, suggesting that HBV screening and monitoring programmes be strengthened in this context. J. Med. Virol. 89:257-266, 2017. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Ian Baudi
- Department of Virology and Liver Unit, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Sayuki Iijima
- Department of Virology and Liver Unit, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Nyasha Chin'ombe
- Department of Medical Microbiology, College of Health Sciences, University of Zimbabwe, Harare, Zimbabwe
| | | | - Shuko Murakami
- Department of Virology and Liver Unit, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Masanori Isogawa
- Department of Virology and Liver Unit, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Atsuko Hachiya
- National Hospital Organization Nagoya Medical Center, Nagoya, Japan
| | - Yasumasa Iwatani
- National Hospital Organization Nagoya Medical Center, Nagoya, Japan
| | - Yasuhito Tanaka
- Department of Virology and Liver Unit, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
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O'Brien S, Broom A. HIV in (and out of) the clinic: biomedicine, traditional medicine and spiritual healing in Harare. SAHARA J 2014; 11:94-104. [PMID: 25017937 PMCID: PMC4272101 DOI: 10.1080/17290376.2014.938102] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Contemporary lived experiences of the human immunodeficiency virus (HIV) are shaped by clinical and cultural encounters with illness. In sub-Saharan countries such as Zimbabwe, HIV is treated in very different ways in various therapeutic contexts including by biomedical experts, traditional medicine and faith healers. The co-existence of such expertise raises important questions around the potencies and limits of medicalisation and alternative healing practices in promoting HIV recovery. First, in this study, drawing on in-depth qualitative interviews with 60 people from poor urban areas in Harare, we explore the experiences of people living with and affected by HIV. Specifically, we sought to document, interrogate and reflect on their perceptions and experiences of biomedicine in relation to traditional medicine and spiritual healing. Their accounts indicate that traditional medicine and spiritual beliefs continue to significantly influence the way in which HIV is understood, and the forms of help and care people seek. Second, we observe the dramatic and overwhelmingly beneficial impact of Antiretroviral Therapy and conclude through Zimbabwean's own stories that limitations around delivery and wider structural inequalities impede its potential. Lastly, we explore some practical implications of the biomedical clinic (and alternative healing practices) being understood as sites of ideological and expert contestation. This paper aimed to add to our knowledge of the relationships between traditional medicine and spiritual healing in connection with biomedicine and how this may influence HIV treatment and prevention.
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Affiliation(s)
- Stephen O'Brien
- a PhD Sociology, is a tutor at the School of Humanities and Social Science , The University of Newcastle , Newcastle , Australia , *
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Ambrosioni J, Nicolas D, Sued O, Agüero F, Manzardo C, Miro JM. Update on antiretroviral treatment during primary HIV infection. Expert Rev Anti Infect Ther 2014; 12:793-807. [PMID: 24803105 DOI: 10.1586/14787210.2014.913981] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Primary HIV-1 infection covers a period of around 12 weeks in which the virus disseminates from the initial site of infection into different tissues and organs. In this phase, viremia is very high and transmission of HIV is an important issue. Most guidelines recommend antiretroviral treatment in patients who are symptomatic, although the indication for treatment remains inconclusive in asymptomatic patients. In this article the authors review the main virological and immunological events during this early phase of infection, and discuss the arguments for and against antiretroviral treatment. Recommendations of different guidelines, the issue of the HIV transmission and transmission of resistance to antiretroviral drugs, as well as recently available information opening perspectives for functional cure in patients treated in very early steps of HIV infection are also discussed.
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Affiliation(s)
- Juan Ambrosioni
- Infectious Diseases Service, Hospital Clinic-IDIBAPS, University of Barcelona, Barcelona, Spain
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Manasa J, Danaviah S, Pillay S, Padayachee P, Mthiyane H, Mkhize C, Lessells RJ, Seebregts C, de Wit TFR, Viljoen J, Katzenstein D, De Oliveira T. An affordable HIV-1 drug resistance monitoring method for resource limited settings. J Vis Exp 2014:51242. [PMID: 24747156 PMCID: PMC4024245 DOI: 10.3791/51242] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
HIV-1 drug resistance has the potential to seriously compromise the effectiveness and impact of antiretroviral therapy (ART). As ART programs in sub-Saharan Africa continue to expand, individuals on ART should be closely monitored for the emergence of drug resistance. Surveillance of transmitted drug resistance to track transmission of viral strains already resistant to ART is also critical. Unfortunately, drug resistance testing is still not readily accessible in resource limited settings, because genotyping is expensive and requires sophisticated laboratory and data management infrastructure. An open access genotypic drug resistance monitoring method to manage individuals and assess transmitted drug resistance is described. The method uses free open source software for the interpretation of drug resistance patterns and the generation of individual patient reports. The genotyping protocol has an amplification rate of greater than 95% for plasma samples with a viral load >1,000 HIV-1 RNA copies/ml. The sensitivity decreases significantly for viral loads <1,000 HIV-1 RNA copies/ml. The method described here was validated against a method of HIV-1 drug resistance testing approved by the United States Food and Drug Administration (FDA), the Viroseq genotyping method. Limitations of the method described here include the fact that it is not automated and that it also failed to amplify the circulating recombinant form CRF02_AG from a validation panel of samples, although it amplified subtypes A and B from the same panel.
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Affiliation(s)
- Justen Manasa
- Africa Centre for Health and Population Studies, College of Health Sciences, University of KwaZulu-Natal, Durban, South Africa
| | - Siva Danaviah
- Africa Centre for Health and Population Studies, College of Health Sciences, University of KwaZulu-Natal, Durban, South Africa
| | - Sureshnee Pillay
- Africa Centre for Health and Population Studies, College of Health Sciences, University of KwaZulu-Natal, Durban, South Africa
| | - Prevashinee Padayachee
- Africa Centre for Health and Population Studies, College of Health Sciences, University of KwaZulu-Natal, Durban, South Africa
| | - Hloniphile Mthiyane
- Africa Centre for Health and Population Studies, College of Health Sciences, University of KwaZulu-Natal, Durban, South Africa
| | - Charity Mkhize
- Africa Centre for Health and Population Studies, College of Health Sciences, University of KwaZulu-Natal, Durban, South Africa
| | - Richard John Lessells
- Africa Centre for Health and Population Studies, College of Health Sciences, University of KwaZulu-Natal, Durban, South Africa
| | | | - Tobias F Rinke de Wit
- Academic Medical Center, Department of Global Health, Amsterdam Institute for Global Health and Development (AIGHD), University of Amsterdam
| | - Johannes Viljoen
- Africa Centre for Health and Population Studies, College of Health Sciences, University of KwaZulu-Natal, Durban, South Africa
| | - David Katzenstein
- Division of Infectious Diseases and Geographic Medicine, Centre for AIDS Research, Stanford Medical School
| | - Tulio De Oliveira
- Africa Centre for Health and Population Studies, College of Health Sciences, University of KwaZulu-Natal, Durban, South Africa;
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Imade GE, Sagay AS, Chaplin B, Chebu P, Musa J, Okpokwu J, Hamel DJ, Pam IC, Agbaji O, Samuels J, Meloni S, Sankale JL, Okonkwo P, Kanki P. Short communication: Transmitted HIV drug resistance in antiretroviral-naive pregnant women in north central Nigeria. AIDS Res Hum Retroviruses 2014; 30:127-33. [PMID: 24164431 DOI: 10.1089/aid.2013.0074] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The World Health Organization (WHO) recommends periodic surveillance of transmitted drug resistance (TDR) in communities in which antiretroviral therapy (ART) has been scaled-up for greater than 3 years. We conducted a survey of TDR mutations among newly detected HIV-infected antiretroviral (ARV)-naive pregnant women. From May 2010 to March 2012, 38 ARV-naive pregnant women were recruited in three hospitals in Jos, Plateau state, north central Nigeria. Eligible subjects were recruited using a modified version of the binomial sequential sampling technique recommended by WHO. HIV-1 genotyping was performed and HIV-1 drug resistance mutations were characterized according to the WHO 2009 surveillance drug resistance mutation (SDRM) list. HIV subtypes were determined by phylogenetic analysis. The women's median age was 25.5 years; the median CD4(+) cell count was 317 cells/μl and the median viral load of 16 was 261 copies/ml. Of the 38 samples tested, 34 (89%) were successfully genotyped. The SDRM rate was <5% for all ART drug classes, with 1/34 (2.9%) for NRTIs/NNRTIs and none for protease inhibitors 0/31 (0%). The specific SDRMs detected were M41L for nucleoside reverse transcriptase inhibitors (NRTIs) and G190A for nonnucleoside reverse transcriptase inhibitors (NNRTIs). HIV-1 subtypes detected were CRF02_AG (38.2%), G' (41.2%), G (14.7%), CRF06-CPX (2.9%), and a unique AG recombinant form (2.9%). The single ARV-native pregnant woman with SDRMs was infected with HIV-1 subtype G'. Access to ART has been available in the Jos area for over 8 years. The prevalence of TDR lower than 5% suggests proper ART administration, although continued surveillance is warranted.
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Affiliation(s)
- Godwin E. Imade
- Jos University Teaching Hospital (JUTH), APIN Centre, Jos, Nigeria
- Department of Obstetrics and Gynecology, Faculty of Medical Sciences, University of Jos, Jos, Nigeria
| | - Atiene S. Sagay
- Jos University Teaching Hospital (JUTH), APIN Centre, Jos, Nigeria
- Department of Obstetrics and Gynecology, Faculty of Medical Sciences, University of Jos, Jos, Nigeria
| | - Beth Chaplin
- Harvard School of Public Health, Boston, Massachusetts
| | - Philippe Chebu
- Jos University Teaching Hospital (JUTH), APIN Centre, Jos, Nigeria
| | - Jonah Musa
- Jos University Teaching Hospital (JUTH), APIN Centre, Jos, Nigeria
| | - Jonathan Okpokwu
- Jos University Teaching Hospital (JUTH), APIN Centre, Jos, Nigeria
| | | | - Ishaya C. Pam
- Department of Obstetrics and Gynecology, Faculty of Medical Sciences, University of Jos, Jos, Nigeria
| | - Oche Agbaji
- Jos University Teaching Hospital (JUTH), APIN Centre, Jos, Nigeria
| | - Jay Samuels
- AIDS Prevention Initiative in Nigeria Ltd, Abuja, Nigeria
| | - Seema Meloni
- Harvard School of Public Health, Boston, Massachusetts
| | | | | | - Phyllis Kanki
- Harvard School of Public Health, Boston, Massachusetts
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High-levels of acquired drug resistance in adult patients failing first-line antiretroviral therapy in a rural HIV treatment programme in KwaZulu-Natal, South Africa. PLoS One 2013; 8:e72152. [PMID: 23991055 PMCID: PMC3749184 DOI: 10.1371/journal.pone.0072152] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2013] [Accepted: 07/05/2013] [Indexed: 11/19/2022] Open
Abstract
Objective To determine the frequency and patterns of acquired antiretroviral drug resistance in a rural primary health care programme in South Africa. Design Cross-sectional study nested within HIV treatment programme. Methods Adult (≥18 years) HIV-infected individuals initially treated with a first-line stavudine- or zidovudine-based antiretroviral therapy (ART) regimen and with evidence of virological failure (one viral load >1000 copies/ml) were enrolled from 17 rural primary health care clinics. Genotypic resistance testing was performed using the in-house SATuRN/Life Technologies system. Sequences were analysed and genotypic susceptibility scores (GSS) for standard second-line regimens were calculated using the Stanford HIVDB 6.0.5 algorithms. Results A total of 222 adults were successfully genotyped for HIV drug resistance between December 2010 and March 2012. The most common regimens at time of genotype were stavudine, lamivudine and efavirenz (51%); and stavudine, lamivudine and nevirapine (24%). Median duration of ART was 42 months (interquartile range (IQR) 32–53) and median duration of antiretroviral failure was 27 months (IQR 17–40). One hundred and ninety one (86%) had at least one drug resistance mutation. For 34 individuals (15%), the GSS for the standard second-line regimen was <2, suggesting a significantly compromised regimen. In univariate analysis, individuals with a prior nucleoside reverse-transcriptase inhibitor (NRTI) substitution were more likely to have a GSS <2 than those on the same NRTIs throughout (odds ratio (OR) 5.70, 95% confidence interval (CI) 2.60–12.49). Conclusions There are high levels of drug resistance in adults with failure of first-line antiretroviral therapy in this rural primary health care programme. Standard second-line regimens could potentially have had reduced efficacy in about one in seven adults involved.
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Phylogenetic inferences on HIV-1 transmission: implications for the design of prevention and treatment interventions. AIDS 2013; 27:1045-57. [PMID: 23902920 DOI: 10.1097/qad.0b013e32835cffd9] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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Wadonda-Kabondo N, Banda R, Moyo K, M'bang'ombe M, Chiwaula M, Porter C, Jordan MR. Prevalence of transmitted HIV drug resistance among newly diagnosed antiretroviral therapy-naive pregnant women in Lilongwe and Blantyre, Malawi. Clin Infect Dis 2012; 54 Suppl 4:S324-7. [PMID: 22544197 DOI: 10.1093/cid/cir993] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
In 2006, a survey of transmitted human immunodeficiency virus (HIV) drug resistance (TDR) was conducted in Lilongwe, Malawi. The survey followed the World Health Organization method to classify TDR to nucleoside reverse transcriptase inhibitors (NRTIs), nonnucleoside reverse transcriptase inhibitors (NNRTIs), and protease inhibitors (PIs) among primigravid women aged <25 years. Results of the 2006 survey showed <5% TDR in all drug classes. In 2009, TDR surveys using the same method were repeated in Lilongwe and expanded to Blantyre. Findings show that in Lilongwe TDR to NRTIs and PIs was <5%, whereas TDR to NNRTIs was 5%-15%. In Blantyre, TDR was <5% to all drug classes. Observed moderate TDR in Lilongwe is cause for concern and signals the need for closer monitoring of Malawi's antiretroviral therapy program.
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Abstract
The efficacy of an antiretroviral (ARV) treatment regimen depends on the activity of the regimen's individual ARV drugs and the number of HIV-1 mutations required for the development of resistance to each ARV - the genetic barrier to resistance. ARV resistance impairs the response to therapy in patients with transmitted resistance, unsuccessful initial ARV therapy and multiple virological failures. Genotypic resistance testing is used to identify transmitted drug resistance, provide insight into the reasons for virological failure in treated patients, and help guide second-line and salvage therapies. In patients with transmitted drug resistance, the virological response to a regimen selected on the basis of standard genotypic testing approaches the responses observed in patients with wild-type viruses. However, because such patients are at a higher risk of harbouring minority drug-resistant variants, initial ARV therapy in this population should contain a boosted protease inhibitor (PI) - the drug class with the highest genetic barrier to resistance. In patients receiving an initial ARV regimen with a high genetic barrier to resistance, the most common reasons for virological failure are nonadherence and, potentially, pharmacokinetic factors or minority transmitted drug-resistant variants. Among patients in whom first-line ARVs have failed, the patterns of drug-resistance mutations and cross-resistance are often predictable. However, the extent of drug resistance correlates with the duration of uncontrolled virological replication. Second-line therapy should include the continued use of a dual nucleoside/nucleotide reverse transcriptase inhibitor (NRTI)-containing backbone, together with a change in the non-NRTI component, most often to an ARV belonging to a new drug class. The number of available fully active ARVs is often diminished with each successive treatment failure. Therefore, a salvage regimen is likely to be more complicated in that it may require multiple ARVs with partial residual activity and compromised genetic barriers of resistance to attain complete virological suppression. A thorough examination of the patient's ARV history and prior resistance tests should be performed because genotypic and/or phenotypic susceptibility testing is often not sufficient to identify drug-resistant variants that emerged during past therapies and may still pose a threat to a new regimen. Phenotypic testing is also often helpful in this subset of patients. ARVs used for salvage therapy can be placed into the following hierarchy: (i) ARVs belonging to a previously unused drug class; (ii) ARVs belonging to a previously used drug class that maintain significant residual antiviral activity; (iii) NRTI combinations, as these often appear to retain in vivo virological activity, even in the presence of reduced in vitro NRTI susceptibility; and rarely (iv) ARVs associated with previous virological failure and drug resistance that appear to have possibly regained their activity as a result of viral reversion to wild type. Understanding the basic principles of HIV drug resistance is helpful in guiding individual clinical decisions and the development of ARV treatment guidelines.
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Affiliation(s)
- Michele W Tang
- Stanford University, Division of Infectious Diseases, Stanford, CA 94305-5107, USA.
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