Nucleoside reverse transcriptase inhibitor resistance mutations associated with first-line stavudine-containing antiretroviral therapy: programmatic implications for countries phasing out stavudine

Characterization of Human Immunodeficiency Virus-1 Transmission Clusters and Transmitted Drug-Resistant Mutations in Croatia from 2019 to 2022

Molecular epidemiology of HIV-1 infection is challenging due to the highly diverse HIV-genome. We investigated the genetic diversity and prevalence of transmitted drug resistance (TDR) followed by phylogenetic analysis in 270 HIV-1 infected, treatment-naïve individuals from Croatia in the period 2019-2022. The results of this research confirmed a high overall prevalence of TDR of 16.7%. Resistance to nucleoside reverse transcriptase inhibitors (NRTIs), non-nucleoside RTIs (NNRTIs), and protease inhibitors (PIs) was found in 9.6%, 7.4%, and 1.5% of persons, respectively. No resistance to integrase strand-transfer inhibitors (INSTIs) was found. Phylogenetic analysis revealed that 173/229 sequences (75.5%) were part of transmission clusters, and the largest identified was T215S, consisting of 45 sequences. Forward transmission was confirmed in several clusters. We compared deep sequencing (DS) with Sanger sequencing (SS) on 60 randomly selected samples and identified additional surveillance drug resistance mutations (SDRMs) in 49 of them. Our data highlight the need for baseline resistance testing in treatment-naïve persons. Although no major INSTIs were found, monitoring of SDRMs to INSTIs should be continued due to the extensive use of first- and second-generation INSTIs.

Transmitted HIV Drug Resistance in Bulgaria Occurs in Clusters of Individuals from Different Transmission Groups and Various Subtypes (2012-2020)

Transmitted HIV drug resistance in Bulgaria was first reported in 2015 using data from 1988-2011. We determined the prevalence of surveillance drug resistance mutations (SDRMs) and HIV-1 genetic diversity in Bulgaria during 2012-2020 using polymerase sequences from 1053 of 2010 (52.4%) antiretroviral therapy (ART)-naive individuals. Sequences were analyzed for DRM using the WHO HIV SDRM list implemented in the calculated population resistance tool at Stanford University. Genetic diversity was inferred using automated subtyping tools and phylogenetics. Cluster detection and characterization was performed using MicrobeTrace. The overall rate of SDRMs was 5.7% (60/1053), with 2.2% having resistance to nucleoside reverse transcriptase inhibitors (NRTIs), 1.8% to non-nucleoside reverse transcriptase inhibitors (NNRTIs), 2.1% to protease inhibitors (PIs), and 0.4% with dual-class SDRMs. We found high HIV-1 diversity, with the majority being subtype B (60.4%), followed by F1 (6.9%), CRF02_AG (5.2%), A1 (3.7%), CRF12_BF (0.8%), and other subtypes and recombinant forms (23%). Most (34/60, 56.7%) of the SDRMs were present in transmission clusters of different subtypes composed mostly of male-to-male sexual contact (MMSC), including a 14-member cluster of subtype B sequences from 12 MMSC and two males reporting heterosexual contact; 13 had the L90M PI mutation and one had the T215S NRTI SDRM. We found a low SDRM prevalence amid high HIV-1 diversity among ART-naive patients in Bulgaria during 2012-2020. The majority of SDRMs were found in transmission clusters containing MMSC, indicative of onward spread of SDRM in drug-naive individuals. Our study provides valuable information on the transmission dynamics of HIV drug resistance in the context of high genetic diversity in Bulgaria, for the development of enhanced prevention strategies to end the epidemic.

The Estimation of Transmitted Drug Resistance Mutation Strains Probability in the Treatment of HIV Using the Beta-Binomial Model

The human immunodeficiency virus (HIV) is a viral infection that destroys the human immune system resulting in acquired immunodeficiency syndrome (AIDS). The Zambia HIV prevalence rate (11.3%) remains among the highest in the sub-Saharan Africa. In the treatment of HIV-naive patients, a problem that relates to the transmitted drug resistance mutation strains (TDRMs) occurs in the administration of antiretroviral (ARV) drugs. To address this problem, we propose the use of transition probabilities when prescribing a switch from the first-line to the second-line or to the third-line regimen on the ARV drugs combination. We formulate a statistical technique to determine an optimal ARV drugs combination. To compute a transition probability matrix chart on ARV drugs combinations of the first-line and second-line regimens, we apply a beta-binomial hierarchical model on HIV data. The transition probability matrices corresponding to the ARV drugs combinations TDF+ETC+NVP, TDF+FTC+EFV, AZT+3TC+NVP, AZT+3TC+EFV, D4T+3TC+NVP, and D4T+3TC+EFV provide an upper triangular matrix of probabilities. We observe a higher probability of remaining in the same regimen state than moving to another state. A transition probability chart provides information on the most effective combination to prescribe to a patient in the presence of transmitted drug resistance mutation (TDRM) test results. The transmission probabilities play a major role in aiding the physicians make an informed decision to prescribe an optimal ARV drugs combination. We suggest a TDRM test to be carried out to all newly diagnosed HIV individuals before prescribing any of the ARV drugs combination.

High HIV-1 Virological Failure and Drug Resistance among Adult Patients Receiving First-Line ART for At least 12 Months at a Decentralized Urban HIV Clinic Setting in Senegal before the Test-and-Treat

BACKGROUND

The feasibility of antiretroviral therapy (ART) monitoring remains problematic in decentralized HIV clinic settings of sub-Saharan Africa. We assessed the rates and correlates of HIV-1 virological failure (VF) and drug resistance (DR) in 2 pre-test-and-treat urban clinic settings of Senegal.

METHODS

Consenting HIV-1-infected adults (⩾18 years) receiving first-line ART for ⩾12 months were cross-sectionally enrolled between January and March 2015, at the referral outpatient treatment center of Dakar (n = 151) and decentralized regional hospital of Saint-Louis (n = 127). In the 12 months preceding plasma specimens' collection patients at Saint-Louis had no viral load (VL) testing. Significant predictors of VF (VL ⩾ 1000 copies/ml) and DR (clinically relevant mutations) were determined using binomial logistic regression in R software.

RESULTS

Of the 278 adults on EFV-/NVP-based regimens, 32 (11.5% [95%CI: 8.0-15.9]) experienced VF. Failing and non-failing patients had comparable median time [interquartile] on ART (69.5 [23.0-89.5] vs 64.0 [34.0-99.0] months; P = .46, Mann-Whitney U-test). Of the 27 viraemic isolates successfully genotyped, 20 (74.1%) carried DR mutations; most frequent were M184VI (55.6%), K103N (37.1%), thymidine analog mutations (29.6%), Y181CY (22.2%). The pattern of mutations did not always correspond to the ongoing treatment. The adjusted odds of VF was significantly associated with the decentralized clinic site (P < .001) and CD4 < 350 cells/mm3 (P < .006). Strong correlates of DR also included Saint-Louis (P < .009), CD4 < 350 cells/mm3 (P <. 001), and nevirapine-based therapies (comparator: efavirenz-based therapies; P < .027). In stratification analyses by site, higher rate of VF at Saint-Louis (20.5% [95%CI: 13.8-28.5] vs 4.0% [95%CI: 1.5-8.5] in Dakar) was associated with nevirapine-based therapies (OR = 3.34 [1.07-11.75], P = .038), self-reported missing doses (OR = 3.30 [1.13-10.24], P = .029), and medical appointments (OR = 2.91 [1.05-8.47], P = .039) in the last 1 and 12 months(s), respectively. The higher rate of DR at Saint-Louis (12.9% [95%CI: 7.6-20.1] vs 2.7% [95%CI: 0.7-6.7] in Dakar) was associated with nevirapine-based therapies (OR = 5.13 [1.12-37.35], P = .035).

CONCLUSION

At decentralized urban settings, there is need for enhanced virological monitoring and adherence support. HIV programs in Senegal should intensify early HIV diagnosis for effective test-and-treat. These interventions, in addition to the superiority of efavirenz-based therapies provide a favorable framework for transitioning to the recommended potent drug dolutegravir, thereby ensuring its long-term use.

Evolution of HIV-1 drug resistance after virological failure of first-line antiretroviral therapy in Lusaka, Zambia

BACKGROUND

HIV viral load (VL) and resistance testing are limited in sub-Saharan Africa, so individuals may have prolonged time on failing first-line antiretroviral therapy (ART). Our objective was to describe the evolution of drug resistance mutations among adults failing first-line ART in Zambia.

METHODS

We analysed data from a trial of VL monitoring in Lusaka, Zambia. From 2006 to 2011, 12 randomized sites provided either routine VL monitoring (intervention) or discretionary (control) after ART initiation. Samples were collected prospectively following the same schedule in each arm but analysed retrospectively in the control group. For those with virological failure (VF; >400 copies/ml), HIV genotyping was performed retrospectively on baseline (BL) and on all subsequent specimens until censored due to study completion, withdrawal or death.

RESULTS

Of 1,973 enrollees, 165 (8.4%) developed VF. 464 genotype results were available including 132 (80%) at BL, 116 (70%) at VF and 125 (76%) had at least one result between VF and censoring. Major nucleoside reverse transcriptase inhibitor (NRTI) or non-nucleoside reverse transcriptase inhibitor (NNRTI) mutations increased from 26% (BL) to 82% (VF) to 89% at last genotype (LG). M184 mutations increased from 2% to 59% to 71%; K65R from 2% to 11% to 13%; 2 or more thymidine analogue mutations from 1% to 3% to 12%. Among those on a failing tenofovir disoproxil fumarate (TDF)-based regimen, TDF resistance increased from 42% to 58%.

CONCLUSIONS

We found substantial resistance to NRTIs and NNRTIs at VF with incremental increases after VF while still on a failing first-line ART; this resistance may compromise attainment of the UNAIDS 90-90-90 goals.

Association between HIV-1 subtype and drug resistance in Nigerian infants

Background

Many lines of evidence point to HIV-1 subtype-specific differences in the development of drug resistance mutations. While variation between subtype C and others has been extensively explored, there has been less emphasis on subtypes common to West Africa. We examined a previously described national survey of pretreatment drug resistance in HIV-1-infected Nigerian children aged <18 months, to explore the association between subtypes and patterns of resistance.

Methods

Five hundred and forty-nine dried blood spots, from 15 early infant diagnostic facilities in Nigeria, were amplified and HIV-1 polymerase was sequenced. Four hundred and twenty-four were analysed for surveillance drug resistance mutations (SDRMs). Associations between subtype and SDRMs were evaluated by Fisher's exact test and logistic regression analysis, controlling for geographical region and exposure.

Results

Using the sub-subtypes of HIV-1 G defined by Delatorre et al. (PLoS One 2014.

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e98908) the most common subtypes were CRF02_AG (174, 41.0%), GWA-I (128, 30.2%), GWA-II (24, 5.7%), GCA (11, 2.6%), A (21, 5.0%) and CRF06_cpx (18, 4.2%). One hundred and ninety infants (44.8%) had ≥1 NNRTI mutation, 92 infants (21.7%) had ≥1 NRTI mutation and 6 infants (1.4%) had ≥1 PI mutation. By logistic regression, 67N was more common in GWA-II/GCA than CRF02_AG (OR 12.0, P = 0.006), as was 70R (OR 23.1, P = 0.007), 184I/V (OR 2.92, P = 0.020), the presence of ≥1 thymidine analogue mutation (TAM) (OR 3.87, P = 0.014), ≥1 type 2 TAM (OR 7.61, P = 0.001) and ≥1 NRTI mutation (OR 3.26, P = 0.005).

Conclusions

This dataset reveals differences among SDRMs by subtype; in particular, between the GWA-II and GCA subclades, compared with CRF02_AG and GWA-I.

Frailty among HIV-1 Infected Adults under Antiretroviral Therapy in Indonesia

BACKGROUND

Increasing age of HIV-1 infected population brought about the risk of frailty as comorbidity, whose prevalence is higher in low and middle-income countries (LMICs). Indonesia as an LMIC also bears a major burden of HIV-1 epidemic with a similarly aging population, but the prevalence of frailty and its predictors are unknown.

OBJECTIVES

To identify the prevalence of frailty and analyze its associated factors, among HIV-1 infected adults under antiretroviral therapy in Indonesia.

METHODS

A cross-sectional study was conducted among HIV-infected individuals with inclusion criteria of age ≥30 years old and underwent ART for at least 6 months. The main assessment was done using Fried's frailty phenotype score, which categorizes subjects into non-frail, pre-frail, or frail. Factors associated with frailty were characterized and multiple logistic regression analysis was performed.

RESULTS

A total of 164 subjects were recruited; male subjects were 118 (72%), the median age was 40.5 years old, and the median CD4 nadir was 53 cells/μl. Frailty was identified among 90 (54.9%) subjects with 84 (51.2%) identified as pre-frail and 6 (3.7%) as frail, with dominant frailty phenotype was weakness in grip strength. The multivariate model showed that depression was the only factor significantly correlated with pre-frailty and frailty (OR 2.14; 95% CI 1.04-4.43, p=0.036).

CONCLUSION

Frailty is a common occurrence among HIV-infected patients under ART, with depression as an independent predictive factor.

Risk factors and outcomes for the Q151M and T69 insertion HIV-1 resistance mutations in historic UK data

Background

The prevalence of HIV-1 resistance to antiretroviral therapies (ART) has declined in high-income countries over recent years, but drug resistance remains a substantial concern in many low and middle-income countries. The Q151M and T69 insertion (T69i) resistance mutations in the viral reverse transcriptase gene can reduce susceptibility to all nucleoside/tide analogue reverse transcriptase inhibitors, motivating the present study to investigate the risk factors and outcomes associated with these mutations.

Methods

We considered all data in the UK HIV Drug Resistance Database for blood samples obtained in the period 1997–2014. Where available, treatment history and patient outcomes were obtained through linkage to the UK Collaborative HIV Cohort study. A matched case–control approach was used to assess risk factors associated with the appearance of each of the mutations in ART-experienced patients, and survival analysis was used to investigate factors associated with viral suppression. A further analysis using matched controls was performed to investigate the impact of each mutation on survival.

Results

A total of 180 patients with Q151M mutation and 85 with T69i mutation were identified, almost entirely from before 2006. Occurrence of both the Q151M and T69i mutations was strongly associated with cumulative period of virological failure while on ART, and for Q151M there was a particular positive association with use of stavudine and negative association with use of boosted-protease inhibitors. Subsequent viral suppression was negatively associated with viral load at sequencing for both mutations, and for Q151M we found a negative association with didanosine use but a positive association with boosted-protease inhibitor use. The results obtained in these analyses were also consistent with potentially large associations with other drugs. Analyses were inconclusive regarding associations between the mutations and mortality, but mortality was high for patients with low CD4 at detection.

Conclusions

The Q151M and T69i resistance mutations are now very rare in the UK. Our results suggest that good outcomes are possible for people with these mutations. However, in this historic sample, viral load and CD4 at detection were important factors in determining prognosis.

Electronic supplementary material

The online version of this article (10.1186/s12981-018-0198-7) contains supplementary material, which is available to authorized users.

Key Factors Influencing the Emergence of Human Immunodeficiency Virus Drug Resistance in Low- and Middle-Income Countries

The emergence and spread of human immunodeficiency virus (HIV) drug resistance from antiretroviral roll-out programs remain a threat to long-term control of the HIV-AIDS epidemic in low- and middle-income countries (LMICs). The patterns of drug resistance and factors driving emergence of resistance are complex and multifactorial. The key drivers of drug resistance in LMICs are reviewed here, and recommendations are made to limit their influence on antiretroviral therapy efficacy.

Virological response, HIV-1 drug resistance mutations and genetic diversity among patients on first-line antiretroviral therapy in N'Djamena, Chad: findings from a cross-sectional study

Background

The national antiretroviral therapy in the Republic of Chad provides free of charge antiretroviral regimens and therapeutic monitoring for patients receiving antiretroviral therapy nationwide. For a successful programmatic uptake, these efforts merit to be supported by thorough assessments of antiretroviral therapy response and HIV-1 drug resistance surveillance, especially with risks of cross-resistance due to the gradual stavudine phasing out in such national settings. We therefore evaluated the virological response to antiretroviral therapy, HIV-1 drug resistance emergence and circulating HIV-1 clades in a Chad context. A cross-sectional and prospective study was conducted among 116 patients (41 [δ ± 6.87] years, 59% female) receiving first-line antiretroviral therapy for ≥ 6 months in Ndjamena, Chad, in 2011–2012, enrolled consecutively. To ensure accuracy, plasma viral load was concomitantly measured using Abbott Real-Time and Cobas AmpliPrep/TaqMan (v2.0), and virological failure defined as ≥ 1000 HIV-1 RNA copies/ml. Plasma from patients experiencing virological failure were processed for sequencing of HIV-1 protease-reverse transcriptase using the ANRS-AC.11 resistance testing protocol; drug resistant mutations were interpreted using the ANRS-AC11 algorithm; and phylogenetic analysis was performed using MEGA.v.6.

Results

Majority of patients was receiving zidovudine plus lamivudine plus nevirapine (46%), stavudine plus lamivudine plus nevirapine (41%) and tenofovir plus emtricitabine plus efavirenz (11%), for a median time-on-treatment of 5 [IQR 4–7] years. The rate of virological failure was 43% (50/116), with 86% (43/50) sequencing performance. Overall, 32% (37/116) patients presented ≥ one major drug resistant mutation(s), with 29% (34/116) to nucleos(t)ide reverse transcriptase inhibitors (67% [29/43] M184V/I, 30% [13/43] T215Y/F, 19% [8/43] V75A/F/I/L/M, 9% [4/43] K70P/R/W, 9% [4/43] K219E/N/Q and 5% [2/43] A62V); 86% (37/43) to non-nulceos(t)ide reverse transcriptase inhibitors (30% [13/43] K103N/S/E, 26% [11/43] Y181C/V/F/L, 2% [1/43] L100I, 2% [1/43] F227L, 2% [1/43] P225H); and 2% (1/43) to protease inhibitors (M46I, I54V, V82S). Six HIV-1 subtypes were found: 30% circulating recombinant form (CRF02_AG), 30% J, 16% G, 9% A, 9% D, 5% F.

Conclusions

In Chad, almost half of patients are failing first-line antiretroviral therapy after 5 years, with considerable drug resistant mutations at failure. Absence of K65R supports the use of tenofovir-containing regimens as preferred first-line and as suitable drug for second-line combinations, in this setting with significant HIV-1 genetic diversity.

Electronic supplementary material

The online version of this article (10.1186/s13104-017-2893-1) contains supplementary material, which is available to authorized users.

Predictors of Virologic Failure on First-line Antiretroviral Therapy Among Children in a Referral Pediatric Center in Cameroon

BACKGROUND

Suboptimal response to antiretroviral therapy (ART) is common among children living with HIV (CLHIV) in resource-limited settings. We sought to assess virologic failure (VF), time for switching to second-line regimens and factors associated with VF in CLHIV receiving first-line ART in Cameroon.

METHODS

An observational cohort study was conducted in 375 CLHIV initiating a first-line ART and treated for ≥6 months at the National Social Insurance Fund Hospital in Yaoundé-Cameroon from 2009 to 2013. Using logistic regression, predictors of VF and delayed switch were assessed by univariate and multivariate analysis. P < 0.05 was considered statistically significant.

RESULTS

Overall, 17% (64/375) CLHIV experienced VF on first-line ART after a median time of 28 (interquartile range: 22-38) months. After VF, median time to switching from first- to second-line ART was 20 (interquartile range: 8-24) months. In multivariate analysis, VF was associated with male gender (adjusted odds ratio: 0.36; 95% confidence interval: 0.19-0.71; P = 0.003), motherless children (adjusted odds ratio: 2.9; 95% confidence interval: 1.3-6.06; P = 0.005) and treatment with stavudine-containing compared with zidovudine-containing regimens (P = 0.022). Overall, male gender, orphanhood (motherless) and treatment with stavudine-containing regimens predicted VF at a rate of 70% (area under curve =0.70).

CONCLUSION

VF on first-line pediatric ART is common, and switching children failing first-line to second-line ART is considerably delayed. These results suggest performance of pediatric ART program can be improved by targeting orphans, adapting counseling for male children, complete phasing-out of stavudine and ensuring timely switch to second-line regimens.

HIV Drug Resistance Mutations in Non-B Subtypes After Prolonged Virological Failure on NNRTI-Based First-Line Regimens in Sub-Saharan Africa

OBJECTIVE

To determine drug resistance mutation (DRM) patterns in a large cohort of patients failing nonnucleoside reverse transcriptase inhibitor (NNRTI)-based first-line antiretroviral therapy regimens in programs without routine viral load (VL) monitoring and to examine intersubtype differences in DRMs.

DESIGN

Sequences from 787 adults/adolescents who failed an NNRTI-based first-line regimen in 13 clinics in Uganda, Kenya, Zimbabwe, and Malawi were analyzed. Multivariable logistic regression was used to determine the association between specific DRMs and Stanford intermediate-/high-level resistance and factors including REGA subtype, first-line antiretroviral therapy drugs, CD4, and VL at failure.

RESULTS

The median first-line treatment duration was 4 years (interquartile range 30-43 months); 42% of participants had VL ≥100,000 copies/mL and 63% participants had CD4 <100 cells/mm. Viral subtype distribution was A1 (40%; Uganda and Kenya), C (31%; Zimbabwe and Malawi), and D (25%; Uganda and Kenya), and recombinant/unclassified (5%). In general, DRMs were more common in subtype-C than in subtype-A and/or subtype-D (nucleoside reverse transcriptase inhibitor mutations K65R and Q151M; NNRTI mutations E138A, V106M, Y181C, K101E, and H221Y). The presence of tenofovir resistance was similar between subtypes [P (adjusted) = 0.32], but resistance to zidovudine, abacavir, etravirine, or rilpivirine was more common in subtype-C than in subtype-D/subtype-A [P (adjusted) < 0.02].

CONCLUSIONS

Non-B subtypes differ in DRMs at first-line failure, which impacts on residual nucleoside reverse transcriptase inhibitor and NNRTI susceptibility. In particular, higher rates of etravirine and rilpivirine resistance in subtype-C may limit their potential utility in salvage regimens.

Structural Insights into HIV Reverse Transcriptase Mutations Q151M and Q151M Complex That Confer Multinucleoside Drug Resistance

HIV-1 reverse transcriptase (RT) is targeted by multiple drugs. RT mutations that confer resistance to nucleoside RT inhibitors (NRTIs) emerge during clinical use. Q151M and four associated mutations, A62V, V75I, F77L, and F116Y, were detected in patients failing therapies with dideoxynucleosides (didanosine [ddI], zalcitabine [ddC]) and/or zidovudine (AZT). The cluster of the five mutations is referred to as the Q151M complex (Q151Mc), and an RT or virus containing Q151Mc exhibits resistance to multiple NRTIs. To understand the structural basis for Q151M and Q151Mc resistance, we systematically determined the crystal structures of the wild-type RT/double-stranded DNA (dsDNA)/dATP (complex I), wild-type RT/dsDNA/ddATP (complex II), Q151M RT/dsDNA/dATP (complex III), Q151Mc RT/dsDNA/dATP (complex IV), and Q151Mc RT/dsDNA/ddATP (complex V) ternary complexes. The structures revealed that the deoxyribose rings of dATP and ddATP have 3'-endo and 3'-exo conformations, respectively. The single mutation Q151M introduces conformational perturbation at the deoxynucleoside triphosphate (dNTP)-binding pocket, and the mutated pocket may exist in multiple conformations. The compensatory set of mutations in Q151Mc, particularly F116Y, restricts the side chain flexibility of M151 and helps restore the DNA polymerization efficiency of the enzyme. The altered dNTP-binding pocket in Q151Mc RT has the Q151-R72 hydrogen bond removed and has a switched conformation for the key conserved residue R72 compared to that in wild-type RT. On the basis of a modeled structure of hepatitis B virus (HBV) polymerase, the residues R72, Y116, M151, and M184 in Q151Mc HIV-1 RT are conserved in wild-type HBV polymerase as residues R41, Y89, M171, and M204, respectively; functionally, both Q151Mc HIV-1 and wild-type HBV are resistant to dideoxynucleoside analogs.

Mutational Correlates of Virological Failure in Individuals Receiving a WHO-Recommended Tenofovir-Containing First-Line Regimen: An International Collaboration

Tenofovir disoproxil fumarate (TDF) genotypic resistance defined by K65R/N and/or K70E/Q/G occurs in 20% to 60% of individuals with virological failure (VF) on a WHO-recommended TDF-containing first-line regimen. However, the full spectrum of reverse transcriptase (RT) mutations selected in individuals with VF on such a regimen is not known. To identify TDF regimen-associated mutations (TRAMs), we compared the proportion of each RT mutation in 2873 individuals with VF on a WHO-recommended first-line TDF-containing regimen to its proportion in a cohort of 50,803 antiretroviral-naïve individuals. To identify TRAMs specifically associated with TDF-selection pressure, we compared the proportion of each TRAM to its proportion in a cohort of 5805 individuals with VF on a first-line thymidine analog-containing regimen. We identified 83 TRAMs including 33 NRTI-associated, 40 NNRTI-associated, and 10 uncommon mutations of uncertain provenance. Of the 33 NRTI-associated TRAMs, 12 - A62V, K65R/N, S68G/N/D, K70E/Q/T, L74I, V75L, and Y115F - were more common among individuals receiving a first-line TDF-containing compared to a first-line thymidine analog-containing regimen. These 12 TDF-selected TRAMs will be important for monitoring TDF-associated transmitted drug-resistance and for determining the extent of reduced TDF susceptibility in individuals with VF on a TDF-containing regimen.

Mechanisms of Accelerated Liver Fibrosis Progression during HIV Infection

With the introduction of antiretroviral therapy (ART), a dramatic reduction in HIV-related morbidity and mortality has been observed. However, it is now becoming increasingly clear that liver-related complications, particularly rapid fibrosis development from ART as well as from the chronic HIV infection itself, are of serious concern to HIV patients. The pathophysiology of liver fibrosis in patients with HIV is a multifactorial process whereby persistent viral replication, and bacterial translocation lead to chronic immune activation and inflammation, which ART is unable to fully suppress, promoting production of fibrinogenic mediators and fibrosis. In addition, mitochondrial toxicity, triggered by both ART and HIV, contributes to intrahepatic damage, which is even more severe in patients co-infected with viral hepatitis. In recent years, new insights into the mechanisms of accelerated fibrosis and liver disease progression in HIV has been obtained, and these are detailed and discussed in this review.

HIV-1 antiretroviral drug resistance patterns in patients failing NNRTI-based treatment: results from a national survey in South Africa

BACKGROUND

Routine HIV-1 antiretroviral drug resistance testing for patients failing NNRTI-based regimens is not recommended in resource-limited settings. Therefore, surveys are required to monitor resistance profiles in patients failing ART.

METHODS

A cross-sectional survey was conducted amongst patients failing NNRTI-based regimens in the public sector throughout South Africa. Virological failure was defined as two consecutive HIV-1 viral load results >1000 RNA copies/mL. Pol sequences were obtained using RT-PCR and Sanger sequencing and submitted to Stanford HIVdb v7.0.1.

RESULTS

A total of 788 sequences were available for analysis. Most patients failed a tenofovir-based NRTI backbone (74.4%) in combination with efavirenz (82.1%) after median treatment duration of 36 months. K103N (48.9%) and V106M (34.9%) were the most common NNRTI mutations. Only one-third of patients retained full susceptibility to second-generation NNRTIs such as etravirine (36.5%) and rilpivirine (27.3%). After M184V/I (82.7%), K65R was the most common NRTI mutation (45.8%). The prevalence of K65R increased to 57.5% in patients failing a tenofovir regimen without prior stavudine exposure. Cross-resistance to NRTIs was often observed, but did not seem to affect the predicted activity of zidovudine as 82.9% of patients remained fully susceptible to this drug.

CONCLUSIONS

The introduction of tenofovir-based first-line regimens has dramatically increased the prevalence of K65R mutations in the HIV-1-infected South African population. However, most patients failing tenofovir-based regimens remained fully susceptible to zidovudine. Based on these data, there is currently no need to change either the recommended first- or second-line ART regimens in South Africa.

Is There a Need for Viral Load Testing to Assess Treatment Failure in HIV-Infected Patients Who Are about to Change to Tenofovir-Based First-Line Antiretroviral Therapy? Programmatic Findings from Myanmar

BACKGROUND

WHO recommends that stavudine is phased out of antiretroviral therapy (ART) programmes and replaced with tenofovir (TDF) for first-line treatment. In this context, the Integrated HIV Care Program, Myanmar, evaluated patients for ART failure using HIV RNA viral load (VL) before making the change. We aimed to determine prevalence and determinants of ART failure in those on first-line treatment.

METHODS

Patients retained on stavudine-based or zidovudine-based ART for >12 months with no clinical/immunological evidence of failure were offered VL testing from August 2012. Plasma samples were tested using real time PCR. Those with detectable VL>250 copies/ml on the first test were provided with adherence counseling and three months later a second test was performed with >1000 copies/ml indicating ART failure. We calculated the prevalence of ART failure and adjusted relative risks (aRR) to identify associated factors using log binomial regression.

RESULTS

Of 4934 patients tested, 4324 (87%) had an undetectable VL at the first test while 610 patients had a VL>250 copies/ml. Of these, 502 had a second VL test, of whom 321 had undetectable VL and 181 had >1000 copies/ml signifying ART failure. There were 108 who failed to have the second test. Altogether, there were 94% with an undetectable VL, 4% with ART failure and 2% who did not follow the VL testing algorithm. Risk factors for ART failure were age 15-24 years (aRR 2.4, 95% CI: 1.5-3.8) compared to 25-44 years and previous ART in the private sector (aRR 1.6, 95% CI: 1.2-2.2) compared to the public sector.

CONCLUSIONS

This strategy of evaluating patients on first-line ART before changing to TDF was feasible and identified a small proportion with ART failure, and could be considered by HIV/AIDS programs in Myanmar and other countries.

HIV drug resistance levels in adults failing first-line antiretroviral therapy in an urban and a rural setting in South Africa

OBJECTIVES

Urban and rural HIV treatment programmes face different challenges in the long-term management of patients. There are few studies comparing drug resistance profiles in patients accessing treatment through these programmes. The aim of this study was to perform such a comparison.

METHODS

HIV drug resistance data and associated treatment and monitoring information for adult patients failing first-line therapy in an urban and a rural programme were collected. Data were curated and managed in SATuRN RegaDB before statistical analysis using Microsoft Excel 2013 and stata Ver14, in which clinical parameters, resistance profiles and predicted treatment responses were compared.

RESULTS

Data for 595 patients were analysed: 492 patients from a rural setting and 103 patients from an urban setting. The urban group had lower CD4 counts at treatment initiation than the rural group (98 vs. 126 cells/μL, respectively; P = 0.05), had more viral load measurements performed per year (median 3 vs. 1.4, respectively; P < 0.01) and were more likely to have no drug resistance mutations detected (35.9% vs. 11.2%, respectively; P < 0.01). Patients in the rural group were more likely to have been on first-line treatment for a longer period, to have failed for longer, and to have thymidine analogue mutations. Notwithstanding these differences, the two groups had comparable predicted responses to the standard second-line regimen, based on the genotypic susceptibility score. Mutations accumulated in a sigmoidal fashion over failure duration.

CONCLUSIONS

The frequency and patterns of drug resistance, as well the intensity of virological monitoring, in adults with first-line therapy failure differed between the urban and rural sites. Despite these differences, based on the genotypic susceptibility scores, the majority of patients across the two sites would be expected to respond well to the standard second-line regimen.

Global Comparison of Drug Resistance Mutations After First-Line Antiretroviral Therapy Across Human Immunodeficiency Virus-1 Subtypes

Background.  Human immunodeficiency virus (HIV)-1 drug resistance mutations (DRMs) often accompany treatment failure. Although subtype differences are widely studied, DRM comparisons between subtypes either focus on specific geographic regions or include populations with heterogeneous treatments. Methods.  We characterized DRM patterns following first-line failure and their impact on future treatment in a global, multi-subtype reverse-transcriptase sequence dataset. We developed a hierarchical modeling approach to address the high-dimensional challenge of modeling and comparing frequencies of multiple DRMs in varying first-line regimens, durations, and subtypes. Drug resistance mutation co-occurrence was characterized using a novel application of a statistical network model. Results.  In 1425 sequences, 202 subtype B, 696 C, 44 G, 351 circulating recombinant forms (CRF)01_AE, 58 CRF02_AG, and 74 from other subtypes mutation frequencies were higher in subtypes C and CRF01_AE compared with B overall. Mutation frequency increased by 9%-20% at reverse transcriptase positions 41, 67, 70, 184, 215, and 219 in subtype C and CRF01_AE vs B. Subtype C and CRF01_AE exhibited higher predicted cross-resistance (+12%-18%) to future therapy options compared with subtype B. Topologies of subtype mutation networks were mostly similar. Conclusions.  We find clear differences in DRM outcomes following first-line failure, suggesting subtype-specific ecological or biological factors that determine DRM patterns.

Phenotype, Genotype, and Drug Resistance in Subtype C HIV-1 Infection

BACKGROUND

Virologic failure in subtype C is characterized by high resistance to first-line antiretroviral (ARV) drugs, including efavirenz, nevirapine, and lamivudine, with nucleoside resistance including type 2 thymidine analog mutations, K65R, a T69del, and M184V. However, genotypic algorithms predicting resistance are mainly based on subtype B viruses and may under- or overestimate drug resistance in non-B subtypes. To explore potential treatment strategies after first-line failure, we compared genotypic and phenotypic susceptibility of subtype C human immunodeficiency virus 1 (HIV-1) following first-line ARV failure.

METHODS

AIDS Clinical Trials Group 5230 evaluated patients failing an initial nonnucleoside reverse-transcriptase inhibitor (NNRTI) regimen in Africa and Asia, comparing the genotypic drug resistance and phenotypic profile from the PhenoSense (Monogram). Site-directed mutagenesis studies of K65R and T69del assessed the phenotypic impact of these mutations.

RESULTS

Genotypic algorithms overestimated resistance to etravirine and rilpivirine, misclassifying 28% and 32%, respectively. Despite K65R with the T69del in 9 samples, tenofovir retained activity in >60%. Reversion of the K65R increased susceptibility to tenofovir and other nucleosides, while reversion of the T69del showed increased resistance to zidovudine, with little impact on other NRTI.

CONCLUSIONS

Although genotype and phenotype were largely concordant for first-line drugs, estimates of genotypic resistance to etravirine and rilpivirine may misclassify subtype C isolates compared to phenotype.

Population-based human immunodeficiency virus 1 drug resistance profiles among individuals who experienced virological failure to first-line antiretroviral therapy in Henan, China during 2010-2011

BACKGROUND

In Henan, China, first-line antiretroviral treatment (ART) was implemented early in a large number of treatment-experienced patients who were more likely to have a drug resistance. Therefore, we investigated the human immunodeficiency virus (HIV)-1 drug resistance profiles among patients in Henan who experienced virological failure to ART.

METHOD

A cross-sectional survey was administered in 10 major epidemic cities from May 2010 to October 2011. Adult patients who experienced virological failure (virus load ≥1,000 copies/mL) with >1 year of first-line antiretroviral treatment consented to provide blood for genotype resistance testing. The clinical and demographic data were obtained from the patients' medical records. Logistic regression analysis was performed to determine the factors associated with ≥1 significant drug resistance mutation.

RESULTS

We included 3,235 patients with integral information and valid genotypic resistance data. The city, age, CD4 counts, virus load, treatment duration, and World Health Organization stage were associated with drug resistance, and 64.76% of patients acquired drug resistance. The nucleoside reverse transcriptase inhibitor (NRTI), non-(N)NRTI, and protease inhibitor resistance mutations were found in 50.26, 63.12, and 1.30% of subjects, respectively. Thymidine analogue mutations, NNRTI and even multidrug resistance complex were quite common in this patient cohort.

CONCLUSION

Multiple and complex patterns of HIV-1 drug resistance mutations were identified among individuals who experienced virological failure to first-line ART in Henan, China during 2010-2011. Therefore, timely virological monitoring, therapy adjustments, and more varieties of drugs and individualized treatment should be immediately considered in this patient population.

High prevalence of the K65R mutation in HIV-1 subtype C infected patients failing tenofovir-based first-line regimens in South Africa

Background

Tenofovir (TDF) has replaced stavudine (d4T) as the preferred nucleoside reverse transcriptase inhibitor (NRTI) in first-line regimens in South Africa, but limited information is available on the resistance patterns that develop after the introduction of TDF. This study investigated the antiretroviral drug resistance patterns in South African HIV-1 subtype C-infected patients failing stavudine- (d4T) and tenofovir- (TDF) based first-line regimens and assess the suitability of TDF as the preferred first-line nucleotide reverse transcriptase inhibitor (NRTI).

Methods

Resistance patterns of HIV-1 from 160 adult patients virologically failing TDF- (n = 80) and d4T- (n = 80) based first-line regimens were retrospectively analyzed. The pol gene was sequenced using an in-house protocol and mutations were analysed using the IAS-USA 2014 Drug Resistance Mutation list.

Results

Compared to d4T-exposed patients (n = 7), patients failing on a TDF-containing regimen (n = 43) were almost 5 times more likely to present with a K65R mutation (aRR 4.86 95% CI 2.29 – 10.34). Y115F was absent in the d4T group, and detected in 13.8% (n = 11) of TDF-exposed patients, p = 0.0007. Virus from 9 of the 11 patients (82.0%) who developed the Y115F mutation also developed K65R. Intermediate or high-level resistance to most NRTIs was common in the TDF-treatment group, but these patients twice more likely to remain susceptible to AZT as compared to those exposed to d4T (aRR 2.09 95% CI 1.13 – 3.90).

Conclusion

The frequency of the TDF induced K65R mutation was higher in our setting compared to non-subtype C dominated countries. However, despite the higher frequency of cross-resistance to NRTIs, most patients remained susceptible to AZT, which is reflected in the South African treatment guidelines that recommend AZT as an essential component of second-line regimens.

Next generation sequencing improves detection of drug resistance mutations in infants after PMTCT failure

BACKGROUND

Next generation sequencing (NGS) allows the detection of minor variant HIV drug resistance mutations (DRMs). However data from new NGS platforms after Prevention-of-Mother-to-Child-Transmission (PMTCT) regimen failure are limited.

OBJECTIVE

To compare major and minor variant HIV DRMs with Illumina MiSeq and Life Technologies Ion Personal Genome Machine (PGM) in infants infected despite a PMTCT regimen.

STUDY DESIGN

We conducted a cross-sectional study of NGS for detecting DRMs in infants infected despite a zidovudine (AZT) and Nevirapine (NVP) regimen, before initiation of combination antiretroviral therapy. Sequencing was performed on PCR products from plasma samples on PGM and MiSeq platforms. Bioinformatic analyses were undertaken using a codon-aware version of the Smith-Waterman mapping algorithm and a mixture multinomial error filtering statistical model.

RESULTS

Of 15 infants, tested at a median age of 3.4 months after birth, 2 (13%) had non-nucleoside reverse transcriptase inhibitor (NNRTI) DRMs (K103N and Y181C) by bulk sequencing, whereas PGM detected 4 (26%) and MiSeq 5 (30%). NGS enabled the detection of additional minor variant DRMs in the infant with K103N. Coverage and instrument quality scores were higher with MiSeq, increasing the confidence of minor variant calls.

CONCLUSIONS

NGS followed by bioinformatic analyses detected multiple minor variant DRMs in HIV-1 RT among infants where PMTCT failed. The high coverage of MiSeq and high read quality improved the confidence of identified DRMs and may make this platform ideal for minor variant detection.

HIV-1 genetic variation and drug resistance development

Up until 10 years ago, basic and clinical HIV-1 research was mainly performed on HIV-1 subtype B that predominated in resource-rich settings. Over the past decade, HIV-1 care and therapy has been scaled up substantially in Latin America, Africa and Asia. These regions are largely dominated by non-B subtype infections, and especially the African continent is affected by the HIV pandemic. Insight on the potency of antiviral drugs and regimens as well as on the emergence of drug resistance in non-B subtypes was lacking triggering research in this field, also partly driven by the introduction and spreading of HIV-1 non-B subtypes in Europe. The scope of this article was to review and discuss the state-of-the-art on the impact of HIV-1 genetic variation on the in vitro activity of antiviral drugs and in vivo response to antiviral therapy; as well as on the in vitro and in vivo emergence of drug resistance.

Beyond first-line HIV treatment regimens: the current state of antiretroviral regimens, viral load monitoring, and resistance testing in resource-limited settings

PURPOSE OF REVIEW

With the availability of antiretroviral drugs in resource-limited settings, there is a rapid scale-up of antiretroviral therapy in developing countries.

RECENT FINDINGS

The review focuses on the issues faced while patients are on first-line antiretroviral therapy in the absence of viral load monitoring, and the availability and progress of the second-line antiretroviral drugs and the salvage regimens in resource-limited settings.

SUMMARY

There is an urgent need for low-cost, low-tech viral load monitoring in resource-limited settings. Fixed-dose combination of antiretrovirals for first-line and second-line therapy will result in better effectiveness. There is a need for newer antiretroviral drugs in resource-limited settings.

Drug susceptibility and resistance mutations after first-line failure in resource limited settings

BACKGROUND

The development of drug resistance to nucleoside reverse transcriptase inhibitors (NRTIs) and nonnucleoside reverse transcriptase inhibitors (NNRTIs) has been associated with baseline human immunodeficiency virus (HIV)-1 RNA level (VL), CD4 cell counts (CD4), subtype, and treatment failure duration. This study describes drug resistance and levels of susceptibility after first-line virologic failure in individuals from Thailand, South Africa, India, Malawi, Tanzania.

METHODS

CD4 and VL were captured at AIDs Clinical Trial Group (ACTG) A5230 study entry, a study of lopinavir/ritonavir (LPV/r) monotherapy after first-line virologic failure on an NNRTI regimen. HIV drug-resistance mutation associations with subtype, site, study entry VL, and CD4 were evaluated using Fisher exact and Kruskall-Wallis tests.

RESULTS

Of the 207 individuals who were screened for A5230, sequence data were available for 148 individuals. Subtypes observed: subtype C (n = 97, 66%) AE (n = 27, 18%), A1 (n = 12, 8%), and D (n = 10, 7%). Of the 148 individuals, 93% (n = 138) and 96% (n = 142) had at least 1 reverse transcriptase (RT) mutation associated with NRTI and NNRTI resistance, respectively. The number of NRTI mutations was significantly associated with a higher study screening VL and lower study screening CD4 (P < .001). Differences in drug-resistance patterns in both NRTI and NNRTI were observed by site.

CONCLUSIONS

The degree of NNRTI and NRTI resistance after first-line virologic failure was associated with higher VL at study entry. Thirty-two percent of individuals remained fully susceptible to etravirine and rilpivirine, protease inhibitor resistance was rare. Some level of susceptibility to NRTI remained; however, VL monitoring and earlier virologic failure detection may result in lower NRTI resistance.

Tenofovir or zidovudine in second-line antiretroviral therapy after stavudine failure in southern Africa

BACKGROUND

There is debate over using tenofovir or zidovudine alongside lamivudine in second-line antiretroviral therapy (ART) following stavudine failure. We analysed outcomes in cohorts from South Africa, Zambia and Zimbabwe

METHODS

Patients aged ≥16 years who switched from a first-line regimen including stavudine to a ritonavir-boosted lopinavir-based second-line regimen with lamivudine or emtricitabine and zidovudine or tenofovir in seven ART programmes in southern Africa were included. We estimated the causal effect of receiving tenofovir or zidovudine on mortality and virological failure using Cox proportional hazards marginal structural models. Its parameters were estimated using inverse probability of treatment weights. Baseline characteristics were age, sex, calendar year and country. CD4(+) T-cell count, creatinine and haemoglobin levels were included as time-dependent confounders.

RESULTS

A total of 1,256 patients on second-line ART, including 958 on tenofovir, were analysed. Patients on tenofovir were more likely to have switched to second-line ART in recent years, spent more time on first-line ART (33 versus 24 months) and had lower CD4(+) T-cell counts (172 versus 341 cells/μl) at initiation of second-line ART. The adjusted hazard ratio comparing tenofovir with zidovudine was 1.00 (95% CI 0.59, 1.68) for virological failure and 1.40 (0.57, 3.41) for death.

CONCLUSIONS

We did not find any difference in treatment outcomes between patients on tenofovir or zidovudine; however, the precision of our estimates was limited. There is an urgent need for randomized trials to inform second-line ART strategies in resource-limited settings.

Emergence of HIV drug resistance during first- and second-line antiretroviral therapy in resource-limited settings

INTRODUCTION

Antiretroviral therapy (ART) in resource-limited settings has expanded in the last decade, reaching >8 million individuals and reducing AIDS mortality and morbidity. Continued success of ART programs will require understanding the emergence of HIV drug resistance patterns among individuals in whom treatment has failed and managing ART from both an individual and public health perspective. We review data on the emergence of HIV drug resistance among individuals in whom first-line therapy has failed and clinical and resistance outcomes of those receiving second-line therapy in resource-limited settings.

RESULTS

Resistance surveys among patients initiating first-line nonnucleoside reverse-transcriptase inhibitor (NNRTI)-based therapy suggest that 76%-90% of living patients achieve HIV RNA suppression by 12 months after ART initiation. Among patients with detectable HIV RNA at 12 months, HIV drug resistance, primarily due to M184V and NNRTI mutations, has been identified in 60%-72%, although the antiretroviral activity of proposed second-line regimens has been preserved. Complex mutation patterns, including thymidine-analog mutations, K65R, and multinucleoside mutations, are prevalent among cases of treatment failure identified by clinical or immunologic methods. Approximately 22% of patients receiving second-line therapy do not achieve HIV RNA suppression by 6 months, with poor adherence, rather than HIV drug resistance, driving most failures. Major protease inhibitor resistance at the time of second-line failure ranges from 0% to 50%, but studies are limited.

CONCLUSIONS

Resistance of HIV to first-line therapy is predictable at 12 months when evaluated by means of HIV RNA monitoring and, when detected, largely preserves second-line therapy options. Optimizing adherence, performing resistance surveillance, and improving treatment monitoring are critical for long-term prevention of drug resistance.