Christian Pou

Deep Molecular Characterization of HIV-1 Dynamics under Suppressive HAART

In order to design strategies for eradication of HIV-1 from infected individuals, detailed insight into the HIV-1 reservoirs that persist in patients on suppressive antiretroviral therapy (ART) is required. In this regard, most studies have focused on integrated (proviral) HIV-1 DNA forms in cells circulating in blood. However, the majority of proviral DNA is replication-defective and archival, and as such, has limited ability to reveal the dynamics of the viral population that persists in patients on suppressive ART. In contrast, extrachromosomal (episomal) viral DNA is labile and as a consequence is a better surrogate for recent infection events and is able to inform on the extent to which residual replication contributes to viral reservoir maintenance. To gain insight into the diversity and compartmentalization of HIV-1 under suppressive ART, we extensively analyzed longitudinal peripheral blood mononuclear cells (PBMC) samples by deep sequencing of episomal and integrated HIV-1 DNA from patients undergoing raltegravir intensification. Reverse-transcriptase genes selectively amplified from episomal and proviral HIV-1 DNA were analyzed by deep sequencing 0, 2, 4, 12, 24 and 48 weeks after raltegravir intensification. We used maximum likelihood phylogenies and statistical tests (AMOVA and Slatkin-Maddison (SM)) in order to determine molecular compartmentalization. We observed low molecular variance (mean variability ≤0.042). Although phylogenies showed that both DNA forms were intermingled within the phylogenetic tree, we found a statistically significant compartmentalization between episomal and proviral DNA samples (P<10−6 AMOVA test; P = 0.001 SM test), suggesting that they belong to different viral populations. In addition, longitudinal analysis of episomal and proviral DNA by phylogeny and AMOVA showed signs of non-chronological temporal compartmentalization (all comparisons P<10−6) suggesting that episomal and proviral DNA forms originated from different anatomical compartments. Collectively, this suggests the presence of a chronic viral reservoir in which there is stochastic release of infectious virus and in which there are limited rounds of de novo infection. This could be explained by the existence of different reservoirs with unique pharmacological accessibility properties, which will require strategies that improve drug penetration/retention within these reservoirs in order to minimise maintenance of the viral reservoir by de novo infection.

Added value of deep sequencing relative to population sequencing in heavily pre-treated HIV-1-infected subjects.

Objective To explore the potential of deep HIV-1 sequencing for adding clinically relevant information relative to viral population sequencing in heavily pre-treated HIV-1-infected subjects. Methods In a proof-of-concept study, deep sequencing was compared to population sequencing in HIV-1-infected individuals with previous triple-class virological failure who also developed virologic failure to deep salvage therapy including, at least, darunavir, tipranavir, etravirine or raltegravir. Viral susceptibility was inferred before salvage therapy initiation and at virological failure using deep and population sequencing genotypes interpreted with the HIVdb, Rega and ANRS algorithms. The threshold level for mutant detection with deep sequencing was 1%. Results 7 subjects with previous exposure to a median of 15 antiretrovirals during a median of 13 years were included. Deep salvage therapy included darunavir, tipranavir, etravirine or raltegravir in 4, 2, 2 and 5 subjects, respectively. Self-reported treatment adherence was adequate in 4 and partial in 2; one individual underwent treatment interruption during follow-up. Deep sequencing detected all mutations found by population sequencing and identified additional resistance mutations in all but one individual, predominantly after virological failure to deep salvage therapy. Additional genotypic information led to consistent decreases in predicted susceptibility to etravirine, efavirenz, nucleoside reverse transcriptase inhibitors and indinavir in 2, 1, 2 and 1 subject, respectively. Deep sequencing data did not consistently modify the susceptibility predictions achieved with population sequencing for darunavir, tipranavir or raltegravir. Conclusions In this subset of heavily pre-treated individuals, deep sequencing improved the assessment of genotypic resistance to etravirine, but did not consistently provide additional information on darunavir, tipranavir or raltegravir susceptibility. These data may inform the design of future studies addressing the clinical value of minority drug-resistant variants in treatment-experienced subjects.

Dynamic escape of pre-existing raltegravir-resistant HIV-1 from raltegravir selection pressure

Using quantitative deep HIV-1 sequencing in a subject who developed virological failure to deep salvage therapy with raltegravir, we found that most Q148R and N155H mutants detected at the time of virological failure originated from pre-existing minority Q148R and N155H variants through independent evolutionary clusters. Double 148R+N155H mutants were also detected in 1.7% of viruses at virological failure in association with E138K and/or G163R. Our findings illustrate the ability of HIV-1 to escape from suboptimal antiretroviral drug pressure through selection of pre-existing drug-resistant mutants, underscoring the importance of using fully active antiretroviral regimens to treat all HIV-1-infected subjects.

Improved Prediction of Salvage Antiretroviral Therapy Outcomes Using Ultrasensitive HIV-1 Drug Resistance Testing

BACKGROUND The clinical relevance of ultrasensitive human immunodeficiency virus type 1 (HIV-1) genotypic resistance testing in antiretroviral treatment (ART)-experienced individuals remains unknown. METHODS This was a retrospective, multicentre, cohort study in ART-experienced, HIV-1-infected adults who initiated salvage ART including, at least 1 ritonavir-boosted protease inhibitor, raltegravir or etravirine. Presalvage ART Sanger and 454 sequencing of plasma HIV-1 were used to generate separate genotypic sensitivity scores (GSS) using the HIVdb, ANRS, and REGA algorithms. Virological failure (VF) was defined as 2 consecutive HIV-1 RNA levels ≥200 copies/mL at least 12 weeks after salvage ART initiation, whereas subjects remained on the same ART. The ability of Sanger and 454-GSS to predict VF was assessed by receiver operating characteristic (ROC) curves and survival analyses. RESULTS The study included 132 evaluable subjects; 28 (21%) developed VF. Using HIVdb, 454 predicted VF better than Sanger sequencing in the ROC curve analysis (area under the curve: 0.69 vs 0.60, Delong test P = .029). Time to VF was shorter for subjects with 454-GSS < 3 vs 454-GSS ≥ 3 (Log-rank P = .003) but not significantly different between Sanger-GSS < 3 and ≥3. Factors independently associated with increased risk of VF in multivariate Cox regression were a 454-GSS < 3 (HR = 4.6, 95 CI, [1.5, 14.0], P = .007), and the number of previous antiretrovirals received (HR = 1.2 per additional drug, 95 CI, [1.1, 1.3], P = .001). Equivalent findings were obtained with the ANRS and REGA algorithms. CONCLUSIONS Ultrasensitive HIV-1 genotyping improves GSS-based predictions of virological outcomes of salvage ART relative to Sanger sequencing. This may improve the clinical management of ART-experienced subjects living with HIV-1. CLINICAL TRIALS REGISTRATION NCT01346878.

Primary resistance to integrase strand-transfer inhibitors in Europe

OBJECTIVES The objective of this study was to define the natural genotypic variation of the HIV-1 integrase gene across Europe for epidemiological surveillance of integrase strand-transfer inhibitor (InSTI) resistance. METHODS This was a multicentre, cross-sectional study within the European SPREAD HIV resistance surveillance programme. A representative set of 300 samples was selected from 1950 naive HIV-positive subjects newly diagnosed in 2006-07. The prevalence of InSTI resistance was evaluated using quality-controlled baseline population sequencing of integrase. Signature raltegravir, elvitegravir and dolutegravir resistance mutations were defined according to the IAS-USA 2014 list. In addition, all integrase substitutions relative to HXB2 were identified, including those with a Stanford HIVdb score ≥ 10 to at least one InSTI. To rule out circulation of minority InSTI-resistant HIV, 65 samples were selected for 454 integrase sequencing. RESULTS For the population sequencing analysis, 278 samples were retrieved and successfully analysed. No signature resistance mutations to any of the InSTIs were detected. Eleven (4%) subjects had mutations at resistance-associated positions with an HIVdb score ≥ 10. Of the 56 samples successfully analysed with 454 sequencing, no InSTI signature mutations were detected, whereas integrase substitutions with an HIVdb score ≥ 10 were found in 8 (14.3%) individuals. CONCLUSIONS No signature InSTI-resistant variants were circulating in Europe before the introduction of InSTIs. However, polymorphisms contributing to InSTI resistance were not rare. As InSTI use becomes more widespread, continuous surveillance of primary InSTI resistance is warranted. These data will be key to modelling the kinetics of InSTI resistance transmission in Europe in the coming years.

Switching the third drug of antiretroviral therapy to maraviroc in aviraemic subjects: a pilot, prospective, randomized clinical trial

OBJECTIVES To evaluate the safety and efficacy of switching the third drug of antiretroviral treatment to maraviroc in aviraemic subjects infected with R5 HIV. PATIENTS AND METHODS This is a pilot, prospective, randomized clinical trial (ClinicalTrials ID: NCT00966329). Eighty HIV-1-infected aviraemic adults on stable antiretroviral treatment for ≥1 year and no antiretroviral drug resistance were screened for the presence of non-R5 HIV by triplicate proviral V3 population sequencing. From them, 30 subjects with R5 HIV-1 were randomized 1 : 1 to switch the non-nucleoside reverse transcriptase inhibitor or ritonavir-boosted protease inhibitor to maraviroc (n = 15) or to continue the same antiretroviral treatment (controls, n = 15). The principal endpoint was the proportion of subjects with HIV-1 RNA <50 copies/mL at week 48. Ultrasensitive proviral HIV-1 tropism testing (454 sequencing) was performed retrospectively at weeks 0, 4, 12, 24, 36 and 48. RESULTS One subject in the maraviroc arm and one control had non-R5 HIV in proviral DNA by retrospective 454 sequencing. The subject receiving maraviroc was the only individual to develop virological failure. However, plasma HIV at failure was R5. Switching to maraviroc was well tolerated and associated with small, but statistically significant, declines in total, high-density lipoprotein and low-density lipoprotein cholesterol. Median (IQR) triglyceride [1 (0.67-1.22) versus 1.6 (1.4-3.1) mmol/L, P = 0.003] and total cholesterol [4.3 (4.1-4.72) versus 5.4 (4-5.7) mmol/L, P = 0.059] values were lower in the maraviroc arm than in controls at week 48. CONCLUSIONS In this pilot, prospective, randomized clinical trial, switching the third drug to maraviroc was safe, efficacious and improved lipid parameters.

A376S in the Connection Subdomain of HIV-1 Reverse Transcriptase Confers Increased Risk of Virological Failure to Nevirapine Therapy

BACKGROUND The clinical relevance of mutations in the connection subdomain and the ribonuclease (RNase) H domain of HIV-1 reverse transcriptase (RT) is uncertain. METHODS The risk of virological failure to nonnucleoside RT inhibitor (NNRTI)-based antiretroviral therapy (ART) was evaluated in NNRTI-naive patients who started NNRTIs in the EuroSIDA study after July 1997 according to preexisting substitutions in the connection subdomain and the RNase H domain of HIV-1 RT. An observed association between A376S and virological failure was further investigated by testing in vitro NNRTI susceptibility of single site-directed mutants and patient-derived recombinant viruses. Enzymatic assays also determined the effects of A376S on nevirapine and template-primer binding to HIV-1 RT. RESULTS Virological failure occurred in 142 of 287 (49%) individuals: 77 receiving nevirapine (67%) and 65 receiving efavirenz (38%) (P < .001). Preexisting A376S was associated with an increased risk of virological failure to nevirapine (relative hazard [RH] = 10.4; 95% confidence interval [CI], 2.0-54.7), but it did not affect efavirenz outcome the same way (RH = 0.5; 95% CI, 0.1-2.2) (P value for interaction = .013). A376S conferred selective low-level nevirapine resistance in vitro, and led to greater affinity for double-stranded DNA. CONCLUSIONS The A376S substitution in the connection subdomain of HIV-1 RT causes selective nevirapine resistance and confers an increased risk of virological failure to nevirapine-based ART.

Determinants of virological failure and antiretroviral drug resistance in Mozambique

OBJECTIVES The objective of this study was to inform public health actions to limit first-line ART failure and HIV drug resistance in Mozambique. METHODS This was a cross-sectional study. HIV-1-infected adults on first-line ART for at least 1 year attending routine visits in the Manhiça District Hospital, in a semi-rural area in southern Mozambique with no HIV-1 RNA monitoring available, were evaluated for clinical, socio-demographic, therapeutic, immunological and virological characteristics. Factors associated with HIV-1 RNA ≥1000 copies/mL and HIV drug resistance were determined using multivariate logistic regression. RESULTS The study included 334 adults on first-line ART for a median of 3 years, of which 65% (214/332) had suppressed viraemia, 11% (37/332) had low-level viraemia (HIV-1 RNA 150-999 copies/mL) and 24% (81/332) had overt virological failure (HIV-1 RNA ≥1000 copies/mL). HIV drug resistance was detected in 89% of subjects with virological failure, but in none with low-level viraemia. Younger age [OR = 0.97 per additional year (95% CI = 0.94-1.00), P = 0.039], ART initiation at WHO stage III/IV [OR = 2.10 (95% CI = 1.23-3.57), P = 0.003] and low ART adherence [OR = 2.69 (95% CI = 1.39-5.19), P = 0.003] were associated with virological failure. Longer time on ART [OR = 1.55 per additional year (95% CI = 1.00-2.43), P = 0.052] and illiteracy [OR = 0.24 (95% CI = 0.07-0.89), P = 0.033] were associated with HIV drug resistance. Compared with HIV-1 RNA, clinicians judgement of ART failure, based on clinical and immunological outcomes, only achieved 29% sensitivity and misdiagnosed 1 out of every 4.5 subjects. CONCLUSIONS Public health programmes in Mozambique should focus on early HIV diagnosis, early ART initiation and adherence support. Virological monitoring drastically improves the diagnosis of ART failure, enabling a better use of resources.

HIV-1 Tropism Testing in Subjects Achieving Undetectable HIV-1 RNA: Diagnostic Accuracy, Viral Evolution and Compartmentalization

Background Technically, HIV-1 tropism can be evaluated in plasma or peripheral blood mononuclear cells (PBMCs). However, only tropism testing of plasma HIV-1 has been validated as a tool to predict virological response to CCR5 antagonists in clinical trials. The preferable tropism testing strategy in subjects with undetectable HIV-1 viremia, in whom plasma tropism testing is not feasible, remains uncertain. Methods & Results We designed a proof-of-concept study including 30 chronically HIV-1-infected individuals who achieved HIV-1 RNA <50 copies/mL during at least 2 years after first-line ART initiation. First, we determined the diagnostic accuracy of 454 and population sequencing of gp120 V3-loops in plasma and PBMCs, as well as of MT-2 assays before ART initiation. The Enhanced Sensitivity Trofile Assay (ESTA) was used as the technical reference standard. 454 sequencing of plasma viruses provided the highest agreement with ESTA. The accuracy of 454 sequencing decreased in PBMCs due to reduced specificity. Population sequencing in plasma and PBMCs was slightly less accurate than plasma 454 sequencing, being less sensitive but more specific. MT-2 assays had low sensitivity but 100% specificity. Then, we used optimized 454 sequence data to investigate viral evolution in PBMCs during viremia suppression and only found evolution of R5 viruses in one subject. No de novo CXCR4-using HIV-1 production was observed over time. Finally, Slatkin-Maddison tests suggested that plasma and cell-associated V3 forms were sometimes compartmentalized. Conclusions The absence of tropism shifts during viremia suppression suggests that, when available, testing of stored plasma samples is generally safe and informative, provided that HIV-1 suppression is maintained. Tropism testing in PBMCs may not necessarily produce equivalent biological results to plasma, because the structure of viral populations and the diagnostic performance of tropism assays may sometimes vary between compartments. Thereby, proviral DNA tropism testing should be specifically validated in clinical trials before it can be applied to routine clinical decision-making.

In-depth characterization of viral isolates from plasma and cells compared with plasma circulating quasispecies in early HIV-1 infection.

Background The use of in vitro models to unravel the phenotypic characteristics of circulating viral variants is key to understanding HIV-1 pathogenesis but limited by the availability of primary viral isolates from biological samples. However, overall in vivo genetic variability of HIV-1 within a subject may not be reflected in the viable viral population obtained after isolation. Although several studies have tried to determine whether viral populations expanded in vitro are representative of in vivo findings, the answer remains unclear due to the reduced number of clonal sequences analyzed or samples compared. In order to overcome previous experimental limitations, here we applied Deep Pyrosequencing (DPS) technology in combination with phenotypic experiments to analyze and compare with unprecedented detail the composition of viral isolates and in vivo quasispecies. Methodology/Principal Findings We amplified by DPS HIV-1 genomic regions covering gag, protease, integrase and env-V3 to characterize paired isolates from plasma and peripheral blood mononuclear cells and compare them with total plasma viral RNA in four recently HIV-1 infected subjects. Our study demonstrated the presence of unique haplotypes scattered between sample types with conservation of major variants. In addition, no differences in intra- and inter-population encoded protein variability were found between the different types of isolates or when these were compared to plasma viral RNA within subjects. Additionally, in vitro experiments demonstrated phenotypic similarities in terms of replicative capacity and co-receptor usage between viral isolates and plasma viral RNA. Conclusion This study is the first in-depth comparison and characterization of viral isolates from different sources and plasma circulating quasispecies using DPS in recently HIV-1 infected subjects. Our data supports the use of primary isolates regardless of their plasma or cellular origin to define genetic variability and biological traits of circulating HIV-1 quasispecies.