Are Confirmatory Assays Reliable for HIV-1/HIV-2 Infection Differentiation? A Multicenter Study.

Immunoblots remain the gold standard for HIV-1/HIV-2 infection confirmation. However, their ability to differentiate HIV-1 from HIV-2 infection on an antigenically diversified HIV-1 and HIV-2 panel remain uncommon. We performed a multicenter study on 116 serum samples accounting for most of the diversity of HIV-1 (9 different subtypes in group M, 17 circulating recombinant forms (CRFs), and 3 group O) and HIV-2 (groups A and B), evaluating seven confirmatory assays (six commercially available assays and one in-house assay) with genotyping as the reference. The assays were INNO-LIA HIV I/II score, HIV-2 blot 1.2, HIV blot 2.2, New Lav blot I and II, Geenius, and an in-house serotyping enzyme-linked immunosorbent assay (ELISA). Among the HIV-1 samples, INNO-LIA, HIV blot 2.2, New Lav blot I, Geenius, and serotyping had comparable high sensitivities, from 98% to 100%, whereas HIV-2 blot 1.2 and New Lav blot II had high rates of "undetermined" results (85% and 95%, respectively). HIV-2 blot 1.2 and New Lav blot II misclassified 7% and 5% of HIV-1 samples as HIV-2, respectively, and HIV-2 blot 1.2 had an 8% false-negative rate. Among the HIV-2 samples, INNO-LIA, New Lav blot II, HIV-2 blot 1.2, and serotyping had high sensitivities, from 96% to 100%. HIV blot 2.2 misclassified 17% of HIV-2 samples as HIV-1/HIV-2 dual infections. New Lav blot I misclassified 19% of HIV-2 samples as HIV-1 with a high (81%) undetermined rate, and Geenius misclassified 2% as HIV-1 and 7% as untypeable HIV positive. For HIV-1/HIV-2 dual infection, the results were less sensitive, with at most 87.5% for INNO-LIA and Geenius and 75% for HIV blot 2.2 and serotyping. Overall, confirmatory assays remain useful for most cases, with the exception of HIV-1/HIV-2 dual-infection suspicion.

More HIV-1 RNA detected and quantified with the Cobas 6800 system in patients on antiretroviral therapy.

BACKGROUND: Target-detected (TD) results or low-level viraemia (LLV) can be observed in HIV-1 patients on ART, which regularly raises questions. OBJECTIVES: We describe here the impact on HIV-1 RNA quantification of switching from the COBAS AmpliPrep/COBAS TaqMan (CAP/CTM) to the Cobas 6800 system (C6800), based on analyses of viraemia close to the lower limit of quantification (LLoQ). PATIENTS AND METHODS: We retrospectively selected two groups of patients: 200 individuals whose viral loads (VLs) were consistently <50 copies/mL with CAP/CTM for at least 3 years before switching to C6800 (group 1), and 35 other patients with confirmed LLV when C6800 was in use (group 2). In both groups, we compared several consecutive VL results performed before and after the change of quantification assay. Analyses were performed with McNemar's paired tests or Fisher's exact tests. RESULTS: In group 1, the frequency of TD results (below or above the LLoQ) increased significantly after the switch to C6800 for patients with <25% of results being TD for VLs performed with CAP/CTM (P < 0.0001). Significantly more patients had at least one VL ≥20 or ≥50 copies/mL with C6800, in both group 1 (37.0% versus 18.5%; P < 0.0001 and 6.5% versus 0%; P = 0.0009, respectively) and group 2 (100% versus 66%; P = 0.0015 and 97% versus 40%; P < 0.0001, respectively). CONCLUSIONS: C6800 revealed residual or low-level HIV-1 RNA that was not detected with CAP/CTM, resulting in twice as many patients being found to have a VL ≥20 copies/mL. Physicians and patients should be aware of possible differences in results between assays, and it is crucial to specify the quantitative assay used in studies.

Kinetics of Archived M184V Mutation in Treatment-Experienced Virally Suppressed HIV-Infected Patients.

BACKGROUND: We aimed to assess the kinetics of drug-resistant viral variants (DRVs) harboring the M184V mutation in proviral DNA of long-term virally suppressed patients, and factors associated with DRV persistence. METHODS: Human immunodeficiency virus (HIV) DNA from blood cells stored in 2016 and 2019 was sequenced using Sanger and ultradeep sequencing (SS and UDS; detection threshold 1%) in antiretroviral therapy (ART)-treated patients with HIV RNA < 50 copies/mL for at least 5 years, with past M184V mutation documented in HIV RNA. RESULTS: Among 79 patients, by combining SS and UDS, M184V was found to be absent in 26/79 (33%) patients and persistent in 53/79 (67%). M184V-positive patients had a longer history of ART, lower CD4 nadir, and higher pretherapeutic HIV RNA. Among 37 patients with viral sequences assessed by UDS, the proportion of M184V-positive DRVs significantly decreased between 2016 and 2019 (40% vs 14%, P = .005). The persistence of M184V was associated with duration and level of HIV RNA replication under lamivudine/emtricitabine (3TC/FTC; P = .0009 and P = .009, respectively). CONCLUSIONS: While it decreased over time in HIV DNA, M184V mutation was more frequently persistent in HIV DNA of more treatment-experienced patients with longer past replication under 3TC/FTC.

Neutralization Heterogeneity of UK and South African Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Variants in BNT162b2-Vaccinated or Convalescent Coronavirus Disease 2019 (COVID-19) Healthcare Workers.

There are concerns about neutralizing antibodies' (NAbs') potency against severe acute respiratory syndrome coronavirus 2 variants. Despite decreased NAb titers elicited by BNT162b2 vaccine against VOC202012/01 and 501Y.V2 strains, 28/29 healthcare workers (HCWs) had an NAb titer ≥1:10. In contrast, 6 months after coronavirus disease 2019 mild forms, only 9/15 (60%) of HCWs displayed detectable NAbs against 501Y.V2 strain.

Prevalence of genotypic baseline risk factors for cabotegravir + rilpivirine failure among ARV-naive patients.

BACKGROUND: Multivariable baseline factor analysis across cabotegravir + rilpivirine clinical trials showed that HIV-1 subtypes A6/A1 and the presence of rilpivirine resistance-associated mutations (RAMs) were associated with an increased risk of virological failure of this dual therapy. The aim of this study was to describe the prevalence of genotypic baseline risk factors for cabotegravir + rilpivirine failure among ARV-naive patients. PATIENTS AND METHODS: From 2010 to 2020, 4212 sequences from ARV-naive patients were collected from three large Parisian academic hospital genotypic databases. Cabotegravir and rilpivirine RAMs were defined according to the ANRS algorithm. RESULTS: Among 4212 ARV-naive patients, 38.6% were infected with subtype B, 32.4% with CRF02_AG (32.4%) and 5.1% with subtype A (85.5% being A6/A1 subtype). Overall, the presence of at least one cabotegravir or rilpivirine RAM was 16.2% and 14.3%, respectively. Considering genotypic resistance interpretation, using the ANRS algorithm, 0.74% (n = 31), 6.2% (n = 261) and 0.09% (n = 4) of sequences were resistant to cabotegravir, rilpivirine or both, respectively. The overall prevalence of L74I in integrase and E138A in RT was 13.0% and 3.2%, respectively, and stable over the decade. Thus, adding 183 subtype A6/A1 sequences to 244 sequences interpreted as resistant to rilpivirine led to 427 (10.1%) sequences combining both baseline virological risk factors for cabotegravir + rilpivirine dual-therapy failure. CONCLUSIONS: Among large sequence databases, when adding prevalence of rilpivirine-resistant viruses and HIV-1 subtype A6/A1 sequences, 10.1% of patients would not be eligible for cabotegravir + rilpivirine dual therapy. These data re-emphasize the need for a pre-therapeutic genotypic resistance test to detect polymorphisms and transmitted drug resistance and to define HIV-1 subtype.

Presence of HIV-1 G-to-A mutations linked to APOBEC editing is more prevalent in non-B HIV-1 subtypes and is associated with lower HIV-1 reservoir.

OBJECTIVES: APOBEC3 editing activity contributes to sequences variation and viral diversification. We aimed to characterize virological and clinical factors associated with G-to-A mutations and stop codons in the HIV-1 reservoir, markers of APOBEC3 footprints, in order to better understand HIV-1 diversity among virologically suppressed HIV-1-infected patients. METHODS: Immuno-virological and clinical factors were compared between 92 patients harbouring G-to-A mutations and stop codons (APOBEC+) in the reverse transcriptase gene and 92 patients without G-to-A mutations (APOBEC-) and stop codons in their DNA genotypes. RESULTS: Patients were predominantly men (74.5%) and were mostly infected by B-subtype (69.0%), with 44.1% and 55.9% in APOBEC+ and APOBEC- groups, respectively. At time of HIV DNA genotypes, the total cell-associated HIV-1 DNA load was 2.34 log10 copies/106 cells (IQR 1.85-2.67) and 33.2% of them had a detectable ultrasensitive plasma viral load. Hypermutated sequences were identified in 28.2% of the APOBEC+ group. The median total cell-associated HIV-1 DNA level was significantly lower in APOBEC+ than APOBEC- group: 2.13 log10 copies/106 cells (IQR 1.60-2.60) versus 2.52 log10 copies/106 cells (IQR 2.19-2.71) (P < 0.001), respectively. Presence of G-to-A mutations and stop codon was independently associated with HIV-1 subtype non-B (P = 0.017). CONCLUSIONS: These results show an independent association between the presence of G-to-A mutations and stop codons with HIV-1 subtype non-B and low proviral DNA that could be explained by the APOBEC3 footprints and restriction of DNA synthesis and integration. However, further investigations are needed to study the contribution of Vif amino acid variability among HIV-1 subtypes.

Intermittent two-drug antiretroviral therapies maintain long-term viral suppression in real life in highly experienced HIV-infected patients.

OBJECTIVES: To assess in real life whether two-drug regimens (2-DRs) given 4-5 days a week in virally suppressed patients can maintain viral suppression over 48 and 96 weeks. METHODS: This observational single-centre study enrolled all patients who initiated an intermittent 2-DR between 01/01/2016 and 30/06/2019. The primary outcome was the rate of virological failure (VF), defined as confirmed plasma viral load (pVL) ≥50 copies/mL or single pVL ≥50 copies/mL followed by ART change at week 48 (W48) and W96. Secondary outcomes were the 2-DR intermittent strategy success rate (pVL <50 copies/mL with no ART change), change in CD4 count, CD4/CD8 ratio and rate of residual viraemia. RESULTS: Eighty-five patients were included; 67/85 (79%) were men, median age = 57 years (IQR = 50-63), CD4 nadir = 233 cells/mm3 (110-327), ART duration = 21 years (13-24), duration of virological suppression = 6.5 years (3.7-10.8) and CD4 count = 658 cells/mm3 (519-867). Intermittent 2-DRs consisted of integrase strand transfer inhibitor (INSTI)/NNRTI (58%), INSTI/NRTI (13%), two NRTIs (11%), PI/NRTI (7%) and other combinations (11%). The median follow-up was 90 weeks (IQR = 64-111). Overall, four VFs occurred, leading to a virological success rate of 98.8% (95% CI = 93.6-100) at W48 and 95.3% (95% CI = 88.4-98.7) at W96. Resuming the same 2-DR 7 days a week led to viral resuppression in three patients, whereas the M184V mutation emerged in one patient, leading to ART modification. There was no significant change in the CD4 count or residual viraemia rate, but a small increase in the CD4/CD8 ratio (P = 0.009) occurred over the study period. CONCLUSIONS: This observational study shows the potential for intermittent 2-DRs to maintain a high virological success rate, which should be assessed in larger prospective randomized studies.

No difference in HIV-1 integrase inhibitor resistance between CSF and blood compartments.

BACKGROUND: Little is known about HIV-1 integrase inhibitor resistance in the CNS. OBJECTIVES: This study aimed to evaluate integrase inhibitor resistance in CSF, as a marker of the CNS, and compare it with the resistance in plasma. METHODS: HIV integrase was sequenced both in plasma and CSF for 59 HIV-1 patients. The clinical and biological data were collected from clinical routine care. RESULTS: Among the 59 HIV-1 patients, 32 (54.2%) were under antiretroviral (ARV) treatment. The median (IQR) HIV-1 RNA in the plasma of viraemic patients was 5.32 (3.85-5.80) and 3.59 (2.16-4.50) log10 copies/mL versus 4.79 (3.56-5.25) and 3.80 (2.68-4.33) log10 copies/mL in the CSF of ARV-naive and ARV-treated patients, respectively. The patients were mainly infected with non-B subtypes (72.2%) with the most prevalent recombinant form being CRF02_AG (42.4%). The HIV-1 integrase sequences from CSF presented resistance mutations for 9/27 (33.3%) and 8/32 (25.0%) for ARV-naive (L74I, n = 3; L74I/M, n = 1; T97A, n = 1; E157Q, n = 4) and ARV-treated (L74I, n = 6; L74M, n = 1; T97A, n = 1; N155H, n = 1) patients, respectively. Integrase inhibitor resistance mutations in CSF were similar to those in plasma, except for 1/59 patients. CONCLUSIONS: This work shows similar integrase inhibitor resistance profiles in the CNS and plasma in a population of HIV-1 viraemic patients.

Multicenter comparison of the Cobas 6800 system with the RealStar RT-PCR kit for the detection of SARS-CoV-2.

BACKGROUND: RT-PCR testing is crucial in the diagnostic of SARS-CoV-2 infection. The use of reliable and comparable PCR assays is a cornerstone to allow use of different PCR assays depending on the local equipment. In this work, we provide a comparison of the Cobas® (Roche) and the RealStar® assay (Altona). METHODS: Assessment of the two assays was performed prospectively in three reference Parisians hospitals, using 170 clinical samples. They were tested with the Cobas® assay, selected to obtain a distribution of cycle threshold (Ct) as large as possible, and tested with the RealStar assay with three largely available extraction platforms: QIAsymphony (Qiagen), MagNAPure (Roche) and NucliSENS-easyMag (BioMérieux). RESULTS: Overall, the agreement (positive for at least one gene) was 76 %. This rate differed considerably depending on the Cobas Ct values for gene E: below 35 (n = 91), the concordance was 99 %. Regarding the positive Ct values, linear regression analysis showed a coefficient of determination (R2) of 0.88 and the Deming regression line revealed a strong correlation with a slope of 1.023 and an intercept of -3.9. Bland-Altman analysis showed that the mean difference (Cobas® minus RealStar®) was + 3.3 Ct, with a SD of + 2.3 Ct. CONCLUSIONS: In this comparison, both RealStar® and Cobas® assays provided comparable qualitative results and a high correlation when both tests were positive. Discrepancies exist after 35 Ct and varied depending on the extraction system used for the RealStar® assay, probably due to a low viral load close to the detection limit of both assays.

No HIV-1 molecular evolution on long-term antiretroviral therapy initiated during primary HIV-1 infection.

OBJECTIVE: Most studies about HIV-1 molecular evolution have shown the lack of viral evolution on effective antiretroviral therapy (ART), although controversial results have been documented. We therefore aimed to look for evidence of HIV-1 evolution in patients who initiated ART at the time of primary HIV-1 infection (PHI). DESIGN: We included retrospectively 20 patients diagnosed at PHI, treated at the time of acute infection and with subsequent effective long-term suppressive ART (HIV viral load <20 copies/ml during at least 5 years without any blips). METHODS: Longitudinal blood samples were deep sequenced using Illumina Miseq. Drug-resistance-associated mutations were retained at 2% cutoff and interpreted using the latest Agence Nationale de Recherches sur le Sida et les Hépatites Virales resistance algorithm. Viral evolution was established when temporal structure on maximum-likelihood phylogenetic tree and significant change over time of HIV-1 genetic diversity measured as the average pairwise distance was observed. RESULTS: Emergences or disappearances of drug-resistance-associated mutations were detected in the blood cells during follow-up despite sustained virological control. In all patients, tree topologies showed an absence of segregation between sequences and blood viral populations from all time-points were intermingled. Comparison of the average pairwise distance showed the absence of significant viral diversity at the time of primary infection and afterwards during 5 years of full virological control under ART. CONCLUSION: Despite a slight variation of minority resistance-associated mutation variants, there was no clear evidence of viral evolution during a prolonged period of time in this population of highly controlled adult patients treated at time of PHI.

Evolution of viral quasispecies during SARS-CoV-2 infection.

OBJECTIVES: Studies are needed to better understand the genomic evolution of the recently emerged severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This study aimed to describe genomic diversity of SARS-CoV-2 by next-generation sequencing (NGS) in a patient with longitudinal follow-up for SARS-CoV-2 infection. METHODS: Sequential samples collected between January 29th and February 4th, 2020, from a patient infected by SARS-CoV-2 were used to perform amplification of two genome fragments-including genes encoding spike, envelope, membrane and nucleocapsid proteins-and NGS was carried out with Illumina® technology. Phylogenetic analysis was performed with PhyML and viral variant identification with VarScan. RESULTS: Majority consensus sequences were identical in most of the samples (5/7) and differed in one synonymous mutation from the Wuhan reference sequence. We identified 233 variants; each sample harboured in median 38 different minority variants, and only four were shared by different samples. The frequency of mutation was similar between genes and correlated with the length of the gene (r = 0.93, p = 0.0002). Most of mutations were substitution variations (n = 217, 93.1%) and about 50% had moderate or high impact on gene expression. Viral variants also differed between lower and upper respiratory tract samples collected on the same day, suggesting independent sites of replication of SARS-CoV-2. CONCLUSIONS: We report for the first time minority viral populations representing up to 1% during the course of SARS-CoV-2 infection. Quasispecies were different from one day to the next, as well as between anatomical sites, suggesting that in vivo this new coronavirus appears as a complex and dynamic distributions of variants.

M184V/I does not impact the efficacy of abacavir/lamivudine/dolutegravir use as switch therapy in virologically suppressed patients.

BACKGROUND: M184V/I NRTI resistance mutations can be selected by either lamivudine/emtricitabine or abacavir. There are controversies about the use of abacavir/lamivudine/dolutegravir combinations in HIV-1-infected treatment-experienced patients with a fully suppressed HIV viral load (VL) and harbouring M184V/I. OBJECTIVES: We assessed the efficacy of abacavir/lamivudine/dolutegravir when used in HIV-infected pretreated patients with an undetectable VL who previously harboured M184V/I as a unique NRTI resistance mutation in a genotypic resistance test and had no resistance to integrase inhibitors. PATIENTS AND METHODS: A total of 154 patients with a fully suppressed HIV-1 plasma VL (<50 copies/mL) treated with tenofovir disoproxil fumarate/emtricitabine/boosted PI or abacavir/lamivudine/boosted PI who switched to an abacavir/lamivudine/dolutegravir regimen and had M184V/I as a unique NRTI resistance mutation in their therapeutic history were retrospectively analysed up to 12 months after the switch to abacavir/lamivudine/dolutegravir. Assessment of residual viraemia was performed at Months 1, 3, 6 and 12. Plasma VL with undetectable HIV-1 RNA corresponded to an absence of residual viraemia. RESULTS: During the 12 months of follow-up, three patients had a blip of VL (53, 62 and 106 copies/mL) at Month 3 followed by a subsequent VL <50 copies/mL. No patient harboured a virological failure during the follow-up. Moreover, there was no change in residual viraemia during the follow-up. CONCLUSIONS: M184V/I as a unique NRTI resistance mutation, regardless of possible selection by regimens containing lamivudine/emtricitabine or abacavir, does not affect the virological response of well-controlled patients who switched to abacavir/lamivudine/dolutegravir for at least 12 months.

Surveillance of HIV-1 primary infections in France from 2014 to 2016: toward stable resistance, but higher diversity, clustering and virulence?

OBJECTIVES: Patients with primary HIV-1 infection (PHI) are a particular population, giving important insight about ongoing evolution of transmitted drug resistance-associated mutation (TDRAM) prevalence, HIV diversity and clustering patterns. We describe these evolutions of PHI patients diagnosed in France from 2014 to 2016. METHODS: A total of 1121 PHI patients were included. TDRAMs were characterized using the 2009 Stanford list and the French ANRS algorithm. Viral subtypes and recent transmission clusters (RTCs) were also determined. RESULTS: Patients were mainly MSM (70%) living in the Paris area (42%). TDRAMs were identified among 10.8% of patients and rose to 18.6% when including etravirine and rilpivirine TDRAMs. Prevalences of PI-, NRTI-, first-generation NNRTI-, second-generation NNRTI- and integrase inhibitor-associated TDRAMs were 2.9%, 5.0%, 4.0%, 9.4% and 5.4%, respectively. In a multivariable analysis, age >40 years and non-R5 tropic viruses were associated with a >2-fold increased risk of TDRAMs. Regarding HIV diversity, subtype B and CRF02_AG (where CRF stands for circulating recombinant form) were the two main lineages (56% and 20%, respectively). CRF02_AG was associated with higher viral load than subtype B (5.83 versus 5.40 log10 copies/mL, P=0.004). We identified 138 RTCs ranging from 2 to 14 patients and including overall 41% from the global population. Patients in RTCs were younger, more frequently born in France and more frequently MSM. CONCLUSIONS: Since 2007, the proportion of TDRAMs has been stable among French PHI patients. Non-B lineages are increasing and may be associated with more virulent CRF02_AG strains. The presence of large RTCs highlights the need for real-time cluster identification to trigger specific prevention action to achieve better control of the epidemic.

New HIV-1 circulating recombinant form 94: from phylogenetic detection of a large transmission cluster to prevention in the age of geosocial-networking apps in France, 2013 to 2017.

BackgroundEnding the HIV pandemic must involve new tools to rapidly identify and control local outbreaks and prevent the emergence of recombinant strains with epidemiological advantages.AimThis observational study aimed to investigate in France a cluster of HIV-1 cases related to a new circulating recombinant form (CRF). The confirmation this CRF's novelty as well as measures to control its spread are presented.MethodsPhylogenetic analyses of HIV sequences routinely generated for drug resistance genotyping before 2018 in French laboratories were employed to detect the transmission chain. The CRF involved was characterised by almost full-length viral sequencing for six cases. Cases' clinical data were reviewed. Where possible, epidemiological information was collected with a questionnaire.ResultsThe transmission cluster comprised 49 cases, mostly diagnosed in 2016-2017 (n = 37). All were infected with a new CRF, CRF94_cpx. The molecular proximity of this CRF to X4 strains and the high median viraemia, exceeding 5.0 log10 copies/mL, at diagnosis, even in chronic infection, raise concerns of enhanced virulence. Overall, 41 cases were diagnosed in the Ile-de-France region and 45 were men who have sex with men. Among 24 cases with available information, 20 reported finding partners through a geosocial networking app. Prevention activities in the area and population affected were undertaken.ConclusionWe advocate the systematic use of routinely generated HIV molecular data by a dedicated reactive network, to improve and accelerate targeted prevention interventions. Geosocial networking apps can play a role in the spread of outbreaks, but could also deliver local targeted preventive alerts.

Antiretroviral drug reduction in highly experienced HIV-infected patients receiving a multidrug regimen: the ECOVIR study.

OBJECTIVES: In a context of life-long therapy, we asked whether it could be possible to reduce the number of antiretroviral drugs without jeopardizing viral suppression. METHODS: ECOVIR was a prospective study aiming to assess whether in patients on combination ART with ≥4 antiretrovirals for ≥24 weeks and virally suppressed for ≥48 weeks, a drug-reduced (DR) regimen could be proposed. The intervention consisted of discontinuing genotypically less susceptible drugs to reach a DR regimen with ≤3 antiretrovirals. The primary endpoint was the proportion of patients maintaining viral suppression at week (W) 24. RESULTS: From 89 eligible individuals for the study, a DR regimen was proposed in 86 (97%) patients, of whom 71 were switched to a DR regimen. Baseline characteristics [median (IQR)] were: age 58 (53-65) years, duration of treatment 24 (21-26) years and viral suppression 8 (6-11) years. The cumulative resistance profile showed full resistance to lamivudine/emtricitabine (91%), abacavir (74%), efavirenz/nevirapine (70%), rilpivirine (56%), darunavir (q24h/q12h) (42%/29%), lopinavir (69%), atazanavir (71%) and raltegravir (24%). The final DR regimen consisted of a two-drug or three-drug regimen in 54 patients (76%) and in 17 patients (24%), respectively. The success rate of a DR regimen at W24 was 93.9% (95% CI 84.4-97.6, Kaplan-Meier estimate). Four patients experienced virological failure (at W4, W8 and W12), all with plasma viral load (pVL) <600 copies/mL and no emergence of resistance mutations. The DR strategy allowed a monthly cost saving of 36%. CONCLUSIONS: In experienced patients with high-level resistance, individualized strategies based on expert advice can offer DR regimen options with fewer drug-drug interactions and a significant economic impact while ensuring virological success.