Protease Inhibitor Resistance Research Articles

Brief Report: HIV-1 Resistance Analysis of Participants With HIV-1 and Hepatitis B Initiating Therapy With Bictegravir/Emtricitabine/Tenofovir Alafenamide or Dolutegravir Plus Emtricitabine/Tenofovir Disoproxil Fumarate: A Subanalysis of ALLIANCE Data

Background: In the phase 3 ALLIANCE study, both bictegravir/emtricitabine/tenofovir alafenamide (B/F/TAF) and dolutegravir plus emtricitabine/tenofovir disoproxil fumarate (DTG + F/TDF) achieved high rates of HIV-1 RNA suppression through week 96 in adults with HIV-1 and hepatitis B virus initiating treatment (NCT03547908). In this study, we quantify preexisting HIV-1 resistance, evaluate its effect on HIV-1 virologic suppression, and describe postbaseline HIV-1 resistance through week 96. Methods: Preexisting HIV-1 resistance was assessed by historical and/or screening genotyping. HIV-1 RNA suppression to <50 copies (c)/mL at week 96 was assessed by the preexisting resistance category. Postbaseline resistance was assessed in participants with HIV-1 RNA ≥200 c/mL through week 96. Results: Primary nucleoside/nucleotide reverse transcriptase inhibitor, nonnucleoside reverse transcriptase inhibitor, and protease inhibitor resistance substitutions were present at baseline in 4 (1.7%), 19 (7.9%), and 5 (2.1%) of 241 participants, respectively. Virologic suppression rates were high, irrespective of preexisting primary resistance substitutions, including M184I. Six participants (3 per group) had confirmed HIV-1 RNA ≥200 c/mL and did not resuppress to <50 c/mL while on study drugs; none of the 5 with postbaseline resistance data had treatment-emergent primary resistance substitutions. One participant on DTG + F/TDF with multiple virologic failures and documented nonadherence by pill count had treatment-emergent K70E and M184V/I, and subsequently resuppressed. Conclusion: In people with HIV-1 and hepatitis B virus treated with first-line B/F/TAF or DTG + F/TDF, preexisting HIV-1 resistance was uncommon and did not affect virologic suppression. No treatment-emergent HIV-1 resistance occurred with B/F/TAF, further supporting the high barrier to resistance of this regimen.

Virologic outcomes with tenofovir-lamivudine-dolutegravir in adults failing PI-based second-line ART.

In South African antiretroviral guidelines, selected patients failing second-line protease inhibitor (PI)-based therapy qualify for genotypic resistance testing - those with PI resistance receive darunavir-based third-line regimens; those without PI resistance continue current regimen with adherence support. The Western Cape province, from September 2020, implemented a strategy of tenofovir-lamivudine-dolutegravir (TLD) for patients, provided there was no tenofovir resistance, irrespective of PI resistance. To evaluate virologic outcomes with TLD among adults failing second-line PI regimens with no tenofovir resistance. An observational cohort study comparing outcomes in patients switched to TLD with those continuing the same PI or switched to darunavir-based regimens. Follow-up was until virologic suppression (HIV-1 RNA < 400 copies/mL), or at the point of censoring. One hundred and thirty-three patients switched to TLD, 101 to darunavir-based regimens, and 121 continued with the same PI. By 12 months, among patients with PI resistance, 42/47 (89%) in the TLD group had HIV-1 RNA < 400 copies/mL compared to 91/99 (92%) in the darunavir group (hazard ratio, 1.11; 95% confidence interval, 0.77-1.60). In patients without PI resistance, 66/86 (77%) in the TLD group had HIV-1 RNA < 400 copies/mL compared to 42/120 (35%) in those continuing with the same PI (hazard ratio, 4.03; 95% confidence interval, 2.71-5.98). Two patients receiving TLD developed virologic failure with high-level dolutegravir resistance. Amongst patients failing second-line PI with no PI resistance, switching to TLD was associated with higher virologic suppression, likely due to improved adherence. Virologic outcomes were similar in patients with PI resistance switched to darunavir-based regimens or TLD.

Prevalence of HIV Drug Resistance Mutations among Treatment-Naive People Living with HIV in a Tertiary Care Center in India.

India has the third-largest number of people living with HIV (PLHIV) in the world. A national program provides free access to standard uniform antiretroviral therapy. However, the program is not monitored by comprehensive drug resistance surveys. The aim of this study was to determine the prevalence of HIV drug resistance mutations (DRMs) among treatment-naive PLHIV in a large antiretroviral treatment center of the national program. This cross-sectional study was done in 2017 and involved 200 consecutive treatment-naive PLHIV. A target fragment of 1,306 bp in the reverse transcriptase and protease regions was amplified. Identification of mutations and drug resistance interpretation was done by HIV Genotypic Resistance Interpretation and International Antiviral Society-USA list. Sequencing was successful in 177 samples. The majority (98.8%; 175/177) belonged to subtype C. Nineteen of 177 patients (10.7%; 95% CI: 6.2%-15.3%) had at least one major DRM. The prevalence of non-nucleoside reverse transcriptase inhibitor (NNRTI) mutations was 10.2% (18/177). The most frequent mutations were E138A/K, A98G, K103N, V179D, and K101H/E. The prevalence of nucleoside reverse transcriptase inhibitor (NRTI) mutations was 1.1% (2/177). None of the samples had major protease inhibitor resistance mutations. The prevalence of NNRTI mutations in this study was >10%, crossing the threshold recommended by the WHO to change the NNRTI-based first-line regimen to non-NNRTI based. In 2021, the national program replaced efavirenz with dolutegravir in the first-line regimen of tenofovir, lamivudine, and efavirenz. As the majority (64%) of PLHIV in India are accessing free ART from the national program, this study highlights the need for regular nationally representative drug resistance surveys for optimizing antiretroviral regimens in the program.

HIV-1 envelope facilitates the development of protease inhibitor resistance through acquiring mutations associated with viral entry and immune escape.

There is increasing evidence supporting a role for HIV-1 envelope in the development of Protease Inhibitor drug resistance, and a recent report from our group suggested that Env mutations co-evolve with Gag-Protease mutations in the pathway to Lopinavir resistance. In this study, we investigated the effect of co-evolving Env mutations on virus function and structure. Co-receptor usage and n-linked glycosylation were investigated using Geno2Pheno as well as tools available at the Los Alamos sequence database. Molecular dynamics simulations were performed using Amber 18 and analyzed using Cpptraj, and molecular interactions were calculated using the Ring server. The results showed that under Protease Inhibitor drug selection pressure, the envelope gene modulates viral entry by protecting the virus from antibody recognition through the increased length and number of N-glycosylation sites observed in V1/V2 and to some extent V5. Furthermore, gp120 mutations appear to modulate viral entry through a switch to the CXCR4 coreceptor, induced by higher charge in the V3 region and specific mutations at the coreceptor binding sites. In gp41, S534A formed a hydrogen bond with L602 found in the disulfide loop region between the Heptad Repeat 1 and Heptad Repeat 2 domains and could negatively affect the association of gp120-gp41 during viral entry. Lastly, P724Q/S formed both intermolecular and intramolecular interactions with residues within the Kennedy loop, a known epitope. In conclusion, the results suggest that mutations in envelope during Protease Inhibitor treatment failure are related to immune escape and that S534A mutants could preferentially use the cell-to-cell route of infection.

Transmitted drug resistance to antiretroviral drugs in Spain during the period 2019-2021.

To evaluate the prevalence of transmitted drug resistance (TDR)to nucleoside and nonnucleoside reverse transcriptase inhibitors (NRTI,NNRTI),protease inhibitors (PI),and integrase strand transfer inhibitors (INSTI)in Spain during the period 2019-2021, as well as to evaluate transmitted clinically relevant resistance (TCRR)to antiretroviral drugs. Reverse transcriptase (RT),protease (Pro), and Integrase (IN)sequences from 1824 PLWH (people living with HIV) were studied. To evaluate TDR we investigated the prevalence of surveillance drug resistance mutations (SDRM).To evaluate TCRR (any resistance level ≥ 3), and for HIV subtyping we used the Stanford v.9.4.1 HIVDB Algorithm and an in-depth phylogenetic analysis. The prevalence of NRTI SDRMs was 3.8% (95% CI,2.8%-4.6%), 6.1% (95% CI,5.0%-7.3%) for NNRTI, 0.9% (95% CI,0.5%-1.4%) for PI, and 0.2% (95% CI,0.0%-0.9%) for INSTI. The prevalence of TCRR to NRTI was 2.1% (95% CI,1.5%-2.9%), 11.8% for NNRTI, (95% CI,10.3%-13.5%), 0.2% (95% CI,0.1%-0.6%) for PI, and 2.5% (95% CI,1.5%-4.1%) for INSTI. Most of the patients were infected by subtype B (79.8%), while the majority of non-Bs were CRF02_AG (n = 109, 6%). The prevalence of INSTI and PI resistance in Spain during the period 2019-2021 is low, while NRTI resistance is moderate, and NNRTI resistance is the highest. Our results support the use of integrase inhibitors as first-line treatment in Spain. Our findings highlight the importance of ongoing surveillance of TDR to antiretroviral drugs in PLWHparticularly with regard to first-line antiretroviral therapy.

Transitioning to Dolutegravir in a Programmatic Setting: Virological Outcomes and Associated Factors Among Treatment-Naive Patients With HIV-1 in the Kilombero and Ulanga Antiretroviral Cohort in Rural Tanzania.

Virological outcome data after programmatic transition from non-nucleoside reverse transcriptase inhibitor (NNRTI)-based to dolutegravir (DTG)-based antiretroviral therapy (ART) regimens in sub-Saharan Africa (SSA) outside of clinical trials are scarce. We compared viral suppression and associated factors in treatment-naïve people living with HIV (PLHIV) starting DTG- based versus NNRTI-based ART. We compared virological suppression at 12 months, after treatment initiation in the two cohorts of participants aged ≥15 years, initiating DTG- and NNRTI-based ART. Drug resistance was assessed among participants with viremia ≥50 copies/mL on DTG. Viral suppression was achieved for 165/195 (85%) and 154/211 (73%) participants in the DTG- and NNRTI- cohorts, respectively (P = 0.003). DTG-based ART was associated with >2 times the odds of viral suppression versus NNRTI-based ART (adjusted odds ratio, 2.10 [95% confidence interval {CI}, 1.12-3.94]; adjusted risk ratio, 1.11 [95% CI, 1.00-1.24]). HIV-1 genotypic resistance testing (GRT) before ART initiation was done in 14 of 30 viremic participants on DTG, among whom nucleoside reverse transcriptase inhibitor (NRTI), NNRTI, and protease inhibitors resistance was detected in 0 (0%), 2 (14%) and 1 (7%), respectively. No resistance was found in the 2 of 30 participants with available GRT at the time of viremia ≥50 copies/mL. Virological suppression at 1 year was higher in participants initiating DTG- versus NNRTI-based ART. In those with viremia ≥50 copies/mL on DTG-based ART, there was no pretreatment or acquired resistance to the DTG co-administered NRTIs, although the number of samples tested was small.

Resistance rates among antiretroviral regimens in pregnant people living with HIV.

To update nucleoside reverse transcriptase inhibitor (NRTI), nonnucleoside reverse transcriptase inhibitor (NNRTI) and protease inhibitor (PI) resistance rates and describe the frequency of HIV subtypes in a cohort of pregnant people living with HIV (PPLH) at a national Prevention of Mother-To-Child HIV Transmission (PMTCT) centre. We evaluated genotypic resistance among PPLH during prenatal care who were antiretroviral therapy-naïve or experienced. We determined mutations by the Surveillance of Drug Resistance Mutations (SDRM) dataset and also focused on studying participants with intermediate or high resistance defined through the Stanford score. From 2018 to 2021, 1170 PPLH received prenatal care at the centre and 550 were genotyped. Among the 295 SDRMs, with respect to NRTI resistance mutations, there were 27/295 (9.2%) M184V/I, 14/295 (4.7%) T215Y/C/D/E/F/V/I/S and 12/295 (4.1%) M41L. For NNRTI, there were 75/295 (25.4%) K103N, 18/295 (6.1%) M230L and 14/295 (4.7%) G190A/E/S mutations. For PI, the most frequent mutations were 13/295 (4.4%) V82A/S/F/T, 12/295 (4.1%) M46I/L and 10/295 (3.4%) D30N. Based on the Stanford score, 36/224 (16%) naïve participants had one or more antiretroviral resistance mutations, 81% of whom had NNRTI resistance. In the treatment-experience group, 108/326 (33%) had one or more mutations, 91% of whom had NNRTI resistance. The most frequent HIV subtype was B (82.5%). Our findings suggest that continuous surveys of HIV genotype appear to be important tools to map the distribution and evolution of HIV subtypes and resistance to provide information to support treatment policies. Furthermore, concerns about the use of rilpivirine-containing regimens underscore the importance of resistance surveillance.

HIV drug resistance in a community-randomized trial of universal testing and treatment: HPTN 071 (PopART).

IntroductionUniversal HIV testing and treatment (UTT) has individual and public health benefits. HPTN 071 (PopART), a community‐randomized trial in Zambia and South Africa, demonstrated that UTT decreased HIV incidence. This endpoint was assessed in a cohort of >48,000 randomly selected adults in the study communities. We evaluated the impact of UTT on HIV drug resistance in this cohort and compared other resistance‐related outcomes in participants with recent versus non‐recent HIV infection.MethodsTwo years after the start of HPTN 071 (2016–2017), 6259 participants were HIV positive and 1902 were viremic (viral load >400 copies/ml). HIV genotyping and antiretroviral (ARV) drug testing were performed for viremic participants in three groups: seroconverters (infected <1 year), non‐seroconverters (infected >1 year, random subset) and participants with unknown duration of infection (random subset). A two‐stage cluster‐based approach was used to assess the impact of the study intervention on drug resistance. Treatment failure was defined as being viremic with ARV drugs detected. Participants were classified as ARV naïve based on self‐report and ARV drug testing.ResultsGenotyping results were obtained for 758 participants (143 seroconverters; 534 non‐seroconverters; and 81 unknown duration of infection). The estimated prevalence of resistance in the study communities was 37% for all viremic persons and 11% for all HIV‐positive persons. There was no association between UTT and drug resistance. Resistance was detected in 14.0% of seroconverters and 40.8% of non‐seroconverters (non‐nucleoside reverse transcriptase inhibitor resistance: 14.0% and 39.9%; nucleoside/nucleotide reverse transcriptase inhibitor resistance: 0.7% and 15.5%; protease inhibitor resistance: 0% and 1.9%; multi‐class resistance: 0.7% and 16.1%, respectively). ARV drugs were detected in 2/139 (1.4%) of seroconverters and 94/534 (17.6%) of non‐seroconverters tested. These participants were classified as failing ART; 88 (93.6%) of the non‐seroconverters failing ART had resistance. Mutations used for surveillance of transmitted drug resistance were detected in 10.5% of seroconverters and 15.1% of non‐seroconverters who were ARV naive.ConclusionsUTT was not associated with an increase in drug resistance in this cohort. Higher rates of drug resistance and multi‐class resistance were observed in non‐seroconverters compared to seroconverters.

HIV- Bidirectional Encoder Representations From Transformers: A Set of Pretrained Transformers for Accelerating HIV Deep Learning Tasks

The human immunodeficiency virus type 1 (HIV-1) is a global health threat that is characterized by extensive genetic diversity both within and between patients, rapid mutation to evade immune controls and antiretroviral therapies, and latent cellular and tissue reservoirs that stymie cure efforts. Viral genomic sequencing has proven effective at surveilling these phenotypes. However, rapid, accurate, and explainable prediction techniques lag our sequencing ability. Modern natural language processing libraries, like the Hugging Face transformers library, have both advanced the technical field and brought much-needed standardization of prediction tasks. Herein, the application of this toolset to an array of classification tasks useful to HIV-1 biology was explored: protease inhibitor resistance, coreceptor utilization, and body-site identification. HIV-Bidirectional Encoder Representations from Transformers (BERT), a protein-based transformer model fine-tuned on HIV-1 genomic sequences, was able to achieve accuracies of 88%, 92%, and 89% on the respective tasks, making it competitive with leading models capable of only one of these tasks. This model was also evaluated using a data augmentation strategy when mutations of known function were introduced. The HIV-BERT model produced results that agreed in directionality 10- to 1000-fold better than traditional machine learning models, indicating an improved ability to generalize biological knowledge to unseen sequences. The HIV-BERT model, trained task-specific models, and the datasets used to construct them have been released to the Hugging Face repository to accelerate research in this field.

Antiretroviral Drug-Resistance Mutations on the Gag Gene: Mutation Dynamics during Analytic Treatment Interruption among Individuals Experiencing Virologic Failure.

We describe drug-resistance mutation dynamics of the gag gene among individuals under antiretroviral virologic failure who underwent analytical treatment interruption (ATI). These mutations occur in and around the cleavage sites that form the particles that become the mature HIV-1 virus. The study involved a 12-week interruption in antiretroviral therapy (ART) and sequencing of the gag gene in 38 individuals experiencing virologic failure and harboring triple-class resistant HIV strains. Regions of the gag gene surrounding the NC-p2 and p1-p6 cleavage sites were sequenced at baseline before ATI and after 12 weeks from plasma HIV RNA using population-based Sanger sequencing. Fourteen of the sixteen patients sequenced presented at least one mutation in the gag gene at baseline, with an average of 4.93 mutations per patient. All the mutations had reverted to the wild type by the end of the study. Mutations in the gag gene complement mutations in the pol gene to restore HIV fitness. Those mutations around cleavage sites and within substrates contribute to protease inhibitor resistance and difficulty in re-establishing effective virologic suppression. ART interruption in the presence of antiretroviral resistant HIV strains was used here as a practical measure for more adapted HIV profiles in the absence of ART selective pressure.

Evaluation of a Novel In-house HIV-1 Genotype Drug Resistance Assay using Clinical Samples in China.

BackgroundHIV drug resistance poses a major challenge for anti-retroviral treatment (ART) and the prevention and control of HIV epidemic.ObjectiveThe study aims to establish a novel in-house assay with high efficiency, named AP in- house method, that would be suitable for HIV-1 drug resistance detection in China.MethodsAn in-house HIV-1 genotyping method was used to sequence the partial pol gene from 60 clinical plasma samples; the results of our test were compared with a commercial ViroSeq HIV-1 genotyping system.ResultsAmong sixty samples, 58(96.7%) were successfully amplified by AP in-house method, five of them harbored viral load below 1,000 copies/ml. The genotype distribution was 43.1% CRF07_BC (25/58), 39.7% CRF01_AE (23/58), 6.9% CRF55_01B (4/58), 5.2% subtype B (3/58) and 5.2% CRF08_BC (3/58). Compared with that of the ViroSeq system, the consistent rate of these nucleotides and amino acids obtained by AP in-house method was up to 99.5 ± 0.4% and 99.5 ± 0.4%, respectively. A total of 290 HIV-1 drug resistance mutations were identified by two methods, including 126 nucleoside reverse transcriptase inhibitors (NRTIs), 145 non-nucleoside reverse transcriptase inhibitors (NNRTIs) and 19 protease inhibitors (PIs) resistance mutations. Out of them, 94.1% (273/290) were completely concordant between the AP in-house method and the ViroSeq system. ConclusionOverall, the evaluation of AP in-house method provided comparable results to those of the ViroSeq system on diversified HIV-1 subtypes in China.

Potential Associations of Mutations within the HIV-1 Env and Gag Genes Conferring Protease Inhibitor (PI) Drug Resistance

An increasing number of patients in Africa are experiencing virological failure on a second-line antiretroviral protease inhibitor (PI)-containing regimen, even without resistance-associated mutations in the protease region, suggesting a potential role of other genes in PI resistance. Here, we investigated the prevalence of mutations associated with Lopinavir/Ritonavir (LPV/r) failure in the Envelope gene and the possible coevolution with mutations within the Gag-protease (gag-PR) region. Env and Gag-PR sequences generated from 24 HIV-1 subtype C infected patients failing an LPV/r inclusive treatment regimen and 344 subtype C drug-naïve isolates downloaded from the Los Alamos Database were analyzed. Fisher’s exact test was used to determine the differences in mutation frequency. Bayesian network probability was applied to determine the relationship between mutations occurring within the env and gag-PR regions and LPV/r treatment. Thirty-five mutations in the env region had significantly higher frequencies in LPV/r-treated patients. A combination of Env and Gag-PR mutations was associated with a potential pathway to LPV/r resistance. While Env mutations were not directly associated with LPV/r resistance, they may exert pressure through the Gag and minor PR mutation pathways. Further investigations using site-directed mutagenesis are needed to determine the impact of Env mutations alone and in combination with Gag-PR mutations on viral fitness and LPV/r efficacy.

Resource and infrastructure challenges on the RESIST-2 Trial: an implementation study of drug resistance genotype-based algorithmic ART switches in HIV-2-infected adults in Senegal

BackgroundSecond-line treatment of HIV-2 in resource-limited settings (RLS) is complicated by a lack of controlled trial data, limited availability of HIV-2-active antiretroviral drugs, and inadequate access to drug resistance testing. We conducted an implementation trial of a dried blood spot- (DBS) based, drug resistance genotype-informed antiretroviral therapy (ART) switching algorithm for HIV-2-infected patients in Senegal.MethodsHIV-2-infected adults initiating or receiving ART through the Senegalese national AIDS program were invited to participate in this single-arm trial. DBS from participants with virologic failure (defined as viral load (VL) > 250 copies/mL after > 6 months on the current ART regimen) were shipped to Seattle for genotypic drug resistance testing. Participants with evidence of drug resistance in protease or reverse transcriptase were switched to new regimens according to a pre-specified algorithm. Participant clinical and immuno-virologic outcomes were assessed, as were implementation challenges.ResultsWe enrolled 152 participants. Ten were initiating ART. The remainder were ART-experienced, with 91.0% virologically suppressed (< 50 copies/mL). Problems with viral load testing capability resulted in obtaining VL results for only 227 of 613 (37.0%) participant-visits. Six of 115 participants (5.2%) with VL available after > 6 months on current ART regimen experienced virologic failure, with per-protocol genotypic testing attempted. One additional test was performed for a participant with a VL of 222 copies/mL. Genotypes from three participants showed no evidence of major drug resistance mutations, two showed nucleoside reverse transcriptase inhibitor (NRTI) resistance, one showed both NRTI and protease inhibitor resistance, and one test failed. No integrase inhibitor resistance was observed. Five of six successfully-tested participants switched to the correct regimen or received additional adherence counseling according to the algorithm; the sixth was lost to follow-up. Follow-up VL testing was available for two participants; both of these were virally suppressed (< 10 copies/mL). The trial was terminated early due to the COVID-19 pandemic (which prevented further VL and genotypic testing), planned rollout of dolutegravir-based 1st-line ART, and funding.ConclusionsThe RESIST-2 trial demonstrated that a DBS-based genotypic test can be used to help inform second-line ART decisions as part of a programmatic algorithm in RLS, albeit with significant implementation challenges.Trial registrationClinicalTrials.govNCT03394196. Registered on January 9, 2018.

HIV-1 drug resistance in adults and adolescents on protease inhibitor-based antiretroviral therapy in KwaZulu-Natal Province, South Africa

In low-middle-income countries, increasing levels of HIV drug resistance (HIVDR) on second-line protease inhibitor (PI)-based regimens are a cause for concern given the limited drug options for third-line antiretroviral therapy (ART). We conducted a retrospective analysis of routine HIV-1 genotyping laboratory data from KwaZulu-Natal, South Africa, to describe the frequency and patterns of HIVDR mutations and their consequent impact on standardised third-line regimens. This was a cross-sectional analysis of all HIV-1 genotypic resistance tests conducted by the National Health Laboratory Service in KwaZulu-Natal (January 2015 to December 2016) for adults and adolescents (age ≥10 years) on second-line PI-based ART with virological failure. We assigned a third-line regimen to each record based on a national treatment algorithm and calculated the genotypic susceptibility score (GSS) for that regimen. Of 348 samples analysed, 287 (82.5%) had at least one drug resistance mutation (DRM) and 114 (32.8%) had at least one major PI DRM. Major PI resistance was associated with longer duration on second-line ART (aOR per 6-months=1.11, 95% CI 1.04-1.19) and older age (aOR=1.03, 95% CI 1.01-1.05). Of 112 patients requiring third-line ART, 12 (10.7%) had a GSS of <2 for the algorithm-assigned third-line regimen. One-third of people failing second-line ART had significant PI DRMs. A subgroup of these individuals had extensive HIVDR, where the predicted activity of third-line ART was suboptimal, highlighting the need for continuous evaluation of outcomes on third-line regimens and close monitoring for emergent HIV-1 integrase inhibitor resistance.

HIV-1 Gag Non-Cleavage Site PI Resistance Mutations Stabilize Protease/Gag Substrate Complexes In Silico via a Substrate-Clamp

HIV-1 protease active site inhibitors are a key part of antiretroviral therapy, though resistance can evolve rendering therapy ineffective. Protease inhibitor resistance typically starts with primary mutations around the active site, which reduces inhibitor binding, protease affinity for substrate cleavage site residues P4-P4′, and viral replication. This is often followed by secondary mutations in the protease substrate-grooves which restore viral replication by increasing protease affinity for cleavage site residues P12-P5/P5′-P12′, while maintaining resistance. However, mutations in Gag alone can also result in resistance. The Gag resistance mutations can occur in cleavage sites (P12-P12′) to increase PR binding, as well as at non-cleavage sites. Here we show in silico that Gag non-cleavage site protease inhibitor resistance mutations can stabilize protease binding to Gag cleavage sites which contain structured subdomains on both sides: SP1/NC, SP2/p6, and MA/CA. The Gag non-cleavage site resistance mutations coordinated a network of H-bond interactions between the adjacent structured subdomains of the Gag substrates to form a substrate-clamp around the protease bound to cleavage site residues P12-P12′. The substrate-clamp likely slows protease disassociation from the substrate, restoring the cleavage rate in the presence of the inhibitor. Native Gag substrates can also form somewhat weaker substrate-clamps. This explains the 350-fold slower cleavage rate for the Gag CA/SP1 cleavage site in that the CA-SP1 substrate lacks structured subdomains on both sides of the cleavage site, and so cannot form a substrate-clamp around the PR.

Increased Rate of Protease Inhibitor-resistance Associated Mutations in Human Immunodeficiency Viruses Infecting Mexicans who Had Been Living Abroad

Migrants face multiple barriers to accessing health services and antiretroviral therapy (ART). We tested the hypothesis that HIV-infected ART-experienced Mexicans with a history of residence in the U.S. have a higher rate of viral drug-resistance associated mutations (RAMs) versus those without such a history. Viral genotypic resistance tests obtained from 336 HIV-infected Mexican patients throughout the country were analysed for the presence of viral-RAMs and its rate was compared between migrants and non-migrants. Adjustment for potential confounders was done though a multivariate analysis. Eighty-four Mexicans who had lived for at least 3 months in the U.S. were more likely to have three or more protease inhibitor (PI)-major RAMs (aOR=2.47; 95% CI=1.06-5.76; p < 0.05) than in 252 individuals without this background, independently of the time spent on ART. A migration background is associated with a higher likelihood of the emergence of HIV variants with decreased susceptibility to several PI.

HIV-1 subtypes and profiles of resistance to protease inhibitors in the Marajo Archipelago (Brazilian Amazon region)

The Marajo Archipelago, located in the rural area of ​​the state of Para (Amazon region of Brazil), is the region with the lowest index of human development in the country, presenting poor health services, which makes adequate epidemiological surveillance of HIV-1 infection difficult. After a serological screening enrolling 1,877 samples, three samples were diagnosed with HIV-1 and the pro gene was sequenced to evaluate the presence of resistance mutations to protease inhibitors. Molecular analyses revealed, for the first time in the region of Marajo Island, the occurrence of HIV-1 subtypes B and D, as well as the presence of transmitted high and intermediate protease inhibitors resistance mutations. The results emphasize the importance of ongoing molecular epidemiological surveillance studies in the Brazilian Amazon region because antiretroviral (ARV) resistance mutations may limit treatment options, and the presence of certain subtypes seems to influence the progression to AIDS, particularly in areas where the entry and spread of the virus can be facilitated by socio-demographic problems that expose the population to sexually transmitted infections.

Coevolved Multidrug-Resistant HIV-1 Protease and Reverse Transcriptase Influences Integrase Drug Susceptibility and Replication Fitness.

Integrase strand transfer inhibitors (InSTIs) are recommended agents in first-line combination antiretroviral therapy (cART). We examined the evolution of drug resistance mutations throughout HIV-1 pol and the effects on InSTI susceptibility and viral fitness. We performed single-genome sequencing of full-length HIV-1 pol in a highly treatment-experienced patient, and determined drug susceptibility of patient-derived HIV-1 genomes using a phenotypic assay encompassing full-length pol gene. We show the genetic linkage of multiple InSTI-resistant haplotypes containing major resistance mutations at Y143, Q148 and N155 to protease inhibitor (PI) and reverse transcriptase inhibitor (RTI) resistance mutations. Phenotypic analysis of viruses expressing patient-derived IN genes with eight different InSTI-resistant haplotypes alone or in combination with coevolved protease (PR) and RT genes exhibited similar levels of InSTI susceptibility, except for three haplotypes that showed up to 3-fold increases in InSTI susceptibility (p ≤ 0.032). The replicative fitness of most viruses expressing patient-derived IN only significantly decreased, ranging from 8% to 56% (p ≤ 0.01). Interestingly, the addition of coevolved PR + RT significantly increased the replicative fitness of some haplotypes by up to 73% (p ≤ 0.024). Coevolved PR + RT contributes to the susceptibility and viral fitness of patient-derived IN viruses. Maintaining patients on failing cART promotes the selection of fitter resistant strains, and thereby limits future therapy options.

Brief Report: Prevalence Trend of Transmitted Drug Resistance in a Prospective Cohort of Thai People With Acute HIV Infection.

The greater availability of different antiretroviral therapy regimens in developing countries may influence the emergence of transmitted drug resistance (TDR). People with acute HIV infection (AHI) represent the best opportunity for real-time monitoring of TDR. This study assessed the TDR prevalence trends over time in a Thai cohort of predominantly men who have sex with men (MSM) with AHI. At the time of RV254/SEARCH010 study (NCT00796146) enrollment and before starting ART, HIV genotyping was used to identify mutations in the reverse transcriptase and protease genes. Testing for TDR mutations was obtained by a validated in-house method with TRUGENE assay in a subset. Genotype sequences were analyzed using the Stanford University HIV Drug Resistance Database. Genotyping was performed for 573 participants with AHI. Their median age was 26 years (interquartile range 22-31), 97.4% were men, and 94.1% were MSM. Overall TDR prevalence was 7.0%, declining from 12.5% in 2009-2010 to 4.8% in 2017-2018. A declining resistance prevalence to nonnucleoside reverse transcriptase inhibitor emerged from 9.4% in 2009-2010 to 3.5% in 2017-2018 and to nucleoside reverse transcriptase inhibitor from 6.3% to 2.1%. Protease inhibitor resistance showed a decreased TDR level from 3.1% in 2009-2010 to 1.4% in 2017-2018. We report an encouraging declining trend in TDR prevalence in a Thai cohort of mainly MSM from 2009 to 2018; in 2017-2018, we observed a low TDR prevalence according to the World Health Organization definition.

The impact of Gag non-cleavage site mutations on HIV-1 viral fitness from integrative modelling and simulations.

The high mutation rate in retroviruses is one of the leading causes of drug resistance. In human immunodeficiency virus type-1 (HIV-1), synergistic mutations in its protease and the protease substrate - the Group-specific antigen (Gag) polyprotein - work together to confer drug resistance against protease inhibitors and compensate the mutations affecting viral fitness. Some Gag mutations can restore Gag-protease binding, yet most Gag-protease correlated mutations occur outside of the Gag cleavage site. To investigate the molecular basis for this, we now report multiscale modelling approaches to investigate various sequentially cleaved Gag products in the context of clinically relevant mutations that occur outside of the cleavage sites, including simulations of the largest Gag proteolytic product in its viral membrane-bound state. We found that some mutations, such as G123E and H219Q, involve direct interaction with cleavage site residues to influence their local environment, while certain mutations in the matrix domain lead to the enrichment of lipids important for Gag targeting and assembly. Collectively, our results reveal why non-cleavage site mutations have far-reaching implications outside of Gag proteolysis, with important consequences for drugging Gag maturation intermediates and tackling protease inhibitor resistance.