Major Protease Inhibitor Mutations Research Articles

Exploring Drug-Resistant Mutations in Protease Inhibitors and Subtype Distribution Among HIV-1 Positive Patients in Lorestan Province, Iran

: This study focuses on drug-resistant mutations in protease inhibitors (PIs) and the distribution of Human immunodeficiency virus type 1 (HIV-1) subtypes in Lorestan province, Iran. A total of 59 patients were categorized into two groups: Recipients of antiretroviral therapy (ART) and drug-naive individuals. Genotypic resistance testing was performed using nested PCR, followed by sequencing and analysis of the PCR product to identify drug-resistance mutations and determine the viral subtype. Among the ART recipients, 11 (78%) exhibited major mutations, while 3 (22%) had minor mutations specifically in PIs. The most commonly observed major protease inhibitor (PI) mutations were D30N (27.2%) and V32I (27.2%), followed by G48A (18.1%), L90M (18.1%), and L76V (9%). The most frequent minor PI mutations recorded were K20R (40%), L10I (20%), F53I (20%), and V11I (20%). No drug resistance was detected in drug-naive patients. Lopinavir (LPV) and nelfinavir (NFV) exhibited the highest levels of resistance, while saquinavir (SQV) and fosamprenavir (FPV) showed the highest levels of susceptibility. All participants were found to be infected with CRF35_AD, the dominant HIV-1 subtype in Iran. This study represents the first attempt in the region to analyze drug-resistant mutations in PIs among ART-experienced patients in Lorestan province. The findings contribute to ongoing efforts aimed at controlling the spread of drug-resistant HIV-1 strains.

Diversity of HIV-1 Subtypes and Transmitted Drug-resistance Mutations Among Minority HIV-1 Variants in a Turkish Cohort.

The World Health Organization (WHO) recommends the surveillance of transmitted drug resistance mutations (TDRMs) to ensure the effectiveness and sustainability of HIV treatment programs. Our aim was to determine the TDRMs and evaluate the distribution of HIV-1 subtypes using and compared next-generation sequencing (NGS) and Sanger-based sequencing (SBS) in a cohort of 44 antiretroviral treatment-naïve patients. All samples that were referred to the microbiology laboratory for HIV drug resistance analysis between December 2016 and February 2018 were included in the study. After exclusions, 44 treatment-naive adult patients with a viral load of >1000 copies/mL were analyzed. DNA sequencing for reverse transcriptase and protease regions was performed using both DeepChek ABL single round kit and Sanger-based ViroSeq HIV-1 Genotyping System. The mutations and HIV-1 subtypes were analyzed using the Stanford HIVdb version 8.6.1 Genotypic Resistance software, and TDRMs were assessed using the WHO surveillance drug-resistance mutation database. HIV-1 subtypes were confirmed by constructing a maximum-likelihood phylogenetic tree using Los Alamos IQ-Tree software. NGS identified nucleos(t)ide reverse transcriptase inhibitor (NRTI)-TDRMs in 9.1 % of the patients, non-nucleos(t)ide reverse transcriptase inhibitor (NNRTI)-TDRMs in 6.8 % of the patients, and protease inhibitor (PI)-TDRMs in 18.2 % of the patients at a detection threshold of ≥ 1 %. Using SBS, 2.3 % and 6.8 % of the patients were found to have NRTI- and NNRTI-TDRMs, respectively, but no major PI mutations were detected. M41L, L74I, K65R, M184V, and M184I related to NRTI, K103N to NNRTI, and N83D, M46I, I84V, V82A, L24I, L90M, I54V to the PI sites were identified using NGS. Most mutations were found in low-abundance (frequency range: 1.0 % - 4.7 %) HIV-1 variants, except M41L and K103N. The subtypes of the isolates were found as follows; 61.4 % subtype B, 18.2 % subtype B/CRF02_AG recombinant, 13.6 % subtype A, 4.5 % CRF43_ 02G, and 2.3 % CRF02_AG. All TDRMs, except K65R, were detected in HIV-1 subtype B isolates. The high diversity of protease site TDRMs in the minority HIV-1 variants and prevalence of CRFs were remarkable in this study. All minority HIV-1 variants were missed by conventional sequencing. TDRM prevalence among minority variants appears to be decreasing over time at our center.

Predictors of failure on second-line antiretroviral therapy with protease inhibitor mutations in Uganda

IntroductionFailure on second-line antiretroviral therapy (ART) with protease inhibitor (PI) mutations (VF-M) is on the rise. However, there is a paucity of information on the factors associated with this observation in low-income countries. Knowledge of underlying factors is critical if we are to minimize the number of PLHIV switched to costly third-line ART. Our study investigated the factors associated with VF-M.MethodsWe conducted a matched case–control analysis of patients' records kept at the Joint Clinical Research Center, starting from January 2008 to May 2018. We matched records of patients who failed the second-line ART with major PI mutations (cases) with records of patients who were virologically suppressed (controls) by a ratio of 1:3. Data analysis was conducted using STATA Version 14. Categorical variables were compared with the outcomesfailure on second-line ART with PI mutations using the Chi-square and Fisher's exact tests where appropriate. Conditional logistic regression for paired data was used to assess the association between the outcome and exposure variables, employing the backward model building procedure.ResultsOf the 340 reviewed patients' records, 53% were women, and 6.2% had previous tuberculosis treatment. Males (aOR = 2.58, [CI 1.42–4.69]), and patients concurrently on tuberculosis treatment while on second-line ART (aOR = 5.65, [CI 1.76–18.09]) had higher odds of VF-M. ART initiation between 2001 and 2015 had lower odds of VF-M relative to initiation before the year 2001.ConclusionMales and patients concomitantly on tuberculosis treatment while on second-line ART are at a higher risk of VF-M. HIV/AIDS response programs should give special attention to this group of people if we are to minimize the need for expensive third-line ART. We recommend more extensive, explorative studies to ascertain underlying factors.

Genetic diversity and antiretroviral resistance-associated mutation profile of treated and naive HIV-1 infected patients from the Northwest and Southwest regions of Cameroon.

BackgroundAntiretroviral therapy (ART) has improved the survival of HIV infected persons. However, rapid scale-up of ART and the high HIV-1 genetic variability, has greatly influenced the emergence of drug-resistant strains. This constitutes a potential threat to achieving the UNAIDS’ 90-90-90 goals by 2020. We investigated the prevalent HIV-1 genotypes, drug resistance-associated mutations and assessed some predictors of the occurrence of these mutations.MethodsThis was a hospital-based cross-sectional study conducted between October 2010 and June 2012. Participants were consecutively enrolled from selected HIV treatment centers of the Southwest and Northwest regions of Cameroon. Viral load was determined with the automated Abbott Real-time HIV-1 m2000rt System. HIV genotyping and antiretroviral resistance mutations analysis were performed using Bayer’s HIV-1 TRUGENE™ Genotyping Kit and OpenGene DNA Sequencing system. The drug resistance mutation was interpreted with the Stanford HIV database. Epidemiological data were obtained using pre-tested semi-structured questionnaires.ResultsOf the 387 participants, 239 were successfully genotyped. The median age of these participants was 33 years (interquartile range, IQR: 28–40 years), and a majority (65.7%) were female. A total of 29.3% of the participants were receiving ART. The median duration of ART was 10.5 months (IQR: 4–17.25 months). The median CD4 count and log10 viral load of study participants were 353.5 cells/ml (IQR:145–471) and 4.89 copies/ml (IQR: 3.91–5.55) respectively. CRF02 (A/G) (69%) was the most prevalent subtype followed by G (8.2%) and F (6.7%). Overall, resistance mutations were present in 37.1% of ART-experienced and 10.7% of ART-naive patients. Nucleoside reverse transcriptase inhibitors (NRTI) mutations occurred in 30% of ART-experienced and 2.4% of ART-naïve patients, while non-nucleoside reverse transcriptase inhibitors (NNRTI) mutations occurred in 34.2% of ART-experienced and 10.1% of -naïve patients. M184V (8.4%, 20/239) and K103N (5.4%, 13/239) were the most prevalent mutations. Major protease inhibitor mutations occurred in 3 (1.3%) out of the 239 sequences. The duration of ART independently predicted the occurrence of resistance mutation among ART-experienced patients.ConclusionThe high resistance to NNRTIs, which are the main support to the backbone (NRTIs) first-line antiretroviral regimen in Cameroon, has prompted the need to rollout an integrase strand transfer inhibitor regimen (containing Dolutegravir) with a higher genetic barrier to resistance as the preferred first line regimen.

Major drug resistance mutations to HIV-1 protease inhibitors (PI) among patients exposed to PI class failing antiretroviral therapy in São Paulo State, Brazil.

BackgroundProtease inhibitors (PI) are especially important in salvage therapy. Previous treatment failure with a PI containing regimen may elicit resistance mutations, reducing PI susceptibility and limiting treatment options. The aim of this study was to describe major PI mutations among patients exposed to at least one PI to evaluate predictors of mutation emergence and the impact of subtypes on resistance.MethodologyPartial HIV-1 pol sequences (Sanger Sequencing) from patients exposed to PI with virological failure were genotyped from January 2014 to December 2017. Drug resistance mutations (DRM), antiretroviral susceptibility (GSS) and subtypes, along clinical and laboratory parameters, were evaluated using logistic regression to access the predictors of mutation emergence.ResultsIn 27.5% (466/1696) of the cases at least one major PI mutations was identified, most commonly M46 (14.7%), V82 (13.8%) and I54 (13.3%). Mutations to NRTI and NNRTI were observed in 69.6% and 59.9%, respectively, of the 1696 sequences. Full activity to darunavir was predicted in 88% (1496/1696), but was only 57% among those with at least one PI-DRM. Subtype C sequences had less major PI-DRMs (10%, 9/87) compared to B (28%, 338/1216) or F (35%, 58/168) (p <0.001) but adjusted analysis suggested that this association is not independent from a shorter treatment time and fewer regimens (OR 0.59, Confidence Interval 95: 0.2–2.5, p = 0.48). Subtype F, together with NRTI mutations and longer time on treatment was associated to presence of PI-DRM, to a lower darunavir GSS and to mutations at codon I50.ConclusionsAmong patients with PI-DRM, full activity to darunavir was compromised in almost half of the cases and efforts to detect failure at earlier time are warranted, particularly for HIV-1 subtype F that showed association to the emergence of resistance, with potential impact in protease inhibitors sequencing. Furthermore, NRTI mutations may serve as an indicative of sufficient adherence to allow PI-DRM emergence.

Characterisation of protease resistance mutations in a South African paediatric cohort with virological failure, 2011 - 2017.

Advances in HIV management have improved treatment outcomes in the HIV-infected population. However, these advances have not been without multifaceted challenges. In sub-Saharan Africa, their impact is reflected in the increased emergence of HIV drug resistance mutations. With the rise in exposure of children to protease inhibitors (PIs), the possibility of increasing PI resistance remains a concern. To describe a group of antiretroviral-experienced children with PI drug resistance mutations after failure on first- or second-line regimens in a public sector setting in South Africa. This was a retrospective cohort study of 22 children perinatally infected with HIV who had HIV genotyping conducted between January 2011 and December 2017. Of the 236 children who had HIV genotyping conducted, 22 (9.3%) had evidence of HIV PI resistance mutations. Twenty-one of the 22 children (95.5%) had major mutations in the protease region of the HIV genome. Of these children, 66.7% (14/21) had loss of response to both boosted lopinavir and atazanavir, with boosted darunavir remaining susceptible in only 12 (57.1%). The most frequent major PI mutations were V82A (76.2%), M46I/M46L (76.2%), I54V (62.0%) and L76V (33.3%). We observed a high rate of PI resistance mutations, with a resulting loss of PIs that could be used in construction of third-line regimens. To build on improvements from the introduction of antiretroviral therapy, increased efforts are needed by both health professionals and caregivers to improve adherence measures in children perinatally infected with HIV.

Determinants of Viral Resuppression or Persistent Virologic Failure After Initial Failure With Second-Line Antiretroviral Treatment Among Asian Children and Adolescents With HIV.

Of 56 children with perinatally acquired human immunodeficiency virus (HIV) who had been prescribed second-line protease inhibitor-based antiretroviral therapy and had ≥1 previous episode of viral failure (HIV RNA, ≥1000 copies/mL), 46% had ≥1, 34% had ≥2, and 23% had ≥3 consecutive episodes of viral failure during the 2 years of follow-up. Two of these children experienced a major protease inhibitor mutation.

HIV-1 Drug Resistance Mutations among Antiretroviral Drug-Experienced Patients in the South of Iran

Background: The therapeutic effect of antiretroviral therapy (ART) is adversely influenced by antiretroviral drug resistance, mainly due to mutations (DRMs) in the human immunodeficiency virus (HIV) genome. These mutations are commonly associated with HIV protease and reverse-transcriptase genes. We sought to determine the frequency of DRMs in a population of ART-experienced patients in the South of Iran. Method: A total of 44 HIV-1-positive participants under ART were selected from April 2016 to March 2017. Their DRMs, antiretroviral resistance status, and viral subtypes were determined. Results: At least one DRM was detected in 61.4% of the participants. The highest frequency was related to nucleotide reverse-transcriptase inhibitor (NRTI) mutations (45.45%). In contrast, major protease inhibitor (PI) mutations had the lowest frequency (6.81%). M184V (40.9%) and K103N (25%), respectively related to NRTI and nonnucleoside reverse-transcriptase inhibitor (NNRTI), were the mutations with the highest frequencies. Susceptibility to PI drugs was higher compared to NRTIs and NNRTIs, which was consistent with the results of genotypic DRMs. Conclusion: The highest frequency of antiretroviral DRMs was related to NRTIs and NNRTIs. In contrast, PI resistance mutations had the lowest frequency. Laboratory-guided ART to avoid the expansion of mutants as well as investigating DRMs in other viral regions, such as integrase, are recommended.

HIV-1 drug resistance testing at second-line regimen failure in Arua, Uganda: avoiding unnecessary switch to an empiric third-line.

The number of patients on second-line antiretroviral therapy is growing, but data on HIV drug resistance patterns at failure in resource-constrained settings are scarce. We aimed to describe drug resistance and investigate the factors associated with extensive resistance to nucleoside/nucleotide reverse transcriptase inhibitors (NRTI), in patients failing second-line therapy in the HIV outpatient clinic at Arua Regional Referral Hospital, Uganda. We included patients who failed on second-line therapy (two consecutive viral loads ≥1000 copies/mm3 by SAMBA-1 point-of-care test) and who had a drug resistance test performed between September 2014 and March 2017. Logistic regression was used to investigate factors associated with NRTI genotypic sensitivity score (GSS) ≤1. Seventy-eight patients were included: 42% female, median age 31years and median time of 29months on second-line therapy. Among 70 cases with drug resistance test results, predominant subtypes were A (47%) and D (40%); 18.5% had ≥1 major protease inhibitor mutation; 82.8% had ≥1 NRTI mutation and 38.5% had extensive NRTI resistance (NRTI GSS ≤1). A nadir CD4 count ≤100/ml was associated with NRTI GSS ≤1 (OR 4.2, 95% CI [1.3-15.1]). Thirty (42.8%) patients were switched to third-line therapy, composed of integrase inhibitor and protease inhibitor (60% darunavir/r)+/-NRTI. A follow-up viral load was available for 19 third-line patients at 12months: 84.2% were undetectable. Our study highlights the need for access to drug resistance tests to avoid unnecessary switches to third-line therapy, but also for access to third-line drugs, in particular integrase inhibitors. Low nadir CD4 count might be an indicator of third-line drug requirement for patients failing second-line therapy.

HIV-1 Drug Resistance and Third-Line Therapy Outcomes in Patients Failing Second-Line Therapy in Zimbabwe.

ObjectivesTo analyze the patterns and risk factors of HIV drug resistance mutations among patients failing second-line treatment and to describe early treatment responses to recommended third-line antiretroviral therapy (ART) in a national referral HIV clinic in Zimbabwe.MethodsPatients on boosted protease inhibitor (PI) regimens for more than 6 months with treatment failure confirmed by 2 viral load (VL) tests >1000 copies/mL were genotyped, and susceptibility to available antiretroviral drugs was estimated by the Stanford HIVdb program. Risk factors for major PI resistance were assessed by logistic regression. Third-line treatment was provided as Darunavir/r, Raltegravir, or Dolutegravir and Zidovudine, Abacavir Lamivudine, or Tenofovir.ResultsGenotypes were performed on 86 patients who had good adherence to treatment. The median duration of first- and second-line ART was 3.8 years (interquartile range [IQR], 2.3–5.1) and 2.6 years (IQR, 1.6–4.9), respectively. The median HIV viral load and CD4 cell count were 65 210 copies/mL (IQR, 8728–208 920 copies/mL) and 201 cells/mm3 (IQR, 49–333 cells/mm3). Major PI resistance-associated mutations (RAMs) were demonstrated in 44 (51%) non-nucleoside reverse transcriptase inhibitor RAMs in 72 patients (83%) and nucleoside reverse transcriptase inhibitors RAMs in 62 patients (72%). PI resistance was associated with age >24 years (P = .003) and CD4 cell count <200 cells/mm3 (P = .007). In multivariable analysis, only age >24 years was significantly associated (adjusted odds ratio, 4.75; 95% confidence interval, 1.69–13.38; P = .003) with major PI mutations. Third-line DRV/r- and InSTI-based therapy achieved virologic suppression in 29/36 patients (81%) after 6 months.ConclusionsThe prevelance of PI mutations was high. Adolescents and young adults had a lower risk of acquiring major PI resistance mutations, possibly due to poor adherence to ART. Third-line treatment with a regimen of Darunavir/r, Raltegravir/Dolutegravir, and optimized nucleoside reverse transcriptase inhibitors was effective.

Prevalence of HIV-1 transmitted drug resistance in recently infected, treatment-naïve persons in the Southwest of Iran, 2014-2015.

The emergence and transmission of drug resistant HIV mutants is a major concern, especially in resource-limited countries with expanding antiretroviral therapy. Studies have recently reported the prevalence of HIV-1 transmitted drug resistance (TDR) mutations in certain Iranian cities; however, no information is currently available about the level of TDR, as well as the nature of the circulating HIV-1 subtypes, in the Southwestern bordering province of Iran, Khuzestan. Herein, we used a WHO-recommended TDR survey method to classify the prevalence of TDR in indigenous people of Khuzestan province. For this purpose, between March 2014 and February 2015, blood samples were collected from 52 newly diagnosed, antiretroviral treatment-naïve, HIV-1 infected persons aged from 18 to 30 years. TDR mutations were determined by sequencing the protease (PR) and reverse transcriptase (RT) genes and interpreted using the WHO drug resistance mutations surveillance list. HIV-1 subtypes were characterized by sequencing the PR-RT, C2-V5, and p17 regions of the pol, env and gag genes, respectively. Two participants had non-nucleoside reverse transcriptase inhibitor (NNRTI) resistance mutations, specifically K103N in one individual and K101EK/K103KN/G190AG in the other. No nucleoside reverse transcriptase inhibitor (NRTI) or major protease inhibitor (PI) mutations were identified. HIV-1 subtyping revealed that all participants were infected with HIV-1 CRF35_AD. According to the WHO sequential sampling method, the prevalence of HIV-1 TDR in the sampling area (Khuzestan province) was classified as moderate for NNRTIs and low for NRTIs and PIs. This is the first HIV-1 drug resistance threshold survey in the Khuzestan province of Iran and shows a predominance of NNRTI TDR mutations in this area.

Prevalence of Antiretroviral Drug Resistance in Patients Who Are Not Responding to Protease Inhibitor-Based Treatment: Results From the First National Survey in South Africa.

Limited data exist on human immunodeficiency virus type 1 (HIV-1) resistance in patients who are not responding to protease inhibitor (PI)-based regimens in resource-limited settings. This study assessed resistance profiles in adults across South Africa who were not responding to PI-based regimens. pol sequencing was undertaken and submitted to the Stanford HIV Drug Resistance Database. At least 1 major PI mutation was detected in 16.4% of 350 participants. A total of 53.4% showed intermediate resistance to darunavir/ritonavir, whereas high-level resistance was not observed. Only 5.2% and 32.8% of participants showed high-level and intermediate resistance to etravirine, respectively. Although the prevalence of major PI mutations was within previously reported ranges, most patients will likely experience virological suppression during receipt of currently available South African third-line regimens.

Outcome of patients on second line antiretroviral therapy under programmatic condition in India.

BackgroundThe National AIDS Control Organization of India has been providing free second line antiretroviral therapy (ART) since 2008. This observational study reports the survival and virologic suppression of patients on second-line ART under programmatic condition and type of mutations acquired by those failing therapy.Methods170 patients initiated on second-line therapy between 2008 and 2012 were followed up till 2013. Viral Load (VL) was repeated at 6 months for all patients and at 12 months for those with VL >400 copies/ml at 6 months. Adequate virological response was defined as plasma HIV-1 VL <400 copies/ml and virological failure was defined as VL >1000 copies/ml. Genotyping was done in 16 patients with virological failure.ResultsOut of 170 patients, 110 (64.7 %) were alive and on therapy and 35 (20.5 %) expired. In the first year the occurrence of death was 13.7 /100 person years while between1 and 5 year it was 3.88 /100 person years. In the first year, duration of immunological failure >12 months, weight <45 kg, WHO clinical stage 3 and 4 and WHO criteria CD4 count less than pretherapy baseline [hazard ratio HR 4.2. 15.8, 11.9 & 4.1 respectively] and beyond first year poor first and second line adherence and first line CD4 count < 200/μL [HR 5.2,15.8, 3.3 respectively] had high risk of death.119/152 (78.2 %) had adequate virological response and 27/152 (17.7 %) had virological failure. High viral load at baseline and poor second line adherence (Odds Ratio 3.4 & 2.8 respectively) had increased risk of virological failure. Among those genotyped, 50 % had major Protease Inhibitor mutation (M46I commonest) however 87.5 % were still susceptible to darunavir.ConclusionsSecond line therapy has shown high early mortality but good virological suppression under programmatic conditions.

Factors Associated with the Development of Drug Resistance Mutations in HIV-1 Infected Children Failing Protease Inhibitor-Based Antiretroviral Therapy in South Africa.

ObjectiveLimited data are available from the developing world on antiretroviral drug resistance in HIV-1 infected children failing protease inhibitor-based antiretroviral therapy, especially in the context of a high tuberculosis burden. We describe the proportion of children with drug resistance mutations after failed protease inhibitor-based antiretroviral therapy as well as associated factors.MethodsData from children initiated on protease inhibitor-based antiretroviral therapy with subsequent virological failure referred for genotypic drug resistance testing between 2008 and 2012 were retrospectively analysed. Frequencies of drug resistance mutations were determined and associations with these mutations identified through logistic regression analysis.ResultsThe study included 65 young children (median age 16.8 months [IQR 7.8; 23.3]) with mostly advanced clinical disease (88.5% WHO stage 3 or 4 disease), severe malnutrition (median weight-for-age Z-score -2.4 [IQR -3.7;-1.5]; median height-for-age Z-score -3.1 [IQR -4.3;-2.4]), high baseline HIV viral load (median 6.04 log10, IQR 5.34;6.47) and frequent tuberculosis co-infection (66%) at antiretroviral therapy initiation. Major protease inhibitor mutations were found in 49% of children and associated with low weight-for-age and height-for-age (p = 0.039; p = 0.05); longer duration of protease inhibitor regimens and virological failure (p = 0.001; p = 0.005); unsuppressed HIV viral load at 12 months of antiretroviral therapy (p = 0.001); tuberculosis treatment at antiretroviral therapy initiation (p = 0.048) and use of ritonavir as single protease inhibitor (p = 0.038). On multivariate analysis, cumulative months on protease inhibitor regimens and use of ritonavir as single protease inhibitor remained significant (p = 0.008; p = 0.033).ConclusionMajor protease inhibitor resistance mutations were common in this study of HIV-1-infected children, with the timing of tuberculosis treatment and subsequent protease inhibitor dosing strategy proving to be important associated factors. There is an urgent need for safe, effective, and practicable HIV/tuberculosis co-treatment in young children and the optimal timing of treatment, optimal dosing of antiretroviral therapy, and alternative tuberculosis treatment strategies should be urgently addressed.

Treatment-Emergent Mutations and Resistance in HIV-Infected Children Treated with Fosamprenavir-Containing Antiretroviral Regimens.

Treatment-emergent mutations and drug resistance were analyzed in virus from HIV-infected children meeting virologic failure (VF) criteria over 48 weeks following treatment with unboosted fosamprenavir or fosamprenavir/ritonavir-containing regimens in studies APV20002 and APV29005. Both antiretroviral therapy (ART)-naïve and ART-experienced patients were enrolled. Patients met VF criteria by either failing to suppress HIV-RNA to <400 copies/mL through week 24 or after confirmed viral rebound (≥400 copies/mL) anytime through week 48. Viral isolates were analyzed for treatment-emergent mutations or reduced drug susceptibility. Through week 48, 25/109 (23%) of APV29005 and 9/54 (17%) APV20002 study patients met VF. VF was more common in ART-experienced patients (68% and 78%, respectively). Major or minor treatment-emergent mutations were detected at VF in virus from 3 patients receiving unboosted fosamprenavir-containing regimens and in virus from 10 patients receiving fosamprenavir/ritonavir-containing regimens across the two studies. Major protease inhibitor mutations and the reverse transcriptase mutation M184V were detected at VF in virus from 4 and 5 patients, respectively, across both studies. Reduced drug susceptibility to any drug emerged in virus from 9 patients at VF, although reduced fosamprenavir susceptibility emerged in virus from only 4 patients (2 ART-naïve and 2 ART-experienced). No cross-resistance to the protease inhibitor darunavir was observed.In conclusion, given the high proportion of ART-experienced children (71%) in these two studies, the overall incidence of children meeting VF criteria through 48 weeks was relatively low (21%) and development of fosamprenavir reduced drug susceptibility at VF was uncommon, further supporting the use of fosamprenavir-containing ART regimens in HIV-infected children.

HIV drug resistance mutations among patients failing second-line antiretroviral therapy in Rwanda.

Studies of patients failing second-line antiretroviral therapy (ART) in resource-limited settings (RLS) are few. Evidence suggests most patients who appear to be virologically failing do so not due to drug resistance but to poor adherence, which, if properly addressed, could allow continued use of less expensive first- and second-line regimens. Drug resistant mutations (DRMs) were characterized among patients virologically failing second-line ART in Rwanda. A total of 128 adult patients receiving second-line ART for at least 6 months were invited to participate; 74 agreed and had HIV-1 viral load (VL) measured. Resistance genotypes were conducted in patients with virological failure (VF; that is, VL ≥1,000 copies/ml). In total, 35 patients met the criteria for VF. The median time on lopinavir/ritonavir-based second-line ART was 2.7 years. Of 30 successful resistance genotype analyses, 13 (43%) had ≥1 nucleoside reverse transcriptase inhibitor (NRTI) mutation, 18 (60%) had at least 1 non-NRTI mutation and 5 (17%) had at least 1 major protease inhibitor mutation. Eleven (37%) had virus without significant mutations that would be fully sensitive to first-line ART; 12 (40%) had DRM to first-line ART but sensitive to second-line ART. Only 7 patients (23%) demonstrated a DRM profile requiring third-line ART. Among 30 genotyped samples of patients with VF on second-line ART, more than one-third had no significant DRMs, implicating poor adherence as the primary cause of VF. The majority of patients (77%) would not have required third-line ART. These findings reinforce the need for intensive adherence assessment and counselling for patients who appear to be failing second-line ART in RLS.

Gag drug resistance mutations in HIV-1 subtype C patients, failing a protease inhibitor inclusive treatment regimen, with detectable lopinavir levels.

The development of antiretroviral (ARV) drugs and their use in human immunodeficiency virus type 1 (HIV-1) has led to the effective control of HIV replication in infected patients. However the emergence of resistant HIV-1 strains still remains a problem. Literature has shown that mutations may accumulate in the protease (PR) and gag regions of HIV-1 patients who fail therapy with protease inhibitor (PI) drugs [1, 2]. Gag mutations have also been found to play an important role in the evolution of PI resistance [2]. Despite this, the standard genotypic drug-resistance test examines mutations in the reverse transcriptase (RT) and PR region of HIV-1 and not gag [3]. This study investigated the frequency of gag drug resistance mutations in the absence of major PI mutations in HIV-1 subtype C patients, failing a PI inclusive treatment regimen. Sixty-eight samples were retrieved from patients that were classified as second line treatment failures as they had a viral load greater than 1000 copies\\mL, as well as detectable lopinavir (LPV) levels. The gag and protease region of these patients were genotyped. Mutations in the gag and protease region were assessed using the REga Db sequencing tool and the CPR programme on the Stanford University HIV drug resistance database. The mean LPV level of these samples was 11.66 µg/mL. 69.11% (n=46) of the patients have no major PI mutations in protease. The following mutations that are associated with PI exposure were present in the data set: G62R (n=6), H219Q (n=11), S737T (n=8), I389T (n=8) and Q474L (n=7). Predictably, mutations that are associated with PI resistance were found, which are generally located in the p7/p1 and p1/p6 cleavage site. These mutations are K436R (n=4), I437V (n=1), L449P (n=5), R452K (n=4) and P453L\\T (n=9). These results contribute to the knowledge of resistance mutations in gag and their impact on PI resistance.

Long-Term Outcome of Second-Line Antiretroviral Therapy in Resource-Limited Settings

There is limited information on efficacy and durability of second-line antiretroviral therapy (2NL) beyond 12 months in resource-limited settings. A total of 73 patients were enrolled into a prospective 2NL observational cohort in Nigeria. Second-line antiretroviral therapy consisted of lopinavir/ritonavir plus nucleoside reverse transcriptase inhibitors. Time on 2NL ranged from 15 to 31 months. Genotypes were retrospectively done and not available to guide second-line regimen choice. At enrollment, median CD4 count was 121 cells/mm3, and median time on first-line antiretroviral therapy (ISL) was 24 months. At 6 to 9 months on 2NL, 72.6% (intention to treat [ITT]) and 88.3% (on treatment [OT]) had an undetectable viral load (UDVL). At 12 months, 65.8% (ITT) and 90.57% (OT) had UDVL. At >12 to 24 months and at >24 months, 57.5% (ITT) and 91.3% (OT) had UDVL. No statistically significant association was observed between CD4 at 2NL start, sex, genotypic sensitivity score of 2NL, or tenofovir (TDF) use in ISL and viral suppression. Two patients developed major protease inhibitor mutations while on 2NL. We observed a high degree of viral suppression at 12 months and little loss of viral suppression thereafter.

Drug resistance in children at virological failure in a rural KwaZulu-Natal, South Africa, cohort

BackgroundBetter understanding of drug resistance patterns in HIV-infected children on antiretroviral therapy (ART) is required to inform public health policies in high prevalence settings. The aim of this study was to characterise the acquired drug resistance in HIV-infected children failing first-line ART in a decentralised rural HIV programme.MethodsPlasma samples were collected from 101 paediatric patients (≤15 yrs of age) identified as failing ART. RNA was extracted from the plasma, reverse transcribed and a 1.3 kb region of the pol gene was amplified and sequenced using Sanger sequencing protocols. Sequences were edited in Geneious and drug resistance mutations were identified using the RegaDB and the Stanford resistance algorithms. The prevalence and frequency of mutations were analysed together with selected clinical and demographic data in STATA v11.ResultsA total of 101 children were enrolled and 89 (88%) were successfully genotyped; 73 on a non-nucleoside reverse-transcriptase inhibitor (NNRTI)-based regimen and 16 on a protease inhibitor (PI)-based regimen at the time of genotyping. The majority of patients on an NNRTI regimen (80%) had both nucleoside reverse-transcriptase inhibitor (NRTI) and NNRTI resistance mutations. M184V and K103N were the most common mutations amongst children on NNRTI-based and M184V among children on PI-based regimens. 30.1% had one or more thymidine analogue mutation (TAM) and 6% had ≥3 TAMs. Only one child on a PI-based regimen harboured a major PI resistance mutation.ConclusionsWhilst the patterns of resistance were largely predictable, the few complex resistance patterns seen with NNRTI-based regimens and the absence of major PI mutations in children failing PI-based regimens suggest the need for wider access to genotypic resistance testing in this setting.

Evaluation of a Benchtop HIV Ultradeep Pyrosequencing Drug Resistance Assay in the Clinical Laboratory

Detection of low-abundance drug resistance mutations (DRMs) of HIV-1 is an evolving approach in clinical practice. Ultradeep pyrosequencing has shown to be effective in detecting such mutations. The lack of a standardized commercially based assay limits the wide use of this method in clinical settings. 454 Life Sciences (Roche) is developing an HIV ultradeep pyrosequencing assay for their benchtop sequencer. We assessed the prototype plate in the clinical laboratory. Plasma samples genotyped by the standardized TruGene kit were retrospectively tested by this assay. Drug-treated subjects failing therapy and drug-naive patients were included. DRM analysis was based on the International AIDS Society USA DRM list and the Stanford algorithm. The prototype assay detected all of the DRMs detected by TruGene and additional 50 low-abundance DRMs. Several patients had low-abundance D67N, K70R, and M184V reverse transcriptase inhibitor mutations that persisted long after discontinuation of the drug that elicited these mutations. Additional patient harbored low-abundance V32I major protease inhibitor mutation, which under darunavir selection evolved later to be detected by TruGene. Stanford analysis suggested that some of the low-abundance DRMs were likely to affect the resistance burden in these subjects. The prototype assay performs at least as well as TruGene and has the advantage of detecting low-abundance drug resistance mutations undetected by TruGene. Its ease of use and lab-scale platform will likely facilitate its use in the clinical laboratory. The extent to which the detection of low-abundance DRMs will affect patient management is still unknown, but it is hoped that use of such an assay in clinical practice will help resolve this important question.