Protease Inhibitor Resistance Research Articles

The prevalence of primary HIV-1 drug resistance in newly reported HIV infections in Henan

To study the prevalence of primary HIV-1 drug resistance in newly reported HIV infected individuals receiving no antiviral treatment in Henan. Network direct reporting information of newly reported HIV infection cases in six cities of Henan during January to June, 2013 and January to June, 2014 were collected, and blood samples were collected from the cases to conduct genotypic drug resistance test and sequence analysis. Primary HIV-1 drug resistance was detected in 45 of 624 newly reported HIV infection cases, the prevalence of primary HIV-1 drug resistance was 7.21%, which was classified as moderate. Univariate analysis revealed that the prevalence of primary HIV-1 drug resistance was higher in females(χ(2)=11.463, P = 0.001), in age group <20 years(χ(2)=8.969, P=0.011), in illiterates(χ(2)=18.072, P=0.001)and in cases of HIV subtype B infection(χ(2)=9.897, P=0.019). Multi-univariate analysis revealed that the risk of primary HIV-1 drug resistance was high in females(OR=2.194, 95%CI: 1.111-4.331). Non-nucleoside reverse transcriptase inhibitor(NNRTI), Nucleoside reverse transcriptase inhibitor(NRTI)and Protease inhibitor(PI)resistance mutations were found in 4.97%, 3.53% and 1.12% of the cases, respectively. M184V/I(2.08%)and K103N/S(2.88%)were the most commonly emerged NRTI and NNRTI resistance mutation. Multiple NRTI resistance mutation was found in four cases. HIV subtype B infections accounted for largest proportion(51.76%, 323/624), followed by CRF07_BC cases(23.72%, 148/624)and CRF01_AE cases(19.71%, 123/624). The prevalence of primary HIV-1 drug resistance was moderate in the newly reported HIV infected individuals in Henan. The surveillance for HIV-1 drug resistance transmission should be strengthened and drug resistance test before the antiviral treatment should be given.

Hepatitis C Virus Genotype 1 to 6 Protease Inhibitor Escape Variants: In Vitro Selection, Fitness, and Resistance Patterns in the Context of the Infectious Viral Life Cycle.

Hepatitis C virus (HCV) NS3 protease inhibitors (PIs) are important components of novel HCV therapy regimens. Studies of PI resistance initially focused on genotype 1. Therefore, knowledge about the determinants of PI resistance for the highly prevalent genotypes 2 to 6 remains limited. Using Huh7.5 cell culture-infectious HCV recombinants with genotype 1 to 6 NS3 protease, we identified protease positions 54, 155, and 156 as hot spots for the selection of resistance substitutions under treatment with the first licensed PIs, telaprevir and boceprevir. Treatment of a genotype 2 isolate with the newer PIs vaniprevir, faldaprevir, simeprevir, grazoprevir, paritaprevir, and deldeprevir identified positions 156 and 168 as hot spots for resistance; the Y56H substitution emerged for three newer PIs. Substitution selection also depended on the specific recombinant. The substitutions identified conferred cross-resistance to several PIs; however, most substitutions selected under telaprevir or boceprevir treatment conferred less resistance to certain newer PIs. In a single-cycle production assay, across genotypes, PI treatment primarily decreased viral replication, which was rescued by PI resistance substitutions. The substitutions identified resulted in differential effects on viral fitness, depending on the original recombinant and the substitution. Across genotypes, fitness impairment induced by resistance substitutions was due primarily to decreased replication. Most combinations of substitutions that were identified increased resistance or fitness. Combinations of resistance substitutions with fitness-compensating substitutions either rescued replication or compensated for decreased replication by increasing assembly. This comprehensive study provides insight into the selection patterns and effects of PI resistance substitutions for HCV genotypes 1 to 6 in the context of the infectious viral life cycle, which is of interest for clinical and virological HCV research.

Resistance-associated mutations to HCV protease inhibitors naturally pre-existed in HIV/HCV coinfected, treatment-naïve patients

Presently, it has been approved to treat hepatitis C virus (HCV) infection with protease inhibitors (PIs). In the present study, we aimed to illustrate the natural prevalence of HCV NS3/4A PI resistance mutations in HIV/HCV coinfected, treatment-naïve patients. Population sequence analysis of the NS3/4A protease was conducted in 96 HIV/HCV coinfected, treatment-naïve patients. Complete HCV NS3/4A sequence information was obtained from 70 (72.92%) samples, including 68 patients (97.14%) with genotype 1b and 2 patients (2.86%) with genotype 2a. A total of 21 patients (30.88%) of the 68 patients with HCV genotype 1b showed amino acid substitutions associated with HCV PI resistance. Mutation F43S was observed in 1.47% of patients with genotype 1b. The mutations of T54S, Q80K/R, R155K, A156G and D168A/E/G were found in 4.41%, 1.47%/1.47%, 2.94%, 23.53% and 1.47%/1.47%/1.47% of patients with genotype 1b, respectively. In addition, 4.41% of patients with genotype 1b showed double mutations in the NS3 region. The multiple mutations of Q80R+R155K+D168G and Q80K+R155K+A156G+D168A were detected in 1.47% and 1.47% of patients with HCV genotype 1b, respectively. The most predominant HCV genotype was 1b in patients with HIV/HCV coinfection. Naturally occurring mutations resistant to HCV PIs (simeprevir, vaniprevir, boceprevir, telaprevir, asunaprevir and paritaprevir) pre-existed in patients with HIV/HCV genotype 1b coinfection. The effects of baseline PI resistance on treatment outcome should be further analyzed.

Long-Term Efficacy, Tolerability, and Renal Safety of Atazanavir/Ritonavir-based Antiretroviral Therapy in a Cohort of Treatment-Naïve Patients with HIV-1 Infection: the REMAIN Study

Background: Boosted protease inhibitors (PIs), including ritonavir-boosted atazanavir (ATV/r), are a recommended option for the initial treatment of HIV-1 infection based upon clinical trial data; however, long-term real-life clinical data are limited.Objective: We evaluated the long-term use of ATV/r as a component of antiretroviral combination therapy in the real-life setting in the REMAIN study.Methods: This was an observational cohort study conducted at sites across Germany, Portugal, and Spain. Retrospective historical and prospective longitudinal follow-up data were extracted every six months from medical records of HIV-infected treatment-naïve patients aged ≥ 18 years initiating a first-line ATV/r-containing regimen.Results: Eligible patients (n = 517) were followed up for a median of 3.4 years. The proportion remaining on ATV/r at 5 years was 51.5% with an estimated Kaplan-Meier median time to treatment discontinuation of 4.9 years. Principal reasons for discontinuation were adverse events (15.9%; 8.9% due to hyperbilirubinemia) and virologic failure (6.8%). The Kaplan-Meier probability of not having virologic failure (HIV-1 RNA < 50 copies/mL) was 0.79 (95% CI: 0.75, 0.83) at five years. No treatment-emergent major PI resistance occurred. ATV/r was generally well tolerated during long-term treatment with no significant changes in estimated glomerular filtration rate over five years.Conclusions: In a real-life clinical setting over five years, treatment-naïve patients with HIV-1 infection initiating an ATV/r-based regimen showed sustained virologic suppression, an overall treatment persistence rate of 51.5%, an absence of treatment-emergent major PI resistance mutations at virologic failure, a long-term safety profile consistent with that observed in clinical trials, and no significant decline in renal function.

An Update on HIV-1 Protease Inhibitor Resistance

Protease inhibitors (PIs) are a potent class of antiretroviral agents which have been used to successfully treat many patients with HIV disease. As with other classes of antiretroviral agents, drug resistance has been described with each of the PIs. PI resistance can occur in newly infected individuals due to transmission of drug resistant strains or, more commonly, evolves from the selective pressure of antiretroviral therapy. When present, PI resistance results in an increased likelihood of drug failure. Individual protease gene mutations have been identified which are associated with phenotypic resistance to these agents. However, protease mutations can exert different effects on individual PIs, as some will produce resistance to one agent and may enhance susceptibility to another. In patients failing PIs, particularly in the setting of prior treatment with multiple agents, protease resistance patterns may be complex and result in broad cross-resistance to the class. Strategies to limit the development of resistance to these agents and manage its occurrence are important for the on-going care of individuals with HIV infection.

Third-line antiretroviral therapy in Africa: effectiveness in a Southern African retrospective cohort study.

Background An increasing number of patients in Africa are experiencing virologic failure on second-line antiretroviral therapy (ART) and those who develop resistance to protease inhibitors (PI) will require third-line ART, but no data on the outcomes of third-line are available from the region. We assessed the virologic outcomes and survival of patients started on salvage ART in a Southern African private sector disease management programme.Methods Retrospective observational cohort study with linkage to the national death register. Adults (≥18 years) who started salvage ART between July 2007 and December 2011 were included. Salvage ART was defined by inclusion of darunavir or tipranavir in an ART regimen after having failed another PI. For Kaplan–Meier (KM) analysis, patients were followed up until event, or censored at death (only for virologic outcomes), leaving the programme, or April 2014.Results152 patients were included. Subtype was known for 113 patients: 111 (98 %) were infected with subtype C. All 152 had a genotype resistance test demonstrating major PI resistance mutations. Salvage drugs included were: darunavir/ritonavir (n = 149), tipranavir/ritonavir (n = 3), raltegravir (n = 58), and etravirine (n = 8). Median follow-up was 2.5 years (IQR = 1.5–3.3). 82.9 % achieved a viral load ≤400 copies/ml and 71.1 % ≤50 copies/ml. By the end of the study 17 (11.2 %) of the patients had died. The KM estimate of cumulative survival was 87.2 % at 2000 days.ConclusionsVirologic suppression was comparable to that demonstrated in clinical trials and observational studies of salvage ART drugs conducted in other regions. Few deaths occurred during short term follow-up. Third-line regimens for patients with multidrug resistant subtype C HIV in Africa are virologically and clinically effective.

Four Amino Acid Changes in HIV-2 Protease Confer Class-Wide Sensitivity to Protease Inhibitors.

Protease is essential for retroviral replication, and protease inhibitors (PI) are important for treating HIV infection. HIV-2 exhibits intrinsic resistance to most FDA-approved HIV-1 PI, retaining clinically useful susceptibility only to lopinavir, darunavir, and saquinavir. The mechanisms for this resistance are unclear; although HIV-1 and HIV-2 proteases share just 38 to 49% sequence identity, all critical structural features of proteases are conserved. Structural studies have implicated four amino acids in the ligand-binding pocket (positions 32, 47, 76, and 82). We constructed HIV-2ROD9 molecular clones encoding the corresponding wild-type HIV-1 amino acids (I32V, V47I, M76L, and I82V) either individually or together (clone PRΔ4) and compared the phenotypic sensitivities (50% effective concentration [EC50]) of mutant and wild-type viruses to nine FDA-approved PI. Single amino acid replacements I32V, V47I, and M76L increased the susceptibility of HIV-2 to multiple PI, but no single change conferred class-wide sensitivity. In contrast, clone PRΔ4 showed PI susceptibility equivalent to or greater than that of HIV-1 for all PI. We also compared crystallographic structures of wild-type HIV-1 and HIV-2 proteases complexed with amprenavir and darunavir to models of the PRΔ4 enzyme. These models suggest that the amprenavir sensitivity of PRΔ4 is attributable to stabilizing enzyme-inhibitor interactions in the P2 and P2' pockets of the protease dimer. Together, our results show that the combination of four amino acid changes in HIV-2 protease confer a pattern of PI susceptibility comparable to that of HIV-1, providing a structural rationale for intrinsic HIV-2 PI resistance and resolving long-standing questions regarding the determinants of differential PI susceptibility in HIV-1 and HIV-2. Proteases are essential for retroviral replication, and HIV-1 and HIV-2 proteases share a great deal of structural similarity. However, only three of nine FDA-approved HIV-1 protease inhibitors (PI) are active against HIV-2. The underlying reasons for intrinsic PI resistance in HIV-2 are not known. We examined the contributions of four amino acids in the ligand-binding pocket of the enzyme that differ between HIV-1 and HIV-2 by constructing HIV-2 clones encoding the corresponding HIV-1 amino acids and testing the PI susceptibilities of the resulting viruses. We found that the HIV-2 clone containing all four changes (PRΔ4) was as susceptible as HIV-1 to all nine PI. We also modeled the PRΔ4 enzyme structure and compared it to existing crystallographic structures of HIV-1 and HIV-2 proteases complexed with amprenavir and darunavir. Our findings demonstrate that four positions in the ligand-binding cleft of protease are the primary cause of HIV-2 PI resistance.

Naturally occurring hepatitis C virus protease inhibitors resistance-associated mutations among chronic hepatitis C genotype 1b patients with or without HIV co-infection

The aim of this study was to measure the frequency of natural mutations in hepatitis C virus (HCV) mono-infected and HIV/HCV co-infected protease inhibitor (PI)-naive patients. Population sequence of the non-structural (NS)3 protease gene was evaluated in 90 HCV mono-infected and 96 HIV/HCV co-infected PI treatment-naive patients. The natural prevalence of PI resistance mutations in both groups was compared. Complete HCV genotype 1b NS3 sequence information was obtained for 152 (81.72%) samples. Seven sequences (8.33%) of the 84 HCV mono-infected patients and 21 sequences (30.88%) of the 68 HIV/HCV co-infected patients showed amino acid substitutions associated with HCV PI resistance. There was a significant difference in the natural prevalence of PI resistance mutations between these two groups (P = 0.000). The mutations T54S, R117H and N174F were observed in 1.19%, 5.95% and 1.19% of HCV mono-infected patients. The mutations F43S, T54S, Q80K/R, R155K, A156G/V, D168A/E/G and V170A were found in 1.47%, 4.41%, 1.47%/1.47%, 2.94%, 23.53%/1.47%, 1.47%/1.47%/1.47% and 1.47% of HIV/HCV co-infected patients, respectively. In addition, the combination mutations in the NS3 region were detected only in HIV/HCV genotype 1b co-infected patients. Naturally occurring HCV PI resistance mutations existed in HCV mono-infected and HIV/HCV co-infected genotype 1b PI-naive patients. HIV co-infection was associated with a greater frequency of PI resistance mutations. The impact of HIV infection on baseline HCV PI resistance mutations and treatment outcome in chronic hepatitis C (CHC) patients should be further analyzed.

Analysis of HIV-1 drug resistance among 1 922 individuals experiencing virological failure of first-line antiretroviral therapy in Henan province

To study the condition of HIV-1 drug resistance mutation among failures of first-line antiretroviral therapy in Henan province. The sub platform of China's legal infectious disease monitoring information reporting system-HIV/AIDS integrated prevention and control data information management system was used to collect the information of patients experiencing first-line antiretroviral treatment failure (virus load ≥ 1 000 copies/ml) more than one year among nine cities of Henan in 2011. A total of 40 cases with no information and 212 cases with incomplete drug resistance results were deleted, and 1 922 cases were included in this study and genotype resistance testing was carried out. Non-conditional logistic regression analysis was used to analyse the influencing factors of drug resistance mutation. A total of 1 922 cases were included in the analysis. 1 039 cases were males, 833 cases were females, the age was (45.7 ± 12.1) years, 82.73% (1 590) were married, and 87.93% (1 690) were transmitted by blood. 64.20% (1 234) patients acquired drug resistance. Nucleoside reverse transcriptase inhibitor (NRTI), non-nucleoside reverse transcriptase inhibitor (NNRTI) and protease inhibitor (PI) resistance mutations were found in 62.59% (1 203), 49.74% (956) and 0.94% (18) of subjects, respectively. 42.09% (809) of patients harbored NRTI and NNRTI resistance mutations synchronously. ≥ 1TAM was the most commonly emerged NRTI resistance mutation (41.94% (806)), the prevalences of TAM-1 and TAM-2 were 8.48% (163) and 4.24% (81), respectively. K65R/N and Q151M complex existed in 23 and 4 patients, respectively. K103N/S was the most commonly emerged NNRTI resistance mutation (34.32% (659)). Non-conditional logistic regression analysis showed that, factors associated with high drug resistance were the following: transmitted by mother to child (OR = 9.05, 95% CI: 1.14-72.12), clinical stage was IV (OR = 1.70, 95% CI: 1.09-2.66) and 5-year-treated (OR = 1.59, 95% CI: 1.03-2.47). Factors associated with low drug resistance were the following: 1-year-treated (OR = 0.19, 95% CI: 0.13-0.27). Complex patterns of HIV-1 drug resistance mutations were identified among individuals experiencing failure of first-line antiretroviral therapy in Henan province. Factors associated with high drug resistance were lived in Luohe, Shangqiu, Nanyang, Xinyang, transmitted by mother to child, clinical stage was IV, and 5-year-treated.

Elucidation of the Molecular Mechanism Driving Duplication of the HIV-1 PTAP Late Domain.

HIV-1 uses cellular machinery to bud from infected cells. This cellular machinery is comprised of several multiprotein complexes known as endosomal sorting complexes required for transport (ESCRTs). A conserved late domain motif, Pro-Thr-Ala-Pro (PTAP), located in the p6 region of Gag (p6(Gag)), plays a central role in ESCRT recruitment to the site of virus budding. Previous studies have demonstrated that PTAP duplications are selected in HIV-1-infected patients during antiretroviral therapy; however, the consequences of these duplications for HIV-1 biology and drug resistance are unclear. To address these questions, we constructed viruses carrying a patient-derived PTAP duplication with and without drug resistance mutations in the viral protease. We evaluated the effect of the PTAP duplication on viral release efficiency, viral infectivity, replication capacity, drug susceptibility, and Gag processing. In the presence of protease inhibitors, we observed that the PTAP duplication in p6(Gag) significantly increased the infectivity and replication capacity of the virus compared to those of viruses bearing only resistance mutations in protease. Our biochemical analysis showed that the PTAP duplication, in combination with mutations in protease, enhances processing between the nucleocapsid and p6 domains of Gag, resulting in more complete Gag cleavage in the presence of protease inhibitors. These results demonstrate that duplication of the PTAP motif in p6(Gag) confers a selective advantage in viral replication by increasing Gag processing efficiency in the context of protease inhibitor treatment, thereby enhancing the drug resistance of the virus. These findings highlight the interconnected role of PTAP duplications and protease mutations in the development of resistance to antiretroviral therapy. Resistance to current drug therapy limits treatment options in many HIV-1-infected patients. Duplications in a Pro-Thr-Ala-Pro (PTAP) motif in the p6 domain of Gag are frequently observed in viruses derived from patients on protease inhibitor (PI) therapy. However, the reason that these duplications arise and their consequences for virus replication remain to be established. In this study, we examined the effect of PTAP duplication on PI resistance in the context of wild-type protease or protease bearing PI resistance mutations. We observe that PTAP duplication markedly enhances resistance to a panel of PIs. Biochemical analysis reveals that the PTAP duplication reverses a Gag processing defect imposed by the PI resistance mutations in the context of PI treatment. The results provide a long-sought explanation for why PTAP duplications arise in PI-treated patients.

Rationale and clinical utility of the darunavir-cobicistat combination in the treatment of HIV/AIDS.

This article is to provide an update overview of cobicistat (COBI)-boosted darunavir in response to its recent approval by the US Food and Drug Administration, and inclusion as an alternative first-line regime in the 2015 treatment guidelines in the US. COBI is a relatively new non-antiretroviral cytochrome P450 3A inhibitor or pharmacoenhancer. The rationale behind COBI development was to provide an alternative to ritonavir (RTV) as a protease inhibitor pharmacoenhancer, due to associated adverse events with short- and long-term RTV use, such as gastrointestinal intolerability, drug–drug interactions, insulin resistance, lipodystrophy, and hyperlipidemia. Although in vitro studies suggest that COBI may result in a lower incidence of undesired drug–drug interactions and lipid-associated disorders than RTV, not all Phase III studies have well addressed these issues, and the data are limited. However, Phase III studies have demonstrated tolerability, noninferiority, and bioequivalence of COBI compared to RTV. Two main advantages of COBI over RTV-containing regimes have been noted as follows: 1) COBI has no anti-HIV activity; therefore, resistance to COBI as a booster in addition to protease inhibitor resistance is of little concern, allowing for COBI-containing regimes in future. 2) COBI’s solubility and dissolution rate allow for co-formulated/fixed-dose combination products. Nonetheless, prior to initiating COBI-containing treatment regimens, the following should be considered: 1) COBI may increase serum creatinine levels and reduce estimated glomerular filtration rate (GFR) without affecting actual GFR; 2) potential drug–drug interaction data are insufficient, warranting caution when initiating COBI in conjunction with concomitant medication or in individuals with multiple comorbidities; 3) food plays a pivotal role in boosting darunavir exposure, warranting caution and patient education on the importance of taking COBI-containing regimens with appropriate amounts of food; and 4) data on the success of COBI-containing regimens in treatment-experienced patients are limited.

Substitutions at NS3 Residue 155, 156, or 168 of Hepatitis C Virus Genotypes 2 to 6 Induce Complex Patterns of Protease Inhibitor Resistance.

Various protease inhibitors (PIs) currently are becoming available for treatment of hepatitis C virus (HCV). For genotype 1, substitutions at NS3 protease positions 155, 156, and 168 are the main determinants of PI resistance. For other genotypes, similar substitutions were selected during PI treatment but were not characterized systematically. To elucidate the impact of key PI resistance substitutions on genotypes 2 to 6, we engineered the substitutions R155A/E/G/H/K/Q/T, A156G/S/T/V, and D/Q168A/E/G/H/N/V into HCV recombinants expressing genotype 2 to 6 proteases. We evaluated viral fitness and sensitivity to nine PIs (telaprevir, boceprevir, simeprevir, asunaprevir, vaniprevir, faldaprevir, paritaprevir, deldeprevir, and grazoprevir) in Huh7.5 cells. We found that most variants showed decreased fitness compared to that of the original viruses. Overall, R155K, A156G/S, and D/Q168A/E/H/N/V variants showed the highest fitness; however, genotype 4 position 168 variants showed strong fitness impairment. Most variants tested were resistant to several PIs. Resistance levels varied significantly depending on the specific substitution, genotype, and PI. For telaprevir and boceprevir, specific 155 and 156, but not 168, variants proved resistant. For the remaining PIs, most genotype 2, 4, 5, and 6, but not genotype 3, variants showed various resistance levels. Overall, grazoprevir (MK-5172) had the highest efficacy against original viruses and variants. This is the first comprehensive study revealing the impact of described key PI resistance substitutions on fitness and PI resistance of HCV genotypes 2 to 6. In conclusion, the studied substitutions induced resistance to a panel of clinically relevant PIs, including the newer PIs paritaprevir, deldeprevir, and grazoprevir. We discovered complex patterns of resistance, with the impact of substitutions varying from increased sensitivity to high resistance.

Evidence for Reduced Drug Susceptibility without Emergence of Major Protease Mutations following Protease Inhibitor Monotherapy Failure in the SARA Trial.

BackgroundMajor protease mutations are rarely observed following failure with protease inhibitors (PI), and other viral determinants of failure to PI are poorly understood. We therefore characterized Gag-Protease phenotypic susceptibility in subtype A and D viruses circulating in East Africa following viral rebound on PIs.MethodsSamples from baseline and treatment failure in patients enrolled in the second line LPV/r trial SARA underwent phenotypic susceptibility testing. Data were expressed as fold-change in susceptibility relative to a LPV-susceptible reference strain.ResultsWe cloned 48 Gag-Protease containing sequences from seven individuals and performed drug resistance phenotyping from pre-PI and treatment failure timepoints in seven patients. For the six patients where major protease inhibitor resistance mutations did not emerge, mean fold-change EC50 to LPV was 4.07 fold (95% CI, 2.08–6.07) at the pre-PI timepoint. Following viral failure the mean fold-change in EC50 to LPV was 4.25 fold (95% CI, 1.39–7.11, p = 0.91). All viruses remained susceptible to DRV. In our assay system, the major PI resistance mutation I84V, which emerged in one individual, conferred a 10.5-fold reduction in LPV susceptibility. One of the six patients exhibited a significant reduction in susceptibility between pre-PI and failure timepoints (from 4.7 fold to 9.6 fold) in the absence of known major mutations in protease, but associated with changes in Gag: V7I, G49D, R69Q, A120D, Q127K, N375S and I462S. Phylogenetic analysis provided evidence of the emergence of genetically distinct viruses at the time of treatment failure, indicating ongoing viral evolution in Gag-protease under PI pressure.ConclusionsHere we observe in one patient the development of significantly reduced susceptibility conferred by changes in Gag which may have contributed to treatment failure on a protease inhibitor containing regimen. Further phenotype-genotype studies are required to elucidate genetic determinants of protease inhibitor failure in those who fail without traditional resistance mutations whilst PI use is being scaled up globally.

P17.28 Assessment of hiv-1 primary drug resistance mutations in antiretroviral therapy-naive cases in morocco

Antiretroviral drug resistance is a major challenge for management and control of HIV-1 infection worldwide and particularly in resource limited countries. Although combined antiretroviral drug therapy has greatly improved the life-span and the life quality of the patients, HIV-1 drug resistance poses a major obstacle for treatment outcome. This study aims to determine the prevalence of primary resistance in a group of newly diagnosed patients naive to treatment, in the region of Souss Massa Draa in sounthern Morocco. A total of 47 antiretroviral treatment (ART) naive patients were included. Virological status was determined by Real time PCR (Abbott, USA). Primary drug resistance mutations were identified according to the Stanford HIV database and the algorithm of the National Agency for AIDS Research (ANRS). The clinical staging of patients was made upon the International Classification of the Centres for Disease Control (CDC). Ninetheen 19% of recruits were diagnosed in stage A, 11% in stage B, and the large proportion of patients in stage C 38%, while 32% of which the stadium has not been determined. VLs Rates among patients ranged from 5000 to 10 million copies/ml, with a large majority of patients (42.55%) whom VL was estimated from 10 000 and 100 000 copies/ml. Most prevalent HIV-1 subtypes were subtype B (74%); and CRF02_G (26%). Drug resistance exploration showed that 17% of the studied group carry at least one resistant mutation that confers resistance to non-nucleoside reverse transcriptase inhibitors (NNRTIs), and 13% have at least one NRTI resistance mutation, while no major resistance mutation was detected for protease inhibitors (IPs). Detected mutations were as follows: M41L, K70E, M184V, L210W and T215C/D/S, responsible for nucleoside RT inhibitor (NRTI) resistance; K103N/S M230L and V106I, responsible for non-nucleoside RT inhibitor (NNRTI) resistance; M46L and L90M, responsible for protease inhibitor (PI) resistance. The primary resistance rate observed in the study group was estimated at 8.5% (4/47). This rate describes the primary resistance level in this region as a moderate level (between 5 and 15%), requiring continuous monitoring of resistance in patients immediately after diagnosis of infection and prior to initiation of treatment antiretroviral. Disclosure of interest statement Nothing to declare.

HIV-1 protease inhibitor drug resistance in Kenyan antiretroviral treatment-naive and -experienced injection drug users and non-drug users.

BackgroundAlthough injection drug use drives antiretroviral drug resistance, the prevalence of protease inhibitor (PI) resistance among Kenyan IDUs remains undetermined. We, therefore, explored PI resistance mutations and their association with viral load and CD4+ T cell counts in HIV-1 infected IDUs (ART-naive, n = 32; and -experienced, n = 47) and non-drug users (ART-naive, n = 21; and -experienced, n = 32) naive for PI treatment from coastal Kenya.ResultsOnly IDUs harboured major PI resistance mutations consisting of L90M, M46I and D30 N among 3 (6.4 %) ART-experienced and 1 (3.1 %) -naive individuals. Minor PI mutations including A71T, G48E, G48R, I13V, K20I, K20R, L10I, L10V, L33F, L63P, T74S, V11I, and V32L were detected among the ART-experienced (36.2 vs. 46.9 %) and -naive (43.8 vs. 66.7 %) IDUs and non-drug users, respectively. All the four IDUs possessing major mutations had high viral load while three presented with CD4+ T cell counts of <500 cells/ml. Among the ART-naive non-drug users, CD4+ T cell counts were significantly lower in carriers of minor mutations compared to non-carriers (P < 0.05).ConclusionTransmitted drug resistance may occur in IDUs underscoring the need for genotyping resistance before initiating PI treatment.

Characterization of drug resistance mutations in ART-naïve HIV-1 infected children in Northern Vietnam

ObjectiveTo investigate the profile of drug resistance-associated mutations in pol gene of antiretroviral therapy-naïve HIV-1 infected children enrolled in National Hospital Pediatrics in Northern Vietnam. MethodsGenotyping was performed on 134 antiretroviral therapy-naïve plasma samples from HIV-1 infected children. HIV-1 pol gene was amplified using primers for protease and reverse transcriptase and sequenced using the BigDye chemistry. The mutations were analyzed based on the Stanford University HIV-1 Drug Resistance Database and ISA-USA list. ResultsAll the children were infected with HIV-1 CRF01_AE subtype. Major protease inhibitor resistance mutations were found in 2 children (2.3%) and reverse-transcriptase inhibitor resistance mutations were found in 5 children (7.7%). The protease inhibitor mutations were observed M46L and L90M and reverse-transcriptase inhibitor mutations were M184I, K65R, Q151M, T69N, L210W, Y181C, M230L and K101E. ConclusionsThis is the first study reporting the prevalence of drug resistance-associated mutation in naïve HIV-1 infected children in Northern Vietnam. These data also emphasize the importance of genotypic resistance testing of HIV-1 infected children before initiating treatment in order to achieve better clinical outcome.

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.

HIV resistance testing and detected drug resistance in Europe.

To describe regional differences and trends in resistance testing among individuals experiencing virological failure and the prevalence of detected resistance among those individuals who had a genotypic resistance test done following virological failure. Multinational cohort study. Individuals in EuroSIDA with virological failure (>1 RNA measurement >500 on ART after >6 months on ART) after 1997 were included. Adjusted odds ratios (aORs) for resistance testing following virological failure and aORs for the detection of resistance among those who had a test were calculated using logistic regression with generalized estimating equations. Compared to 74.2% of ART-experienced individuals in 1997, only 5.1% showed evidence of virological failure in 2012. The odds of resistance testing declined after 2004 (global P < 0.001). Resistance was detected in 77.9% of the tests, NRTI resistance being most common (70.3%), followed by NNRTI (51.6%) and protease inhibitor (46.1%) resistance. The odds of detecting resistance were lower in tests done in 1997-1998, 1999-2000 and 2009-2010, compared to those carried out in 2003-2004 (global P < 0.001). Resistance testing was less common in Eastern Europe [aOR 0.72, 95% confidence interval (CI) 0.55-0.94] compared to Southern Europe, whereas the detection of resistance given that a test was done was less common in Northern (aOR 0.29, 95% CI 0.21-0.39) and Central Eastern (aOR 0.47, 95% CI 0.29-0.76) Europe, compared to Southern Europe. Despite a concurrent decline in virological failure and testing, drug resistance was commonly detected. This suggests a selective approach to resistance testing. The regional differences identified indicate that policy aiming to minimize the emergence of resistance is of particular relevance in some European regions, notably in the countries in Eastern Europe.

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

BackgroundIn Henan, China, first-line antiretroviral treatment (ART) was implemented early in a large number of treatment-experienced patients who were more likely to have a drug resistance. Therefore, we investigated the human immunodeficiency virus (HIV)-1 drug resistance profiles among patients in Henan who experienced virological failure to ART.MethodA cross-sectional survey was administered in 10 major epidemic cities from May 2010 to October 2011. Adult patients who experienced virological failure (virus load ≥1,000 copies/mL) with >1 year of first-line antiretroviral treatment consented to provide blood for genotype resistance testing. The clinical and demographic data were obtained from the patients’ medical records. Logistic regression analysis was performed to determine the factors associated with ≥1 significant drug resistance mutation.ResultsWe included 3,235 patients with integral information and valid genotypic resistance data. The city, age, CD4 counts, virus load, treatment duration, and World Health Organization stage were associated with drug resistance, and 64.76% of patients acquired drug resistance. The nucleoside reverse transcriptase inhibitor (NRTI), non-(N)NRTI, and protease inhibitor resistance mutations were found in 50.26, 63.12, and 1.30% of subjects, respectively. Thymidine analogue mutations, NNRTI and even multidrug resistance complex were quite common in this patient cohort.ConclusionMultiple and complex patterns of HIV-1 drug resistance mutations were identified among individuals who experienced virological failure to first-line ART in Henan, China during 2010–2011. Therefore, timely virological monitoring, therapy adjustments, and more varieties of drugs and individualized treatment should be immediately considered in this patient population.

Single Genome Analysis for the Detection of Linked Multiclass Drug Resistance Mutations in HIV-1-Infected Children After Failure of Protease Inhibitor-Based First-Line Therapy.

The WHO recommends protease inhibitor (PI)-based antiretroviral therapy (ART) for vertically infected children after failed nevirapine (NVP) prophylaxis. Emergence of PI resistance on the backdrop of preexisting non-nucleoside reverse transcriptase inhibitor (NNRTI) resistance could compromise long-term treatment options in such children. We characterized multiclass drug resistance using single genome sequencing (SGS) in children with viremia while receiving PI-based ART. We applied SGS of HIV-1 protease (PR) and reverse transcriptase to longitudinal samples from a cohort of the Children with HIV Early Antiretroviral Therapy trial with viral loads >1000 copies per milliliter after 40 weeks of early ART. Bulk sequencing revealed NVP-selected resistance in 50% of these children, whereas SGS revealed NVP-selected resistance in 70%. Two children had baseline NRTI and PI mutations, suggesting previous maternal ART. Linked multiclass drug resistance after PI-based ART was detected by SGS in 2 of 10 children. In one child, the majority species contained M184V in reverse transcriptase linked to L10F, M46I/L, I54V, and V82A in PR and a triple-class drug-resistant variant with these mutations linked to the NNRTI mutation V108I. In the second child, the majority species contained M184V and V82A linked within viral genomes. We conclude that when PI-based ART is initiated soon after birth after single dose-NVP prophylaxis, PI and NRTI resistance can occur in the majority species as expected and also be selected on the same genomes as preexisting NNRTI-resistant mutations. These observations highlight a future therapeutic challenge for vertically infected children where antiretroviral drug classes are limited.