Tracking the prevalence of transmitted antiretroviral drug-resistant HIV-1: a decade of experience

Moderate prevalence of HIV-1 transmitted drug resistance mutations in southern Brazil

Background

Despite the advances in therapy, the occurrence of drug-resistant human immunodeficiency virus type 1 (HIV-1) is a major obstacle to successful treatment. This study aimed to characterize the genetic diversity and to determine the prevalence of transmitted drug resistance mutations (TDRM) between individuals recently or chronically diagnosed with HIV-1 from Paraná, Brazil.

Methods

A total of 260 HIV-1 positive antiretroviral therapy-naïve patients were recruited to participate on the study, of which 39 were recently diagnosed. HIV-1 genotyping was performed using sequencing reaction followed by phylogenetic analyses to determine the HIV-1 subtype. TDRM were defined using the Calibrated Population Resistance Tool program.

Results

The HIV-1 subtypes frequency found in the studied population were 54.0% of subtype B, 26.7% subtype C, 6.7% subtype F1 and 12.7% recombinant forms. The overall prevalence of TDRM was 6.7%, including 13.3% for recently diagnosed subjects and 5.9% for the chronic group.

Conclusions

The prevalence of resistance mutations found in this study is considered moderate, thus to perform genotyping tests before the initiation of antiretroviral therapy may be important to define the first line therapy and contribute for the improvement of regional prevention strategies for epidemic control.

Electronic supplementary material

The online version of this article (10.1186/s12981-019-0219-1) contains supplementary material, which is available to authorized users.

Implementation of a point mutation assay for HIV drug resistance testing in Kenya

OBJECTIVES

An increasing prevalence of HIV pretreatment drug resistance (PDR) has been observed in Africa, which could decrease the effectiveness of antiretroviral therapy (ART) programs. We describe our experiences, the costs and challenges of implementing an oligonucleotide ligation assay (OLA) for management of PDR in Nairobi, Kenya.

DESIGN

An observational report of the implementation of OLA in a Kenyan laboratory for a randomized clinical trial evaluating whether onsite use of OLA in individuals initiating ART would decrease rates of virologic failure.

METHODS

Compared detection of mutations and proportion of mutants in participants' viral quasispecies by OLA in Kenya vs. Seattle. Reviewed records of laboratory workflow and performance of OLA. Calculated the costs of laboratory set-up and of performing the OLA based on equipment purchase receipts and supplies and labor utilization, respectively.

RESULTS

OLA was performed on 492 trial participants. Weekly batch-testing of median of seven (range: 2-13) specimens provided test results to Kenyan clinicians within 10-14 days of sample collection at a cost of US$ 42 per person tested. Cost of laboratory setup was US$ 32 594. Challenges included an unreliable local supply chain for reagents and the need for an experienced molecular biologist to supervise OLA performance.

CONCLUSION

OLA was successfully implemented in a Kenyan research laboratory. Cost was twice that projected because of fewer than predicted specimens per batch because of slow enrollment. OLA is a potential simple, low-cost method for PDR testing in resource-limited settings (RLS). Ongoing work to develop a simplified kit could improve future implementation of OLA in RLS.

HIV-1C proviral DNA for detection of drug resistance mutations

Background

Using HIV proviral DNA as a template may be suitable for initial detection of transmitted drug resistance mutations (TDRMs) as it is easy to handle and less expensive compared to RNA. However, existing literatures which are mainly focused on HIV-1B subtypes DNA extracted from PBMCs revealed controversial findings ranging from the detection of significantly lower or higher mutations in proviral DNA compared to historic viral RNA. Thus, to verify whether viral RNA or proviral DNA has improved sensitivity in detecting transmitted genotypic drug resistance mutations paired viral RNA and proviral DNA (which is directly extracted from stored whole blood) samples were tested from Ethiopian antiretroviral naive HIV-1C infected subjects.

Methods

In the present comparative study the frequency of TDR mutations was assessed in paired samples of viral RNA and proviral DNA (extracted directly from stored whole blood) of HIV-1C infected treatment naïve patients and interpreted using the 2009 WHO drug resistance surveillance mutation lists, Stanford University drug resistance data base and International Antiviral Society-USA mutation lists.

Results

High agreement in rate of TDR between the two compartments was observed using the WHO mutation lists. While mutations G190A and E138A were concurrently found in both compartments, others such as G73S on PR and A62V, M184I, M230I on RT were identified in proviral DNA only. All signature mutations seen in viral RNA were not missed in proviral DNA.

Conclusions

The concordance of major genotype drug resistance mutation between RNA and proviral DNA in treatment naïve patients suggests that proviral DNA might be an alternative approaches for an initial assessment of drug resistance prior to initiation of antiretroviral therapy using the WHO mutations lists in resource-limited countries. However, the clinical importance of TDRMs observed only in proviral DNA in terms of being a risk factor for virologic failure and whether they limit future treatment options needs additional investigation using more sensitive sequencing approaches such as Next Generation Sequencing (NGS).

Successes and challenges in optimizing the viral load cascade to improve antiretroviral therapy adherence and rationalize second-line switches in Swaziland

INTRODUCTION

As antiretroviral therapy (ART) is scaled up, more patients become eligible for routine viral load (VL) monitoring, the most important tool for monitoring ART efficacy. For HIV programmes to become effective, leakages along the VL cascade need to be minimized and treatment switching needs to be optimized. However, many HIV programmes in resource-constrained settings report significant shortfalls.

METHODS

From a public sector HIV programme in rural Swaziland, we evaluated the VL cascade of adults (≥18 years) on ART from the time of the first elevated VL (>1000 copies/mL) between January 2013 and June 2014 to treatment switching by December 2015. We additionally described HIV drug resistance for patients with virological failure. We used descriptive statistics and Kaplan-Meier estimates to describe the different steps along the cascade and regression models to determine factors associated with outcomes.

RESULTS AND DISCUSSION

Of 828 patients with a first elevated VL, 252 (30.4%) did not receive any enhanced adherence counselling (EAC). Six hundred and ninety-six (84.1%) patients had a follow-up VL measurement, and the predictors of receiving a follow-up VL were being a second-line patient (adjusted hazard ratio (aHR): 0.72; p = 0.051), Hlathikhulu health zone (aHR: 0.79; p = 0.013) and having received two EAC sessions (aHR: 1.31; p = 0.023). Four hundred and ten patients (58.9%) achieved VL re-suppression. Predictors of re-suppression were age 50 to 64 (adjusted odds ratio (aOR): 2.02; p = 0.015) compared with age 18 to 34 years, being on second-line treatment (aOR: 3.29; p = 0.003) and two (aOR: 1.66; p = 0.045) or three (aOR: 1.86; p = 0.003) EAC sessions. Of 278 patients eligible to switch to second-line therapy, 120 (43.2%) had switched by the end of the study. Finally, of 155 successfully sequenced dried blood spots, 144 (92.9%) were from first-line patients. Of these, 133 (positive predictive value: 92.4%) had resistance patterns that necessitated treatment switching.

CONCLUSIONS

Patients on ART with high VLs were more likely to re-suppress if they received EAC. Failure to re-suppress after counselling was predictive of genotypically confirmed resistance patterns requiring treatment switching. Delays in switching were significant despite the ability of the WHO algorithm to predict treatment failure. Despite significant progress in recent years, enhanced focus on quality care along the VL cascade in resource-limited settings is crucial.

Role of Gag mutations in PI resistance in the Swiss HIV cohort study: bystanders or contributors?

Background

HIV Gag mutations have been reported to confer PI drug resistance. However, clinical implications are still controversial and most current genotyping algorithms consider solely the protease gene for assessing PI resistance.

Objectives

Our goal was to describe for HIV infections in Switzerland the potential role of the C-terminus of Gag (NC-p6) in PI resistance. We aimed to characterize resistance-relevant mutational patterns in Gag and protease and their possible interactions.

Methods

Resistance information on plasma samples from 2004-12 was collected for patients treated by two diagnostic centres of the Swiss HIV Cohort Study. Sequence information on protease and the C-terminal Gag region was paired with the corresponding patient treatment history. The prevalence of Gag and protease mutations was analysed for PI treatment-experienced patients versus PI treatment-naive patients. In addition, we modelled multiple paths of an assumed ordered accumulation of genetic changes using random tree mixture models.

Results

More than half of all PI treatment-experienced patients in our sample set carried HIV variants with at least one of the known Gag mutations, and 17.9% (66/369) carried at least one Gag mutation for which a phenotypic proof of PI resistance by in vitro mutagenesis has been reported. We were able to identify several novel Gag mutations that are associated with PI exposure and therapy failure.

Conclusions

Our analysis confirmed the association of Gag mutations, well known and new, with PI exposure. This could have clinical implications, since the level of potential PI drug resistance might be underestimated.

Prevalence and trends in transmitted and acquired antiretroviral drug resistance, Washington, DC, 1999-2014

Background

Drug resistance limits options for antiretroviral therapy (ART) and results in poorer health outcomes among HIV-infected persons. We sought to characterize resistance patterns and to identify predictors of resistance in Washington, DC.

Methods

We analyzed resistance in the DC Cohort, a longitudinal study of HIV-infected persons in care in Washington, DC. We measured cumulative drug resistance (CDR) among participants with any genotype between 1999 and 2014 (n = 3411), transmitted drug resistance (TDR) in ART-naïve persons (n = 1503), and acquired drug resistance (ADR) in persons with genotypes before and after ART initiation (n = 309). Using logistic regression, we assessed associations between patient characteristics and transmitted resistance to any antiretroviral.

Results

Prevalence of TDR was 20.5%, of ADR 40.5%, and of CDR 45.1% in the respective analysis groups. From 2004 to 2013, TDR prevalence decreased for nucleoside and nucleotide analogue reverse transcriptase inhibitors (15.0 to 5.5%; p = 0.0003) and increased for integrase strand transfer inhibitors (INSTIs) (0.0–1.4%; p = 0.04). In multivariable analysis, TDR was not associated with age, race/ethnicity, HIV risk group, or years from HIV diagnosis.

Conclusions

In this urban cohort of HIV-infected persons, almost half of participants tested had evidence of CDR; and resistance to INSTIs was increasing. If this trend continues, inclusion of the integrase-encoding region in baseline genotype testing should be strongly considered.

Prevalence of HIV-1 transmitted drug resistance in the incarcerated population

OBJECTIVES

The aim of the study was to determine the prevalence of transmitted drug resistance (TDR)-associated mutations among treatment-naïve, incarcerated individuals with HIV-1 infection in the USA as well as the class TDR and antiretroviral (ARV) mutations present at baseline.

METHODS

Patients over the age of 18 years were included in the study if they had been diagnosed with HIV infection, if their HIV infection was managed through telemedicine and if they were incarcerated in the State of Illinois Department of Corrections between 10 July 2010 and 29 April 2016. Additionally, the patients were required to have a documented genotype and be ARV-naïve. A medical chart review was conducted to assess demographic information, disease burden, and risk factors for acquiring the virus.

RESULTS

The inclusion criteria were met for 105 patients. A total of 24 patients (23%) had a clinically significant mutation associated with resistance to any drug class. The prevalence of mutations conferring clinically significant resistance was 19% for nonnucleoside reverse transcriptase inhibitors (NNRTIs), 18% for nucleoside reverse transcriptase inhibitors (NRTIs), and 4% for protease inhibitors (PIs). Five per cent of patients had dual-class TDR to both NRTI and NNRTI drug classes and 2% of patients had mutations to both NNRTI and PI drug classes. There was no significant increase in the prevalence of clinically relevant drug resistance mutations based on demographics, burden of disease, or risk factors for acquiring the virus.

CONCLUSIONS

A high prevalence of TDR was identified in the ARV-naïve incarcerated population. The results of this study indicate an increased prevalence of TDR in a largely unstudied incarcerated population, demonstrating the need for increased monitoring of resistance in HIV-infected patients world-wide.

Response to Therapy in Antiretroviral Therapy-Naive Patients With Isolated Nonnucleoside Reverse Transcriptase Inhibitor-Associated Transmitted Drug Resistance

BACKGROUND

Nonnucleoside reverse transcriptase inhibitor (NNRTI)-associated transmitted drug resistance (TDR) is the most common type of TDR. Few data guide the selection of antiretroviral therapy (ART) for patients with such resistance.

METHODS

We reviewed treatment outcomes in a cohort of HIV-1-infected patients with isolated NNRTI TDR who initiated ART between April 2002 and May 2014. In an as-treated analysis, virological failure (VF) was defined as not reaching undetectable virus levels within 24 weeks, virological rebound, or switching regimens during viremia. In an intention-to-treat analysis, failure was defined more broadly as VF, loss to follow-up, and switching during virological suppression.

RESULTS

Of 3245 patients, 131 (4.0%) had isolated NNRTI TDR; 122 received a standard regimen comprising 2 NRTIs plus a boosted protease inhibitor (bPI; n = 54), an integrase strand transfer inhibitor (INSTI; n = 52), or an NNRTI (n = 16). The median follow-up was 100 weeks. In the as-treated analysis, VF occurred in 15% (n = 8), 2% (n = 1), and 25% (n = 4) of patients in the bPI, INSTI, and NNRTI groups, respectively. In multivariate regression, there was a trend toward a lower risk of VF with INSTIs than with bPIs (hazard ratio: 0.14; 95% confidence interval: 0.02 to 1.1; P = 0.07). In intention-to-treat multivariate regression, INSTIs had a lower risk of failure than bPIs (hazard ratio: 0.38; 95% confidence interval: 0.18 to 0.82; P = 0.01).

CONCLUSIONS

Patients with isolated NNRTI TDR experienced low VF rates with INSTIs and bPIs. INSTIs were noninferior to bPIs in an analysis of VF but superior to bPIs when frequency of switching and loss to follow-up were also considered.

Genotypic susceptibility score (GSS) and CD4+ T cell recovery in HIV-1 patients with suppressed viral load

OBJECTIVES

HIV drug resistance, measured by the genotypic susceptibility score (GSS), has a deleterious effect on the virological outcome of HIV-1-infected patients. However, it is not known if GSS retains any predictive value for CD4 recovery in patients with suppressed viral load.

METHODS

Four hundred and six patients on virological failure (>500 copies/mL) with GSS  : <6 months prior to switch therapy who achieved undetectable plasma viral load (<50 copies/mL) within 1 year, remained undetectable >1 year on an unchanged regimen and had CD4 data available during entire follow-up were included. Adjusted and unadjusted analyses of all characteristics at switch related to CD4 recovery were made for three time frames: (i) 'switch-suppression'; (ii) 'suppression-1 year'; and (iii) 'switch-1 year'.

RESULTS

Higher GSS was associated with a greater CD4 recovery between 'switch' and '1 year' in the unadjusted analysis (P = 0.010); however, the effect of GSS was no longer statistically significant after adjusting for pre-switch clinical (CD4 count and plasma viral load) and demographic variables. Furthermore, only a lower pre-switch CD4 count was associated with increased CD4 recovery in the 'suppression-1 year' period in both unadjusted and adjusted models. The main CD4 recovery occurred in 'switch-suppression' and the variables associated, both unadjusted and adjusted, were CD4 and plasma viral load at switch, maintaining a trend for GSS (P = 0.06).

CONCLUSIONS

In individuals who re-suppressed HIV viraemia after switching therapy, regimens having a higher GSS were associated with improved CD4 recovery only during the period from switch to virological suppression, but, once viral load is re-suppressed, the GSS of the new regimen has no further effect on subsequent CD4 recovery.

HIV-1 drug resistance and resistance testing

The global scale-up of antiretroviral (ARV) therapy (ART) has led to dramatic reductions in HIV-1 mortality and incidence. However, HIV drug resistance (HIVDR) poses a potential threat to the long-term success of ART and is emerging as a threat to the elimination of AIDS as a public health problem by 2030. In this review we describe the genetic mechanisms, epidemiology, and management of HIVDR at both individual and population levels across diverse economic and geographic settings. To describe the genetic mechanisms of HIVDR, we review the genetic barriers to resistance for the most commonly used ARVs and describe the extent of cross-resistance between them. To describe the epidemiology of HIVDR, we summarize the prevalence and patterns of transmitted drug resistance (TDR) and acquired drug resistance (ADR) in both high-income and low- and middle-income countries (LMICs). We also review to two categories of HIVDR with important public health relevance: (i) pre-treatment drug resistance (PDR), a World Health Organization-recommended HIVDR surveillance metric and (ii) and pre-exposure prophylaxis (PrEP)-related drug resistance, a type of ADR that can impact clinical outcomes if present at the time of treatment initiation. To summarize the implications of HIVDR for patient management, we review the role of genotypic resistance testing and treatment practices in both high-income and LMIC settings. In high-income countries where drug resistance testing is part of routine care, such an understanding can help clinicians prevent virological failure and accumulation of further HIVDR on an individual level by selecting the most efficacious regimens for their patients. Although there is reduced access to diagnostic testing and to many ARVs in LMIC, understanding the scientific basis and clinical implications of HIVDR is useful in all regions in order to shape appropriate surveillance, inform treatment algorithms, and manage difficult cases.

Development and Validation of the HIV Medication Readiness Scale

Excellent medication adherence (> 95%) is required for optimal HIV treatment success. This study aimed to develop and validate a brief scale to assess psychological readiness for successfully starting and adhering to HIV medications. HIV-positive men and women (N = 142) from an HIV outpatient clinic completed the proposed HIV Medication Readiness Scale (HMRS) prior to starting HIV medications. The 10-item HMRS demonstrated high internal consistency (alpha = .90), test-retest reliability (r = .83), and sensitivity to change following a standardized 4-session psychoeducational intervention designed to increase readiness for successful adherence. Predictive validity was supported by higher readiness scores on the day starting HIV medications, predicting higher treatment adherence at 1-month follow-up. The HMRS is a brief, easy-to-use, clinically relevant tool that can assist in identifying people living with HIV at high risk of nonadherence, who might benefit from tailored readiness counseling prior to initiating HIV medications.

Prevalence of Transmitted HIV Drug Resistance Among Recently Infected Persons in San Diego, CA 1996-2013

BACKGROUND

Transmitted drug resistance (TDR) remains an important concern when initiating antiretroviral therapy (ART). Here, we describe the prevalence and phylogenetic relationships of TDR among ART-naive, HIV-infected individuals in San Diego from 1996 to 2013.

METHODS

Data were analyzed from 496 participants of the San Diego Primary Infection Cohort who underwent genotypic resistance testing before initiating therapy. Mutations associated with drug resistance were identified according to the WHO-2009 surveillance list. Network and phylogenetic analyses of the HIV-1 pol sequences were used to evaluate the relationships of TDR within the context of the entire cohort.

RESULTS

The overall prevalence of TDR was 13.5% (67/496), with an increasing trend over the study period (P = 0.005). TDR was predominantly toward nonnucleoside reverse transcriptase inhibitors (NNRTIs) [8.5% (42/496)], also increasing over the study period (P = 0.005). By contrast, TDR to protease inhibitors and nucleos(t)ide reverse transcriptase inhibitors were 4.4% (22/496) and 3.8% (19/496), respectively, and did not vary with time. TDR prevalence did not differ by age, gender, race/ethnicity, or risk factors. Using phylogenetic analysis, we identified 52 transmission clusters, including 8 with at least 2 individuals sharing the same mutation, accounting for 23.8% (16/67) of the individuals with TDR.

CONCLUSIONS

Between 1996 and 2013, the prevalence of TDR significantly increased among recently infected ART-naive individuals in San Diego. Around one-fourth of TDR occurred within clusters of recently infected individuals. These findings highlight the importance of baseline resistance testing to guide selection of ART and for public health monitoring.

Tipranavir/Ritonavir (500/200 mg and 500/100 mg) Was Virologically Non-Inferior to Lopinavir/Ritonavir (400/100 mg) at Week 48 in Treatment-Naïve HIV-1-Infected Patients: A Randomized, Multinational, Multicenter Trial

Ritonavir-boosted tipranavir (TPV/r) was evaluated as initial therapy in treatment-naïve HIV-1-infected patients because of its potency, unique resistance profile, and high genetic barrier. Trial 1182.33, an open-label, randomized trial, compared two TPV/r dose combinations versus ritonavir-boosted lopinavir (LPV/r). Eligible adults, who had no prior antiretroviral therapy were randomized to twice daily (BID) 500/100 mg TPV/r, 500/200 mg TPV/r, or 400/100 mg LPV/r. Each treatment group also received Tenofovir 300 mg + Lamivudine 300 mg QD. The primary endpoint was a confirmed viral load (VL) <50 copies/mL at week 48 without prior antiretroviral regimen changes. Primary analyses examined CD4-adjusted response rates for non-inferiority, using a 15% non-inferiority margin. At week 48, VL<50 copies/mL was 68.4%, 69.9%, and 72.4% in TPV/r100, TPV/r200, and LPV/r groups, respectively, and TPV/r groups showed non-inferiority to LPV/r. Discontinuation due to adverse events was higher in TPV/r100 (10.3%) and TPV/r200 (15.3%) recipients versus LPV/r (3.2%) recipients. The frequency of grade ≥3 transaminase elevations was higher in the TPV/r200 group than the other groups, leading to closure of this group. However, upon continued treatment or following re-introduction after treatment interruption, transaminase elevations returned to grade ≤2 in >65% of patients receiving either TPV/r200 or TPV/r100. The trial was subsequently discontinued; primary objectives were achieved and continuing TPV/r100 was less tolerable than standard of care for initial highly active antiretroviral therapy. All treatment groups had similar 48-week treatment responses. TPV/r100 and TPV/r200 regimens resulted in sustained treatment responses, which were non-inferior to LPV/r at 48 weeks. When compared with the LPV/r regimen and examined in the light of more current regimens, these TPV/r regimens do not appear to be the best options for treatment-naïve patients based on their safety profiles.

Preclinical discovery and development of maraviroc for the treatment of HIV

INTRODUCTION

Maraviroc is a first-in-class antiretroviral (ARV) drug acting on a host cell target (CCR5), which blocks the entry of the HIV virus into the cell. Maraviroc is currently indicated for combination ARV treatment in adults infected only with CCR5-tropic HIV-1.

AREAS COVERED

This drug discovery case history focuses on the key studies that led to the discovery and approval of maraviroc, as well as on post-launch clinical reports. The article is based on the data reported in published preclinical and clinical studies, conference posters and on drug package data.

EXPERT OPINION

The profound understanding of HIV's entry mechanisms has provided a strong biological rationale for targeting the chemokine receptor CCR5. The CCR5-antagonist mariviroc, with its unique mode of action and excellent safety profile, is an important therapeutic option for HIV patients. In general, the authors believe that targeting host factors is a useful approach for combating new and re-emerging transmissible diseases, as well as pathogens that easily become resistant to common antiviral drugs. Maraviroc, offering a potent and safe cellular receptor-mediated pharmacological response to HIV, has paved the way for the development of a new generation of host-targeting antivirals.

Drug resistance in non-B subtype HIV-1: impact of HIV-1 reverse transcriptase inhibitors

Human immunodeficiency virus (HIV) causes approximately 2.5 million new infections every year, and nearly 1.6 million patients succumb to HIV each year. Several factors, including cross-species transmission and error-prone replication have resulted in extraordinary genetic diversity of HIV groups. One of these groups, known as group M (main) contains nine subtypes (A-D, F-H and J-K) and causes ~95% of all HIV infections. Most reported data on susceptibility and resistance to anti-HIV therapies are from subtype B HIV infections, which are prevalent in developed countries but account for only ~12% of all global HIV infections, whereas non-B subtype HIV infections that account for ~88% of all HIV infections are prevalent primarily in low and middle-income countries. Although the treatments for subtype B infections are generally effective against non-B subtype infections, there are differences in response to therapies. Here, we review how polymorphisms, transmission efficiency of drug-resistant strains, and differences in genetic barrier for drug resistance can differentially alter the response to reverse transcriptase-targeting therapies in various subtypes.

Factors informing HIV providers' decisions to start antiretroviral therapy for young people living with behaviorally acquired HIV

PURPOSE

Young people with behaviorally acquired HIV (BHIV) are less likely than adults to initiate antiretroviral therapy (ART) despite meeting treatment criteria. We explored critical factors involved in healthcare providers' decision making regarding ART initiation for young people with BHIV (aged 12-24 years).

METHODS

Semistructured interviews were conducted with 23 HIV providers from diverse training backgrounds caring for youth with BHIV at four adult clinics and one pediatric clinic in a high prevalence urban city. Interview domains probed clinical and nonclinical patient characteristics, the role of adherence, and provider attitudes working with youth to establish decision-making priorities for ART initiation. The constant comparative approach was used to develop grounded theory on providers' decision making on ART initiation.

RESULTS

Clinical criteria, particularly the CD4 count, and the public health implications of HIV transmission determined the urgency for ART initiation. However, patient-related concerns regarding treatment readiness and adherence hampered the decision to initiate, especially at higher CD4 counts. Providers who acknowledged developmental characteristics of youth (e.g., evolving adult identity and self-efficacy around health management) appeared more cautious in assessing future ART adherence and responded with intensive clinical support. Extensive involvement of multidisciplinary teams was identified as an important strategy to retain youth in care, whereas strengthening youth-targeted approaches may be an unmet need in adult clinics.

CONCLUSION

Evaluation of providers' awareness of the developmental features of youth and characteristics of youth-targeted approaches in clinics caring for youth with BHIV may inform interventions to increase youth engagement in care and subsequent decisions to successfully initiate ART.

X4 tropic viruses are on the rise in recent HIV-1 seroconverters in Spain

BACKGROUND

Transmission of HIV-1 with drug resistance mutations (DRMs) in Spain remains stable around 13%. However, the profile of recent HIV-1 seroconverters has experienced significant changes.

METHODS

Retrospective analyses of all individuals with HIV-1 infection acquired within the past 12 months recruited at a national registry since year 1997.

RESULTS

A total of 1032 recent HIV-1 seroconverters were examined (92.2% men; median age 31 years; 84% homosexual men). At the moment of diagnosis, median plasma HIV-RNA and CD4 cell counts were 4.5  log copies/ml and 558 cells/μl, respectively. A total of 136 individuals (13.8%) carried non-B subtypes. Major primary DRMs were found in 13.4%, being 7.7% for nucleoside reverse transcriptase inhibitor (NRTI), 5.8% for nonnucleoside reverse transcriptase inhibitor (NNRTI) and 2.9% for protease inhibitor. NRTI DRM significantly declined from 23.7% in 1997-2000 to 5.7% in 2010-2012 (P<0.01). Overall, X4 viruses were found in 19.7% of HIV-1 seroconverters, increasing from 11.5% before 2001 to 23.3% since year 2010 (P=0.04). Interestingly, median CD4 cell counts were significantly lower in seroconverters diagnosed during the last period after adjusting for potential confounders. In multivariate analyses, X4 tropism, high HIV-RNA, foreigners and non-B subtypes were independent predictors of lower CD4 cell counts.

CONCLUSION

Transmission of NRTI DRM has declined significantly in recent HIV-1 seroconverters in Spain. Conversely, X4 tropic viruses are on the rise and currently account for 23.3% of new HIV-1 infections. These individuals present with lower CD4 cell counts suggesting that circulating HIV-1 strains might have gained virulence.

Ten years survey of primary HIV-1 resistance in Serbia: the occurrence of multiclass resistance

In Serbia, the first cases of HIV infection were reported in 1985, whereas antiretroviral (ARV) therapy has been in use since 1987. With this study we aimed to assess the occurrence and pattern of HIV resistance mutations among newly diagnosed patients in the period 2002-2011. The study prospectively included 181 adult patients. Genotypic HIV-1 drug resistance testing was performed and drug resistance was scored according to the 2009 WHO list for surveillance of drug resistance mutations (SDRMs). A bioinformatic approach was used to estimate the duration of infection by calculating the percentage of ambiguous basecalls per sequence, with a cutoff of 0.47% as the delimiter for recent infection. The overall prevalence of transmitted drug resistance (TDR) found in the study was 8.8% (16/181, 95% CI=5.5-13.8). Thirty-one percent of resistant samples contained multiple SDRMs. In particular, 5/16 patients with resistance carried viral strains with SDRMs to multiple ARV classes, hence one-third of resistant strains were multiclass resistant, including non-B strains. A total of 51.9% of samples (94/181) were classified as recent infection, with a significant increase in the second part of the study period. However, the prevalence of TDR in recent infection was 6.4% (6/94, 95% CI=2.9-13.2), not statistically different from that found in nonrecent infection. We showed a changing pattern of TDR mutations over the study period, with a substantial occurrence of multiclass resistance, across different HIV subtypes. Our results highlight the need for continued surveillance of primary resistance.

Transmitted drug resistance and antiretroviral treatment outcomes in non-subtype B HIV-1-infected patients in South East Asia

BACKGROUND

We compared treatment outcomes of transmitted drug resistance (TDR) in patients on fully or partially sensitive drug regimens.

METHODS

Factors associated with survival and failure were analyzed using Cox proportional hazards and discrete time conditional logistic models.

RESULTS

TDR, found in 60 (4.1%) of 1471 Asian treatment-naive patients, was one of the significant predictors of failure. Patients with TDR to >1 drug in their regimen were >3 times as likely to fail compared to no TDR.

CONCLUSIONS

TDR was associated with failure in the context of non-fully sensitive regimens. Efforts are needed to incorporate resistance testing into national treatment programs.

First line treatment response in patients with transmitted HIV drug resistance and well defined time point of HIV infection: updated results from the German HIV-1 seroconverter study

Background

Transmission of drug-resistant HIV-1 (TDR) can impair the virologic response to antiretroviral combination therapy. Aim of the study was to assess the impact of TDR on treatment success of resistance test-guided first-line therapy in the German HIV-1 Seroconverter Cohort for patients infected with HIV between 1996 and 2010. An update of the prevalence of TDR and trend over time was performed.

Methods

Data of 1,667 HIV-infected individuals who seroconverted between 1996 and 2010 were analysed. The WHO drug resistance mutations list was used to identify resistance-associated HIV mutations in drug-naïve patients for epidemiological analysis. For treatment success analysis the Stanford algorithm was used to classify a subset of 323 drug-naïve genotyped patients who received a first-line cART into three resistance groups: patients without TDR, patients with TDR and fully active cART and patients with TDR and non-fully active cART. The frequency of virologic failure 5 to 12 months after treatment initiation was determined.

Results

Prevalence of TDR was stable at a high mean level of 11.9% (198/1,667) in the HIV-1 Seroconverter Cohort without significant trend over time. Nucleotide reverse transcriptase inhibitor resistance was predominant (6.0%) and decreased significantly over time (OR = 0.92, CI = 0.87–0.98, p = 0.01). Non-nucleoside reverse transcriptase inhibitor (2.4%; OR = 1.00, CI = 0.92–1.09, p = 0.96) and protease inhibitor resistance (2.0%; OR = 0.94, CI = 0.861.03, p = 0.17) remained stable. Virologic failure was observed in 6.5% of patients with TDR receiving fully active cART, 5,6% of patients with TDR receiving non-fully active cART and 3.2% of patients without TDR. The difference between the three groups was not significant (p = 0.41).

Conclusion

Overall prevalence of TDR remained stable at a rather high level. No significant differences in the frequency of virologic failure were identified during first-line cART between patients with TDR and fully-active cART, patients with TDR and non-fully active cART and patients without TDR.

Incidence of Transmitted Antiretroviral Drug Resistance in Treatment-Naive HIV-1-Infected Persons in a Large South Central United States Clinic

Background: Transmitted drug resistance (TDR) can limit effective treatment options to antiretroviral-naive HIV-infected persons and increase the risk of treatment failure. Limited estimates of TDR have been reported from the South Central United States. Objective: To describe the incidence of TDR in Oklahoma and to examine whether TDR rates have increased with time. Methods: This was a retrospective observational study of antiretroviral-naive patients at the Infectious Diseases Institute, a large infectious diseases clinic in Oklahoma City, Oklahoma, who had received baseline antiretroviral resistance testing. Mutations were screened using the 2011 International Antiviral Society-USA Drug Resistance Mutation (DRM) update, and categorized using the 2009 World Health Organization (WHO) Surveillance Drug Resistance Mutation (SDRM) list. Results: Genotypic sequences from 428 patients revealed a 6.0% to 13.6% incidence of SDRMs between 2007 and 2011, though no progression in the frequency was apparent during the study period. Primary DRMs were detected in 12.6% of the sampled patients, most commonly involving nonnucleoside reverse transcriptase inhibitors (NNRTIs; 8.2%), followed by protease inhibitors (PIs; 3.5%) and nucleoside reverse transcriptase inhibitors (NRTIs; 3.3%). The K103N/S and E138A reverse transcriptase mutations were the most common DRMs identified, both present in 3.5% of patients. The L90M mutation was the most frequently observed PI SDRM (1.6%), while the T215C/D/I mutation was the most common NRTI SDRM identified (1.9%). This study was limited by the fact that the WHO SDRM list was last updated in 2009. Conclusions: The frequency of DRMs in central and western Oklahoma is similar to recently reported rates in the United States which lack data from this region. However, the frequency of second-generation NNRTI DRMs (4.4%) suggests the need to closely monitor epidemiologic trends for increasing resistance rates to individual classes of ARVs in order to predict the impact of TDR on therapeutic options.

Nevirapine inhibits the anti-HIV activity of CD8+ cells

Antiretroviral therapy (ART) significantly reduced the CD8 cell noncytotoxic anti-HIV response in 12 HIV-1-infected subjects (P < 0.0001). In separate experiments, CD8(+) cells from long-term survivors were cocultured with HIV-infected CD4(+) cells using varying concentrations of anti-HIV drugs. The antiviral function of CD8(+) cells from 4 of the 14 LTSs was reduced with exposure to 10 μM of nevirapine (P < 0.05). The antiviral activity of CD8(+) cells from 2 LTSs was inhibited by 5 μM of zidovudine. These studies indicate that nevirapine and probably zidovudine can inhibit the anti-HIV activity of CD8(+) cells and thus could influence the effectiveness of antiretroviral therapy.

Etravirine for the treatment of HIV/AIDS

INTRODUCTION

Etravirine (TMC125) is an orally administered second-generation non-nucleoside reverse transcriptase inhibitor (NNRTI) that is approved in treatment-experienced patients as addition to an optimized background therapy (OBT).

AREAS COVERED

A Medline search was conducted of Phase II - IV clinical trials, as well as a review of abstracts from major HIV and infectious disease conferences from 2010 - 2013, involving etravirine.

EXPERT OPINION

Etravirine is a well-tolerated NNRTI with a good safety profile and a higher genetic barrier for resistance compared to first-generation NNRTIs. Rash is a potential side effect but remains mostly mild to moderate. The necessity of taking it twice daily with food (200 mg bid.), potential pharmacokinetic interactions and low concentrations in the central nervous system (CNS) represent limitations. The efficacy of once daily etravirine (400 mg qid.) and the use in treatment modification/simplification strategies requires further research. Despite its favorable profile, etravirine is currently not sufficiently investigated nor approved for use in treatment-naïve patients which should be balanced against its potential as a backup NNRTI and the broad cross-resistance conferred by etravirine failure to other NNRTIs. Etravirine should be avoided following treatment failure with regimens containing rilpivirine, another second-generation NNRTI.

Moderate prevalence of transmitted drug resistance mutations among antiretroviral-naive HIV-infected pregnant women in Rio de Janeiro, Brazil

Transmission of drug-resistant HIV-1 strains has been gaining attention and is becoming a growing problem throughout the world. The aim of this study was to determine the prevalence of transmitted drug resistance mutations (TDRM) among antiretroviral (ARV)-naive HIV-infected pregnant women in Rio de Janeiro, Brazil. ARV-naive pregnant women were recruited at Hospital Geral de Nova Iguacu (HGNI), Rio de Janeiro, from 2005 to 2008. HIV genotyping was carried out using ViroSeq (Abbott v. 2.0). TDRM were detected using the Calibrated Population Resistance Tool-CPR v. 6.0.The prevalence of mutations associated with resistance in the protease and reverse transcriptase regions of the HIV genome were assessed in samples collected prior to initiation of ARV prophylaxis or treatment. Among 238 eligible specimens that were collected, 197 samples were successfully amplified using reverse transcription polymerase chain reaction. Eighty-one percent of women were infected with HIV subtype B, 10% with subtype F1 viruses, 1.0% with subtype C virus, and 8.0% with recombinant forms of the virus. The prevalence of HIV TDRM was 5.6% for nucleoside reverse transcriptase inhibitors, 2.0% for nonnucleoside reverse transcriptase inhibitors, and 3.0% for protease inhibitors. The overall prevalence of any drug resistance was 10.7%. There were no multiclass resistant strains identified in the analyzed samples. The prevalence of HIV TDRM among the pregnant women in our cohort was moderate. Resistance testing should be encouraged in Rio de Janeiro, among other locations, for all HIV-infected pregnant women prior to prevention of mother-to-child transmission of HIV.

CCR5 inhibitors in HIV-1 therapy

BACKGROUND

The human immunodeficiency virus 1 (HIV-1) is the causative pathogen of AIDS, the world's biggest infectious disease killer. About 33 million people are infected worldwide, with 2.1 million deaths a year as a direct consequence. The devastating nature of AIDS has prompted widespread research, which has led to an extensive array of therapies to suppress viral replication and enable recovery of the immune system to prolong and improve patient life substantially. However, the genetic plasticity and replication rate of HIV-1 are considerable, which has lead to rapid drug resistance. This, together with the need for reducing drug side effects and increasing regimen compliance, has led researchers to identify antiretroviral drugs with new modes of action.

OBJECTIVE

This review describes the discovery and clinical development of CCR5 antagonists and the recent approval of maraviroc as a breakthrough in anti-HIV-1 therapy.

CONCLUSION

CCR5 inhibitors target a human cofactor to disable HIV-1 entry into the cells, and thereby provide a new hurdle for the virus to overcome. The status and expert opinion of CCR5 antagonists for the treatment of HIV-1 infection are detailed.

Transmitted drug resistance and phylogenetic relationships among acute and early HIV-1-infected individuals in New York City

BACKGROUND

Transmitted drug resistance (TDR) is critical to managing HIV-1-infected individuals and being a public health concern. We report on TDR prevalence and include analyses of phylogenetic clustering of HIV-1 in a predominantly men who have sex with men cohort diagnosed during acute/recent HIV-1 infection in New York City.

METHODS

Genotypic resistance testing was conducted on plasma samples of 600 individuals with acute/recent HIV-1 infection (1995-2010). Sequences were used for resistance and phylogenetic analyses. Demographic and clinical data were abstracted from medical records. TDR was defined according to International AIDS Society-USA and Stanford HIV database guidelines. Phylogenetic and other analyses were conducted using PAUP*4.0 and SAS, respectively.

RESULTS

The mean duration since HIV-1 infection was 66.5 days. TDR prevalence was 14.3% and stably ranged between 10.8% and 21.6% (P(trend) = 0.42). Nucleoside reverse transcriptase inhibitors resistance declined from 15.5% to 2.7% over the study period (P(trend) = 0.005). M41L (3.7%), T215Y (4.0%), and K103N/S (4.7%) were the most common mutations. K103N/S prevalence increased from 1.9% to 8.0% between 1995 and 2010 (P(trend) = 0.04). Using a rigorous definition of clustering, 19.3% (112 of 581) of subtype B viral sequences cosegregated into transmission clusters and clusters increased over time. There were fewer and smaller transmission clusters than had been reported in a similar cohort in Montreal but similar to reports from elsewhere.

CONCLUSIONS

TDR is stable in this cohort and remains a significant concern to both individual patient management and the public health.

Etravirine: a guide to its use in treatment-experienced pediatric patients with HIV-1 infection in the US

Etravirine (Intelence®), an oral next-generation non-nucleoside reverse transcriptase inhibitor (NNRTI), is approved for the treatment of HIV-1 infection in treatment-experienced patients. In the US, the approved use of etravirine in patients who have evidence of viral replication and harbor HIV-1 strains resistant to other antiretroviral agents has recently been expanded to include pediatric patients aged ≥ 6 to <18 years. At 24 and 48 weeks in an open-label trial, etravirine 5.2 mg/kg twice daily (maximum dosage 200 mg twice daily) plus an optimized background therapy regimen achieved complete viral response (defined as HIV-1 RNA <50 copies/mL) in approximately half of treatment-experienced children and adolescents with HIV-1 infection and evidence of viral replication, and had an acceptable tolerability profile.

Transmitted antiretroviral drug resistance in New York State, 2006-2008: results from a new surveillance system

Background

HIV transmitted drug resistance (TDR) is a public health concern because it has the potential to compromise antiretroviral therapy (ART) at the population level. In New York State, high prevalence of TDR in a local cohort and a multiclass resistant case cluster led to the development and implementation of a statewide resistance surveillance system.

Methodology

We conducted a cross-sectional analysis of the 13,109 cases of HIV infection that were newly diagnosed and reported in New York State between 2006 and 2008, including 4,155 with HIV genotypes drawn within 3 months of initial diagnosis and electronically reported to the new resistance surveillance system. We assessed compliance with DHHS recommendations for genotypic resistance testing and estimated TDR among new HIV diagnoses.

Principal Findings

Of 13,109 new HIV diagnoses, 9,785 (75%) had laboratory evidence of utilization of HIV-related medical care, and 4,155 (43%) had a genotype performed within 3 months of initial diagnosis. Of these, 11.2% (95% confidence interval [CI], 10.2%–12.1%) had any evidence of TDR. The proportion with mutations associated with any antiretroviral agent in the NNRTI, NRTI or PI class was 6.3% (5.5%–7.0%), 4.3% (3.6%–4.9%) and 2.9% (2.4%–3.4%), respectively. Multiclass resistance was observed in <1%. TDR did not increase significantly over time (p for trend = 0.204). Men who have sex with men were not more likely to have TDR than persons with heterosexual risk factor (OR 1.0 (0.77–1.30)). TDR to EFV+TDF+FTC and LPV/r+TDF+FTC regimens was 7.1% (6.3%–7.9%) and 1.4% (1.0%–1.8%), respectively.

Conclusions/Significance

TDR appears to be evenly distributed and stable among new HIV diagnoses in New York State; multiclass TDR is rare. Less than half of new diagnoses initiating care received a genotype per DHHS guidelines.

Highly active antiretroviral therapy does not completely suppress HIV in semen of sexually active HIV-infected men who have sex with men

OBJECTIVE

Although HAART can suppress genital shedding and sexual transmission of HIV, men who have sex with men (MSM) have experienced a resurgent HIV epidemic in the HAART era. Many HIV-infected MSM continue to engage in unsafe sex, and sexually transmitted infections (STIs) or other factors may promote genital HIV shedding and transmission in this population despite HAART. In this study, we determined the prevalence of seminal HIV shedding in HIV-infected MSM on stable HAART, and its relationship with a number of clinical, behavioral and biological variables.

DESIGN

Sexually active HIV-infected men using HAART were recruited from an MSM health clinic to provide semen and blood samples.

METHODS

HIV levels were assessed in paired semen and blood samples by PCR. Clinical and behavioral data were obtained from medical records and questionnaires. Herpes simplex virus 2 (HSV-2) serostatus, seminal HSV-2 DNA, and markers of genital inflammation were measured using standard laboratory methods.

RESULTS

Overall, HIV-1 was detected in 18 of 101 (18%) blood and 30 of 101 (30%) semen samples. Of 83 men with undetectable HIV in blood plasma, 25% had HIV in semen with copy numbers ranging from 80 to 2560. Multivariate analysis identified STI/urethritis (P = 0.003), tumor necrosis factor α (P = 0.0003), and unprotected insertive anal sex with an HIV-infected partner (P = 0.007) as independent predictors of seminal HIV detection.

CONCLUSION

STIs and genital inflammation can partially override the suppressive effect of HAART on seminal HIV shedding in sexually active HIV-infected MSM. Low seminal HIV titers could potentially pose a transmission risk in MSM, who are highly susceptible to HIV infection.

Increase in transmitted HIV drug resistance among persons undergoing genotypic resistance testing in Ontario, Canada, 2002-09

OBJECTIVES

To characterize persons undergoing HIV genotypic resistance testing (GRT) while treatment naive and to estimate the prevalence of transmitted HIV drug resistance (TDR) among HIV-positive outpatients in Ontario, Canada.

METHODS

We analysed data from a multi-site cohort of persons receiving HIV care. Data were obtained from medical chart abstractions, interviews and record linkage with the Public Health Laboratories, Public Health Ontario. The analysis was restricted to 626 treatment-naive persons diagnosed in 2002-09. TDR mutations were identified using the calibrated population resistance tool. We used descriptive statistics and regression methods to characterize treatment-naive GRT test uptake and patterns of TDR.

RESULTS

Overall, 53.2% (333/626) of participants had baseline GRT. The proportion increased with year of HIV diagnosis from 30.0% in 2002 to 82.6% in 2009 (P < 0.0001). Among those tested, 13.6% (CI 9.9-17.3%) had one or more drug resistance mutations, and 8.8% (CI 5.7-11.8%), 4.8% (CI 2.5-7.2%) and 2.7% (CI 1.0-4.5%) had mutations conferring resistance to nucleoside/tide reverse transcriptase inhibitors (NRTIs), non-nucleoside reverse transcriptase inhibitors (NNRTIs) and protease inhibitors (PIs), respectively. TDR prevalence increased from 2002-07 to 2008-09 (adjusted OR 3.7, 95% CI 1.7-8.2), driven by a higher proportion with NRTI (18.2% versus 5.9%, P = 0.0009) and NNRTI mutations (11.7% versus 2.8%, P = 0.004) in the later time period. PI TDR remained unchanged.

CONCLUSIONS

Baseline GRT increased dramatically since 2002, but remains below 100%. The prevalence of overall TDR tripled due to increases in NRTI and NNRTI mutations. These findings highlight the value of routine baseline GRT for TDR surveillance and patient care.

Identification of HIV inhibitors guided by free energy perturbation calculations

Free energy perturbation (FEP) theory coupled to molecular dynamics (MD) or Monte Carlo (MC) statistical mechanics offers a theoretically precise method for determining the free energy differences of related biological inhibitors. Traditionally requiring extensive computational resources and expertise, it is only recently that its impact is being felt in drug discovery. A review of computer-aided anti-HIV efforts employing FEP calculations is provided here that describes early and recent successes in the design of human immunodeficiency virus type 1 (HIV-1) protease and non-nucleoside reverse transcriptase inhibitors. In addition, our ongoing work developing and optimizing leads for small molecule inhibitors of cyclophilin A (CypA) is highlighted as an update on the current capabilities of the field. CypA has been shown to aid HIV-1 replication by catalyzing the cis/trans isomerization of a conserved Gly-Pro motif in the Nterminal domain of HIV-1 capsid (CA) protein. In the absence of a functional CypA, e.g., by the addition of an inhibitor such as cyclosporine A (CsA), HIV-1 has reduced infectivity. Our simulations of acylurea-based and 1-indanylketone-based CypA inhibitors have determined that their nanomolar and micromolar binding affinities, respectively, are tied to their ability to stabilize Arg55 and Asn102. A structurally novel 1-(2,6-dichlorobenzamido) indole core was proposed to maximize these interactions. FEP-guided optimization, experimental synthesis, and biological testing of lead compounds for toxicity and inhibition of wild-type HIV-1 and CA mutants have demonstrated a dose-dependent inhibition of HIV-1 infection in two cell lines. While the inhibition is modest compared to CsA, the results are encouraging.

Transmitted drug resistance among antiretroviral-naive patients with established HIV type 1 infection in Santo Domingo, Dominican Republic and review of the Latin American and Caribbean literature

Emergence of HIV resistance is a concerning consequence of global scale-up of antiretroviral therapy (ART). To date, there is no published information about HIV resistance from the Dominican Republic. The study's aim was to determine the prevalence of transmitted drug resistance (TDR) to reverse transcriptase and protease inhibitors in a sample of chronically HIV-1-infected patients in one clinic in Santo Domingo. The data are presented in the context of a review of the TDR literature from Latin America and the Caribbean. Genotype testing was successfully performed on 103 treatment-naive adults planning to initiate antiretroviral therapy; the World Health Organization (WHO) list of surveillance drug resistance mutations (SDRM) was used to determine the presence of TDR mutations. WHO SDRM were identified in eight patients (7.8%); none had received sdNVP. There were no significant differences in epidemiologic or clinical variables between those with or without WHO SDRM. The prevalence of WHO SDRM was 1.0% and 6.8% for nucleoside reverse transcriptase inhibitors and nonnucleoside reverse transcriptase inhibitors, respectively. No WHO SDRMs for protease inhibitors were identified. Among 12 studies of TDR in the region with a sample size of at least 100 subjects, the reported prevalence of SDRM ranged from 2.8% to 8.1%. The most commonly identified SDRM was K103N. This information adds to our understanding of the epidemiology of TDR in the region and the possible role such mutations could play in undermining first-line treatment. Ongoing surveillance is clearly needed to better understand the TDR phenomenon in the Caribbean.

The dual role of pharmacogenetics in HIV treatment: mutations and polymorphisms regulating antiretroviral drug resistance and disposition

Significant intra- and interindividual variability has been observed in response to use of pharmacological agents in treatment of HIV infection. Treatment of HIV infection is limited by high rates of adverse drug reactions and development of resistance in a significant proportion of patients as a result of suboptimal drug concentrations. The efficacy of antiretroviral therapy is challenged by the emergence of resistant HIV-1 mutants with reduced susceptibility to antiretroviral drugs. Moreover, pharmacotherapy of patients infected with HIV is challenging because a great number of comorbidities increase polypharmacy and the risk for drug-drug interactions. Drug-metabolizing enzymes and drug transporters regulate drug access to the systemic circulation, target cells, and sanctuary sites. These factors, which determine drug exposure, along with the emergence of mutations conferring resistance to HIV medications, could explain variability in efficacy and adverse drug reactions associated with antiretroviral drugs. In this review, the major factors affecting the disposition of antiretroviral drugs, including key drug-metabolizing enzymes and membrane drug transporters, are outlined. Genetic polymorphisms affecting the activity and/or the expression of cytochromes P450 or UGT isozymes and membrane drug transport proteins are highlighted and include such examples as the association of neurotoxicity with efavirenz, nephrotoxicity with tenofovir, hepatotoxicity with nevirapine, and hyperbilirubinemia with indinavir and atazanavir. Mechanisms of drug resistance conferred by specific viral mutations are also reviewed, with particular attention to replicative viral fitness and transmitted HIV drug resistance with the objectives of providing a better understanding of mechanisms involved in HIV drug resistance and helping health care providers to better manage interpatient variability in drug efficacy and toxicity.

Should we treat acute HIV infection?

Critical advances in the early diagnosis of HIV now allow for treatment opportunities during acute infection. It remains unclear whether treatment of acute HIV infection with antiretroviral therapy improves long-term clinical outcomes for the individual and current guidelines are not definitive in recommending therapy at this stage of infection. However, treatment of acute HIV infection may have short-term benefit on viral set point when compared to delayed therapy as well as reducing the risk of transmission to others. Herein we review the immunological and clinical literature to discuss whether we should treat acute HIV infection, both from the perspective of the individual HIV-infected patient and from the public health perspective. As transmission of drug-resistant HIV variants are of concern, we also review recent clinical trial data to provide recommendations for which specific antiretroviral treatment regimens should be considered for the treatment of acute HIV infection.

Prevalence of Drug Resistance and Associated Mutations in a Population of HIV-1(+) Puerto Ricans: 2006-2010

This is a continuation of our efforts to maintain a record of the evolution of HIV-1 infection in Puerto Rico by monitoring the expression levels of antiretroviral drug-resistance-associated mutations. Samples from 2,500 patients from 2006–2010 were analyzed using the TruGene HIV-1 genotyping kit and the OpenGene DNA sequencing system. Results show that 58.8% of males and 65.3% of females had HIV-1 with resistance to at least one medication. The average number of HIV mutations was 6.0 in males and 6.1 in females. Statistically significant differences between men and women were recorded in the levels of HIV-1 expressed mutations and antiretroviral drug resistance. The most prevalent antiretroviral medication resistance shifted from zalcitabine to nevirapine and efavirenz in the five-year period. M184V and L63P were the dominant mutations for the reverse transcriptase and the protease genes, respectively, but an increase in the incidence of minority mutations was observed.

Prevalence and impact of minority variant drug resistance mutations in primary HIV-1 infection

Objective

To evaluate minority variant drug resistance mutations detected by the oligonucleotide ligation assay (OLA) but not consensus sequencing among subjects with primary HIV-1 infection.

Design/Methods

Observational, longitudinal cohort study. Consensus sequencing and OLA were performed on the first available specimens from 99 subjects enrolled after 1996. Survival analyses, adjusted for HIV-1 RNA levels at the start of antiretroviral (ARV) therapy, evaluated the time to virologic suppression (HIV-1 RNA<50 copies/mL) among subjects with minority variants conferring intermediate or high-level resistance.

Results

Consensus sequencing and OLA detected resistance mutations in 5% and 27% of subjects, respectively, in specimens obtained a median of 30 days after infection. Median time to virologic suppression was 110 (IQR 62–147) days for 63 treated subjects without detectable mutations, 84 (IQR 56–109) days for ten subjects with minority variant mutations treated with ≥3 active ARVs, and 104 (IQR 60–162) days for nine subjects with minority variant mutations treated with <3 active ARVs (p = .9). Compared to subjects without mutations, time to virologic suppression was similar for subjects with minority variant mutations treated with ≥3 active ARVs (aHR 1.2, 95% CI 0.6–2.4, p = .6) and subjects with minority variant mutations treated with <3 active ARVs (aHR 1.0, 95% CI 0.4–2.4, p = .9). Two subjects with drug resistance and two subjects without detectable resistance experienced virologic failure.

Conclusions

Consensus sequencing significantly underestimated the prevalence of drug resistance mutations in ARV-naïve subjects with primary HIV-1 infection. Minority variants were not associated with impaired ARV response, possibly due to the small sample size. It is also possible that, with highly-potent ARVs, minority variant mutations may be relevant only at certain critical codons.

Increase of transmitted drug resistance among HIV-infected sub-Saharan Africans residing in Spain in contrast to the native population

Background

The prevalence of transmitted HIV drug resistance (TDR) is stabilizing or decreasing in developed countries. However, this trend is not specifically evaluated among immigrants from regions without well-implemented antiretroviral strategies.

Methods

TDR trends during 1996–2010 were analyzed among naïve HIV-infected patients in Spain, considering their origin and other factors. TDR mutations were defined according to the World Health Organization list.

Results

Pol sequence was available for 732 HIV-infected patients: 292 native Spanish, 226 sub-Saharan Africans (SSA), 114 Central-South Americans (CSA) and 100 from other regions. Global TDR prevalence was 9.7% (10.6% for Spanish, 8.4% for SSA and 7.9% for CSA). The highest prevalences were found for protease inhibitors (PI) in Spanish (3.1%), for non-nucleoside reverse transcriptase inhibitors (NNRTI) in SSA (6.5%) and for nucleoside reverse transcriptase inhibitors (NRTI) in both Spanish and SSA (6.5%). The global TDR rate decreased from 11.3% in 2004–2006 to 8.4% in 2007–2010. Characteristics related to a decreasing TDR trend in 2007-10 were Spanish and CSA origin, NRTI- and NNRTI-resistance, HIV-1 subtype B, male sex and infection through injection drug use. TDR remained stable for PI-resistance, in patients infected through sexual intercourse and in those carrying non-B variants. However, TDR increased among SSA and females. K103N was the predominant mutation in all groups and periods.

Conclusion

TDR prevalence tended to decrease among HIV-infected native Spanish and Central-South Americans, but it increased up to 13% in sub-Saharan immigrants in 2007–2010. These results highlight the importance of a specific TDR surveillance among immigrants to prevent future therapeutic failures, especially when administering NNRTIs.

HIV-1 drug resistance mutations among antiretroviral-naive HIV-1-infected patients in Asia: results from the TREAT Asia Studies to Evaluate Resistance-Monitoring Study

Of 682 antiretroviral-naïve patients initiating antiretroviral therapy in a prospective, multicenter human immunodeficiency virus type 1 (HIV-1) drug resistance monitoring study involving 8 sites in Hong Kong, Malaysia, and Thailand, the prevalence of patients with ≥1 drug resistance mutation was 13.8%. Primary HIV drug resistance is emerging after rapid scaling-up of antiretroviral therapy use in Asia.

New approaches in the treatment of HIV/AIDS - focus on maraviroc and other CCR5 antagonists

Treatment of HIV-1 infection has produced dramatic success for many patients. Nevertheless, viral resistance continues to limit the efficacy of currently available agents in many patients. The CCR5 antagonists are a new class of antiretroviral agents that target a necessary coreceptor for viral entry of many strains of HIV-1. Recently, the first agent within this class, maraviroc, was approved by a number of regulatory agencies, including the Food and Drug Administration. Herein we review the role of the CCR5 receptor in HIV-1 infection and potential methods to target it in anti-HIV-1 therapy. We review the various categories of agents and discuss specific agents that have progressed to clinical study. We discuss in detail the recently approved, first in class CCR5 antagonist, maraviroc, and discuss aspects of resistance to CCR5 antagonism and the potential role of CCR5 antagonism in the management of HIV-1 infection.

Inhibition of HIV-1 Tat-mediated transcription by a coumarin derivative, BPRHIV001, through the Akt pathway

The human immunodeficiency virus type 1 (HIV-1)-encoded RNA-binding protein Tat is known to play an essential role in viral gene expression. In the search for novel compounds to inhibit Tat transactivity, one coumarin derivative, BPRHIV001, was identified, with a 50% effective concentration (EC(50)) against HIV-1 at 1.3 nM. BPRHIV001 is likely to exert its effects at the stage after initiation of RNAPII elongation since Tat protein expression and the assembly of the Tat/P-TEFb complex remained unchanged. Next, a reduction of the p300 protein level, known to modulate Tat function through acetylation, was observed upon BPRHIV001 treatment, while the p300 mRNA level was unaffected. A concordant reduction of phosphorylated Akt, which was shown to be closely related to p300 stability, was observed in the presence of BPRHIV001 and was accompanied by a decrease of phosphorylated PDPK1, a well-known Akt activator. Furthermore, the docking analysis revealed that the reduced PDPK1 phosphorylation likely resulted from the allosteric effect of interaction between BPRHIV001 and PDPK1. With strong synergistic effects with current reverse transcriptase inhibitors, BPRHIV001 has the potential to become a promising lead compound for the development of a novel therapeutic agent against HIV-1 infection.

Transmitted drug resistance in the CFAR network of integrated clinical systems cohort: prevalence and effects on pre-therapy CD4 and viral load

Human immunodeficiency virus type 1 (HIV-1) genomes often carry one or more mutations associated with drug resistance upon transmission into a therapy-naïve individual. We assessed the prevalence and clinical significance of transmitted drug resistance (TDR) in chronically-infected therapy-naïve patients enrolled in a multi-center cohort in North America. Pre-therapy clinical significance was quantified by plasma viral load (pVL) and CD4+ cell count (CD4) at baseline. Naïve bulk sequences of HIV-1 protease and reverse transcriptase (RT) were screened for resistance mutations as defined by the World Health Organization surveillance list. The overall prevalence of TDR was 14.2%. We used a Bayesian network to identify co-transmission of TDR mutations in clusters associated with specific drugs or drug classes. Aggregate effects of mutations by drug class were estimated by fitting linear models of pVL and CD4 on weighted sums over TDR mutations according to the Stanford HIV Database algorithm. Transmitted resistance to both classes of reverse transcriptase inhibitors was significantly associated with lower CD4, but had opposing effects on pVL. In contrast, position-specific analyses of TDR mutations revealed substantial effects on CD4 and pVL at several residue positions that were being masked in the aggregate analyses, and significant interaction effects as well. Residue positions in RT with predominant effects on CD4 or pVL (D67 and M184) were re-evaluated in causal models using an inverse probability-weighting scheme to address the problem of confounding by other mutations and demographic or risk factors. We found that causal effect estimates of mutations M184V/I (-1.7 log₁₀pVL) and D67N/G (-2.1[³√CD4] and 0.4 log₁₀pVL) were compensated by K103N/S and K219Q/E/N/R. As TDR becomes an increasing dilemma in this modern era of highly-active antiretroviral therapy, these results have immediate significance for the clinical management of HIV-1 infections and our understanding of the ongoing adaptation of HIV-1 to human populations.

Raltegravir: the first HIV-1 integrase strand transfer inhibitor in the HIV armamentarium

Raltegravir is the first integrase strand transfer inhibitor approved for the treatment of HIV-1 infection. As the first agent in this new class of antiretroviral therapies, raltegravir has demonstrated safety and efficacy in treatment-naive as well as heavily pretreated HIV-infected patients failing therapy with multidrug-resistant virus. Raltegravir has a favorable drug interaction profile that permits both administration to a wide, demographically diverse patient population and coadministration with many other therapeutic agents, including antiretroviral agents and supportive medications, without restrictions or dose adjustment. Data through 96 weeks of follow-up in three phase III studies, protocol 021 (STARTMRK) in treatment-naive patients, and protocols 018 (BENCHMRK-1) and 019 (BENCHMRK-2) in treatment-experienced patients, demonstrated the potent and durable antiretroviral and immunologic effects and the favorable long-term safety profile of raltegravir in both treatment-naive and treatment-experienced patients. Raltegravir represents an important addition to the current armamentarium for the treatment of HIV infection.