Antiretroviral-drug resistance among patients recently infected with HIV

Primary drug resistance in South Africa: data from 10 years of surveys

HIV-1 transmitted drug resistance (TDR) could reverse the gains of antiretroviral rollout. To ensure that current first-line therapies remain effective, TDR levels in recently infected treatment-naive patients need to be monitored. A literature review and data mining exercise was carried out to determine the temporal trends in TDR in South Africa. In addition, 72 sequences from seroconvertors identified from Africa Centre's 2010 HIV surveillance round were also examined for TDR. Publicly available data on TDR were retrieved from GenBank, curated in RegaDB, and analyzed using the Calibrated Population Resistance Program. There was no evidence of TDR from the 2010 rural KwaZulu Natal samples. Ten datasets with a total of 1618 sequences collected between 2000 and 2010 were pooled to provide a temporal analysis of TDR. The year with the highest TDR rate was 2002 [6.67%, 95% confidence interval (CI): 3.09-13.79%; n=6/90]. After 2002, TDR levels returned to <5% (WHO low-level threshold) and showed no statistically significant increase in the interval between 2002 and 2010. The most common mutations were associated with NNRTI resistance, K103N, followed by Y181C and Y188C/L. Five sequences had multiple resistance mutations associated with NNRTI resistance. There is no evidence of TDR in rural KwaZulu-Natal. TDR levels in South Africa have remained low following a downward trend since 2003. Continuous vigilance in monitoring of TDR is needed as more patients are initiated and maintained onto antiretroviral therapy.

The HIV Epidemic: High-Income Countries

The HIV epidemic in higher-income nations is driven by receptive anal intercourse, injection drug use through needle/syringe sharing, and, less efficiently, vaginal intercourse. Alcohol and noninjecting drug use increase sexual HIV vulnerability. Appropriate diagnostic screening has nearly eliminated blood/blood product-related transmissions and, with antiretroviral therapy, has reduced mother-to-child transmission radically. Affected subgroups have changed over time (e.g., increasing numbers of Black and minority ethnic men who have sex with men). Molecular phylogenetic approaches have established historical links between HIV strains from central Africa to those in the United States and thence to Europe. However, Europe did not just receive virus from the United States, as it was also imported from Africa directly. Initial introductions led to epidemics in different risk groups in Western Europe distinguished by viral clades/sequences, and likewise, more recent explosive epidemics linked to injection drug use in Eastern Europe are associated with specific strains. Recent developments in phylodynamic approaches have made it possible to obtain estimates of sequence evolution rates and network parameters for epidemics.

Antiretroviral therapy in treatment-naïve patients with HIV infection

PURPOSE OF REVIEW

This review discusses the current status of antiretroviral therapy (ART) in treatment-naïve patients. ART initiation in such patients needs to be carefully planned, as the aim of therapy has shifted from prolonging life to ensuring maintained adherence to ART and optimization of quality of life. There is a plethora of first-line antiretroviral agents available, and physicians must consider several patient-related and therapy-related factors before selecting the most appropriate initial ART.

RECENT FINDINGS

Current treatment guidelines recommend the use of nonnucleoside reverse transcriptase inhibitor (NNRTI), ritonavir-boosted protease inhibitor (PI), or integrase strand transfer inhibitor (INSTI)-based regimens in treatment-naïve patients. Treatment selection and modification to achieve optimal response is based primarily on regular assessment of viral load (and resistance testing if necessary) and CD4 cell count. The use of genotypic resistance testing, on initiation of therapy and on treatment failure, is becoming more widespread. In selected patients, due to increasing transmitted drug resistance (TDR), a PI-based regimen may be a better option. Classic ART combinations are being challenged by new combinations, although there is currently insufficient evidence to recommend use of the newer over classic combinations. Co-formulations of drugs and single-tablet regimens are fast becoming available and their convenience may increase patient treatment adherence.

SUMMARY

All drug classes currently available for first-line ART are efficacious and have good tolerability; however, differences between individual drugs must be carefully considered when deciding a first-line regimen. Each first-line regimen must be tailored to the individual patient to attain optimal efficacy, acceptable long-term tolerability, and good adherence to ART.

Transmitted HIV resistance to first-line antiretroviral therapy in Lima, Peru

Transmission of drug-resistant HIV (TDR) has been associated with virologic failure of "first-line," nonnucleoside reverse transcriptase inhibitor (NNRTI)-based antiretroviral therapy (ART). A national ART program began in Peru in 2004. We evaluated the prevalence of TDR in individuals initiating ART and their virologic outcome during 2 years of ART. HIV-infected, ARV-naive subjects who met criteria to start ART in Lima, Peru were enrolled in a longitudinal observational study between July 2007 and February 2009. Blood plasma and cells obtained prior to ART initiation were assessed for antiretroviral (ARV) resistance by an oligonucleotide ligation assay (OLA) sensitive to 2% mutant at reverse transcriptase (RT) codons K103N, Y181C, G190A, and M184V and a subset by consensus sequencing. A total of 112 participants were enrolled; the mean CD4 was 134 ± 89 cells/μl and the median plasma HIV RNA was 93,556 copies/ml (IQR 62,776-291,364). Drug resistance mutations conferring high-level resistance to ARV were rare, detected in one of 96 (1%) evaluable participants. This subject had the Y181C mutation detected in both plasma and peripheral blood mononuclear cells (PBMCs) at a concentration of 100% by OLA and consensus sequencing; nevertheless nevirapine-ART suppressed her viral replication. Consensus sequencing of 37 (19%) participants revealed multiple polymorphisms that occasionally have been associated with low-level reductions in ARV susceptibility. A low prevalence of TDR was detected among Peruvians initiating ART. Given the increasing availability of ART, continuing surveillance is needed to determine if TDR increases and the mutant codons associated with virologic failure.

HIV-1 drug resistance in antiretroviral-naive individuals with HIV-1-associated tuberculous meningitis initiating antiretroviral therapy in Vietnam

BACKGROUND

Access to antiretroviral therapy (ART) for HIV-infected individuals in Vietnam is rapidly expanding, but there are limited data on HIV drug resistance (HIVDR) to guide ART strategies.

METHODS

We retrospectively conducted HIVDR testing in 220 ART-naive individuals recruited to a randomized controlled trial of immediate versus deferred ART in individuals with HIV-associated tuberculous meningitis in Ho Chi Minh City (HCMC) from 2005-2008. HIVDR mutations were identified by population sequencing of the HIV pol gene and were defined based on 2009 WHO surveillance drug resistance mutations (SDRMs).

RESULTS

We successfully sequenced 219/220 plasma samples of subjects prior to ART; 218 were subtype CRF01_AE and 1 was subtype B. SDRMs were identified in 14/219 (6.4%) subjects; 8/14 were resistant to nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs; T69D, L74V, V75M, M184V/I and K219R), 5/14 to non-nucleoside reverse transcriptase inhibitors (NNRTIs; K103N, V106M, Y181C, Y188C and G190A), 1/14 to both NRTIs and NNRTIs (D67N and Y181C) and none to protease inhibitors. After 6 months of ART, eight subjects developed protocol-defined virological failure. HIVDR mutations were identified in 5/8 subjects. All five had mutations with high-level resistance to NNRTIs and three had mutations with high-level resistance to NRTIs. Due to a high early mortality rate (58%), the effect of pre-existing HIVDR mutations on treatment outcome could not be accurately assessed.

CONCLUSIONS

The prevalence of WHO SDRMs in ART-naive individuals with HIV-associated tuberculous meningitis in HCMC from 2005-2008 is 6.4%. The SDRMs identified conferred resistance to NRTIs and/or NNRTIs, reflecting the standard first-line ART regimens in Vietnam.

Outwitting evolution: fighting drug-resistant TB, malaria, and HIV

Although caused by vastly different pathogens, the world's three most serious infectious diseases, tuberculosis, malaria, and HIV-1 infection, share the common problem of drug resistance. The pace of drug development has been very slow for tuberculosis and malaria and rapid for HIV-1. But for each disease, resistance to most drugs has appeared quickly after the introduction of the drug. Learning how to manage and prevent resistance is a major medical challenge that requires an understanding of the evolutionary dynamics of each pathogen. This Review summarizes the similarities and differences in the evolution of drug resistance for these three pathogens.

Prevalence of HIV Drug Resistance Mutations in HIV Type 1 Isolates in Antiretroviral Therapy Naïve Population from Northern India

Objective. The increased use of antiretroviral therapy (ART) has reduced the morbidity and mortality associated with HIV, adversely leading to the emergence of HIV drug resistance (HIVDR). In this study we aim to evaluate the prevalence of HIVDR mutations in ART-naive HIV-1 infected patients from northern India. Design. Analysis was performed using Viroseq genotyping system based on sequencing of entire protease and two-thirds of the Reverse Transcriptase (RT) region of pol gene. Results. Seventy three chronic HIV-1 infected ART naïve patients eligible for first line ART were enrolled from April 2006 to August 2008. In 68 patients DNA was successfully amplified and sequencing was done. 97% of HIV-1 strains belonged to subtype C, and one each to subtype A1 and subtype B. The overall prevalence of primary DRMs was 2.9% [2/68, 95% confidence interval (CI), 0.3%–10.2%]. One patient had a major RT mutation M184V, known to confer resistance to lamivudine, and another had a major protease inhibitor (PI) mutation D30N that imparts resistance to nelfinavir. Conclusion. Our study shows that primary HIVDR mutations have a prevalence of 2.9% among ART-naive chronic HIV-1 infected individuals.

Blocking HIV-1 entry by a gp120 surface binding inhibitor

We report the mode of action of a proteomimetic compound that binds to the exterior surface of gp120 and blocks HIV-1 entry into cells. Using a one cycle time-of-addition study and antibody competition binding studies, we have determined that the compound blocks HIV-1 entry through modulation of key protein-protein interactions mediated by gp120. The compound exhibits anti-HIV-1 replication activities against several pseudotype viruses derived from primary isolates and the resistant strains isolated from existing drug candidates with equal potency. Together, these data provide evidence that the proteomimetic compound represents a novel class of HIV-1 viral entry inhibitor that functions through protein surface recognition in analogy to an antibody.

Documented prevalence of HIV type 1 antiretroviral transmitted drug resistance in Ireland from 2004 to 2008

HIV-1-infected individuals with transmitted HIV drug resistance (TDR) begin antiretroviral therapy (ART) with a lower genetic barrier to resistance and a higher risk of both virological failure and of developing further resistance. TDR surveillance informs HIV-1 public health strategies and first line ART. TDR has not been studied nationally in an Irish population. This study includes all new HIV diagnoses from January 2004 to September 2008 from the National Virus Reference Laboratory, University College Dublin. HIV-1 protease and reverse transcriptase sequences were generated, and resistance mutations identified using the Siemens TRUGENE HIV-1 Genotyping System. Subtypes were determined using web-based genotyping tools. The study comprised 1579 patients. There were 305 new diagnoses in 2004 (173 male; 132 female), 298 in 2005 (175M; 123F), 321 in 2006 (197M; 124F), 297 in 2007 (184M; 113F), and 358 (235M; 123F) in 2008. HIV-1 RNA was sequenced from 158/305 patients in 2004, 199/298 in 2005, 225/321 in 2006, 203/297 in 2007, and 275/358 in 2008. The overall TDR rate was 6.3%, peaking in 2006 at 10.4% and declining to 5.3% in 2008. The majority of TDR was seen in Irish born individuals with HIV-1 subtype B infection. The TDR rate in Ireland is comparatively low. Thus, a health technology assessment is required to ascertain the most cost effective use of genotypic antiretroviral resistance testing (GART) in the future: the current approach of performing baseline GART on all new diagnoses, or perhaps a more targeted approach that focuses on patients commencing nonnucleoside reverse transcriptase inhibitor (NNRTI)-based ART.

Preclinical evaluation of the HIV-1 fusion inhibitor L'644 as a potential candidate microbicide

Topical blockade of the gp41 fusogenic protein of HIV-1 is one possible strategy by which microbicides could prevent HIV transmission, working early against infection, by inhibiting viral entry into host cells. In this study, we examined the potential of gp41 fusion inhibitors (FIs) as candidate anti-HIV microbicides. Preclinical evaluation of four FIs, C34, T20, T1249, and L'644, was performed using cellular and ex vivo genital and colorectal tissue explant models. Increased and sustained activity was detected for L'644, a cholesterol-derivatized version of C34, relative to the other FIs. The higher potency of L'644 was further increased with sustained exposure of cells or tissue to the compound. The activity of L'644 was not affected by biological fluids, and the compound was still active when tissue explants were treated after viral exposure. L'644 was also more active than other FIs against a viral escape mutant resistant to reverse transcriptase inhibitors (RTIs), demonstrating the potential of L'644 to be included as part of a multiactive antiretroviral (ARV) combination-based microbicide. These data support the further development of L'644 for microbicide application.

Excision of HIV-1 proviral DNA by recombinant cell permeable tre-recombinase

Over the previous years, comprehensive studies on antiretroviral drugs resulted in the successful introduction of highly active antiretroviral therapy (HAART) into clinical practice for treatment of HIV/AIDS. However, there is still need for new therapeutic approaches, since HAART cannot eradicate HIV-1 from the infected organism and, unfortunately, can be associated with long-term toxicity and the development of drug resistance. In contrast, novel gene therapy strategies may have the potential to reverse the infection by eradicating HIV-1. For example, expression of long terminal repeat (LTR)-specific recombinase (Tre-recombinase) has been shown to result in chromosomal excision of proviral DNA and, in consequence, in the eradication of HIV-1 from infected cell cultures. However, the delivery of Tre-recombinase currently depends on the genetic manipulation of target cells, a process that is complicating such therapeutic approaches and, thus, might be undesirable in a clinical setting. In this report we demonstrate that E.coli expressed Tre-recombinases, tagged either with the protein transduction domain (PTD) from the HIV-1 Tat trans-activator or the translocation motif (TLM) of the Hepatitis B virus PreS2 protein, were able to translocate efficiently into cells and showed significant recombination activity on HIV-1 LTR sequences. Tre activity was observed using episomal and stable integrated reporter constructs in transfected HeLa cells. Furthermore, the TLM-tagged enzyme was able to excise the full-length proviral DNA from chromosomal integration sites of HIV-1-infected HeLa and CEM-SS cells. The presented data confirm Tre-recombinase activity on integrated HIV-1 and provide the basis for the non-genetic transient application of engineered recombinases, which may be a valuable component of future HIV eradication strategies.

Substituent effects on P2-cyclopentyltetrahydrofuranyl urethanes: design, synthesis, and X-ray studies of potent HIV-1 protease inhibitors

The design, synthesis, and biological evaluation of novel C3-substituted cyclopentyltetrahydrofuranyl (Cp-THF)-derived HIV-1 protease inhibitors are described. Various C3-functional groups on the Cp-THF ligand were investigated in order to maximize the ligand-binding site interactions in the flap region of the protease. Inhibitors 3c and 3d have displayed the most potent enzyme inhibitory and antiviral activity. Both inhibitors have maintained impressive activity against a panel of multidrug resistant HIV-1 variants. A high-resolution X-ray crystal structure of 3c-bound HIV-1 protease revealed a number of important molecular insights into the ligand-binding site interactions.

Epidemiology of transmitted drug resistance in chronically HIV-infected patients in Germany: the RESINA study 2001-2009

OBJECTIVES

Transmitted HIV drug resistance may impair treatment efficacy of combination antiretroviral therapy (ART). This study describes the epidemiology of transmitted resistance in chronically infected patients.

METHODS

In a prospective multicenter trial in Nordrhein-Westfalen, Germany, transmitted drug resistance was determined by genotypic resistance testing in patients on initiation of first-line ART.

RESULTS

From 2001 to 2009, 2,078 patients were enrolled in the study. 79.9% were male, 81.2% were Caucasians, and a homosexual transmission mode was found in 51.3%. Of these patients, 41.5% were at the stage of AIDS, median CD4 cell count was 230/μl, and median viral load was 64.466 copies/ml. Transmitted drug resistance mutations were seen in 9.2% (95% CI, 7.9-10.4). Resistance in the nucleoside reverse transcriptase inhibitor class was found in 5.8% (4.8-6.8), in the nonnucleoside reverse transcriptase inhibitor class in 2.8% (2.1-3.6), and in the protease inhibitor class in 2.7% (2.0-3.4). After a continuous increase to a level above 10% in the years 2006 and 2007, a decline of drug resistance prevalence followed in 2008 and 2009.

CONCLUSIONS

Transmitted HIV drug resistance was found in around 10% of chronically infected patients in Germany who started their ART. We showed a moderate decline of the prevalence of mutant virus strains in recent years. Further surveillance of this phenomenon is mandatory.

Description of two commercially available assays for genotyping of HIV-1

HIV-1 resistance testing is one important part in the diagnostics of antiretroviral treatment and is commonly done by genotyping. Currently, two systems are commercially available and, despite being far from easy to use, these have achieved a high degree of sophistication. Modifications of standard kit protocols might be necessary based on the clinical situation. Although resistance reports based on decision rules are a part of both systems, considerable knowledge and skills are nevertheless required by the user to establish useful clinical data out of detected resistance patterns. Both systems described here have their advantages and disadvantages; a decision for one or the other system needs to be based on individual requirements. The future might lie in so-called 'next-generation sequencing' systems based on pyrosequencing, which enable a high throughput and the detection of minor variants of less than 1%.

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.

Technology-based self-care methods of improving antiretroviral adherence: a systematic review

BACKGROUND

As HIV infection has shifted to a chronic condition, self-care practices have emerged as an important topic for HIV-positive individuals in maintaining an optimal level of health. Self-care refers to activities that patients undertake to maintain and improve health, such as strategies to achieve and maintain high levels of antiretroviral adherence.

METHODOLOGY/PRINCIPAL FINDINGS

Technology-based methods are increasingly used to enhance antiretroviral adherence; therefore, we systematically reviewed the literature to examine technology-based self-care methods that HIV-positive individuals utilize to improve adherence. Seven electronic databases were searched from 1/1/1980 through 12/31/2010. We included quantitative and qualitative studies. Among quantitative studies, the primary outcomes included ARV adherence, viral load, and CD4+ cell count and secondary outcomes consisted of quality of life, adverse effects, and feasibility/acceptability data. For qualitative/descriptive studies, interview themes, reports of use, and perceptions of use were summarized. Thirty-six publications were included (24 quantitative and 12 qualitative/descriptive). Studies with exclusive utilization of medication reminder devices demonstrated less evidence of enhancing adherence in comparison to multi-component methods.

CONCLUSIONS/SIGNIFICANCE

This systematic review offers support for self-care technology-based approaches that may result in improved antiretroviral adherence. There was a clear pattern of results that favored individually-tailored, multi-function technologies, which allowed for periodic communication with health care providers rather than sole reliance on electronic reminder devices.

Mechanism of HIV antiretroviral drugs progress toward drug resistance

The rapid replication rate of HIV-1 RNA and its inherent genetic variation have led to the production of many HIV-1 variants with decreased drug susceptibility. The capacity of HIV to develop drug resistance mutations is a major obstacle to long-term effective anti-HIV therapy. Incomplete suppression of viral replication with an initial drug regimen diminishes the clinical benefit to the patient and may promote the development of broader drug resistance that may cause subsequent treatment regimens to be ineffective. The increased clinical use of combination antiretroviral treatment for HIV-1 infection has led to the selection of viral strains resistant to multiple drugs, including strains resistant to all licensed nucleoside analog RT inhibitors and protease inhibitors. Therefore, it is important to understand the influence of such mutations on viral properties such as replicative fitness, fidelity, and mutation rates. Although research continues to improve our understanding of resistance, leading to refined treatment strategies and, in some cases, improved outcome, resistance to antiretroviral therapy remains a major cause of treatment failure among patients living with HIV-1.

Scale-up of antiretroviral treatment in sub-Saharan Africa is accompanied by increasing HIV-1 drug resistance mutations in drug-naive patients

OBJECTIVES

To evaluate the frequency and progression over time of the WHO-defined transmitted HIV-1 drug resistance mutations (DRMs) among antiretroviral treatment (ART)-naive HIV-1-infected patients in Cameroon.

DESIGN

We analyzed HIV-1 DRM data generated from 369 ART-naive individuals consecutively recruited between 1996 and 2007 in urban and rural areas in Cameroon.

METHODS

HIV-1 drug resistance genotyping was performed in the pol gene using plasma samples and surveillance DRMs were identified using the 2009 WHO-DRM list.

RESULTS

We observed in Yaounde, the capital city, an increasing prevalence of DRMs over time: 0.0% (none of 61 participants) in 1996-1999; 1.9% (one of 53 participants) in 2001; 4.1% (two of 49 participants) in 2002; and 12.3% (10 of 81 participants) in 2007. In the rural areas with more recently implemented ART programs, we found DRMs in six of 125 (4.8%) ART-naive individuals recruited in 2006-2007. DRMs identified in both areas included resistance mutations to protease inhibitors, nucleoside reverse transcriptase inhibitors (NRTIs) and non-NRTIs (NNRTIs) that might impair the efficacy of available first-line and second-line treatments.

CONCLUSION

This report showed an increase in transmitted DRMs in areas where antiretroviral drugs were introduced earlier, although other factors such as natural viral polymorphisms and acquired DRMs through exposure to antiretroviral cannot be totally excluded. Further surveillances are needed to confirm this evolution and inform public health policies on adequate actions to help limit the selection and transmission of drug-resistant HIV, while scaling up access to ART in developing countries.

Genetic Diversity and Drug Resistance Mutations in HIV-1 from Untreated Patients in Niamey, Niger

The objective of the study was to estimate the prevalence of transmitted resistance to antiretroviral of HIV-1 circulating in Niger. We collected plasmas from 96 drug-naive patients followed up in the main HIV/AIDS Care Center of Niamey, the capital city of Niger. After RNA extraction and retrotranscription to proviral DNA, nested PCR was performed to amplify PR (codons 1–99) and RT (codons 1–240) fragments for sequencing. Sequences were analysed for phylogeny, then for resistance-associated mutations according to IAS-USA and Stanford's lists of mutations. We characterized six HIV-1 genetic variants: CRF02-AG (56.3%), CRF30_0206 (15.6%), subtype G (15.6%), CRF06_cpx (9.4%), CRF11_cpx (2.1%), and CRF01_AE (1%). About 8.3% of HIV strains had at least 1 resistance mutation: 4 strains with at least 1 mutation to NRTI, 5 for NNRTI, and 1 for PI, respectiveley 4.2%, 5.2%, and 1.0%. These preliminary results gave enough information for the need of instauring HIV drug resistance national surveillance.

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.

Colorectal microbicide design: triple combinations of reverse transcriptase inhibitors are optimal against HIV-1 in tissue explants

OBJECTIVE

Receptive anal intercourse in both men and women is associated with the highest probability for sexual acquisition of HIV infection. As part of a strategy to develop an effective rectal microbicide, we performed an ex-vivo preclinical evaluation to determine the efficacy and limitation of multiple combinations of reverse transcriptase inhibitors (RTIs).

DESIGN

A nucleotide, PMPA (tenofovir), a nucleoside, FTC (emtricitabine), RTIs and two nonnucleoside RTIs, UC781 and TMC120 (dapivirine), were used in double, triple and quadruple combinations against a panel of CCR5-uing and CXCR4-using clade B HIV-1 isolates and against RTI-escape variants.

METHODS

Indicator cells and colorectal tissue explants were used to assess antiviral activity of drug combinations.

RESULTS

All combinations inhibited the isolates tested in a cellular model and in colorectal explants and produced, for at least one of the compounds, a change in the dose-response curve. Double and triple combinations incrementally augmented activity, even against RTI-escape mutants, whereas quadruple combinations conferred little further advantage.

CONCLUSION

The colorectal explant model may be used to identify the best candidate molecules and their combinations at the preclinical stage. Furthermore, this study demonstrates that combinations based on RTIs with different HIV-1 inhibitory mechanisms have potential as colorectal microbicides.

Resistance-associated mutations in HIV-1 among patients failing first-line antiretroviral therapy

Thirty-five HIV-1 infected patients showing clinical and/or immunological failure to first line antiretroviral therapy (ART) according to WHO criteria were recruited from the ART center of Lok Nayak Hospital, New Delhi to detect the presence of resistance-mutations in reverse transcriptase (RT) and protease (PR) region of pol gene of HIV-1. Plasma viral load (PVL) was estimated. HIV-1 pol gene region encoding complete protease and reverse transcriptase (codons; 1-232 to 1-242) was reverse transcribed, followed by nested PCR. The PCR product was sequenced and analyzed. Plasma samples from 94.3% of patients with PVL >log(10) 3.0 c/mL could be amplified and analyzed. Virologic failure was detected in 65.7% of patients according to WHO criteria (PVL >log(10) 4.0). All patients were found to be infected with subtype C. One or more resistance-mutations were observed among 90.9% of study sequences. Nucleoside reverse transcriptase inhibitor (NRTI) resistance mutations were seen among all patients, with M184V and thymidine analogue mutations (TAM) being most frequently detected (75.6% and 72.7%, respectively). Nonnucleoside reverse transcriptase inhibitor (NNRTI) resistance-mutations were detected in 63.6% of sequences, of which Y181C/I (47.6%), K103N (33.3%) and G190S (28.6%) are the most common. None of the sequences showed major protease inhibitors (PIs) resistance mutation. High prevalence of NRTI and NNRTI drug resistance mutations among the study participants warrants the use of genotypic resistance testing to prevent accumulation of resistance mutations, which would limit future treatment options.

[Bioinformatics studies on drug resistance against anti-HIV-1 drugs]

More than 20 drugs have been available for anti-HIV-1 treatment in Japan. Combination therapy with these drugs dramatically decreases in morbidity and mortality of AIDS. However, due to high mutation rate of HIV-1, treatment with ineffective drugs toward patients infected with HIV-1 causes accumulation of mutations in the virus, and emergence of drug resistant viruses. Thus, to achieve appropriate application of the drugs toward the respective patients living with HIV-1, methods for predicting the level of drug-resistance using viral sequence information has been developed on the basis of bioinformatics. Furthermore, ultra-deep sequencing by next-generation sequencer whose data analysis is also based on bioinformatics, or in silico structural modeling have been achieved to understand drug resistant mechanisms. In this review, I overview the bioinformatics studies about drug resistance against anti-HIV-1 drugs.

Moderate prevalence of transmitted drug resistance and interiorization of HIV type 1 subtype C in the inland North State of Tocantins, Brazil

The diverse Brazilian AIDS epidemic has reached small cities and scant molecular information is available about the epidemic in Northern Brazil, where the incidence is growing. This study describes transmitted drug resistance and subtypes in the protease (PR) and reverse transcriptase (RT) regions among naive patients recruited in Palmas, the capital of Tocantins State, a newly built city in Northern Brazil. PR/RT regions were retrotranscribed from plasma HIV-1 RNA and 52 were sequenced after direct nested PCR. HIV-1 subtypes were assigned by phylogenetic analysis. Transmitted drug resistance was analyzed by the Calibrated Population Resistance tool Stanford Surveillance Drug Resistance Mutation. Most patients included (59.6%) were males, the median age was 30 years and were mainly referred because of heterosexual or homosexual unprotected sex. One male patient was from the Karajás indigenous tribe. The prevalence of transmitted resistance was 11.5% (CI 95%, 4.4-23.4%): nonnucleoside RT inhibitor mutations (n=3), nucleoside RT inhibitor mutations (n=2), and protease inhibitor mutations (n=1). Dual or triple class resistance was not observed. HIV-1 subtype B(PR)/B(RT) represented 78.8%, 5.8% were subtype C(PR)/C(RT), and 1.9% were subtype F1(PR)/F1(RT). Recombinant viruses represented 13.5% (07/52): B(PR)/F1(RT) (n=1), B(PR)/BF1(RT) (n=4), and C(PR)/CF1(RT) (n=2). This study about the AIDS epidemic in the recently founded city of Palmas/Tocantins in inland Northern Brazil shows moderate levels of transmitted drug resistance and the circulation of diverse recombinant viruses. This pattern is similar to what has been described in major metropolitan cities, suggesting the influence of imported cases from the south/southeast. Moreover these results indicate that patients from this setting should be monitored regarding transmitted drug resistance mutations.

Loss of protease dimerization inhibition activity of darunavir is associated with the acquisition of resistance to darunavir by HIV-1

Dimerization of HIV protease is essential for the acquisition of protease's proteolytic activity. We previously identified a group of HIV protease dimerization inhibitors, including darunavir (DRV). In the present work, we examine whether loss of DRV's protease dimerization inhibition activity is associated with HIV development of DRV resistance. Single amino acid substitutions, including I3A, L5A, R8A/Q, L24A, T26A, D29N, R87K, T96A, L97A, and F99A, disrupted protease dimerization, as examined using an intermolecular fluorescence resonance energy transfer (FRET)-based HIV expression assay. All recombinant HIV(NL4-3)-based clones with such a protease dimerization-disrupting substitution failed to replicate. A highly DRV-resistant in vitro-selected HIV variant and clinical HIV strains isolated from AIDS patients failing to respond to DRV-containing antiviral regimens typically had the V32I, L33F, I54M, and I84V substitutions in common in protease. None of up to 3 of the 4 substitutions affected DRV's protease dimerization inhibition, which was significantly compromised by the four combined substitutions. Recombinant infectious clones containing up to 3 of the 4 substitutions remained sensitive to DRV, while a clonal HIV variant with all 4 substitutions proved highly resistant to DRV with a 205-fold 50% effective concentration (EC(50)) difference compared to HIV(NL4-3). The present data suggest that the loss of DRV activity to inhibit protease dimerization represents a novel mechanism contributing to HIV resistance to DRV. The finding that 4 substitutions in PR are required for significant loss of DRV's protease dimerization inhibition should at least partially explain the reason DRV has a high genetic barrier against HIV's acquisition of DRV resistance.

High-risk behaviors associated with injection drug use among recently HIV-infected men who have sex with men in San Diego, CA

The contribution of injection drug use to HIV risk among men who have sex with men (MSM) is understudied. MSM infected with HIV within the prior 12 months completed a questionnaire assessing sociodemographic, sexual, drug use, and social factors. Analyses were performed to identify factors associated with lifetime history of injection drug use. Among 212 participants, the mean age was 33.8 years, 72% were White, 89% had attended college, and 9.4% reported ever injecting drugs. In multivariable logistic regression analysis, ever trading sex and using methamphetamine during sex with at least one of their last three partners were associated with injection drug use. Adjusting for these variables, in separate models, ever perpetrating violence against others (Adjusted Odds Ratio [AOR] = 3.16), having physically abusive sexual partners (AOR = 3.08), or physically abusing sexual partners (AOR = 10.17) were significantly (P < 0.05) associated with injection drug use. These findings suggest that violence is more common among MSM who inject drugs, which should be considered in HIV prevention efforts.

Clinical implications of the nelfinavir-proton pump inhibitor drug interaction in patients with human immunodeficiency virus

STUDY OBJECTIVE

To determine if the concomitant use of nelfinavir and proton pump inhibitors (PPIs) in patients with human immunodeficiency virus (HIV) infection results in the loss of virologic control.

DESIGN

Retrospective cohort study.

DATA SOURCE

Pharmacy, laboratory, and administrative databases of a large integrated health care system in northern California.

PATIENTS

A total of 1147 HIV-positive adults who started nelfinavir therapy between November 1, 1998, and June 20, 2003; within this cohort, 141 patients (12.3%) were also prescribed PPIs.

MEASUREMENTS AND MAIN RESULTS

The effects on two virologic outcomes--achievement of undetectable HIV viral load and subsequent virologic rebound--were compared between patients receiving nelfinavir alone and those receiving nelfinavir with PPIs. Cox proportional hazards models were used, with adjustments for age, sex, race, HIV risk factors, hepatitis B or C coinfection, and other concurrent drugs known to affect the metabolism of nelfinavir. The use of PPIs had little effect on the ability to achieve an undetectable HIV viral load (adjusted hazard ratio [HR] 0.82, 95% confidence interval [CI] 0.58-1.19, p=0.29), but there was an approximate 50% increased risk of virologic rebound with the concurrent use of PPIs (adjusted HR 1.53, 95% CI 1.06-2.19, p=0.02). Short-term use of PPIs (defined as within 30 days of initial PPI dispensation) was not associated with increased risk of virologic rebound (HR 1.07, 95% CI 0.26-4.41, p=0.93) compared with no use of PPIs.

CONCLUSION

Use of PPIs should be minimized or avoided in patients who have attained an undetectable HIV viral load while taking a nelfinavir-based antiretroviral regimen. However, concomitant use of these drugs may be acceptable for indications where PPIs are required for fewer than 30 days.

Molecular and epidemiological characterization of HIV-1 infection networks involving transmitted drug resistance mutations in Northern Greece

OBJECTIVES

To determine the contribution of transmission clusters to transmitted drug resistance (TDR) in newly diagnosed antiretroviral-naive HIV-1-infected patients in Northern Greece during 2000-07.

METHODS

The prevalence of TDR was estimated in 369 individuals who were diagnosed with HIV-1 infection in the period 2000-07 at the National AIDS Reference Laboratory of Northern Greece. Phylogenetic analysis was performed using a maximum likelihood method on partial pol sequences. TDR was defined in accordance with the surveillance drug resistance mutation list (2009 update).

RESULTS

The overall prevalence of TDR in our population was 12.5% [46/369, 95% confidence interval (CI) 9.1%-15.8%], comprising 7.6% (28/369) resistant to nucleoside reverse transcriptase inhibitors, 5.4% (20/369) resistant to non-nucleoside reverse transcriptase inhibitors and 3.3% (12/369) resistant to protease inhibitors. Dual class resistance was identified in 3.8% (14/369). Infection with subtype A was the sole predictor associated with TDR in multivariate analysis (odds ratio 2.15, 95% CI 1.10-4.19, P = 0.025). Phylogenetic analyses revealed three statistically robust transmission clusters involving drug-resistant strains, including one cluster of 12 patients, 10 of whom were infected with a strain carrying both T215 revertants and Y181C mutations.

CONCLUSIONS

Our findings underline the substantial impact of transmission networks on TDR in our population.

Missing data on the estimation of the prevalence of accumulated human immunodeficiency virus drug resistance in patients treated with antiretroviral drugs in north america

Determination of the prevalence of accumulated antiretroviral drug resistance among persons infected with human immunodeficiency virus (HIV) is complicated by the lack of routine measurement in clinical care. By using data from 8 clinic-based cohorts from the North American AIDS Cohort Collaboration on Research and Design, drug-resistance mutations from those with genotype tests were determined and scored using the Genotypic Resistance Interpretation Algorithm developed at Stanford University. For each year from 2000 through 2005, the prevalence was calculated using data from the tested subset, assumptions that incorporated clinical knowledge, and multiple imputation methods to yield a complete data set. A total of 9,289 patients contributed data to the analysis; 3,959 had at least 1 viral load above 1,000 copies/mL, of whom 2,962 (75%) had undergone at least 1 genotype test. Using these methods, the authors estimated that the prevalence of accumulated resistance to 2 or more antiretroviral drug classes had increased from 14% in 2000 to 17% in 2005 (P < 0.001). In contrast, the prevalence of resistance in the tested subset declined from 57% to 36% for 2 or more classes. The authors' use of clinical knowledge and multiple imputation methods revealed trends in HIV drug resistance among patients in care that were markedly different from those observed using only data from patients who had undergone genotype tests.

Antibodies in infectious diseases: polyclonals, monoclonals and niche biotechnology

Antibody preparations have a long history of providing protection from infectious diseases. Although antibodies remain the only natural host-derived defense mechanism capable of completely preventing infection, as products, they compete against inexpensive therapeutics such as antibiotics, small molecule inhibitors and active vaccines. The continued discovery in the monoclonal antibody (mAb) field of leads with broadened cross neutralization of viruses and demonstrable synergy of antibody with antibiotics for bacterial diseases, clearly show that innovation remains. The commercial success of mAbs in chronic disease has not been paralleled in infectious diseases for several reasons. Infectious disease immunotherapeutics are limited in scope as endemic diseases necessitate active vaccine development. Also, the complexity of these small markets draws the interest of niche companies rather than big pharmaceutical corporations. Lastly, the cost of goods for mAb therapeutics is inherently high for infectious agents due to the need for antibody cocktails, which better mimic polyclonal immunoglobulin preparations and prevent antigenic escape. In cases where vaccine or convalescent populations are available, current polyclonal hyperimmune immunoglobulin preparations (pIgG), with modern and highly efficient purification technology and standardized assays for potency, can make economic sense. Recent innovations to broaden the potency of mAb therapies, while reducing cost of production, are discussed herein. On the basis of centuries of effective use of Ab treatments, and with growing immunocompromised populations, the question is not whether antibodies have a bright future for infectious agents, but rather what formats are cost effective and generate safe and efficacious treatments to satisfy regulatory approval.

Quality of sleep: associations with antiretroviral nonadherence

Poor quality of sleep (QOS) is frequently reported in HIV-positive individuals; however, despite its clinical and public health significance, few studies have examined the correlation between QOS and antiretroviral (ARV) adherence. The objective of this study was to estimate the prevalence of sleep disturbances, determine the characteristics of those with poor QOS, and establish the relationship between QOS and ARV nonadherence among HIV-positive individuals. We conducted a cross-sectional secondary data analysis of 2845 HIV-positive adults taking ARV therapy from the Healthy Living Project baseline cohort. Mean self-reported ARV nonadherence was estimated using a 3-day measure. QOS was assessed using three questions regarding sleep pattern changes, amount of bother from difficulty falling/staying asleep, and amount of bother from vivid dreams. Over 68% of individuals reported sleep pattern changes, 50.3% reported difficulty falling/staying asleep, and 20.5% reported bother from vivid dreams. Depression, suicidal ideation, unemployment, use of illicit substances, history of incarceration, and HIV viral load were all independently associated with poor QOS. Individuals reporting feeling bothered about difficulty falling/staying asleep had a 1.66 higher odds of nonadherence (95% confidence interval [CI]=1.18, 2.33; p=0.004). Those reporting the highest degree of bother from difficulty falling/staying asleep and from vivid dreams had a 1.42 (95% CI=1.13, 1.78; p=0.002) and 1.31 (95% CI=0.98, 1.75; p=0.07) higher odds of nonadherence, respectively. With higher incremental reports of poor QOS there were considerable increases in ARV nonadherence. Recognition and timely treatment of sleep difficulties may result in reduced ARV nonadherence with beneficial clinical and public health implications.

Host factors mediating HIV-1 replication

Human immunodeficiency virus type 1(HIV-1) infection is the leading cause of death worldwide in adults attributable to infectious diseases. Although the majority of infections are in sub-Saharan Africa and Southeast Asia, HIV-1 is also a major health concern in most countries throughout the globe. While current antiretroviral treatments are generally effective, particularly in combination therapy, limitations exist due to drug resistance occurring among the drug classes. Traditionally, HIV-1 drugs have targeted viral proteins, which are mutable targets. As cellular genes mutate relatively infrequently, host proteins may prove to be more durable targets than viral proteins. HIV-1 replication is dependent upon cellular proteins that perform essential roles during the viral life cycle. Maraviroc is the first FDA-approved antiretroviral drug to target a cellular factor, HIV-1 coreceptor CCR5, and serves to intercept viral-host protein-protein interactions mediating entry. Recent large-scale siRNA and shRNA screens have revealed over 1000 candidate host factors that potentially support HIV-1 replication, and have implicated new pathways in the viral life cycle. These host proteins and cellular pathways may represent important targets for future therapeutic discoveries. This review discusses critical cellular factors that facilitate the successive steps in HIV-1 replication.

HIV treatment adherence, drug resistance, virologic failure: evolving concepts

Poor adherence to combined antiretroviral therapy (cART) has been shown to be a major determinant of virologic failure, emergence of drug resistant virus, disease progression, hospitalizations, mortality, and health care costs. While high adherence levels can be achieved in both resource-rich and resource-limited settings following initiation of cART, long-term adherence remains a challenge regardless of available resources. Barriers to optimal adherence may originate from individual (biological, socio-cultural, behavioral), pharmacological, and societal factors. Although patients and providers should continuously strive for maximum adherence to cART, there is accumulating evidence that each class of antiretroviral therapy has specific adherence-drug resistance relationship characteristics allowing certain regimens more flexibility than others. There is not a universally accepted measure for cART adherence, since each method has distinct advantages and disadvantages including cost, complexity, accuracy, precision, intrusiveness and bias. Development of a real-time cART adherence monitoring tool will enable the development of novel, pre-emptive adherence-improving strategies. The application of these strategies may ultimately prove to be the most cost-effective method to reduce morbidity and mortality for the individual and decrease the likelihood of HIV transmission and emergence of resistance in the community.

Characteristics of HIV epidemics driven by men who have sex with men and people who inject drugs

PURPOSE OF REVIEW

To highlight the latest developments in mathematical transmission modelling of HIV epidemics among men who have sex with men (MSM) and people who inject drugs (PWID).

RECENT FINDINGS

Mathematical approaches have been applied to a wide range of topics in recent HIV research. Epidemiological models have evaluated past and forecasted future trends in prevalence and incidence, evaluated innovative behaviour modification strategies and public health programmes aimed at minimizing risk, and explored the potential impact of various biomedical interventions. MSM have developed new risk reduction strategies which models have deemed to be effective at a population level only in certain settings, such as when there are high rates of HIV testing. Modelling has also indicated that persistent circulation of drug-resistant HIV strains is likely to become an inevitable public health issue in the near future in resource-rich settings among MSM. Models have also recently been used to demonstrate that needle and syringe programmes for harm reduction among PWID are effective and cost-effective.

SUMMARY

Mathematical modelling is particularly amenable to single population groups of concentrated HIV epidemics, such as among MSM and PWID. Models have been utilized to evaluate innovative areas in clinical, biomedical and public health research that cannot be conducted in other population groups. Future directions are likely to include evaluation of specific public health programmes and providing understanding of the importance of specific treatment regimens and incidence and interaction of comorbid conditions associated with HIV.

Baseline clinical characteristics, antiretroviral therapy use, and viral load suppression among HIV-positive young men of color who have sex with men

Given the continued high incidence of HIV infection in the United States among racial/ethnic minority young men who have sex with men (YMSM), and an appreciation that antiretroviral therapy (ART) can provide personal and public health benefits, attention is needed to enhance the detection of HIV-infected youth and engage them in medical care and support services that encourage sustained HIV treatment and suppression of viremia. Poor retention in clinical care has been associated with higher mortality, an increase in HIV RNA, and decreased CD4 cell count. The goal of the current study was to evaluate the health care utilization and health outcomes of HIV-infected racial/ethnic minority YMSM enrolled in an outreach, linkage, and retention study funded by the Health Resources and Services Administration (HRSA) HIV/AIDS Bureau (HAB). We hypothesized that among racial/ethnic minority YMSM, baseline CD4 counts and usage of ART are influenced by age, race, drug and alcohol use, and mental health symptoms. Overall, 155 subjects had at least a baseline CD4 count recorded at study entry. There was a low rate of ART use in this population with only one-half of the cohort with CD4 counts ≤ 350 cells/mm(3) being prescribed ART to treat their infection. However, of those youth who were started on ART, the majority (74%) did achieve undetectable viral loads (< 400 copies). Given the continued increase in cases of HIV infection among racial/ethnic minority YMSM, efforts to increase both the provision of ART and support services that encourage adherence in this population are warranted.

HIV-1 drug resistance in antiretroviral-naive individuals in sub-Saharan Africa after rollout of antiretroviral therapy: a multicentre observational study

BACKGROUND

There are few data on the epidemiology of primary HIV-1 drug resistance after the roll-out of antiretroviral treatment (ART) in sub-Saharan Africa. We aimed to assess the prevalence of primary resistance in six African countries after ART roll-out and if wider use of ART in sub-Saharan Africa is associated with rising prevalence of drug resistance.

METHODS

We did a cross-sectional study in antiretroviral-naive adults infected with HIV-1 who had not started first-line ART, recruited between 2007 and 2009 from 11 regions in Kenya, Nigeria, South Africa, Uganda, Zambia, and Zimbabwe. We did population-based sequencing of the pol gene on plasma specimens with greater than 1000 copies per mL of HIV RNA. We identified drug-resistance mutations with the WHO list for transmitted resistance. The prevalence of sequences containing at least one drug-resistance mutation was calculated accounting for the sampling weights of the sites. We assessed the risk factors of resistance with multilevel logistic regression with random coefficients.

FINDINGS

2436 (94.1%) of 2590 participants had a pretreatment genotypic resistance result. 1486 participants (57.4%) were women, 1575 (60.8%) had WHO clinical stage 3 or 4 disease, and the median CD4 count was 133 cells per μL (IQR 62-204). Overall sample-weighted drug-resistance prevalence was 5.6% (139 of 2436; 95% CI 4.6-6.7), ranging from 1.1% (two of 176; 0.0-2.7) in Pretoria, South Africa, to 12.3% (22 of 179; 7.5-17.1) in Kampala, Uganda. The pooled prevalence for all three Ugandan sites was 11.6% (66 of 570; 8.9-14.2), compared with 3.5% (73 of 1866; 2.5-4.5) for all other sites. Drug class-specific resistance prevalence was 2.5% (54 of 2436; 1.8-3.2) for nucleoside reverse-transcriptase inhibitors (NRTIs), 3.3% (83 of 2436; 2.5-4.2) for non-NRTIs (NNRTIs), 1.3% (31 of 2436; 0.8-1.8) for protease inhibitors, and 1.2% (25 of 2436; 0.7-1.7) for dual-class resistance to NRTIs and NNRTIs. The most common drug-resistance mutations were K103N (43 [1.8%] of 2436), thymidine analogue mutations (33 [1.6%] of 2436), M184V (25 [1.2%] of 2436), and Y181C/I (19 [0.7%] of 2436). The odds ratio for drug resistance associated with each additional year since the start of the ART roll-out in a region was 1.38 (95% CI 1.13-1.68; p=0.001).

INTERPRETATION

The higher prevalence of primary drug resistance in Uganda than in other African countries is probably related to the earlier start of ART roll-out in Uganda. Resistance surveillance and prevention should be prioritised in settings where ART programmes are scaled up.

FUNDING

Ministry of Foreign Affairs of the Netherlands.

Transmitted resistance to HIV integrase strand-transfer inhibitors: right on schedule

Transmitted drug resistance (TDR), the primary acquisition of an HIV variant already resistant to antiretrovirals, affects approximately 15% of all new infections in the United States. Historically, from the time initial agents in the reverse transcriptase, protease and entry inhibitor classes were introduced, it took 3-5 years before the first case reports of TDR appeared. With the description of the first two cases of transmitted integrase stand-transfer inhibitor resistance, it is only a matter of time before the prevalence of TDR affecting this newest antiretroviral class reaches a level warranting baseline resistance testing for all patients entering care.

Transmission of integrase strand-transfer inhibitor multidrug-resistant HIV-1: case report and response to raltegravir-containing antiretroviral therapy

We report the case of an integrase strand-transfer inhibitor (INI)-resistant and four-drug-class-resistant HIV-1 variant infecting an antiretroviral therapy-naive man. The virus harboured INI drug resistance substitutions (Q148H and G140S) along with multiple reverse transcriptase and protease inhibitor resistance mutations. This case illustrates an emerging need to consider the possibility of acquired INI resistance among newly diagnosed treatment-naive individuals harbouring multidrug-resistant HIV-1.

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.